Passive Solar Home Principles

Beginner

Inside this Article

Beautiful passive solar home
Passive solar homes do not have to be strictly utilitarian, they can be built with modern design and architecture.
Ancient cliff dwellings
Time-tested passive solar design: The ancient Mesa Verde residents built cliff dwellings that took advantage of passive solar gain.
Early passive solar attempt
Early passive solar designs set the stage for the technology but also suffered from design errors, including excessive glazing area, lack of overhangs, and sloped glazing.
Balance of thermal mass & glazing
Balancing thermal mass and glazing is the key to moderating solar-gain temperature swings.
Shows overhang
Everyone knows a solar house needs south-facing windows. But a lesser-known important element is properly designed overhangs or exterior shade structures that shade those windows from the high-angled summer sun, while allowing low-angled winter sun to enter.
Shows awning for shade
Everyone knows a solar house needs south-facing windows. But a lesser-known important element is properly designed overhangs or exterior shade structures that shade those windows from the high-angled summer sun, while allowing low-angled winter sun to enter.
Sun Paths
Sun-paths for your location will display the sun’s altitude and azimuth for the entire year. This is valuable for determining your available solar exposure for any orientation; specific obstructions can be sketched in. Notice, for example, how the winter solstice noon sun in Portland, Maine (left), is only 22.5° above the horizon, while in Fort Worth, Texas, on the same day, the noon sun is at 34°. Generate a sun chart for your location using the University of Oregon calculator at bit.ly/UOsuncharts.
Traditional homes can be made passive
Traditional designs can accommodate passive solar strategies if the proper orientation and adequate south-facing glazing is maintained.
Avoid north-facing glazing
As important as adequate south-facing glazing is minimizing glazing on the north side to reduce heat losses through the home’s envelope.
Illustration of proper orientation
The dos and don'ts of building orientation for passive solar.
Room placement
Placing rooms to take advantage of solar gain.
Home with screened porch
A west-end screened porch provides some protection from the afternoon sun, helping to prevent overheating and reduce summertime cooling loads.
Beautiful passive solar home
Ancient cliff dwellings
Early passive solar attempt
Balance of thermal mass & glazing
Shows overhang
Shows awning for shade
Sun Paths
Traditional homes can be made passive
Avoid north-facing glazing
Illustration of proper orientation
Room placement
Home with screened porch

Implementing solar design principles can slash heating and cooling bills, reducing the size of the renewable energy system you’d need. This article, the first of three, covers siting, orientation, building shape, and room placement.

Solar installer Bristol Stickney wistfully remembers passive solar conferences in the 1970s that drew hundreds of building tradespeople—all excited about building houses that derived a big part of their space heating from the sun. He had to look only as far as Mesa Verde, the spectacular Pueblo settlement in southern Colorado, to see how long passive solar has been in use. Those solar advocates of 40 years ago thought the ideas were finally making it into the building mainstream.

But passive solar design never reached its full potential—politics, cheap utility energy, and missteps by early passive solar practitioners helped cause the passive solar movement to lose its zip. Now, when people talk about “solar,” says Stickney, an industry veteran based in Santa Fe, New Mexico, they usually mean rooftop PV modules that produce electricity, not the building practices that allow homeowners to reap free heating from the sun.

Despite its second-class status, passive solar works—and well. The passive solar vanguards were correct—even in northern climates, a well-designed passive solar house will reduce a home’s energy costs. And unlike technologies such as ground-source heat pumps or PV arrays, many passive-solar features add little or no construction cost.

Basic Building Blocks

Passive solar design includes practices that help keep buildings cool in summer as well as warm in winter—something that early solar designers struggled to master. “A good passive solar house provides comfort no matter what the weather,” Stickney says. “In the past, a lot of passive solar houses had too much glass and would overheat when it was sunny and the weather was mild. It would get too hot in the spring and fall, but not hot enough in winter.”

Designers have since learned how to deal more effectively with that challenge. But any good design is site-specific, since each building site has its own weather and temperature patterns, as well as a unique topography that affects heating and cooling. A passive solar house designed for the high deserts of New Mexico might be pretty uncomfortable if transferred to coastal Maine. The house design must match its site.

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