Building orientation is the practice of facing a building so as to maximize certain aspects of its surroundings, such as street appeal, to capture a scenic view, for drainage considerations, etc. With rising energy costs, it’s becoming increasingly important for builders to orient buildings to capitalize on the Sun’s free energy. For developers and builders, orienting a new home to take advantage of the warmth of the Sun will increase the home's appeal and marketability.  For homeowners, it will increase their indoor comfort and reduce their energy bills. 
 
Thus, building orientation, along with daylighting and thermal mass, are crucial considerations of passive solar construction that can be incorporated into virtually any new home design.  InterNACHI inspectors who consult with new homeowners can pass along this valuable information to help their clients reap long-term energy benefits and savings.
 Facts and Figures

• Many older homes’ designs were oriented through the use of a heliodon, which is a moveable light source used to mimic the Sun’s path that hovered over a small-scale model of a proposed building. Today, mathematical computer models calculate location-specific solar gain and seasonal thermal performance with precision, and have the added ability to rotate and animate a 3D color graphic model of a proposed building design in relation to the Sun’s path.
  
  
• Homeowners may now tap into a specialty market of homes designed to spin on their axis in order to follow the hourly and seasonal path of the Sun. These UFO-shaped homes can spin a full 360 degrees in minutes and are built with unusually tall ceilings and windows for maximum efficiency in powering their solar energy system.
  
  
• While some passive solar features are relatively recent innovations, the practice of orienting a home to the path of the Sun is as old as civilization itself. Examples are numerous, from south-facing doors on Neolithic and ancient Ming Dynasty houses, to the astonishing Pueblo ruins in southwestern Colorado. 

The Sun’s True Position
Schoolchildren (and most homeowners) will tell you that the Sun rises in the east and sets in the west, and, if this were true, building orientation would be a fairly simple matter. In reality, the sun rises and sets in the east and west only on the autumnal and vernal equinoxes, and something very different happens during the remaining 363 days of the year. The Earth’s tilt causes the Sun to rise and set slightly south of east and west in the winter, and slightly north of east and west in the summer.  This slight angle depends on the time of year and the observer’s distance from the equator. 
As a result, the winter sun spends all of its time in the southern sky, and the summer sun spends much of its time in the northern sky (the sun crosses over into the southern sky during part of the day, depending on latitude). In the Southern Hemisphere, all of these directions are reversed, so the winter sun rises and sets in the northeast and northwest, respectively, and the summer sun rises and sets in the southeast and southwest, respectively. 
How the Sun’s Variations in Position Can Affect Building Design
The relative position of the Sun is a major factor in heat gain in buildings, which makes accurate orientation of the building a fundamental consideration in passive solar construction. 
Most importantly, a rectangular house’s ridgeline should run east-west to maximize the length of the southern side, which should also incorporate several windows in its design. For this reason, fewer windows should be located on the northern side of the house, where the summer sun can be intense. A deep roof overhang can shade the few windows in this area, as can different types of shade trees and bushes. Research supports an east-west ridgeline.  Homes re-oriented toward the Sun without any additional solar features save between 10% and 20% and some can save up to 40% on home heating, according to the Bonneville Power Administration and the City of San Jose, California. 
Builders should note that these directions are given in reference to the Sun and not magnetic north, which can vary significantly from the Sun’s actual position. Magnetic north, as read from a compass, can still be used as a reference if the builder adjusts the figure based on the location-specific magnetic variation, which can be found in publicly available maps. 
Building Tips for New Construction
The following tips will also assist homeowners and builders in maximizing heat gain through building orientation:

• Orient the floor plan – not merely the building’s profile – toward the Sun. Design the home so that frequently used rooms, such as the kitchen and living room, are on the southern side. Occupants will appreciate the sunrays in the winter and relief from the sun in the summer. Patios and decks should be built on the south side of the house, where direct sunlight will permit their use for more hours during the day and more days during the year. Likewise, the garage, laundry room and other areas that are less frequently used should be situated at the northern part of the house, where they will act as buffers against cold winter winds.

• Beware of mountains. The north/south sun differential is exaggerated in hilly and mountainous regions, where significant climatic differences can be seen over comparatively small areas. A passive solar house should be constructed on the south-facing slope of a mountain to avoid the extreme shading created where the low-angled sun is blocked by the mountain on the north side. Halfway up the slope is ideal, as the mountain’s peak is exposed to strong winds, while cold night-time air flows into the underlying valley, which is also a natural drainage point.
  
  
• Plan for tree shade. Trees are an important factor in passive solar design because they can both provide needed shade on a balmy summer day and starve the house of natural light when it is needed most. Deciduous trees planted on the south side will lose their leaves in the winter and allow natural light to enter the house, while evergreen trees planted on the north side will provide shade from the summer sun. Builders should carefully consider the age, species, growth rate and mature canopy cover of existing trees before deciding where to orient a structure on a building lot. Trees also pose unique dangers, which are covered in InterNACHI’s article on Tree Dangers.
  
  
• Install as many windows as possible, but not too many! The exact number of windows required is different for each house because it’s based on – among other considerations – the local climate.  A “sun-tempered” house should include enough glazing to equal 5% of the conditioned square footage of the house. Remember, though, that windows allow heat transfer more easily than walls, so too many windows can actually drain heat from the house during the cold winter months. Read InterNACHI’s article on Window Gas Fills and Window Films to learn how to insulate a house’s glazing.
  
  
• Stray from the rule on east-west orientation, if needed. The east-west orientation of the ridgeline may be adjusted to accommodate other factors by up to 20 degrees with only a minimal impact on heat gain.
  
  
• Driveways can get hot! Driveways and parking lots are made using gravel and asphalt – materials that heat up faster and reach higher temperatures than the rest of the yard. Excessive heat there can spill over to the adjacent house, which is why placement of the driveway or parking lot to the south or east of the building can reduce summer heat buildup in southern climates. During the cold winter months in northern climates, a south- or west-oriented driveway will melt snow faster and provide the home with greater warmth.
  
  
• Glass need not be vertical. Custom glass is available that may be tilted to match the angle of the sun and minimize reflection. Angling glass away from the vertical makes it less insulative, however, so builders should balance potential gains in sun exposure with loss of heat to the outdoors. 

• Another environmental factor that should be considered in the equation of building orientation and positioning is prevailing winds, which are the winds that blow predominantly from a single, general direction over a particular point. Data for these winds can be used to design a building that can take advantage of summer breezes for passive cooling, as well as shield against adverse winds that can further chill the interior on an already cold winter day, or even prevent snow from piling up against windows and doors. Detailed information about prevailing winds for specific locations are plotted in a graphic tool called a wind rose, which is usually available from airports, larger libraries, Internet sources, and county agricultural extension offices. As a general rule of thumb, cold winter winds generally come from the north and west, which can be limited by using insulating glazing on these sides of the house. Also, remember that coastal areas typically experience breezes from an onshore direction, while cool breezes flow down valleys from mountain slopes. 

Ultimately, factors such as street appeal and the property’s lot dimensions may restrict a builder’s ability to orient a building in strict accordance with passive solar techniques. Even while working under these constraints, however, a builder can still create an energy-efficient home through the implementation of energy-saving features, such as low-E windows, adequate insulation, air sealing, and cool roofs.  Read more about these energy investment features in InterNACHI’s Green Resources for Inspectors and Consumers.
In summary, homes oriented to the path of the Sun with require less energy for heating and cooling, resulting in lower energy bills and increased indoor comfort.  Homeowners who are considering new builds should consult an InterNACHI inspector who can meet with them and their builder to discuss ways to maximize low-cost and no-cost energy strategies.

Nearly all building codes restrict the use of cavity spaces as supply ducts. However, it has been common practice to use cavity spaces as return-air pathways. Building cavities used as return-air plenums is one of the leading causes of duct leakage in homes today. Inspectors can learn how air leakage from ductwork may cause home energy loss, increase utility bills, lower comfort levels, and make the HVAC system less efficient.  
 
 
Still commonly used is the panned floor joist. Using floor joists as return ducts by panning can cause leakage because negative pressure in the cavity will draw air from the outside into the cavity through the construction joints of the rim area at the end of the joist cavity.
 
The illustration above shows a floor joist cavity used as a return-air duct by nailing material, such as gypsum board, sheet metal, foil insulation or OSB, to the bottom of the floor joists. There are manufacturers that advertise “insulating” panning sheet products that aid in this practice; however, using panned floor joists as an HVAC air pathway is highly discouraged because air leakage will be very difficult, if not impossible, to prevent.
 
Some builders create pan joists by attaching a solid panning sheet material to the bottom of a floor joist to create a return-air pathway. Using panned joists is not the best practice because the return-air pathways cannot be air-sealed properly.  
 
Wall Cavities
 
Cavities (or interstitial spaces) within walls are also sometimes used as supply- or return-air pathways. These cavities often create a connection of inside air with outside air from an attic or crawlspace. It is very difficult to make such cavity spaces airtight. When cavity spaces are used as return-air pathways or supply-air ducts, a few issues will arise. 
 
Because cavity spaces are leaky, building pressure imbalances across the building envelope will occur, driving air infiltration into the building. A cavity space used as a return-air pathway will pull pollutants into the building from unknown sources. Another issue with using cavity spaces as return-air pathways is fire safety. Building materials, such as wood products, do not meet the flame- and smoke-spread criteria as do approved duct materials. Using cavities as return or supply ducts is not a fire hazard in itself, but it will encourage a fire to spread throughout the building. In humid climates, a cavity space used as a return-air pathway will pull humid air into the cavity space, possibly encouraging mold growth or the deterioration of building materials.
 
Other common framing cavities used as return-air pathways or plenums are air-handler platforms, open-floor truss cavities, and dropped ceilings. Open-floor trusses used as return-air plenums can draw air from any place connected to that floor. Air-handler platforms used as return-air plenums can draw air from vented attics and crawlspaces through other connected framing cavities. While none of these spaces makes an acceptable air pathway on its own, some building cavities, such as floor joists, can make acceptable duct chases to contain an insulated, air-sealed, metal, or flex supply or return duct.
 
How to Use Building Cavities as Duct Chases for Supply and Return Pathways

1. The builder must plan the duct layout at the design stage. Floor joist cavities, dropped-ceiling soffits, or other building cavities that will be used as duct chases should be indicated. Required duct sizes using ACCA Manual D (ACCA 2009) must be calculated. The cavity spaces must be free of obstructions and large enough to hold the duct plus insulation.

 Floor joist cavities can make acceptable duct chases for insulated, air-sealed metal, flex, or fiberboard ducts. See the illustration by the U.S. Department of Energy below.
2. Only approved duct materials, such as galvanized steel, aluminum, fiberglass duct board, and flexible duct, that meet local code smoke- and flame-spread criteria must be used. 
3. All supply- and return-duct connections should be sealed with mastic or approved tape.
4. Because ductwork in cavity spaces is likely to be inaccessible, the duct system for airtightness should be tested with a duct-blaster test before installing the drywall.

 
Duct Distribution Quality Installation

Building cavities used as supply or return ducts should be avoided because of the difficulty of properly air sealing and insulating them. 

If building cavities are used, insulation should be installed without misalignments, compressions, gaps, or voids in all cavities used for ducts. If non-rigid insulation is used, a rigid air barrier or other supporting material should be installed to hold insulation in place. All seams, gaps and holes of the air barrier should be sealed with caulk or foam.
 
