Passive solar
Passive solar simply means allowing heat from the sun to enter your home directly and heating it (for free)! South-facing windows made of a standard thermal-pane glass allow the maximum amount of sunlight to come in during the day. The trick is to orient your home and windows to capture sunlight when you want it (positive solar gain) and not when you don't (which would be negative solar gain). Proper location, overhangs, and east- and west shading are used to keep unwanted sun out. At night, special blinds can be drawn over the windows to prevent heat loss (or in the summer, they can be opened at night and shut during the day to maximize cooling).
Passive solar is not generally sufficient to heat an entire house (unless you build quite small, which is a great idea). It must be coupled with sufficient mass to be effective, and can be complemented with the other two heating methods below.
Solar thermal panels and hydronic systems
This thermal system gathers heat directly from the sun in simple panels usually made of aluminum, copper, and glass. These are typically installed on the ground, though they can sometimes be placed on top of (or preferably as part of) the roof. The panels are tilted toward the south and the sun's heat is absorbed into a liquid mixture (or less commonly an air chamber). This liquid is then circulated through your home via a hydronic system. This is a system of pipes laid directly under your floor (above your earth-mass) to provide in-floor heating, which will radiate up into the home. The heated pipes can also be used to heat domestic hot water.
Solar thermal panels are not to be confused with photovoltaic panels which produce electricity. In theory, the heat from solar thermal panels could also be used to produce electrical energy, but this has not yet become practical.
Masonry mass stoves
Masonry mass stoves have been used around the world for thousands of years. Unlike an ordinary wood-burning stove, mass stoves have a combustion chamber with full open air access for a very clean, very efficient burn. In ordinary stoves this would give off too much heat too fast and overheat the building. In a mass stove, the heat must first move through a twisted chamber inside the large brick mass. This mass absorbs the heat, which then radiates slowly into the home. By the time a tiny amount of smoke exits the chimney, most of its heat has already been stored inside your home.
Almost all of the masonry mass stoves we build incorporate an oven and a large heated bench, both warmed by the same few logs that heat your home.
The above heating methods can sometimes be retrofitted onto older homes, but have limited effect due to their reliance on total house mass (which conventional housing has very little of).
For information on other ways to save energy and how to make your older home more efficient, please visit our page on lifestyle choices.
