Passive Solar Design Basics

Plan a comfortable, energy-efficient home that saves you money on heating and cooling with these passive solar design basics.


| June/July 2012



Solar Living Room

The great room of the Myers home is designed to let in plenty of sun in the winter, while blocking it in the summer.

PHOTO: DAVID WRIGHT

Passive solar design begins with the simple idea that you can build a house that uses natural heating, cooling, ventilation and daylighting. These homes require much less fossil fuel energy to heat and cool than conventional homes do, which is better for the environment and saves passive solar homeowners money. Passive solar homes are comfortable to live in because they are designed to radiate heat in winter, maintain a comfortable year-round temperature, ventilate naturally, and let in plenty of natural light.

I became interested in sustainable design, specifically passive solar design, as a young architect — first while working in the Peace Corps in Africa, and later while working professionally in New Mexico. The details of any particular passive solar home design depend on the climate and the specifics of the site. Over the course of my 35-year career, I’ve designed a variety of passive solar houses throughout the country using different configurations of south-facing windows, sunrooms and other passive solar design features. (For specifics on one of them, read “The Western Solar Farmhouse: A Passive Solar Design” near the end of the article) What follows are the principles used to design any passive solar home.

Passive Solar Design: House Orientation and Window Placement

The first consideration for optimizing passive solar energy is to select a house site with adequate solar exposure. For solar heating in winter, a good measure of solar exposure is to have at least four hours of direct solar gain on the winter solstice. The best orientation is to have the “solar” side of the house face within 15 degrees of true south. In climates where summer heat is a major concern, it’s a good idea to aim the solar windows a little east of south to get morning sun in winter and avoid the intense western sun in the warm season.

Typically, you would locate the day-use rooms, such as a living room or family room, on the south portion of the home’s floor plan to allow the greatest amount of solar energy to penetrate these rooms on winter days. This layout also allows you to take advantage of the sunlight and view of the outdoors.

The “shell” of the house is composed of exterior insulated walls and “glazing,” or windows. In a conventional home, the window area is equally distributed on all four sides of the home, or the majority of the window area may be focused on the direction with the best view. For a passive solar design, one would locate more of the window area on the south side, which has the best solar access. Some windows would be placed on the east and west sides of the house for daylighting and cross-ventilation with only a few windows to the north.

The glazing is important. Choose high-quality, tightly constructed windows to reduce air infiltration. At a minimum, use double-insulated glass. Some of my favorite high-quality windows are Loewen metal-clad wood windows, but all-vinyl windows are more economical and perform well. Double glazing is adequate for most climates, although in locations with severe winter conditions, triple glazing is advisable to reduce heat loss and condensation on the glass.

alexes
1/12/2016 2:08:46 PM

How much would it cost to build this home?


steven eyring
6/5/2012 4:42:35 AM

I enjoyed the article, very helpful overview of solar design. In doing some additional reading about passive solar design I read about the " solar slab". In his book "The Passive Solar House", author James Kachadorian proposes an innovative way to rearrange the building materials of your house to construct a highly effective passive solar slab. I am wondering has anyone had any hands on experience building with a solar slab?






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