According to the U.S. Department of Energy's ENERGY STAR program, if building cavities are used as supply and return ducts, then:

• Supply ducts in an unconditioned attic must have insulation equal to or greater than R-8.
• Supply ducts in an unconditioned attic must have insulation equal to or greater than R-6.
• All other supply ducts and all return ducts in unconditioned spaces must have insulation equal to or greater than R-6.
• Total rater-measured duct leakage must be equal to or less than 8 CFM25 per 100 square feet of conditioned area.
• Rater-measured duct leakage to the exterior must be equal to or less than 4 CFM25 per 100 square feet of conditioned floor area. 
• Duct leakage shall be determined and documented by a rater using RESNET-approved testing protocol only after all components of the system have been installed (e.g., air handler and register grilles). Leakage limits shall be assessed on a per-system (rather than per-home) basis.
• For homes that have 1,200 square feet or less of conditioned floor area, measured duct leakage to the outdoors shall be equal to or less than 5 CFM25 per 100 square feet of conditioned floor area. Testing of duct leakage to the outside can be waived if all ducts and air-handler equipment are located within the home’s air and thermal barriers, and envelope leakage has been tested to be less than or equal to half of the Prescriptive Path infiltration limit for the Climate Zone where the home is to be built. Alternatively, testing of duct leakage to the outside can be waived if total duct leakage is equal to or less than 4 CFM25 per 100 square feet of conditioned floor area, or equal to or less than 5 CFM25 per 100 square feet of conditioned floor area for homes that have less than 1,200 square feet of conditioned floor area.

Duct Installation Tips

 
ENERGY STAR requires that all ducts in exterior walls must be within the air barrier as well as the thermal boundary. It is important for the framer and HVAC contractor to coordinate on the location of a return duct. This allows for proper spacing of the floor or roof structure for installation of the return. If installing supply ducts within the walls, verify that the duct is capable of outputting the necessary air flow. Typically, only double-wall assemblies will have enough depth to allow for proper insulation and duct size. If installing return ducts using the floor or ceiling structure, ENERGY STAR recommends sealing both the exterior and the interior of all return boxes to prevent air leakage.

2009 IECC
Section 403.2.3 Building cavities (Mandatory). Building framing cavities cannot be used as supply ducts. Section 403.2.1 Insulation (Prescriptive). Supply ducts in attics are insulated to a minimum of R-8. All other ducts in unconditioned spaces or outside the building envelope are insulated to at least R-6.
2009 IRC
Section M1601.1.1 Above-ground duct systems. Stud wall cavities and spaces between solid floor joists cannot be used as supply-air plenums.
2012 IECC
Section R403.2.3 Building cavities (Mandatory). Building framing cavities cannot be used as supply ducts or plenums. Section R403.2.1 Insulation (Prescriptive). Supply ducts in attics are insulated to a minimum of R-8. All other ducts in unconditioned spaces or outside the building envelope are insulated to at least R-6.
2012 IRC
Section M1601.1.1 Above-ground duct systems. Stud-wall cavities and spaces between solid floor joists cannot be used as supply-air plenums. Stud-wall cavities in building envelope exterior walls cannot be used as air plenums.

If you want to build a new home, there are things you need to know before you begin. Learn about construction standards and about buying land, so you know your rights. 
 
MPS Supplementing Model Building Codes
  
The Minimum Property Standards (MPS) establish certain minimum standards for buildings constructed under HUD housing programs. This includes new single-family homes, multi-family housing and healthcare-type facilities. 
 
HUD Minimum Property Standards and How They Supplement the Model Building Codes
Until the mid-1980s, HUD maintained separate Minimum Property Standards for different types of structures. Since that time, HUD has accepted the model building codes, including over 250 referenced standards and local building codes, in lieu of separate and prescriptive HUD standards. However, there is one major area of difference between the MPS and other model building codes -- durability requirements. Homes and projects financed by FHA-insured mortgages are the collateral for these loans, and their lack of durability can increase the FHA's financial risk in the event of default. More specifically, the model codes do not contain any minimum requirements for the durability of items such as doors, windows, gutters and downspouts, painting and wall coverings, kitchen cabinets and carpeting. The MPS includes minimum standards for these, and other items, to ensure that the value of an FHA-insured home is not reduced by the deterioration of these components. 
 
HUD Field Office Acceptance for Areas Without Building Codes
  
HUD requires that each property insured with an FHA mortgage meet one of the nationally recognized building codes or a state or local building code based on a nationally recognized building code. In areas where such state or local codes are used, HUD determines if the state or local code is comparable to the model building code. There are also areas of the United States that do not have building codes. If no state or local building code has been adopted, the appropriate HUD Field Office will specify a building code that is comparable to one of the nationally recognized model building codes. 

Interstate Land Sales
  
The Interstate Land Sales program protects consumers from fraud and abuse in the sale or lease of land. In 1968, Congress enacted the Interstate Land Sales Full Disclosure Act, which is patterned after the Securities Law of 1933, and requires land developers to register subdivisions of 100 or more non-exempt lots with HUD, and to provide each purchaser with a disclosure document called a property report. The property report contains relevant information about the subdivision and must be delivered to each purchaser before the signing of the contract or agreement. 
 
Buying Lots from Developers 

Be well informed when shopping for land. Lots may be marketed as sites for future retirement homes, for second home locations, or for recreational or campsite use. However, be wary of any investment aspect that may be stressed by sales personnel. If you plan to purchase a lot which is offered by promotional land sales, take plenty of time before coming to a decision. Before signing a purchase agreement, a contract, or a check: 

• know your rights as a buyer; 
• know something about the developer; 
• know the facts about the development and the lot you plan to buy; and 
• know what you are doing when you encounter high-pressure sales campaigns. 

Generally, if the company from which you plan to buy is offering 100 or more unimproved lots for sale or lease through the mail or by means of interstate commerce, it may be required to register with the U.S. Department of Housing and Urban Development (HUD). This means that the company must file with HUD and provide prospective buyers with a property report containing detailed information about the property. Failure to do this may be a violation of federal law, punishable by up to five years in prison, a $10,000 fine, or both. The information filed by the developer and retained by HUD must contain such items as these:

• a copy of the corporate charter and financial statement; 
• information about the land, including title policy or attorney's title opinion, and copies of the deed and mortgages;  
• information on local ordinances, health regulations, etc.;  
• information about facilities available in the area, such as schools, hospitals and transportation systems;  
• information about availability of utilities and water, and plans for sewage disposal;  
• development plans for the property, including information on roads, streets and recreational facilities; and 
• supporting documents, such as maps, plans and letters from suppliers of water and sewer facilities. 

The company filing this information must swear and affirm that it is correct and complete, and an appropriate fee must accompany submission. The information is retained by HUD and is available for public inspection. The property report, which is also prepared by the developer, goes to the buyer. The law requires the seller to give the report to a prospective lot purchaser prior to the time a purchase agreement is signed. Ask for it. The seller is also required to have the buyer sign a receipt acknowledging receipt of the property report. Do not sign the receipt unless you have actually received the property report. Check the developer’s property report before buying. This is the kind of information you will find in a property report: 

• distances to nearby communities over paved and unpaved roads; 
• existence of mortgages or liens on the property; 
• whether contract payments are placed in escrow;  
• availability and location of recreational facilities;  
• availability of sewer and water service or septic tanks and wells;  
• present and proposed utility services and charges;  
• the number of homes currently occupied;  
• soil and foundation conditions which could cause problems in construction or in using septic tanks; and 
• the type of title the buyer may receive and when it should be received. 

Read the Property Report Before Signing Anything
  
This report is prepared and issued by the developer of this subdivision. It is not prepared or issued by the federal government. Federal law requires that you receive this report prior to signing a contract or agreement to buy or lease a lot in this subdivision. However, no federal agency has judged the merits or value of the property. If you received the report prior to signing a contract or agreement, you may cancel your contract or agreement by giving notice to the seller any time before midnight of the seventh day following the signing of the contract or agreement. If you did not receive this report before you signed a contract or agreement, you may cancel the contract or agreement any time within two years from the date of signing. 

Your Contract Rights
  
If the lot you are buying is subject to the jurisdiction of the Interstate Land Sales Full Disclosure Act, the contract or purchase agreement must inform you of certain rights given to buyers by that Act. The contract should state that the buyer has a "cooling-off" period of seven days (or longer, if provided by state law) following the day that the contract is signed to cancel the contract, for any reason, by notice to the seller, and get his or her money back. Furthermore, unless the contract states that the seller will give the buyer a warranty deed, within 180 days after the contract is signed, the buyer has a right to cancel the contract for up to two years from the day that the contract is signed, unless the contract contains the following provisions: 

• a clear description of the lot so that the buyer may record the contract with the proper county authority; 
• the right of the buyer to a notice of any default (by the buyer), and at least 20 days after receipt of that notice to cure or remedy the default;  
• a limitation on the amount of money the seller may keep as liquidated damages, of 15% of the principal paid by the buyer (exclusive of interest) or the seller's actual damages, whichever is greater. 

Contract Rights Concerning Property Reports 
It has always been the law that if the developer has an obligation to register with the Interstate Land Sales Division, the developer or sales agent must give the buyer a copy of the current property report before the buyer signs a contract. Otherwise, the buyer has up to two years to cancel the contract and get their money back. That fact must also be clearly set forth in all contracts. You may have the right to void the contract if the subdivision has not been registered with HUD, or you were not given a property report. Furthermore, if the developer has represented that it will provide or complete roads, water, sewer, gas, electricity or recreational facilities in its property report, in its advertising, or in its sales promotions, the developer must obligate itself to do so in the contract, clearly and conditionally (except for acts of nature or impossibility of performance). In addition to the right to a full disclosure of information about the lot, the prospective buyer may have the right to void the contract and receive a refund of their money if the developer has failed to register the subdivision with HUD or has failed to supply the purchaser with a property report. While a purchaser may have the right to void the contract with the developer under these conditions, the purchaser may still be liable for contract payments to a third party if that contract has been assigned to a financing institution or some similar entity. The registration is retained by HUD and is available for public inspection. If the property report contains misstatements of fact, if there are omissions, if fraudulent sales practices are used, or if other provisions of the law have been violated, the purchaser may also sue to recover damages and actual costs and expenses in court against the developer. However, depending on when your sale occurred, you may be barred from taking further action due to the Act's statute of limitations. Your attorney can advise you further on this matter. 
 
"Cooling-Off" Period
  
Even if you received the property report prior to the time of your signing of the contract or agreement, you have the right to revoke the contract or agreement by notice to the seller until midnight of the seventh day following the signing of the contract. You should contact the developer, preferably in writing, if you wish to revoke your contract and receive a refund of any money paid to date. Even if the property report is delivered to you before you sign a sales agreement, the law gives you a "cooling-off " period. This right cannot be waived. 
 
A Word About the Interstate Land Sales Division
The HUD unit which administers the law, examines the developer's registration statement, and registers the land sales operator is the Interstate Land Sales Division. Except for disclosure purposes, this office is not concerned with zoning or land-use planning, and has no control over the quality of the subdivision. It does not dictate what land can be sold, to whom, or at what price. It cannot act as a purchaser's attorney. But it will help purchasers secure the rights given to them by the Interstate Land Sales Full Disclosure Act. HUD is authorized by law to conduct investigations and public hearings, to subpoena witnesses and secure evidence, and to seek court injunctions to prevent violations of the law. If necessary, HUD may seek criminal indictments. HUD is authorized by law to conduct investigations and, if necessary, seek criminal indictments. 
 
