Passive solar design principles have been incorporated into building design for thousands of years on every continent. Its sensible to take advantage of the sun’s warmth to heat a home in the winter and to minimize the sun’s heat in the summer – while taking advantage of natural ventilation and cool evening temperatures.
PASSIVE SOLAR PRINCIPLES
- Site Orientation: Site the structure so that the longest sides are aligned within 20 degrees of the east/west axis.
- Window Sizing and Placement: Install the most window area along the south side to let in the sunlight and warmth, less window area on the north side to let in subdued light and views while minimizing cold surfaces in the winter, and the least window area on the east and west sides to protect from glare and heat of the rising and setting sun.
- Overhang Sizing and Placement: Size overhangs to allow full direct sunlight into the home during the winter and little or no direct sunlight in the summer.
- Interior Thermal Mass Sizing and Placement: Size and place interior thermal mass to store the sun’s energy within the structure to prevent overheating during winter days and release the sun’s energy for night-time heating. Interior thermal mass also cools down with summer night-time ventilation and absorbs heat from the structure’s interior air during summer days.
- Room Layout: As a general rule of thumb, locate the most active rooms (family, kitchen, study, etc) on the south side of a structure, with morning active rooms (kitchen, breakfast nook, etc) on the east and active rooms in the center (family, living room, dining room, etc), and the least active or quiet rooms on the north or west (bedrooms, closets, utility rooms, bathrooms, etc).
- Ventilation: Ensure adequate natural ventilation for health and cooling by installing operable windows on the windward and leeward sides of the structure, and/or operable windows on different levels of the structure to create a chimney effect. If necessary, augment natural ventilation with ceiling or whole house fans.
- Insulation: Though insulation requirements are driven by climate zones, a good rule of thumb in high desert regions is minimum R-49 in the ceiling/roof and minimum R-27 in exterior walls to keep winter heat inside and summer heat outside.