What is a Sun-Tempered Home?

You are here

As you research passive solar home design, you may run into the term "sun-tempered" for homes. A sun-tempered home is a sort of "halfway house" option, rather than the whole-hog option of true passive solar design. Let's look at how the two compare:

Passive solar homes

A true passive solar home captures and uses far more solar energy than a sun-tempered design ever will. It does this by aligning the home along an east-west axis, so that the long wall faces the sun in true south. Window surface area is concentrated on the south side of the building and limited on the north, east and west.

Thermal mass is used extensively in passive solar homes, and must be carefully positioned to maximize the amount of energy it absorbs. Room design and layout is affected because of this and many passive solar homes use an open plan design for better air flow and heat transfer.

A true passive solar home can easily provide between 50% and 80% of a home's annual heating demand, depending on design, construction, availability of sunlight and the local climate.

Sun-tempered homes

Sun-tempering means making small changes to a home to maximize incidental solar gain. This means orienting the long wall to true south (so the home is on an east-west axis) and moderately increasing the window surface area along the south side. This is usually achieved by moving windows which would normally be placed on the other sides of the house, so no extra construction cost is incurred on new builds.

Thermal mass inside the building is not affected. The existing mass usually provides sufficient storage to prevent overheating and make the home comfortable. No extra insulation is needed beyond the building code standard, assuming the standard is good, although it can be boosted to provide extra returns on the sun's input.

As new builds, sun-tempered homes rarely cost more than a standard build, but provide substantial benefits. With very little effort at the construction stage, a sun-tempered home can provide 20% to 30% of the annual heating requirement from passive solar, again depending on design, construction, availability of sunlight and the local climate.

A sun-tempered home is an excellent choice for a prospective homeowner who wants to go for energy efficiency but isn't ready for – or cannot afford – the full-on passive solar choice.