Exemptions from the Law 
The prospective buyer should be aware that not all promotional land sales operations are covered by the law. If the land sales program is exempt, no registration is required by HUD, and there will be no property report. Here are some of the specific situations for which the statute allows exemptions without review by HUD, including the sale of: 

• tracts of fewer than 100 lots which are not otherwise exempt; 
• lots in a subdivision where every lot is 20 acres or more in size; 
• lots upon which a residential, commercial or industrial building has been erected, or where a sales contract obligates the seller to build one within two years;  
• certain lots which are sold only to residents of the state or metropolitan area in which the subdivision is located;  
• certain low-volume sales operations (no more than 12 lots a year);  
• certain lots that meet certain local codes and standards and are zoned for single-family residences or are limited to single-family residences by enforceable codes and restrictions; and 
• certain lots, contained in multiple sites of fewer than 100 lots each, offered pursuant to a common promotional plan. 

Other exemptions are available which are not listed above. If you have reason to believe that your sale is not exempt and may still be covered by the law, contact the Interstate Land Sales Division. 
 
Know the Developer
  
Knowing your rights under the law is the first step in making a sensible land purchase. To exercise those rights, you also must know something about the honesty and reliability of the developer who offers the subdivision that interests you. Don’t fail to ask questions. Whether you are contacted by a sales agent on the phone or by mail, at a promotional luncheon or dinner, in a sales booth at a shopping center, or in the course of your own inspection of the subdivision, make it your business to find out all you can about the company and the property. In addition, get any verbal promises or representations in writing. Don’t fail to ask questions. If you are seriously interested in buying a lot, ask if the company is registered with HUD or is entitled to an exemption. Request a copy of the property report and take the time to study it carefully and thoroughly. If you still have unanswered questions, delay any commitment until you have investigated. Discuss current prices in the area with local independent brokers. Talk to other people who have purchased lots. A local Chamber of Commerce, Better Business Bureau, or consumer protection group may have information about the seller's reputation. Inquire through county or municipal authorities about local ordinances or regulations affecting properties similar to that which you plan to buy. Don't be high-pressured by sales agents. 
 
Know the Facts About the Lot
  
Once you have decided on an appealing subdivision, inspect the property. Don't buy "sight unseen." Better yet, hire an InterNACHI inspector to perform a thorough property inspection. Also, check the developer's plans for the project and know what you are getting with your lot purchase. It's a good idea to make a list of the facts you will need to know. Some of the questions you should be asking, and answering, are these:  

• How large will the development become? 
• What zoning controls are specified? 
• What amenities are promised? 
• What provision has the developer made to assure construction and maintenance?  
• What are the provisions for sewer and water service? 
• Are all of the promised facilities and utilities in the contract?  
• Will there be access roads or streets to your property, and how will they be surfaced? Who maintains them? How much will they cost?  
• Will you have clear title to the property? What liens, reservations or encumbrances exist?  
• Will you receive a deed upon purchase or a recordable sales contract?  
• What happens to your payments? Are they placed in a special escrow account to pay for the property, or are they spent at once by the developer?  
• If the developer defaults on the mortgage or goes bankrupt, could you lose your lot and investment to date to satisfy a claim against the development?  
• What happens when the developer moves out? Is there a homeowners' association to take over community management?  
• Are there restrictions against using the lot for a campsite until you are ready to build?  
• Are there any annual maintenance fees or special assessments required of property owners? 

This is a partial list of points to consider before you commit your money or your signature. 
 
Know What You are Doing
Interstate land sales promotions often are conducted in a high-pressure atmosphere that sweeps unsophisticated buyers along. Before they are aware that they have made a commitment, these buyers may have signed a sales contract and started to make payments on a lot. They may be delighted with the selection made, but, if not, it may be too late for a change of mind. 
 
Nine Dishonest Sales Practices
  
Here are some of the practices avoided by reliable sales operations. Watch out for them and exercise sales resistance if you suspect they are occurring:
 
1. concealing or misrepresenting facts about current and resale value. Sales agents may present general facts about the area’s population growth, industrial or residential development, and real estate price levels as if they apply to your specific lot. You may be encouraged to believe that your piece of land represents an investment which will increase in value as regional development occurs. A sales agent may tell you that the developer will re-sell the lot, if you request. This promise may not be kept. Future resale is difficult or impossible in many promotional developments because much of your purchase price -- sometimes as much as 40% -- has gone for an intensive advertising campaign and commissions for sales agents. You are already paying a top price and it is unlikely that anyone else would pay you more than you are paying the developer. You may even have to sell for less than the price you originally paid for the lot. Sales promotions often are conducted in a high-pressure atmosphere. Furthermore, when you attempt to sell your lot, you are in competition with the developer, who probably holds extensive, unsold acreage in the same subdivision. In most areas, real estate brokers find it impractical to undertake the sale of lots in subdivisions and will not accept such listings. It is unlikely that the lot you purchase through interstate land sales represents an investment, in the view of professional land investors. Remember, the elements of value of a piece of land are its usefulness, the supply, the demand, and the buyer's ability to re-sell it. The Urban Land Institute estimates that land must double in value every five years to justify holding it as an investment. In some areas, the cost of holding the land, such as taxes and other assessments, can run as high as 11% a year. 
 
2. failure to honor refund promises or agreements. Some sales promotions conducted by mail, email or long-distance telephone include the offer of a refund if the property has been misrepresented, or if the customer inspects the land within a certain period of time and decides not to buy. When the customers request the refund, s/he may encounter arguments about the terms of the agreement. The company may even accuse its own agent of having made a money-back guarantee without the consent or knowledge of the developer. Sometimes, the promised refund is made, but only after a long delay. 
 
3. misrepresentation of facts about the subdivision. This is where the property report offers an added measure of protection. A sales agent may offer false or incomplete information relating to either a distant subdivision or one which you visit. Misrepresentations often relate to matters such as the legal title, claims against it, latent dangers (such as swamps or cliffs), unusual physical features (such as poor drainage), restrictions on use, or lack of necessary facilities and utilities. Read the property report carefully with an eye to omissions, generalizations, or unproved statements that may tend to mislead you. If you are concerned about overlooking something important, discuss the report and the contract with a lawyer who understands real estate matters. The developer also may use advertisements that imply that certain facilities and amenities are currently available when they are not. Read the property report to determine whether these facilities and amenities are actually completed, or proposed to be completed in the future. If the company advertises sales on credit terms, the Truth in Lending Act requires the sales contract to fully set forth all terms of financing. This information must include total cost, simple annual interest, and total finance charges. 
 
4. failure to develop the subdivision as planned. Many buyers rely upon the developer's contractual agreement or a verbal promise to develop the subdivision in a certain way. The promised attractions that influenced your purchase (golf course, marina, swimming pool, etc.) may never materialize after you become an owner. If they are provided, it may be only after a long delay. If you are planning on immediate vacation use of the property, or are working toward a specific retirement date, you may find that the special features promised of the development are not available when you need them. 
 
5. failure to deliver deeds and/or title insurance policies. Documents relating to the sales transaction may not be delivered as promised. Some sales in the promotional land development industry are made by contract for a deed to be delivered when the purchaser makes the last payment under the terms of the contract. A dishonest developer may fail to deliver the deed, or deliver it only after a long delay. A sales agent may offer false or incomplete information. 
 
6. abusive treatment and high-pressure sales tactics. Some sales agents drive prospective customers around a subdivision in automobiles equipped with citizen band radios which provide a running commentary on lot sales in progress. The customer may be misled by this and other sales techniques to believe that desirable lots are selling rapidly and that a hurried choice must be made. Hurrying the buyers into a purchase they may later regret is only one ploy of high-pressure sales agents. More offensive is abusive language used to embarrass customers who delay an immediate decision to buy. In some instances, hesitant buyers have been isolated in remote or unfamiliar places where transportation is controlled by the sales agent or the agent's organization. 
 
7. failure to make good on sales inducements. Free vacations, gifts, savings bonds, trading stamps, and other promised inducements are used to lure people to sales presentations or to development sites. These promised treats may never materialize. Sometimes, special conditions are attached to the lure, or a customer is advised that gifts go only to lot purchasers. A "free vacation" may be the means of delivering the prospective buyer to a battery of high-pressure sales agents in a distant place. The promised attractions may never materialize. 
 
8. "bait and switch" tactics. Lots are frequently advertised at extremely low prices. When prospective buyers appear, they are told that the low-priced lots are all sold and then are pressured to buy one that is much more expensive. If the cheaper lot is available, it may be located on the side of a cliff or in another inaccessible location. If accessible, it may be much too small for a building or have other undesirable features. The buyers may be lured to the property with a certificate entitling them to a "free" lot. Often, the certificate bears a face value of $500 to $1,000. If the buyers attempt to cash it in, the amount is simply included in the regular price (often inflated) of the lot they choose. Often, this so-called "bait and switch" technique has a delayed fuse. Buyers who purchase an unseen lot for later retirement may be unpleasantly surprised when they visit the development. The lot they have paid for may be remote from other homes, shopping and medical facilities. It may be insufficiently developed for use. When the buyers complain, sales personnel attempt to switch them to a more expensive lot, applying the money paid for the original lot to an inflated price for the new one, and tacking on additional financing charges. If the unhappy purchasers lack sufficient funds to accept this alternative, they are left with an unusable, unmarketable first choice.  
 
9. failure to grant rights under the Interstate Land Sales Full Disclosure Act. Purchasers may not be given copies of the property report before they sign a sales contract. Some sales agents withhold this detailed statement until customers choose a specific lot. Sometimes, the buyers receive the report in a mass of promotional materials and legal documents. Unaware that the report is in their possession, they fail to read and understand it before signing a sales contract.

A bug zapper is a popular exterior appliance installed by a homeowner or food handler to attempt localized control of flying insect populations. Its name comes from the characteristic "zap" sound produced when an insect is electrocuted. Around homes, they are primarily used to kill biting (female) mosquitoes, which create itchy bumps and can transmit the West Nile Virus or encephalitis, malaria and yellow fever. While Popular Mechanics produced a sketch of a bug zapper as early as 1911, it wasn't until 1934 that parasitology professor Dr. W.B. Herms introduced the electronic insect killer that became the model for all future bug zappers. 
 
How They Work 

 Bug zappers typically consist of the following components:

• the housing, which is a plastic or grounded metal exterior casing that contains the zapper’s parts. It may be shaped liked a lantern, a cylinder or a rectangular cube. A grid design may be incorporated to prevent children and animals from touching the electrified grids inside the device;
• a light source, which is usually fluorescent-type, such as mercury, neon or ultraviolet light;
• wire grids or screens, which are electrified layers of wire mesh that surround the light source. These grids are separated by a tiny gap roughly the size of a typical insect (several millimeters); and
• the transformer, which is the device that electrifies the wire mesh, changing the 120-volt, electrical-line voltage to 2,000 volts or more. 

Bug zappers work by luring flying insects with fluorescent (typically ultraviolet) light into a deadly electrical current. Because the flower patterns that attract insects are better revealed in ultraviolet light, many flying insects that feed on flowers will be drawn to the bug zapper. Before they reach the light, however, they will come into contact with the wire mesh, completing the electrical circuit and disintegrating. 
 
Bug zappers can kill many thousands of flying insects nightly. Some models incorporate a tray designed to collect scattered insect parts, although many models allow the debris to fall to the ground below. 
 
Effective or Not? 

