Although thermal Trombe walls work well in all climates and for almost any home, you need to choose the correct design for your particular needs. This choice depends on your local climate. Here are some essential guidelines:
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The single most widely applicable passive solar design option is thermal or Trombe walls. The option works in every climate and every location, from the hottest and sunniest to the coldest and darkest. But like everything, Trombe walls have their disadvantages as well.
Sunspaces – especially those attached outside the main home – are extremely popular. However, like all things, you need to carefully consider the benefits and disadvantages rather than just jumping in and building one.
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:
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).
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.
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.
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.
Radiant floor installations rarely need more than seasonal adjustment. Typically, they are set up at the time of installation and just need to be switched on or off depending on the time of year.
At installation, the ball valve on the heat exchanger bypass stays about 1/3 closed at all times, forcing some of the hot solar fluid through the heat exchanger, but allowing most of it to go to the radiant floor heating (or shunt loop in the off-season).