Indoor Air Quality (IAQ) is a term used to describe the quality of air in the home as it relates to the health and comfort of the occupants. Indoor pollutants like dust, mold, bacteria, carbon monoxide, radon and Volatile Organic Compounds (VOCs) all have adverse effects on IAQ. The following are some of the methods we use to enhance the IAQ of our homes.
The system fan located in the furnace is set to periodically circulate the air in the home. The air passes through a large filter that has a Minimum Efficiency Reporting Value (MERV) of 10. The pleated filter is 5 inches thick to give it increased surface area so that it does not have to be changed as often and to prevent it from degrading system performance.
The HRV is the heart of the whole house ventilation system that provides a steady supply of fresh, filtered air to the home. Most new homes do not require a ventilation system since they are so leaky. This uncontrolled leakage can result in humidity control problems and contamination of the indoor air.
The HRV uses a small variable speed fan to bring in fresh air from outside while exhausting stale indoor air outside. It filters the air it brings in and uses a heat exchanger to condition this air with the air it exhausts. The heat exchanger operates at an efficiency of 78%. The fan system has multiple speeds and is meant to run on low most of the time, though it can be manually set higher when guests are over or more fresh air is desired. Even when this fan is run at full speed, this home will average far less leakage than a normal new home.
Ezell-Morgan uses carpeting that carries the Carpet and Rug Institute’s Green Label to improve the indoor air quality of their homes. This label signifies that CRI has certified that the product emits very low quantities of Volatile Organic Compounds.
The Environmental Protection Agency (EPA) estimates that radon is responsible for about 21,000 lung cancer deaths each year. Since Douglas County is located within a zone of high radon concentration, Ezell-Morgan installs a passive radon mitigation system in all their homes. The homes are then tested upon completion to ensure that the concentration of radon is within EPA acceptable levels. If not, Ezell-Morgan will upgrade the passive system to an active radon mitigation system at no additional charge to the owner.
Carbon monoxide is an odorless, colorless gas that is highly toxic. For this reason all the combustion appliances installed in Ezell-Morgan homes are either direct-vent or power-vented to prevent CO from contaminating indoor air. Even so, Ezell-Morgan still includes carbon monoxide detectors outside each group of bedrooms. These are combination fire and CO detectors and are a small price to pay for the extra margin of safety.
Normal water heaters have open flues that rely on the heat of combustion to create a draft to carry the exhaust up the flue. If a large fan, like the one on a clothes dryer, is pushing air out of the home, it can create a vacuum that will pull replacement air down the open water heater flue carrrying noxious gases into the home. This process is called “back drafting” which is especially problematic in airtight homes.
For this reason, Ezell Morgan will not use atmospherically-vented gas appliances in their homes. The water heater is either placed in the garage with an additional insulating blanket or a direct-vent water heater is used where combustion gases are isolated from interior air.
The underside of the concrete basement floor in our homes feature a thick plastic vapor barrier. This barrier prevents moisture from moving through the concrete into the basement by a process called diffusion. This moisture can breakdown the adhesives used on floor covering and rot padding and the backing on carpet. Vapor diffusion is one of the leading causes of poor indoor air quality.
Ezell-Morgan always vents their range hoods or over range microwaves directly to outdoors. Many builders simply route exhaust through a “filter” and back into the home.