 
Despite their widespread use, numerous studies have called into question the effectiveness and safety of bug zappers. Two of the more pressing issues are the following:

• Female (biting) mosquitoes and other biting insects are more attracted to the carbon dioxide (CO2) and water vapor in the breath of animals than to ultraviolet light. As a consequence, standard bug zappers typically kill large numbers of harmless and beneficial insects, such as beetles and fireflies, and ultimately fail to reduce the number of the types of insects that prompt the purchase of a bug zapper in the first place. In fact, one study found that just 0.22% of the insects killed by bug zappers were biting insects, while nearly half of those killed were harmless, non-biting aquatic insects from nearby rivers and streams. The study even found “the probability of being bitten by mosquitoes increases in the vicinity of these traps,” perhaps because the biting insects are actually lured by the ultraviolet light but become distracted by the far more attractive human prey nearby. Some newer bug zappers address this issue by incorporating a CO2 container at the bottom of the lamp. Other designs attract mosquitoes into a netting device on the outside of the bug zapper that traps the mosquito, and eventually the insect dies of dehydration.
  
  
• The electrocuted insects are blasted into a fine mist that contains insect parts as well as unkilled bacteria and viruses up to 7 feet (2.1 m) from the device. The air surrounding the zapper may become contaminated with campylobacter jejuni, staphylococci, serratia marcescens, enterococci, and other potentially dangerous organisms commonly carried by flies. For this reason, a bug zapper should never be placed over a food preparation area or in a hospital or any other sterile environment to prevent the potential spread of disease. Children should not be allowed to play beneath an operating bug zapper. Models that contain a tray to catch insect debris are less of a health risk.

Tips for Homeowners 

 
Bug zappers do not present more of a fire hazard than other electrical devices. Most units have been UL-tested, but, as with any outdoor electrical appliance, care must be taken to ensure that electrical cords do not become frayed or wet.  They should also be connected to GFCI-protected receptacles. 
 Inspectors may pass on the following mosquito-control techniques to concerned homeowners:

• Do not allow water to accumulate anywhere in your yard for more than a few days. Eliminate sources of standing water, especially old tires, flower pots, clogged gutters, tin cans or buckets. Fill in or drain ruts, puddles and other low places in the yard. Even holes in trees from rot and hollow stumps can collect water that can harbor mosquitoes. Cover trash containers to keep rainwater out, and drill holes in the bottom of trash containers to allow any water to drain. Repair leaky pipes and outdoor faucets. 
• Bug zappers should be cleaned out at least annually to prevent the accumulation of bug parts on the wire mesh, which will decrease the effectiveness of the unit, and may lead to illness if the bug parts contaminate foods, drink or items used by people or pets. 
• Keep grass cut short and any shrubbery well-trimmed, as adult mosquitoes use these places to rest and hide. 
• Encourage the presence of bats by installing a bat house. These winged mammals pose little danger to humans, and a single brown bat can consume up to 600 mosquitoes per hour.
• Install a fan. Mosquitoes and other flying insects will avoid moving air.
• Wear long-sleeve shirts and pants. The pesticide permethrin may be applied to clothing to protect against mosquitoes and ticks. Beware that while permethrin is relatively safe for people and dogs, it is toxic to cats.

In summary, bug zappers are a common yet controversial means of controlling biting insect populations around the home, and caution should be taken in their selection and use.

Brownfields, also known as brownfield lands and brownfield sites, are former industrial and commercial sites where redevelopment is complicated by chemical, physical and/or biological contamination, as well as potential suspicion as to whether such sites have been adequately remediated. The term "brownfield" first came into use in 1992 to describe these blighted areas that can be found in virtually every community across the United States. Brownfields are a significant concern because they affect property values, and endanger the safety of curious neighborhood children as well as future owners. Moreover, brownfields pose significant public health threats and incite heated debate within communities concerning the question of devoting public resources to their cleanup and reuse.  Commercial and residential property inspectors may be asked to inspect a property that is built on a brownfield.
 While the U.S. Department of Labor states that brownfield sites “are generally not highly contaminated,” unlike designated Superfund sites, the agency warns that “the types and levels of contaminants present can vary considerably,” and pollutants may contaminate underground aquifers, drums, tanks, and subsurface and surface soils. Common pollutants include petroleum hydrocarbons, lead, construction debris, asbestos, polychlorinated biphenyls, wood that's been treated with creosote, cadmium chromium and arsenic, and industrial chemicals and diesel fuel, according to the U.S. Environmental Protection Agency. Mechanical dangers, such as uncovered holes, sharp objects and unsafe structures, also plague many brownfield sites. 
Pressure exists in many communities, especially congested, inner-city areas where undeveloped land is sparse, to remediate brownfields into usable commercial and residential real estate. Brownfield restoration for such uses is no simple feat, however, as builders typically must remove and replace the upper layer of soil, and then separate the new soil from the underlying earth with an impervious concrete cap. Engineered systems may be required to pump contaminated materials from the soil. Still, redevelopment can be successful and lucrative, as exemplified by one such undertaking in Pittsburgh, Pennsylvania, where many former steel mill sites have been converted into high-end residences, shopping centers and offices. In one successful endeavor, a former Pittsburgh slag dump was turned into Summerset at Frick Park, a $243 million residential development.
Inspectors should be aware that even after a successful brownfield restoration, residential use of these properties is often restricted, and many otherwise harmless activities may represent grave public health threats. Owners may not be permitted, for instance, to grow outdoor gardens for food. They also may not be allowed to drive fence posts into the ground, as such activities can pierce the concrete cap and allow subsoil contaminants to flow to the surface. 
 
Inspectors may want to be on the lookout for chemical and mechanical hazards, such as previously unknown underground storage tanks, buried drums, and buried railroad tank cars that were not discovered or remedied during the initial restoration. Clients who want specific information about their property’s history may obtain the site characterization and hazard assessment documents from previous owners and county records.  Inspectors may also recommend soil testing by a qualified soil engineer.  While inspecting such potentially or formerly toxic properties, inspectors should be sure to wear personal protective equipment, such as coveralls, boots, a respirator, and thick gloves.
 
In summary, brownfields are former industrial and commercial sites that may be cleaned up and reclaimed for use as commercial properties and residences, under certain approved conditions.  Inspectors should be made aware of such a commercial or residential property's history to decide whether additional research and expert assistance are required in order to perform a competent and thorough inspection.

Brominated flame or fire retardants (BFRs) include a wide range of chemicals added to household furnishings and products to inhibit their ignition and reduce the chance of fire. In recent years, concern surrounding the toxicity of this class of chemicals has risen due to the widespread accumulation of several types of BFRs in humans and in the natural environment.
 There are more than 175 different types of flame retardants, which are generally divided into classes that include brominated, chlorinated, phosphorus-containing, nitrogen-containing, and inorganic flame retardants. Producing BFRs, at a rate of 5 million metric tons annually, is a $2 billion business, and this particular arm of consumer fire safety is currently the industry leader. For several decades, BFRs have been routinely added to consumer products, including computers, TVs, electrical cables, carpets, furniture and textiles, in a largely successful effort to reduce fire-related injuries and property damage. 
BFRs are found virtually everywhere in the environment, from house dust and indoor and outdoor air, to sediments in rivers, estuaries and oceans. BFR contamination has been discovered in polar bears, eagles, and even in the blubber of sperm whales in the deep, remote waters of the Atlantic Ocean. High levels of the chemicals have been found in the atmosphere and rivers near urban and industrialized areas. Perhaps the greatest concern, though, is the concentration of the chemicals found in the blood of office workers and in human breast milk, where it can be transferred from mother to child. 
One type of BFR is TBBP-A, which has been linked to breast cancer, and has been shown in mice and rats to disrupt the thyroid hormone system, which plays a crucial role in the development of the brain and body. Laboratory research has demonstrated that low-level exposure of young mice to PBDE – another BFR -- causes permanent disturbances in behavior, memory and learning. Linda Birnbaum, a toxicologist with the EPA, told CBS News that PBDEs "can affect the developing brain, and they can affect the developing reproductive system.”
The World Health Organization has called for disuse of PBDEs where adequate alternatives are available, and the Swedish Chemicals Inspectorate has called for the chemicals to be entirely phased out.  By contrast, the UK Department for Trade and Industry calls fears over PBDEs “chemical paranoia,” arguing that there is no conclusive proof that BFRs are harmful to humans. Still, the European Union has banned PBDEs in electronic devices, and in the United States, PBDEs are now heavily regulated, notably in Washington state, Maine and California. 
Alternatives to BFRs that provide comparable fire safety are available, and many products have been redesigned so that flame-retardant chemicals are unnecessary. Apple and Sony have changed the casing material for the MacBook Air and Vaio, respectively, in order to reduce the need for flame-retardant additives. However, BFRs are still used in a wide array of products, and testing for the presence of the chemicals is difficult for the layperson.
 
In summary, BFRs, although highly regulated, continue to pervade homes and the natural environment, exposing humans and animals to potential danger.

What is a Blower Door?
Inspectors should become familiar with blower doors, as they can be a valuable tool in energy audits.  A blower door is a powerful, variable-speed fan that can be temporarily mounted into an exterior door frame to provide controlled air flow for analysis.  The way that air flows through a building can have a serious impact on air quality, comfort and energy expenses.  The use of a blower door allows air flow through a structure, and the resulting loss of heat can be immediately quantified, providing a way to pinpoint the location of air leaks. 
Blower doors were originally developed in the 1970s for use as a research tool.  As technology has evolved, allowing for the development of more portable equipment, blower doors have transitioned into use as a valuable field tool, as well.  The first portable blower doors weighed as much as 200 pounds and took up quite a bit of space, and were also very expensive.  Today, they are much more affordable and are built lighter and smaller.  The reduced set-up time allowed by their more compact designs has led to the standard use of blower doors as part of energy audits for measuring air flow.
 
How It Works
 When air pressure and air flow are controlled and measured, they can provide data about how airtight a building is.  The three variables involved are pressure, flow and holes or leaks.  A change in one of these factors will produce a change in at least one other factor.  Since the goal of a blower door test is to locate air leaks in the building envelope, data regarding air pressure and flow can provide information about the holes, which may otherwise be tough to find. 
The blower door utilizes controlled differences in air pressure to collect data.  Once installed in an exterior door frame, the air pressure inside a building can be changed in relation to the outside pressure by forcing air into or out of the interior.  The difference in pressure forces air through holes or leaks in the building envelope.  The pressure and air flow are measured by gauges, which are part of the blower door equipment.  By measuring the pressure and air flow in relation to each other, the airtightness of the building envelope can be quantified.  The amount of air flow needed to create a change in pressure increases as the airtightness of the building envelope decreases.  A well-sealed building requires less air flow to generate a change in pressure.
 
