This issue we are going to do a summary on heating systems.  This may seem to be a fall issue, but we are into the building season and hopefully this will help people decide what to use in new construction and be available as a reference when people turn on their heating systems in the fall.  Due to space limitations, we will simply be summarizing the key features to look for in a heating system.  It is advisable to seek additional information and advice to ensure the system you choose will meet your needs.  This article will not give you all the answers, but it should help you to ask the right questions.
 
     What follows are 5 key principles to keep in mind when looking at a heating system from the perspective of good indoor air quality, the rationale for each and some examples of how different heating systems rank according to each principle.

1. The heat source should operate at a low temperature.
     Anything which is heated will release contaminants into the air.  The higher the temperature of the heating source, the more it will cause dust and other particles hitting the surface to decompose, releasing even more contaminants into the air than those released when the dust is simply heated.

Normal Systems
· Electric baseboard
· Forced air: wood, coal, oil, natural gas, propane or electric with standard filters.
· Wood, coal or oil stoves.
· Fireplaces.

Better Systems
· Forces air: Heat pumps (when the electric backup is not on)
· Forced air: Hot water fan coil
· Hot water baseboard
· Low temperature electric baseboard

Best Systems
· Radiant floor, wall and ceiling systems.

2. No products of combustion should be released into the living space.
The emissions from burning fuels for heat are often a major source of pollution.  System design will affect how much of this pollution is released into the living space.

Problem Systems
· Coal stoves
· Wood stoves
· Portable gas, propane, or kerosene heaters
· Wood fireplaces
· Gas ranges (not ventilated to the outdoors)

Normal Systems
· Oil
· Natural gas
· Propane
· Pellet stoves
· Wood or coal stoves if isolated from the occupied spaces

Better Systems
· The normal systems if isolated from the occupied spaces by a sealed furnace room or preferably in a separate building

Best Systems
· Electric (as long as you are not living near a combustion fired power plant!)
· Solar

3. The system should not distribute pollutants from one area of the building to another.
Any system which distributes or allows movement of air from one part of a building to another will carry pollutants along with it, so that the air quality in the building will only be as good as that in the most contaminated room.

Normal Systems
· Forced air

Better Systems
· Forced air if no area in the system contains a pollutant source and the ducting is well sealed

Best Systems
· Base board heating
· Radiant floor, wall and ceiling systems
· Forced air if no area in the system contains a pollutant source, the ducting is well sealed, and the filters are upgraded to improve the air quality each time the air passes through the heating system

4. Heating Surfaces must always remain free from pollutants.
Due to the increased off-gassing of any heated surface, it is important that the finishes used on these areas be such that they will not become sources of pollution and also that these surfaces be kept free of dust and debris.

Problem Systems
· Radiant flooring if covered by materials such as carpeting or vinyl flooring

Normal Systems
· Portable gas, propane and kerosene heaters
· Wood, wood pellet and coal stoves
· Forced air systems
· Radiant floor, wall and ceiling systems with standard materials
· Baseboard heating systems

Better Systems
· Forced air systems with very good filtration
· Radiant systems with concrete or ceramic tile if it is kept clean and free from contaminant spills.
· Baseboard system if cleaned regularly

Best System
· Smooth surface baseboard (i.e. no fins) that is wiped down regularly

5. The energy source (i.e. fuel) should not be stored inside the building.
Exposure to most commonly used energy sources is hazardous to sensitive individuals.  This could be directly from the fuel itself or a “tag along” contaminant such as the moulds found on firewood.

Problem System
· Wood stored inside the house
· Fuel storage tanks inside the house

Normal Systems
· Fuel storage tanks inside the house but sealed from occupied spaces
· Coal or wood pellets stored inside the house
· Electric radiant (NOTE: Electric radiant systems may not be appropriate for those with electromagnetic sensitivities)

Better Systems
· Fuel storage tanks are outside the house and away from windows and air intakes
· Low electrical fields in highly occupied rooms (i.e. the electrical entrance is not near the bedrooms)

Best System
· Solar

Robin Barrett is a past president of AEHA NS Branch.  He has been involved in helping people create healthier housing since 1980.  In 1991 he started his own business, Healthy Homes Consulting.