Designed by Thad Johnson of Solar Terra (Williams, AZ) and built by Isaac Page of Bristlecone Builders (Flagstaff, AZ), our home is designed to stay cool in summer and warm in winter. Our passive solar home design incorporates a variety of features that enhance energy efficiency and sustainability. Some key elements include:
- Orientation, Window Placement, and U Values: The house is oriented with the longest side facing south, maximizing exposure to sunlight, which is crucial for winter heating. Strategic window placement allows for maximum solar gain in the winter and minimizes heat entry in the summer. Further, our south-facing windows have low U-values that allow for high solar heat gain, something we needed special permitting permission to do. The south-facing walls are tall, accommodating clerestory windows that allow light all the way to the back (north) side of the interior in chilly winter months.
- Sustainable Building Materials: The use of insulating composite concrete forms (ICCF) blocks, made from recycled materials, contributes to the home’s resilience and sustainability. Manufactured by The Perfect Block in Gilbert, AZ, these blocks provide excellent insulation and are resistant to fire, storms, and earthquakes.
- Thermal Mass: Materials that absorb, store, and evenly distribute heat help regulate indoor temperatures by absorbing heat during the day and releasing it at night. Our home has concrete floors throughout, and several concrete block walls strategically placed to act as thermal mass. The ICCF block walls also capture, store, and distribute heat.
- Shading and Overhangs: Overhangs provide shade during the summer months, reducing cooling needs by preventing excessive sunlight from entering the house. The size and placement of the overhangs also allows sunlight to penetrate the south-facing windows in winter and are strategically placed so that sunlight heats up the concrete floors and thermal mass block walls.
- White Metal Roof: Although a gray roof might enhance our home’s aesthetic appeal, a white roof offers significant benefits in terms of energy efficiency. Its high reflectivity can lower indoor temperatures up to seven degrees, which is particularly advantageous during the summer months, potentially reducing cooling costs and improving comfort. Installing a metal roof allows us to harvest rainwater and snowmelt (see my January 16 post on rainwater harvesting).
- Airtight Building Envelope and Insulation: Creating an airtight seal and using highly rated insulation ensures that our home maintains its temperature, reducing the need for additional heating or cooling.
Passive solar design orients the longest dimension of the house so that it faces south and strategically places many windows on the south side to capture solar heat in the winter. Long overhangs on the southside shade windows in summer. The white metal roof reflects summer heat, keeping the home cool when it the hot summer sun shines on the roof all day.
Inside the house several block walls provide additional thermal mass.
The large windows on the southside plus the clerestory windows up high allow light to penetrate all the way to the back (north) wall of the building, reducing the need for electrical lighting during the day, and keeping the main living spaces of the house warm even in winter.
A solid concrete floor acts as thermal mass throughout the house helping to regulate indoor temperature even in extreme outdoor weather conditions.
The ICCF is reinforced with rebar both vertically and horizontally before it is filled with concrete. The walls create a building highly resilient to wind, fire, and pests, while also providing one of the highest wall insulation values available.