Finding the Problems
 During a blower door test, the interior air pressure needed to be maintained in order to gather useful data is 50 pascals, which is roughly equal to the pressure created when a 20-mph wind hits the building.  The blower door equipment has a gauge to indicate when this pressure has been achieved, as well as a gauge to indicate the cubic feet per minute (CFM), which is the standard unit of measure for air flow.  Air flow in a well-sealed building will generally be less than 1,500 CFM at 50 pascals.  Air flow above 4,000 CFM would be considered leaky.  This is valuable data that can be acquired in about half an hour with the use of a blower door.
Since the blower door forces air through cracks and holes, the locations of the leaky spots can be identified.  The draft of air entering through the holes can often be felt with the hand.  Smoke and infrared imaging can also be employed to locate smaller, more subtle leaks.  It is often assumed, especially by homeowners, that poorly sealed windows and doors are the major culprits of air leaks.  In reality, leaks in other areas are usually much more significant.  The difference in air pressure between the interior and the exterior is greater both at ground level and up high, so leaks in basements and crawlspaces, as well as in attics, are the most important to locate.  
When looking for air leaks, check through basement rim joists, holes for plumbing traps under tubs and showers, cracks between finish flooring and baseboards, utility chases, plumbing vent-pipe penetrations, kitchen soffits, fireplace surrounds, recessed can lights, and cracks between partition top plates and drywall.  These are all common places where significant leaks can develop.
Accounting for Outside Factors 
Wind and temperature can have an effect on the test data.  Wind blowing on the outside of the building can add to pressure differences between the interior and exterior.  It can also affect the flow rate of the blower fan.  It is best not to conduct blower door tests in windy conditions.  But if wind is not severe, tests can be conducted at multiple points in the building and then averaged together. 
Differences in temperature can create differences in pressure.  Accounting for a baseline stack-effect pressure will ensure that the test results are not skewed.  The stack-effect pressure is a function of the height of the building and the difference in temperature from the interior to the exterior.  A 15-foot tall building with a 50º-temperature difference between the inside and outside will have a 5-pascal pressure difference from the top of the building to the bottom.  Some blower door equipment has a gauge with a built-in baseline feature, so this difference can be easily determined at the outset of the test.
Temperature and barometric pressure affect both air density and viscosity, which is its resistance to flow.  Because of this, an adjustment for density is required.  Some software packaged with blower door equipment is designed to make these calculations, and if it is not available during the test, the manual supplied with the equipment should have information about making the necessary adjustments and applying it to the results.
Preparation and Safety
In order to ensure accurate results, as well as safe conditions for performing the test, some preparation is necessary before beginning.  Any fireplaces or stoves used for heating should not be operating, and all furnaces and pilot lights should be turned off.  There should be no open flames anywhere indoors.  Ashes in fireplaces or stoves should be removed so they do not get sucked into the building.  Dampers should be closed.  Every door and window must be closed tightly so that air flowing through them does not affect the test, while all interior doors should be left open.
If there is a basement, it must be determined whether this area is to be considered part of the building envelope for testing purposes.  Generally, if there is heat in the basement, even if only because the furnace is located there, it will be considered part of the envelope, and access to it should be left open during the test.  Sometimes, the test may be done both ways -- with the basement access open and with it closed, and this is quick and simple to accomplish.
Since blower door testing is a standard tool used during an energy audit, it is helpful for inspectors to understand how the test works.  Knowing a bit about the outside factors that can influence the results will ensure that the test is performed correctly.  Setting up the equipment properly will ensure that testers and occupants are safe, and that the testing and results are accurate. 

A Bloom Box® is a refrigerator-sized domestic power plant that produces electricity cleanly and cheaply, and may one day replace the traditional power grid. Its inventor wants to put one in every home by the year 2020.
 The Bloom Box® is the creation of Bloom Energy, a Sunnyvale, California-based company that promises to revolutionize energy with its “power plant in a box.” While essentially a fuel cell – green energy devices that have been around for decades and have yet to compete with even marginal renewable energy sources – Bloom Energy claims to have designed a product that could transform how buildings are powered. A recent 60 Minutes interview with Bloom Energy’s CEO, combined with a handful of high-profile customers, have generated buzz among environmentalists, engineers and builders.
How Do They Work?
The technology for the Bloom Box® comes from an oxygen generator originally designed for NASA's Mars program. When that program was scrapped, the design was converted, with the help of $400 million in funding, into a new type of fuel cell. In Bloom's design, fuel and oxygen are fed to cells (relatively inexpensive, painted ceramic disks) where they combine chemically to create electricity. The cells are separated by a cheap metal alloy, deviating from earlier designs that required precious metals, such as platinum. The cells are stacked into a cube of flexible capabilities; a stack of 64 can power a small business, but an assortment of sizes is fully customizable.
Bloom Boxes® in Service
Bloom Boxes® are still experimental, but 20 Fortune 100 companies in California have purchased the devices at $700,000 to $800,000 each. FedEx, Wal-Mart, eBay and Google have all taken advantage of state and federal subsides by purchasing Bloom Boxes® for use at their headquarters. The primary motive for these companies to embrace green power may be based in public relations, but eBay has boasted that its five boxes have saved the company $100,000 in energy costs. 
Benefits of Bloom Boxes®

• flexible fuel sources. While Bloom Boxes® can use traditional fuels such as natural gas, green sources such as bio-gas made from landfill waste, and even solar energy, can also be exploited. 
• powerful. Even in its early stages, one Bloom Box® can power one European home, or two to four homes in India. It would take two standard Bloom Boxes® to power the average American home, however. eBay’s Bloom Boxes® (which are powered by bio-gas from landfill waste) generate significantly more electricity than the 3,000 solar panels on the building’s roof. 
• inconspicuous. The unit does not vibrate, has no odor, and emits no sound. 
• reduced need for traditional power plants, and associated power lines. The box’s creator and Bloom Energy CEO, K.R. Sridhar, said in the 60 Minutes interview, “The idea is to one day replace the big power plants and transmission line grids the way the laptop moved in on the desktop and cell phones supplanted landlines.” 
• consistent and reliable electricity. Solar panels and wind turbines, by contrast, are of little use when clouds or the earth obscures the sun, or when the sporadic wind ceases to blow. In homes and businesses powered by Bloom Boxes®, power outages due to downed power lines or rolling blackouts would be nonexistent.  

Concerns

• price. Although Sridhar publicly hopes to reduce the price tag of his boxes to $3,000 within the next decade, skeptics have reason to doubt such optimism. Bloom Energy still has to figure out how to mass-produce the unit and get its costs down low enough to outfit every home with a Bloom Box®. The company has been quiet about the product, leaving skeptics to wonder what makes the Bloom Box® unique from fuel cells made by competing companies who have yet to meet such lofty goals, or even find profitability. Bloom Energy will need to conquer the commercial market, which can afford to utilize larger-scale units, before it can develop affordable residential models. 
• need for around-the-clock functionality. Fuel cells must work all the time, as even a minor hiccup could disrupt power to an entire building. At Google headquarters, the units stopped functioning when dust kicked up from a nearby highway and caused the air filters to become clogged. Perhaps power that goes unused can be directed to charge on-site batteries, which can be tapped during power failures.  
• carbon footprint. If natural gas is used to power the Bloom Box®, CO2 will be released. Sridhar argues that conventional power plants vent twice as much of this greenhouse gas as Bloom Boxes® do. This comparison must be balanced with the fact that California, where all of the units have thus far been sold, gets much of its energy from renewable energy sources.

In summary, Bloom Boxes® are a new type of fuel cell that may someday power a large number of businesses and homes.

Biowalls -- also referred to as living walls, vertical gardens, green facades, and green walls -- are interior or exterior walls that are covered with living vegetation. Biowalls have practical applications for both indoor and outdoor use. Many indoor biowalls are implemented in homes and offices for their natural air-filtration properties, and are used in tandem with traditional HVAC systems. Outdoor biowalls are most commonly found in urban environments, and serve to insulate buildings and combat the urban heat island (or UHI) effect, where exposed concrete surfaces reflect heat and cause urban centers to be excessively hot in the summertime.  Biowalls are also effective for mitigating the UHI effect in urban centers located in warm and dry climates.  
Facts and Figures

• The EPA estimates that even in buildings employing state-of-the-art HVAC systems, indoor air quality can be significantly worse than outdoor air quality due to the emission of volatile organic compounds (or VOCs). VOCs result from the off-gassing of paint, refrigerants, new carpeting, glues, electronics, and other petrochemical products. VOCs may not be hazardous in small quantities but, over time, they contribute to Sick Building Syndrome (SBS), which causes occupants of affected buildings to suffer headaches, dizziness, and irritation of the eyes, nose and throat. 
• In a 1984 study, NASA found that vegetation sequesters and purifies a significant amount of VOCs from enclosed indoor spaces. 
• Plant foliage is responsible for turning carbon dioxide into oxygen, but it is the root system that actually sequesters hazardous VOCs. 
 

How do biowalls function?
There are two main types biowalls:

• In panel systems, soil packed in plastic bags oftentimes comprises the growing medium. Plants and soil are placed in compartments and connected to a support and irrigation system. 
• In felt systems, panels of felt are used as the growth medium that the plants fit into. The felt sits against a waterproof layer, which is mounted onto a support structure. Roots grow downward and hold the plants in place.

A drip-irrigation system may be installed to run across the top of the biowall, allowing water and added nutrients to cascade down and soak the growth medium and plant roots. Excess water that pools at the bottom then recirculates back to the top of the wall by means of a pump. Some systems utilize captured rainwater or recycled greywater to minimize the water requirements of a biowall. 
There are two main classifications that distinguish biofiltration intensity:

• passive biowalls filter air naturally, as plant foliage absorbs carbon dioxide and emits fresh oxygen; and 
• active biowalls are indoor systems that take this process a step further. Fans draw polluted air through the biowall's growing medium.  The plants' roots trap harmful VOCs, which microbes may use as a source of energy. The building's HVAC system then circulates newly filtered air throughout indoor areas.  

Advantages of Biowalls

• Active biowalls perform natural biofiltration and decrease the incidence of SBS. 
• Active biowalls reduce the need for indoor heating and cooling, which saves energy and money. Traditional HVAC systems replace indoor air with outdoor air on an hourly basis. This necessitates additional heating or cooling of new air to meet the desired temperature of indoor air. Active biowalls recirculate the same air, thus eliminating the need for further heating or cooling. 
• Active biowalls may remediate hazardous pollutants that some mechanical filtering systems cannot. 
• Vegetation on a building's exterior walls minimizes direct sunlight on the surface of the building. In this way, the biowall minimizes the summertime UHI effect in cities, as less heat is re-radiated. This shading effect also translates into a reduced need for air conditioning in summer or in warm climates. 
• Vegetation on exterior walls protects buildings from harmful acid rain and UV rays. It also protects building materials from excessive expansion and contraction, as it minimizes temperature fluctuations. 
• Outdoor biowalls provide insulation to buildings, which reduces the energy required for indoor heating and cooling, and saves money. This is particularly noticeable in temperate climates, where buildings lack hardy insulation. 
• Biowalls can tolerate non-potable water, and may even have the capacity to purify polluted water. 
• Water moving through vegetation on a vertical plane is less likely to evaporate than water moving on a horizontal plane. 
• Some biowalls may produce edible foods. 
• Biowalls provide a sense of pleasure and ease for people. This is particularly relevant in office settings, as some studies reported that workers placed amid vegetated walls expressed higher levels of satisfaction and productivity. 
• Biowalls provide some soundproofing to rooms and buildings. 
• Outdoor biowalls capture rainwater and minimize urban runoff. 
• Biowalls provide less structural strain on buildings than green roofs.  
• Existing walls may be retrofitted to accommodate biowalls.

Disadvantages of Biowalls

• Systems that utilize loose soil are not well-suited for areas that are frequented by the public or that are prone to high winds or rain. Loose soil can become dislodged and spill out. 
• All biowall systems require some maintenance. 
• Felt systems are not thick, and even multi-layer systems are not conducive to the growth of extensive root systems. 
• Felt systems are not efficient at capturing and holding water, and thus require frequent watering or automated re-circulation. 
• Many local building codes typically require traditional air-filtration systems for code compliance. In these cases, biowalls cannot entirely take the place of standard systems. 
• Biowalls may be costly to implement, especially when traditional air-filtration systems are also required. 

