Almost every passive solar building has a backup heating system, whether it's really needed or not. It is possible to design a passive solar home that heats itself, but it may not pass local building regulations. It will also be very hard to sell, as most home buyers simply won't believe that the house needs no heater other than the sun!
There are five options commonly available as backup heating for passive solar homes:
If your home's air pollution problems cannot be completely solved by eliminating and isolating sources of pollutants, you will need to install some kind of air filter. Whether that is a small, portable unit for occasional use or a large, whole-house ventilation system depends on how bad the problem is.
It is one of life's cruel ironies that the most common heating system in the USA is also one of the least environmentally friendly. Forced-air heating installations are present in over 60% of homes in the country. Of course, some are better than others – these systems have heat generated by solar thermal systems, heat pumps, and furnaces of all types (oil-fired, gas-fired, electric, or wood).
If your home needs air filters to remove airborne pollutants, you should consider very carefully which model you buy. It needs to be big enough, efficient enough, and also good enough to remove problem particles if a home's inhabitants are asthmatic or allergic.
Regardless of what kind of backup heating system you put in your passive solar home – forced-air, radiant floor, baseboard hot-water, or something else – you're going to need a source of heat. And that means a high-efficiency boiler or furnace.
That title might fill you with apprehension and, in many ways, you'd be right: analyzing such a complex thing as a home's energy performance without using software is a daunting task. But it is possible. There are even several books which include worksheets and detailed descriptions of how to build a more accurate assessment than the one we'll outline here.
If your passive solar home is properly designed and everything is optimized, one of the most cost-effective backup heating systems available may be wall-mounted space heaters. For homes which only need an occasional top-up of heat or for infrequently-used rooms, they are ideal.
Analyzing your passive solar home's energy performance by hand is long-winded, cumbersome, and prone to error. Between ten and twenty years ago, a variety of software tools appeared on the market, ranging from DOS-based utilities to basic Windows apps.
Over time, most of these programs have disappeared. Some were discontinued because they weren't popular enough, some vanished because they were based on obsolete operating systems, and others were simply discontinued through lack of support.
Modern wood stoves are not simple metal boxes to burn fuel in. They are much more efficient than traditional fireplaces and can be just as attractive. Stoves also rely on a renewable source of energy. Most modern wood stoves fit into one of two categories: radiant or circulating.
Designing a passive solar home is not the end of the road for sustainability. There are many more choices you can make to improve your home's sustainability and, at the same time, reduce the impact of traditional living on the environment.
