Tips for Designing an Energy-Efficient Solar Home

How to build and insulate an energy-efficient solar house. Covers collection, storage, distribution, and retention of solar energy.


| February/March 1995



solar power

Passive solar energy can warm your home.


PHOTO: FOTOLIA/WENANI

To many, the concepts of a solar home and an energy-efficient home have been mutually exclusive; any home with sufficient south-facing glass to heat the interior had too much glass to be sufficiently insulated. All too many home designers and builders still labor under that misconception. An energy-efficient home can and should always incorporate solar principles into its design. Likewise, a solar home must be energy efficient to be practical. Jeff and Priscilla Dickenson knew this when they designed their new home in Carbondale, CO, and were determined to find some answers.

Although Rocky Mountain winters are notoriously cold, their house remains a comfortable 55°-75°F year round, using very little backup heat and no air conditioning whatsoever. The sun heats their home and the energy-efficient design works to store and distribute the heat slowly and continuously.

In designing their home, Jeff and Priscilla relied heavily upon four major energy factors: collection, storage, distribution, and retention.

"We built the house in the fashion of an Amish barn raising," Jeff reported. "with over 30 friends helping throughout. It's a very gratifying way to build, and adds so much life to the project."

Collection

The sun enters the home through a large surface area of vertical, south-facing, high-performance, direct-gain windows. These dramatically out perform older window designs in that they are several times more efficient at reducing heat loss. Conventional window designs actually lose two to three times more energy at night than they manage to collect all day, making all that south-facing glass, however well intentioned, an energy liability in both summer and winter months. Better designed windows work to amplify the sun's energy and retain that heat indoors for extended periods.

Storage

Thermal mass absorbs and stores heat when the sun shines and releases that heat during evenings or cooler periods. Such mass is the critical component of any passive solar energy storage design. The importance of this factor, however, has been seriously overestimated in the past. There is seldom need to fill all the south-facing walls with barrels of water, for instance, but this continues to be common practice in many areas. Dozens of barrels will require something just short of a nuclear explosion to heat. Too much mass, or mass in the wrong space is inefficient and expensive. Concrete, brick, adobe, stone, and drywall are all examples of material that can act as good thermal mass when applied appropriately.





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