By Marge Padgitt
As people close up their homes for winter, sealing every open gap, and installing thermal windows and insulation, they may be doing more than making their home energy efficient. They might be doing things that can make their family ill.
Houses need at least six air exchanges per day, according to the Environmental Protection Agency. These air exchanges are necessary in order to move out tobacco smoke, Carbon Dioxide, Carbon Monoxide, Nitrogen Dioxide, Radon, and a host of other chemicals such as Formaldehyde that off-gas from furniture, carpet and woodwork. These air exchanges bring in fresh air for the occupants to breathe.
Exacerbating the problem are appliances that take air out of the house such as attic fans, range hoods, bathroom fans, clothes dryers, and central vacuums. If the house is tightly constructed replacement air needs to be introduced somehow.
Appliances such as furnaces, hot water heaters, fireplaces, and wood-burning stoves need air for combustion, and they take house air for this purpose. Open fireplaces are only -10 - +10% efficient, and use heated air from the home, causing the furnace to work harder. Even if an outside air source is supplied to a fireplace in an attempt to use less house air, this is often inadequate, and is not the best solution. Cold air dumped on a hot fire cools it down, causes it to burn inefficiently, and to produce more CO.
High-efficiency gas fireplace inserts are 75% + efficient and use no indoor air for combustion, and wood-burning fireplace inserts and freestanding stoves are 70%+ efficient and use much less air for combustion than traditional open fireplaces do. These are good choices whether a home has inadequate air for combustion or not. Other methods to improve fireplace efficiency include installation of glass doors, use of a grate heater, and improvement in design. A Rumford style fireplace is a better choice than a standard style fireplace because it uses less air and is more efficient. Efficient fireplaces or inserts use less wood than standard fireplaces to produce the same amount of heat, so an added benefit is lower energy cost.
Health effects associated with poor indoor air quality are unexplained flu-like symptoms, headaches, dizziness, fatigue, confusion, eye and nose irritation, and in more serious cases, inability to wake up, asthma, cancer, irreversible brain damage, or death.
Another problem that can occur in larger homes or homes that are tightly constructed is unbalanced house pressure. Symptoms of negative house pressure are moisture condensation on cold surfaces, smoking fireplaces or wood-burning stoves, difficulty lighting a fire in a fireplace, CO backup from gas and wood appliances, back-drafting of appliances (and CO), CO detector alarms frequently, and cold air infiltration through leaks. Children and pets may be more affected than adults. If a person feels ill when at home, but better when outside the home, this is an indication that something is wrong with the house.
A good solution is the PlusAire whole house ventilator, which mixes cool outside air with warm air before sending it on to the furnace and the rest of the house where it is used as combustion air and fresh air for the occupants to breathe.
Strategies to improve air quality:
- Install portable air cleaners
- Maintain humidifiers and dehumidifiers and empty water trays
- Replace air filters on schedule
- Turn on whole house fans or bathroom and kitchen fans with doors or windows open occasionally in Spring and Summer (not during cold weather)
- Install a heat recovery ventilator (HRV) to the furnace (assists the furnace only)
- Install a whole-house ventilator such as Plus-Aire to bring in make-up air for appliances and fresh air to breathe
- Install EPA Certified high-efficiency gas or wood-burning inserts in fireplaces
- Be sure clothes dryers are properly vented outdoors and vents are cleaned twice per year
- Use a vented gas space heater or stove rather than an un-vented gas appliance
- Never use kerosene heaters inside the house
- Have a trained licensed HVAC contractor clean and tune-up furnaces annually
- Have a professional CSIA Certified Chimney Sweep inspect and clean furnace, fireplace, masonry heater, and wood stove flues annually
- Have an energy specialist do a blower door test on the home, which will indicate leaking areas and negative pressure issues