Hazards

• Biowalls are ecosystems and, as such, may attract unwanted insects and pests. 
• Roots penetrating into wall structures may be a hazard in systems that are not planned properly. 
• Mold or damage to a biowall may be a problem in systems that do not drain properly. 
• Greywater that is improperly handled poses a human health hazard. 
 

Inspection

• Loose-growth media should be replaced regularly, approximately once every two years for interior systems, and once every year on exterior systems. 
• Artificial lighting should supplement indoor systems that do not receive sufficient sunlight. Outdoor systems should face the direction that provides appropriate sunlight for the needs of the specific vegetation planted. 
• Irrigation systems should achieve maximum efficiency by timing the watering cycles appropriately. 
• Root structures should have a sufficient growth medium such that they do not become overly compacted, leading to plant die-off. 
• A ratio of approximately 1 square foot of active biowall for every 100 square feet of floor space should be ensured for adequate air filtration. 
• The system should be drained regularly so as to avoid the growth of mold or the buildup of salts. 
• Adequate air flow is required so that active biowalls achieve maximize efficiency. 
• Plants chosen to populate the biowall should reflect the conditions of the locale, especially in outdoor systems. 
• Indoor systems should employ plants that do not release excessive pollen. 
• A backup water supply should provide irrigation in case of a power failure. 
• An overflow basin should be installed to catch excess water in case of a mechanical failure. 
• Wall structures chosen for biowall implementation should be resistant to moisture penetration.  

In summary, biowalls have many health, environmental and financial benefits when they are properly installed and maintained.

Outdoor air pollution in cities is a major health problem. Much effort and money continue to be spent cleaning up pollution in the outdoor air. But air pollution can be a problem where you least expect it, in the place you may have thought was safest -- your home. Many ordinary activities, such as cooking, heating, cooling, cleaning and redecorating, can cause the release and spread of indoor pollutants at home. Studies have shown that the air in our homes can be even more polluted than outdoor air. Many Americans spend up to 90% of their time indoors, often at home. Therefore, breathing clean indoor air can have an important impact on health. People who are inside a great deal may be at greater risk of developing health problems, or having problems made worse by indoor air pollutants. These people include infants, young children, the elderly and those with chronic illnesses. Many factors determine whether pollutants in your home will affect your health. They include the presence, use and condition of pollutant sources, the level of pollutants both indoors and out, the amount of ventilation in your home, and your overall health.
 
What are Biological Pollutants?
 
Biological pollutants are or were living organisms. They promote poor indoor air quality and may be a major cause of days lost from work and school, and of doctor and hospital visits. Some can even damage surfaces inside and outside your house. Biological pollutants can travel through the air and are often invisible. Some common indoor biological pollutants are: 

• animal dander (minute scales from hair, feathers, or skin); 
• dust mite and cockroach parts; 
• infectious agents (bacteria and viruses); and  
• pollen.

Some of these substances are in every home. It is impossible to get rid of them all. Even a spotless home may permit the growth of biological pollutants. Two conditions are essential to support biological growth:  nutrients and moisture. These conditions can be found in many locations, such as bathrooms, damp or flooded basements, wet appliances (such as humidifiers and air conditioners), and even some carpets and furniture. Modern materials and construction techniques may reduce the amount of outside air brought into buildings, which may result in high moisture levels inside. Using humidifiers, unvented heaters, and air conditioners in our homes has increased the chances of moisture forming on interior surfaces. This encourages the growth of certain biological pollutants.
 
The Scope of the Problem
 
Most information about sources and health effects of biological pollutants is based on studies of large office buildings and surveys of homes in the northern U.S. and Canada. These surveys show that 30% to 50% of all structures have damp conditions which may encourage the growth and buildup of biological pollutants. This percentage is likely to be higher in warm, moist climates. Some diseases and illnesses have been linked with biological pollutants in the indoor environment. However, many of them also have causes unrelated to the indoor environment. Therefore, we do not know how many health problems relate only to poor indoor air.
 
Health Effects of Biological Pollutants
 
All of us are exposed to biological pollutants. However, the effects on our health depend on the type and amount of biological pollution and the individual person. Some people do not experience health reactions from certain biological pollutants, while others may experience one or more of the following reactions:

• allergic; 
• infectious; and/or  
• toxic.

Except for the spread of infections indoors, allergic reactions may be the most common health problem with indoor air quality in homes. They are often connected with animal dander (mostly from cats and dogs), with house dust mites (microscopic animals living in household dust), and with pollen. Allergic reactions can range from mildly uncomfortable to life-threatening, as in a severe asthma attack. Some common signs and symptoms are:

• watery eyes; 
• runny nose and sneezing; 
• nasal congestion; 
• itching; 
• coughing; 
• wheezing and difficulty breathing; 
• headache; and  
• fatigue.

Health experts are especially concerned about people with asthma. These people have very sensitive airways that can react to various irritants, making breathing difficult. The number of people who have asthma has greatly increased in recent years. The number of people with asthma has gone up by 59% since 1970, to a total of 9.6 million people. Asthma in children under 15 years of age has increased 41% in the same period, to a total of 2.6 million children. The number of deaths from asthma is up by 68% since 1979, to a total of almost 4,400 deaths per year.
 
Talking to Your Doctor
 
Are you concerned about the effects on your health that may be related to biological pollutants in your home? Before you discuss your concerns with your doctor, you should know the answers to the following questions. This information can help the doctor determine whether your health problems may be related to biological pollution.

• Does anyone in the family have frequent headaches, fevers, itchy and watery eyes, a stuffy nose, dry throat, or a cough? Does anyone complain of feeling tired or dizzy all the time? Is anyone wheezing or having difficulties breathing on a regular basis? 
• Did these symptoms appear after you moved into a new or different home? 
• Do the symptoms disappear when you go to school or the office or go away on a trip, and return when you come back? 
• Have you recently remodeled your home or done any energy-conservation work, such as installing insulation, storm windows, or weather stripping? Did your symptoms occur during or after these activities? 
• Does your home feel humid? Can you see moisture on the windows or on other surfaces, such as walls and ceilings? 
• What is the usual temperature in your home? Is it very hot or cold? 
• Have you recently had water damage? 
• Is your basement wet or damp? 
• Is there any obvious mold or mildew? 
• Does any part of your home have a musty or moldy odor? 
• Is the air stale? 
• Do you have pets? 
• Do your house plants show signs of mold? 
• Do you have air conditioners or humidifiers that have not been properly cleaned? 
• Does your home have cockroaches or rodents?

Infectious diseases caused by bacteria and viruses, such as the flu, measles, chicken pox, and tuberculosis, may be spread indoors. Most infectious diseases pass from person to person through physical contact. Crowded conditions with poor air circulation can promote this spread. Some bacteria and viruses thrive in buildings and circulate through indoor ventilation systems. For example, the bacterium causing Legionnaire's Disease, a serious and sometimes lethal infection, and Pontiac Fever, a flu-like illness, have circulated in some large buildings.
 
Toxic reactions are the least studied or understood health problem caused by some biological air pollutants in the home. Toxins can damage a variety of organs and tissues in the body, including the liver, the central nervous system, the digestive tract, and the immune system.
 
Checking Your Home
 
There is no simple or cheap way to sample the air in your home to determine the level of all biological pollutants. Experts suggest that sampling for biological pollutants is not a useful problem-solving tool. Even if you had your home tested, it is almost impossible to know which biological pollutant(s) cause various symptoms or health problems. The amount of most biological substances required to cause disease is unknown and varies from one person to the next. Does this make the problem sound hopeless? On the contrary, you can take several simple, practical actions to help remove sources of biological pollutants, to help get rid of pollutants, and to prevent their return.
 
Self-Inspection: A Walk Through Your Home
 
Begin by touring your household. Follow your nose, and use your eyes. Two major factors help create conditions for biological pollutants to grow:  nutrients and constant moisture with poor air circulation.

1. Dust and construction materials, such as wood, wallboard and insulation, contain nutrients that allow biological pollutants to grow. Firewood also is a source of moisture, fungi and bugs. 
2. Appliances, such as humidifiers, kerosene and gas heaters, washers and clothes dryers, dishwashers and gas stoves, add moisture to the air.

A musty odor, moisture on hard surfaces, and even water stains, may be caused by: 

• air-conditioning units; 
• basements, attics and crawlspaces; 
• bathrooms; 
• carpets; 
• heating and air-conditioning ducts; 
• humidifiers and dehumidifiers; and 
• refrigerator drip pans.

What You Can Do About Biological Pollutants
 
Before you give away the family pet or move, there are less drastic steps you can take to reduce potential problems. Properly cleaning and maintaining your home can help reduce the problem and may avoid interrupting your normal routine. People who have health problems, such as asthma, or who are allergic, may need to do this and more. Discuss this with your doctor.
 
Moisture Control
 
Water in your home can come from many sources. Water can enter your home by leaking or by seeping through basement floors. Showers and even cooking can add moisture to the air in your home. The amount of moisture that the air in your home can hold depends on the temperature of the air. As the temperature goes down, the air is able to hold less moisture. This is why, in cold weather, moisture condenses on cold surfaces (for example, drops of water form on the inside of a window). This moisture can encourage biological pollutants to grow.
 
There are many ways to control moisture in your home:

• Fix leaks and seepage. If water is entering the house from the outside, your options range from simple landscaping to extensive excavation and waterproofing. (The ground should slope away from the house.) Water in the basement can result from the lack of gutters or a water flow toward the house. Water leaks in pipes and around tubs and sinks can provide a place for biological pollutants to grow. 
• Put a plastic cover over dirt crawlspaces to prevent moisture from coming in from the ground. Be sure crawlspaces are well-ventilated. 
• Use exhaust fans in bathrooms and kitchens to remove moisture to the outside (not into the attic). Vent your clothes dryer to the outside. 
• Turn off certain appliances (such as humidifiers and kerosene heaters) if you notice moisture on windows and other surfaces. 
• Use dehumidifiers and air conditioners, especially in hot, humid climates, to reduce moisture in the air, but be sure that the appliances themselves don't become sources of biological pollutants. 
• Raise the temperature of cold surfaces where moisture condenses. Use insulation and storm windows. (A storm window installed on the inside works better than one installed on the outside) Open doors between rooms (especially doors to closets which may be colder than the rooms) to increase circulation. Circulation carries heat to the cold surfaces Increase air circulation by using fans and by moving furniture from wall corners to promote air and heat circulation. Be sure that your house has a source of fresh air and can expel excessive moisture from the home. 
• Pay special attention to carpet on concrete floors. Carpet can absorb moisture and serve as a place for biological pollutants to grow. Use area rugs, which can be taken up and washed often. In certain climates, if carpet is to be installed over a concrete floor, it maybe necessary to use a vapor barrier (plastic sheeting) over the concrete and cover that with sub-flooring (insulation covered with plywood) to prevent a moisture problem. 
• Moisture problems and their solutions differ from one climate to another. The Northeast is cold and wet, the Southwest is hot and dry, the South is hot and wet, and the Western Mountain states are cold and dry. All of these regions can have moisture problems. For example, evaporative coolers used in the Southwest can encourage the growth of biological pollutants. In other hot regions, the use of air conditioners which cool the air too quickly may not be left running long enough to remove excess moisture from the air. The types of construction and weather for the different climates can lead to different problems and solutions.

Where Biological Pollutants May Be Found in the Home

• dirty air conditioners; 
• dirty humidifiers and/or dehumidifiers; 
• bathroom without vents or windows; 
• kitchen without vents or windows; 
• dirty refrigerator drip pans; 
• laundry room with an unvented dryer; 
• an unventilated attic; 
• carpet on damp basement floor; 
• bedding; 
• closet on outside wall; 
• dirty heating/air-conditioning system; 
• pets; and  
• water damage (around windows, the roof, the basement).

