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Energy By Design
New Homes with Air Leakage Issues?
Builders today are using many excellent materials that are designed to conserve energy and create homes that are very airtight. Utilizing building wraps and moisture barriers, spray foam insulation, high efficiency windows, and caulking around doors, windows and wall penetrations all work together to reduce air leakage and infiltration. These advances in building techniques and materials have resulted in homes that are much more efficient and air tight than even 10 years ago.
The problems arise when there are so few openings through which fresh air can enter the building that the quality of the air within the home is reduced. Without fresh air entering the home, the air can become stagnant, moisture issues can develop and combustion appliances may not vent properly creating carbon monoxide poisoning hazards. Conversely, homes that are not airtight enough waste energy through loss of conditioned air, are uncomfortable due to drafts and air leaks and are costly due to high energy bills.
Until recently, the building community has had to rely on subjective testing methods that did not produce evidence as to how air tight their buildings were. A visual inspection does not provide the definitive answer we need to this question. It is difficult to design for effective approaches to ventilation and air quality and impossible to accurately diagnose performance problems through visual inspections alone.
Why is Air Leakage Such a Big Deal?
What are the problems with a leaky house? Leaky houses have a whole host of problems ranging from drafty cold rooms, blistering and peeling paint, ice dams and frozen pipes in the winter. These issues lead to others that cause a plethora of problems of their own. The damage caused by a leaky house costs the owner money not only in higher energy bills but much more in home repairs and damage reversal. Although leaks around window and door seals are most often treated, hidden leaks in the attic, crawlspace and framing connections are most often the cause of home performance problems and are responsible for most of the air leaks in a typical home.
So what could be wrong with building an airtight house? Without proper ventilation the potential for health and safety problems increase. Moisture levels can quickly become a problem without adequate ventilation creating an ideal environment for molds, dust mites and other allergens. Not only is air quality affected but damage in the form of blistering and peeling paint and ugly mildew stains are the cosmetic result of improper ventilation. The real dangers come into play when improper ventilation is combined with combustion appliances. This is because in tight houses, it is easier for exhaust devices to create large pressure differences between inside and outside air, which can interfere with the ventilation of combustion appliances. Tighter houses are also more likely to expose occupants to the dangers of backdrafting and spillage of combustion products from naturally drafting furnaces, water heaters and fireplaces.
Whether your home is airtight or leaky, moisture is it's biggest enemy causing damage and deterioration very quickly. Moisture can be reduced through proper ventilation in airtight homes. However, most moisture problems are the consequence of uncontrolled air leakage through the building envelope.
How Does a Blower Door Measure Air Leakage?
We've gotten to the point where we need to know....how leaky or airtight is your home and how can you know for sure? The most efficient way to measure the air leakage in a building is by performing a blower door test. A blower door is a tool used in the home performance industry to measure the airtightness of the building envelope.
The blower door consists of a powerful, calibrated fan, installed in an exterior doorway which creates a pressure difference between the inside and outside of the building, thereby forcing air through the breaches and penetrations of the building envelope. The blower door system measures the amount of air needed to create a change in pressure by calculating the air flow through the fan and its effect on the air pressure inside the building. The less air needed through the fan, the more airtight the building.
The pressure created by the use of the blower door makes leakages easier to find using chemical smoke, or an infrared camera. Blower door calculations are very valuable in estimating annual average and designed air infiltration rates. These can be used to help in gauging the size of heating and cooling equipment and for determining the necessary installation of mechanical ventilation for moisture control, proper combustion appliance ventilation and air quality purposes.
All new homes in Florida are now required to have a blower door test. Energy By Design is qualified to perform these tests and provide you with the documentation necessary to meet the Florida Energy Code.
To schedule a Blower Door Test call Energy By Design at: 407-450-0295