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The EPA (www.epa.gov) has found the levels of common organic pollutants to be two to five times higher inside homes than outside, whether they were located in rural or highly industrialized areas. Elements contained in indoor air quality can trigger asthma and allergy attacks as well as aggravate other respiratory conditions. The American Lung Association (www.lungusa.com) estimated that in 2004, approximately 20.5 million Americans suffered from asthma. Asthma is the most common chronic disorder in childhood, currently affecting the lives of an estimated 6.2 million children. Considering that people spend about 90 percent of their time indoors (65 percent in their homes), researchers continue to study the effects of indoor air on these ailments. STEP 1: Build it tight. Although curb appeal and aesthetic features are still dominant factors when we think about building or buying a house, today’s buyers are starting to focus their attention on requiring more energy efficient and healthier homes. Building science 101 says to “build it tight and ventilate it right”. Today’s homes are advertised to be more energy efficient because they have to follow stricter standards for insulation and air tightness, but according to Arnie Katz at Advanced Energy (www.advancedenergy.com) “you shouldn’t assume your house is tight because it’s new, or expensive or beautiful. Sadly, most houses we test, even new houses, are leaky”. Air leakage is a major problem in both old and new homes. It not only drives up your energy costs, but permits the entry of insects, water vapor, pollens and other pollutants. Air leakage is tested by attaching a fan and monitoring aparatus to a door and “sucking” the air out of the house. This is called a “Blower Door” test – since the air being pulled out of the house must be replaced by air seeping through the various and often invisible cracks in a house we can measure how “leaky” the home is by measuring the rate at which air is being evacuated from the structure. Eco-Panels can provide you with a VERY tight house – often significantly tighter than homes built with traditional stick-built methods (and yes, even much better than homes stick-built with spray foam insulation). Amy Musser, PhD and senior building scientist with Vandemusser Design has studied homes using Eco-Panels and concluded: “Recent Energy Star test results on a house in western North Carolina constructed with Eco-Panels demonstrated the best blower door test results I have ever seen.” Step 2: Ventilate it Right A poorly designed or installed HVAC system will not only increase your energy usage and lead to discomfort, but it can also compromise your indoor air quality. Are the ducts in the attic or crawl space properly sealed against moisture and other pollutants? Does your HVAV system properly deal with the removal of excess moisture within the building envelope? Has your HVAC system been properly sized and balanced? Specialists at Advanced Energy, along with many building scientists from all over the country have concluded that the most sensible approach is to build a house as air-tight as possible and install a “whole house” mechanical ventilation system to bring in fresh air from the outside and to remove stale air from the inside. These ventilation systems can be operated separately or combined to work with your duct work that may supply your heating and cooling. Filtration of this air also plays an important role in creating better indoor air quality. Removing particulates, VOCs (volatile organic compounds), combustion gases and other chemicals and pollutants from your living space will depend on the types and locations of filters integrated into your whole house ventilation system. All filter systems are not created equal and the MERV (Minimum Efficiency Reporting Value) is a good way to begin making comparisons, with higher values being better. Eco-Panels homes require the use of an ERV or HRV which will be determined by your climate zone. Heat and energy recovery ventilators bring in and filter fresh air from the outdoors while exhausting stale air from the home. Both HRVs and ERVs moderate the temperature of the fresh air by conducting heat from one air stream to the other reducing energy costs. Additionally, ERVs modify the humidity content of the fresh air through the transfer of water vapor from one air stream to the other. Very humid climate zones may need the addition of a “whole house” dehumidification system to be installed. Since HRVs and ERVs combine both exhaust and fresh air intakes, they are describes as balanced systems. Step #3: Spot Ventilation Too much moisture can contribute to allergy problems and structural damage by encouraging the growth of mold, mildew, bacteria, dust mites, dry rot and insects. Moisture can come in from the outside, from attics and crawlspaces, but most of the moisture inside a home is directly created by the homeowners themselves. Key areas of moisture management and spot ventilation in the home are bathrooms, kitchens and laundry rooms. Properly exhausting moisture from these rooms is a crucial step to healthy indoor air quality and structural integrity. Fans are rated in CFMs (cubic feet per minute) and sones (loudness). Too many cfms can lead to negative pressure problems and too few cfms may not properly remove the moisture and other contaminants from the room. Step #4: Understanding common causes of indoor pollutants Common household chemicals
Combustion products These are produced by fuel burning heating equipment, gas water heaters, fireplaces, woodstoves, gas ranges and candles. They include but are not limited to:
Building scientists and indoor air quality specialists continually recommend that these combustion appliances be directly vented to the outside. Passive ventilation may only provide minimal extraction of these harmful byproducts. Vent free fireplaces are highly discouraged for a variety of reasons. Heat Attics can overheat from long days of summer sunshine, and excess moisture can accumulate in the winter. Control of these factors through proper ventilation will enhance the comfort and indoor air quality of the home to help keep the occupants breathing safely. How a homeowner defines their thermal boundary can also reduce the overheating problems associated with attics. |
Whole House Ventilation Systems Home Ventilating Institute (HVI) Bathroom Ventilation Recommendations Effective Ventilation Systems General Guidelines article by Ron Pariseau |
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