Natural Ways to Heat & Cool
Keep Warm & Stay Cool
You can create an environment that controls the temperature in your home – without using electrical equipment like A/Cs, heaters or fans.
Heat Loss: Convection
Your home can lose heat through convection – or air movement. As warmer air rises up and out of chimneys and poorly sealed attics, cooler air is drawn in from the basement and gaps around windows, doors, and other openings in your home. By controlling convection in a room, you can maintain comfortable temperatures without mechanically pumping in warm air.
Heat Gain: Radiation
A dark roof on a hot, sunny day will absorb 70% to 90% of the sun’s energy and re-radiate this into your home.1 Without adequate ventilation or insulation in the attic, this heat gain can add approximately 40% to the cooling load of your A/C.2 Heat from your body also radiates off you in chilly weather, which can make you feel cold when you are in a poorly insulated room or near a window that is not properly sealed.
Heat Loss & Gain: Conduction
Heat also moves out of your home via conduction – the transfer of heat caused by a temperature difference between solid objects. Adding insulation may help to reduce conduction loss through your home’s exterior walls, roof, and foundation. Maintaining windows is also important to reduce conduction. Conduction causes heat loss through the glass and frame, and air can leak around the edges of the assembly. Objects and people inside the building can also radiate heat toward windows.
Passive Heating & Cooling Measures
Passive measures can help control the amount of heat gain or loss in your home without using electrical equipment like A/Cs, heaters, or fans. You should always implement passive measures before you invest in new cooling or heating equipment. By reducing your cooling or heating load, you can save money by purchasing smaller cooling or heating systems.
These measures also help extend the life of your cooling or heating system. The most effective passive cooling and heating measures, in order of increasing cost, are:3
Open windows at night to cool your home by flushing out heat and moisture that accumulates in the home during the day.
Indoor heat reduction:
Use energy-efficient light bulbs, reduce hot water use, use smaller and more efficient appliances, and schedule heat-producing tasks — like clothes drying — for cooler hours of the day.
Insulation and weatherization:
Window shading and glazing:
Solar radiation passing through windows can contribute up to 20% of heat gain in hot and humid climates.4 Window shading devices and glazing technologies minimize heat gain, while transmitting daylight — reducing the need for electrical lighting.
Cool roofs and attic ventilation:
These are two effective ways to reduce heat gain by either reflecting heat away from the roof with special cool roof materials, or flushing heat out through the attic using vents and fans.
Trees and landscaping:
Plant broad, leafy shade trees to block the sun and reduce the amount of solar radiation absorbed into the house. Trees are water-intensive to grow in dry or desert climates, so choose trees that are native to California or drought resistant.
Solar energy admitted into the home through south-facing windows can collect and store in floors, walls, fireplaces, and other structures with high thermal mass, like those made from masonry or concrete. These and other dense materials like stone, adobe, and water absorb and store excess heat then release it slowly — providing cooling and heating when needed. According to Rocky Mountain Institute, a well-designed passive solar home can hold a constant interior temperature of 68ºF to 70ºF, with minimal supplemental heating and cooling throughout the day.5
Content in part adapted with permission from Rocky Mountain Institute’s Home Energy Briefs.
 Yardi, Ramola, Wang, K., Smith, A. (2004). Home Energy Briefs: #1 Building Envelope. Snowmass: Rocky Mountain Institute. Retrieved September 28, 2012, from http://www.rmi.org/rmi/pid217 (p. 1).
 Yardi, Ramola, Wang, K., Smith, A. (2004). Home Energy Briefs: #3 Space Cooling. Snowmass: Rocky Mountain Institute. Retrieved September 28, 2012, from http://www.rmi.org/rmi/pid217 (p. 1).
 Ibid (p. 2).
 Yardi, Ramola, Archambault, T., Wang, K., Eubank, H. (2004). Home Energy Briefs: #9 Whole System Design. Snowmass: Rocky Mountain Institute. Retrieved October 4, 2012, from http://www.rmi.org/rmi/pid217 (p. 3).
This program is funded by California utility customers and administered by Southern California Edison under the auspices of the California Public Utilities Commission.