Maintain and Clean All Appliances that Come in Contact with Water

• Have major appliances, such as furnaces, heat pumps and central air conditioners, inspected regularly by a professional InterNACHI inspector. Change filters on heating and cooling systems according to manufacturer's directions. (In general, change filters monthly during use.) When first turning on the heating or air conditioner at the start of the season, consider leaving your home until it airs out. 
• Have window and wall air-conditioning units cleaned and serviced regularly by a professional, especially before the cooling season. Air conditioners can help reduce the entry of allergy-causing pollen. But they may also become a source of biological pollutants if not properly maintained. Clean the coils and rinse the drain pans, according to the manufacturer's instructions, so water cannot collect in pools. 
• Have furnace-attached humidifiers cleaned and serviced regularly by a professional, especially before the heating season. 
• Follow the manufacturer's instructions when using any type of humidifier. Experts differ on the benefits of using humidifiers. If you do use a portable humidifier (approximately 1- to 2-gallon tanks), be sure to empty its tank every day and refill it with distilled or demineralized water, or even fresh tap water, if the other types of water are unavailable.  For larger portable humidifiers, change the water as recommended by the manufacturer. Unplug the appliance before cleaning. Every third day, clean all surfaces coming in contact with water with a 3% solution of hydrogen peroxide, using a brush to loosen deposits.  Some manufacturers recommend using diluted household bleach for cleaning and maintenance, generally in a solution of one-half cup bleach to 1 gallon of water. With any household chemical, rinse well to remove all traces of chemical before refilling the humidifier. 
• Empty dehumidifiers daily and clean often. If possible, have the appliance drip directly into a drain. Follow manufacturer's instructions for cleaning and maintenance. Always disconnect the appliance before cleaning. 
• Clean refrigerator drip pans regularly, according to manufacturer's instructions. If refrigerator and freezer doors don't seal properly, moisture may build up and mold can grow. Remove any mold on door gaskets, and replace faulty gaskets.

Clean Surfaces

• Clean moist surfaces, such as showers and kitchen counters. 
• Remove mold from walls, ceilings, floors and paneling. Do not simply cover mold with paint, stain, varnish, or a moisture-proof sealer, as the mold may resurface. 
• Replace moldy shower curtains, or remove them and scrub them well with a household cleaner, and rinse them before rehanging them.

Dust Control
 
Controlling dust is very important for people who are allergic to animal dander and mites. You cannot see mites, but you can either remove their favorite breeding grounds or keep these areas dry and clean. Dust mites can thrive in sofas, stuffed chairs, carpets and bedding. Open shelves, fabric wallpaper, knickknacks, and venetian blinds are also sources of dust mites. Dust mites live deep in the carpet and are not removed by vacuuming. Many doctors suggest that their mite-allergic patients use washable area rugs rather than wall-to-wall carpet.

• Always wash bedding in hot water (at least 130° F) to kill dust mites. Cold water won't do the job. Launder bedding at least every seven to 10 days. 
• Use synthetic or foam rubber mattress pads and pillows, and plastic mattress covers, if you are allergic. Do not use fuzzy wool blankets, feather or wool-stuffed comforters, and feather pillows. 
• Clean rooms and closets well.  Dust and vacuum often to remove surface dust. Vacuuming and other cleaning may not remove all animal dander, dust mite material, and other biological pollutants. Some particles are so small, they can pass through vacuum bags and remain in the air. If you are allergic to dust, wear a mask when vacuuming and dusting. People who are highly allergy-prone should not perform these tasks. They may even need to leave the house when someone else is cleaning.

Before You Move
 
Protect yourself by hiring an InterNACHI inspector to inspect your potential new home. If you identify problems, have the landlord or seller correct them before you move in, or even consider moving elsewhere. 

• Have professionals check the heating and cooling system, including humidifiers and vents. Have duct lining and insulation checked for growth. 
• Check for exhaust fans in bathrooms and kitchens. If there are no vents, do the kitchen and bathrooms have at least one window in each room? Does the stovetop have a hood vented outside? Does the clothes dryer vent outside? Do all vents exhaust to the outside of the building, and not in attics or crawlspaces? 
• Look for obvious mold growth throughout the house, including attics, basements and crawlspaces, and around the foundation outside. See if there are many plants close to the house, particularly if they are damp and rotting. They are a potential source of biological pollutants. Downspouts from roof gutters should route water away from the building. 
• Look for stains on the walls, floor or carpet (including any carpet over concrete floors) as evidence of previous flooding or moisture problems. Is there moisture on windows and surfaces? Are there signs of leaks or seepage in the basement? 
• Look for rotted building materials, which may suggest moisture or water damage. 
• If you or anyone else in the family has a pet allergy, ask if any pets have lived in the home. 
• Examine the design of the building. Remember that in cold climates, overhanging areas, rooms over unheated garages, and closets on outside walls may be prone to problems with biological pollutants. 
• Look for signs of cockroaches. (Carefully read instructions for use and any cautionary labeling on cleaning products before beginning cleaning procedures.) 
• Do not mix any chemical products. Especially, never mix cleaners containing bleach with any product (such as ammonia) which does not have instructions for such mixing.  When chemicals are combined, a dangerous gas can sometimes be formed. 
• Household chemicals may cause burning or irritation to skin and eyes. 
• Household chemicals may be harmful if swallowed or inhaled. 
• Avoid contact with skin, eyes, mucous membranes, and clothing. 
• Avoid breathing vapor. Open all windows and doors, and use an exhaust fan that sends the air outside. 
• Keep household chemicals out of reach of children. 
• Rinse treated surface areas well to remove all traces of chemicals. 

Correcting Water Damage
 
What if damage is already done? Follow these guidelines for correcting water damage:

• Throw out mattresses, wicker furniture, straw baskets and the like that have been water damaged or contain mold. These cannot be recovered. 
• Discard any water-damaged furnishings, such as carpets, drapes, stuffed toys, upholstered furniture, and ceiling tiles, unless they can be recovered by steam cleaning or hot-water washing and thorough drying. 
• Remove and replace wet insulation to prevent conditions where biological pollutants can grow.

Reducing Exposure to Biological Contaminants
 
General good housekeeping, and maintenance of heating and air-conditioning equipment, are very important. Adequate ventilation and good air distribution also help. The key to mold control is moisture control. If mold is a problem, clean up the mold and get rid of excess water and moisture. Maintaining the relative humidity between 30% to 60% will help control mold, dust mites and cockroaches. Employ integrated pest management to control insect and animal allergens. Cooling-tower treatment procedures exist to reduce levels of Legionella and other organisms. 
 
Install and use exhaust fans that are vented to the outdoors in kitchens and bathrooms, and vent clothes dryers outdoors. These actions can eliminate much of the moisture that builds up from everyday activities. There are exhaust fans on the market that produce little noise, an important consideration for some people. Another benefit to using kitchen and bathroom exhaust fans is that they can reduce levels of organic pollutants that vaporize from hot water used in showers and dishwashers. Ventilate the attic and crawlspaces to prevent moisture build-up. Keeping humidity levels in these areas below 50% can prevent water condensation on building materials.
 
If using cool mist or ultrasonic humidifiers, clean appliances according to the manufacturer's instructions and refill with fresh water daily. Because these humidifiers can become breeding grounds for biological contaminants, they have the potential for causing diseases such as hypersensitivity pneumonitis and humidifier fever. Evaporation trays in air conditioners, dehumidifiers, and refrigerators should also be cleaned frequently.
 
Thoroughly clean and dry water-damaged carpets and building materials (within 24 hours, if possible), or consider removal and replacement. Water-damaged carpets and building materials can harbor mold and bacteria. It is very difficult to completely rid such materials of biological contaminants.
 
Keep the house clean. House dust mites, pollens, animal dander, and other allergy-causing agents can be reduced, although not eliminated, through regular cleaning. People who are allergic to these pollutants should use allergen-proof mattress encasements, wash bedding in hot water (130° F), and avoid room furnishings that accumulate dust, especially if they cannot be washed in hot water. Allergic individuals should also leave the house while it is being vacuumed because vacuuming can actually increase airborne levels of mite allergens and other biological contaminants. Using central vacuum systems that are vented to the outdoors, or vacuums with high efficiency filters may also be of help.
 
Take steps to minimize biological pollutants in basements. Clean and disinfect the basement floor drain regularly. Do not finish a basement below ground level unless all water leaks are patched and outdoor ventilation and adequate heat to prevent condensation are provided. Operate a dehumidifier in the basement, if needed, to keep relative humidity levels between 30% to 50%.
Health Effects From Biological Contaminants
 
Some biological contaminants trigger allergic reactions, including hypersensitivity pneumonitis, allergic rhinitis, and some types of asthma. Infectious illnesses, such as influenza, measles and chicken pox, are transmitted through the air. Molds and mildews release disease-causing toxins. Symptoms of health problems caused by biological pollutants include sneezing, watery eyes, coughing, shortness of breath, dizziness, lethargy, fever and digestive problems.
 
Allergic reactions occur only after repeated exposure to a specific biological allergen. However, that reaction may occur immediately upon re-exposure, or after multiple exposures over time. As a result, people who have noticed only mild allergic reactions, or no reactions at all, may suddenly find themselves very sensitive to particular allergens. Some diseases, such as humidifier fever, are associated with exposure to toxins from microorganisms that can grow in large buildings' ventilation systems. However, these diseases can also be traced to micro-organisms that grow in home heating and cooling systems and humidifiers. Children, elderly people, and people with breathing problems, allergies, and lung diseases are particularly susceptible to disease-causing biological agents in the indoor air. Mold, dust mites, pet dander, and pest droppings or body parts can trigger asthma. Biological contaminants, including molds and pollens, can cause allergic reactions for a significant portion of the population. Tuberculosis, measles, staphylococcus infections, Legionella and influenza are known to be transmitted by air.
 
Combustion Pollutants
 
Combustion appliances are those which burn fuels for warmth, cooking or decorative purposes. Typical fuels are gas, both natural and liquefied petroleum (LP), kerosene, oil, coal and wood. Examples of the appliances are space heaters, ranges, ovens, stoves, furnaces, fireplaces, water heaters, and clothes dryers. These appliances are usually safe. However, under certain conditions, these appliances can produce combustion pollutants that can damage your health, or even kill you.
 
What are Combustion Pollutants?
 
Combustion pollutants are gases and particles that come from burning materials. The combustion pollutants come from burning fuels in appliances. The types and amounts of pollutants produced depend on the type of appliance, how well the appliance is installed, maintained and vented, and the kind of fuel it uses. Some of the common pollutants produced from burning these fuels are carbon monoxide, nitrogen dioxide, particles, and sulfur dioxide. Particles can have hazardous chemicals attached to them. Other pollutants that can be produced by some appliances are unburned hydrocarbons and aldehydes. Combustion always produces water vapor. Water vapor is not usually considered a pollutant, but it can act as one. It can result in high humidity and wet surfaces. 
 
Where do Combustion Pollutants Come From?
 
Combustion pollutants found indoors include outdoor air, tobacco smoke, exhaust from car and lawn mower internal combustion engines, and some hobby activities, such as welding, woodburning and soldering. Combustion pollutants can also come from vented or unvented combustion appliances. These appliances include space heaters, gas ranges and ovens, furnaces, gas water heaters, gas clothes dryers, wood and coal-burning stoves, and fireplaces. As a group, these are called "combustion appliances."
 
