Quick Answer
Retrofitting houses for passive solar involves strategic adjustments to the building's design, windows, and insulation to maximize natural light and heat gain during winter months and minimize heat gain during summer months.
Assessing Current Conditions
Before retrofitting a house for passive solar heating, it’s essential to assess its current conditions, including the orientation, size, and shape of the building, as well as the type and condition of its windows, insulation, and exterior finishes. This evaluation will help identify areas that can be improved to maximize passive solar potential. Consider factors such as the building’s solar path, which is the path the sun travels across the sky, and its latitude, to determine the best orientation for solar gain.
Design and Window Modifications
To optimize passive solar heating, consider making the following design and window modifications: install south-facing windows that are at least 10% of the building’s floor area, use low-E coatings to reduce heat loss, and add overhangs or awnings to block summer sun. A well-designed overhang can be 7-9 feet deep and extend 1-2 feet beyond the building’s facade to effectively block direct sunlight during summer. Additionally, consider installing thermal mass elements, such as concrete or masonry walls, which can absorb and release heat throughout the day.
Insulation and Air Tightness
Proper insulation and air tightness are crucial for a successful passive solar retrofit. Ensure that the building’s envelope is well-insulated, with a minimum of R-38 insulation in the attic and R-19 insulation in exterior walls. Seal any air leaks and add weatherstripping around doors and windows to prevent heat loss. A well-insulated and air-tight building will help retain heat gained through passive solar heating and reduce the need for supplemental heating.
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