Appliances

Vented appliances are appliances designed to be used with a duct, chimney, pipe, or other device that carries the combustion pollutants outside the home. These appliances can release large amounts of pollutants directly into your home if a vent is not properly installed, or is blocked or leaking. Unvented appliances do not vent to the outside, so they release combustion pollutants directly into the home. Many of these problems are hard for a homeowner to identify. A professional is needed.
What are the Health Effects of Combustion Pollutants?
 
The health effects of combustion pollutants range from headaches and breathing difficulties to death. The health effects may show up immediately after exposure, or occur after being exposed to the pollutants for a long time. The effects depend on the type and amount of pollutants, and the length of time of exposure to them. They also depend upon several factors related to the exposed person. These include the age and any existing health problems. There are still some questions about the level of pollutants or the period of exposure needed to produce specific health effects. Further studies to better define the release of pollutants from combustion appliances and their health effects are needed.
 
The sections below discuss health problems associated with some common combustion pollutants. These pollutants include carbon monoxide, nitrogen dioxide, particles, and sulfur dioxide. Even if you are healthy, high levels of carbon monoxide can kill you within a short time. The health effects of the other pollutants are generally more subtle and are more likely to affect susceptible people. It is always a good idea to reduce exposure to combustion pollutants by using and maintaining combustion appliances properly.
 
Carbon Monoxide:
Each year, according to CPSC, there are more than 200 carbon monoxide deaths related to the use of all types of combustion appliances in the home. Exposure to carbon monoxide reduces the blood's ability to carry oxygen. Often, a person or an entire family may not recognize that carbon monoxide is poisoning them. The chemical is odorless, and some of the symptoms are similar to common illnesses. This is particularly dangerous because carbon monoxide's deadly effects will not be recognized until it is too late to take action against them. Carbon monoxide exposures especially affect unborn babies, infants, and people with anemia or a history of heart disease. Breathing low levels of the chemical can cause fatigue and increase chest pain in people with chronic heart disease. Breathing higher levels of carbon monoxide causes symptoms such as headaches, dizziness, and weakness in healthy people. Carbon monoxide also causes sleepiness, nausea, vomiting, confusion and disorientation. At very high levels, it causes loss of consciousness and death.
 
Nitrogen Dioxide:
Breathing high levels of nitrogen dioxide causes irritation of the respiratory tract and causes shortness of breath. Compared to healthy people, children, and individuals with respiratory illnesses such as asthma, may be more susceptible to the effects of nitrogen dioxide. Some studies have shown that children may have more colds and flu when exposed to low levels of nitrogen dioxide. When people with asthma inhale low levels of nitrogen dioxide while exercising, their lung airways can narrow and react more to inhaled materials.
 
Particles:
Particles suspended in the air can cause eye, nose, throat and lung irritation. They can increase respiratory symptoms, especially in people with chronic lung disease or heart problems. Certain chemicals attached to particles may cause lung cancer, if they are inhaled. The risk of lung cancer increases with the amount and length of exposure. The health effects from inhaling particles depend upon many factors, including the size of the particle and its chemical make-up.
 
Sulfur Dioxide:
Sulfur dioxide at low levels of exposure can cause eye, nose, and respiratory tract irritation. At high exposure levels, it causes the lung airways to narrow. This causes wheezing, chest tightness, and breathing problems. People with asthma are particularly susceptible to the effects of sulfur dioxide. They may have symptoms at levels that are much lower than the rest of the population.
 
Other Pollutants: 
Combustion may release other pollutants. They include unburned hydrocarbons and aldehydes. Little is known about the levels of these pollutants in indoor air and the resulting health effects.
 
What do I do if I suspect that combustion pollutants are affecting my health?
 
If you suspect you are being subjected to carbon monoxide poisoning, get fresh air immediately. Open windows and doors for more ventilation, turn off any combustion appliances, and leave the house. You could lose consciousness and die from carbon monoxide poisoning if you do nothing. It is also important to contact a doctor immediately for a proper diagnosis. Remember to tell your doctor that you suspect carbon monoxide poisoning is causing your problems. Prompt medical attention is important. Some symptoms from combustion pollutants -- including headaches, dizziness, sleepiness, coughing, and watery eyes -- may also occur because of common medical problems. These medical problems include colds, the flu, and allergies. Similar symptoms may also occur because of other indoor air pollutants. Contact your doctor for a proper diagnosis.
How can I reduce my exposure to combustion pollutants?
 
Proper selection, installation, inspection and maintenance of your appliances are extremely important in reducing your exposure to these pollutants. Providing good ventilation in your home and correctly using your appliance can also reduce your exposure to these pollutants. Additionally, there are several different residential carbon monoxide detectors for sale. These detectors alert consumers to harmful carbon monoxide levels in the home. They may soon be widely available to reduce deaths from carbon monoxide poisoning.
 
Appliance Selection

• Choose vented appliances whenever possible. 
• Buy only combustion appliances that have been tested and certified to meet current safety standards. Examples of certifying organizations are Underwriters Laboratories (UL) and the American Gas Association (AGA) Laboratories. Look for a label that clearly shows the certification. 
• All currently manufactured vented gas heaters are required by industry safety standards to have a safety shut-off device. This device helps protect you from carbon monoxide poisoning by shutting off an improperly vented heater. 
• Check your local and state building codes and fire ordinances to see if you can use an unvented space heater, if you are considering purchasing one. They are not allowed to be used in some communities, dwellings, and certain rooms in the house. 
• If you must replace an unvented gas space heater with another, make it a new one. Heaters made after 1982 have a pilot light safety system called an oxygen depletion sensor (ODS). This system shuts off the heater when there is not enough fresh air, before the heater begins producing large amounts of carbon monoxide. Look for the label that tells you that the appliance has this safety system. Older heaters will not have this protection system. 
• Consider buying gas appliances that have electronic ignitions rather than pilot lights. These appliances are usually more energy-efficient and eliminate the continuous low-level pollutants from pilot lights. 
• Buy appliances that are the correct size for the area you want to heat. Using the wrong size heater may produce more pollutants in your home and is not an efficient use of energy. 
• All new wood stoves are EPA-certified to limit the amounts of pollutants released into the outdoor air. For more information on selecting, installing, operating, and maintaining wood-burning stoves, write to the EPA Wood Heater Program. Before buying a wood stove, check your local laws about the installation and use of wood stoves.

Ventilation
 
To reduce indoor air pollution, a good supply of fresh, outdoor air is needed. The movement of air into and out of your home is very important. Normally, air comes in through cracks around doors and windows. This air helps reduce the level of pollutants indoors. This supply of fresh air is also important to help carry pollutants up the chimney, stovepipe or flue to the outside.

• Keep doors open to the rest of the house from the room where you are using an unvented gas space heater or kerosene heater, and crack open a window. This allows enough air for proper combustion, and reduces the level of pollutants, especially carbon monoxide. 
• Use a hood fan if you are using a range. They reduce the level of pollutants you breathe if they exhaust to the outside. Make sure that enough air is coming into the house when you use an exhaust fan. If needed, open a door or window slightly, especially if other appliances are in use. For proper operation of most combustion appliances and their venting systems, the air pressure in the house should be greater than that outside. If not, the vented appliances could release combustion pollutants into the house rather than outdoors. If you suspect that you have this problem, you may need the help of a qualified person to solve it. 
• Make sure that your vented appliance has the vent connected and that nothing is blocking it. Make sure there are no holes or cracks in the vent. Do not vent gas clothes dryers or water heaters into the house for heating. This is unsafe. 
• Open the stove's damper when adding wood. This allows more air into the stove. More air helps the wood burn properly, and prevents pollutants from being drawn back into the house instead of going up the chimney. If there is isible smoke or a constant smoky odor inside the home while using a wood-burning stove, this is a sign that the stove is not working properly. Soot on furniture in the rooms where you are using the stove also tells this. Smoke and soot are signs that the stove is releasing pollutants into the indoor air.

Correct Use of Appliances

• Read and follow the instructions for all appliances so that you understand how they work. Keep the owner's manual in a convenient place to refer to when needed. Also, read and follow the warning labels because they tell you important safety information that you need to know. Reading and following the instructions and warning labels could save your life. 
• Always use the correct fuel for the appliance. 
• Use only water-clear ASTM 1-K kerosene for kerosene heaters. The use of kerosene other than 1-K could lead to a release of more pollutants in your home. Never use gasoline in a kerosene heater because it can cause a fire or an explosion. Using even small amounts of gasoline could cause a fire. 
• Use seasoned hardwoods (elm, maple, oak) instead of softwoods (cedar, fir, pine) in wood-burning stoves and fireplaces. Hardwoods are better because they burn hotter and form less creosote, an oily, black tar that sticks to chimneys and stove pipes. Do not use green or wet woods as the primary wood because they make more creosote and smoke. Never burn painted scrap wood or wood treated with preservatives, because they could release highly toxic pollutants, such as arsenic or lead. Plastics, charcoal, and colored paper, such as comics and wrapping paper, also produce pollutants. Never burn anything that the stove or fireplace manufacturer does not recommend. 
• Never use a range, oven or dryer to heat your home. When you misuse gas appliances in this way, they can produce fatal amounts of carbon monoxide. They can produce high levels of nitrogen dioxide, too. 
• Never use an unvented combustion heater overnight or in a room where you are sleeping. Carbon monoxide from combustion heaters can reach dangerous levels. 
• Never ignore a safety device when it shuts off an appliance. It means that something is wrong. Read your appliance instructions to find out what you should do, or have a professional check out the problem. 
• Never ignore the smell of fuel. This usually indicates that the appliance is not operating properly or is leaking fuel. Leaking fuel will not always be detectable by smell. If you suspect that you have a fuel leak, have it fixed as soon as possible. In most cases, you should shut off the appliance, extinguish any other flames or pilot lights, shut off other appliances in the area, open windows and doors, call for help, and leave the area.

Inspection and Maintenance
 
Have your combustion appliance regularly inspected and maintained to reduce your exposure to pollutants. Appliances that are not working properly can release harmful and even fatal amounts of pollutants, especially carbon monoxide. Have chimneys and vents inspected when installing or changing vented heating appliances. Some modifications may be required. For example, if a change was made in your heating system from oil to natural gas, the flue gas produced by the gas system could be hot enough to melt accumulated oil-combustion debris in the chimney or vent. This debris could block the vent, forcing pollutants into the house. It is important to clean your chimney and vents, especially when changing heating systems. Always hire an InterNACHI inspector to perform your home inspections, as they all must pass the most comprehensive, rigorous training program available.  
 
What are the Inspection and Maintenance Procedures?
 
The best advice is to follow the recommendations of the manufacturer. The same combustion appliance may have different inspection and maintenance requirements, depending on where you live. In general, check the flame in the furnace combustion chamber at the beginning of the heating season. Natural gas furnaces should have a blue flame with perhaps only a slight yellow tip. Call your appliance service representative to adjust the burner if there is a lot of yellow in the flame, or call your local utility company for this service. LP units should have a flame with a bright blue center that may have a light yellow tip. Pilot lights on gas water heaters and gas cooking appliances should also have a blue flame. Have a trained service representative adjust the pilot light if it is yellow or orange. Before each heating season, have flues and chimneys inspected before each heating season for leakage and for blockage by creosote or debris. Creosote buildup or leakage could cause black stains on the outside of the chimney or flue. These stains can mean that pollutants are leaking into the house.