How to Stay Cool while Saving Energy

The guide outlines three primary passive strategies for maintaining cool indoor temperatures: preventing heat gain through shading and reflective materials, utilizing natural ventilation like 'night flushes', and improving interior comfort with air movement and thermal mass. For active cooling, it recommends high-efficiency options such as ductless heat pumps and heat recovery ventilators (HRVs). The document illustrates these principles through two case studies in Colorado, demonstrating how super insulation, solar PV, and passive design can maintain comfortable indoor temperatures without traditional air conditioning during extreme heat.

• Passive cooling can be achieved through three main steps: protecting the home from heat gain, utilizing natural ventilation, and using cooler interior surfaces.
• Heat gain can be mitigated by shading southern and western sides of the house with plants, using light-colored building facades to reflect radiation, installing Energy Star rated windows with overhangs or light-colored interior shades, and venting heat from stoves and showers.
• In regions with large diurnal temperature swings, a "night flush"—opening windows at night and closing them in the morning—is an effective way to bring in cool air and vent warm air, provided the outside air is clean.
• When active cooling is necessary, the most efficient options include evaporative coolers for dry climates, ductless heat pump systems for all climates, and heat recovery ventilators (HRVs) to precool and dehumidify incoming fresh air.
• Case studies in Colorado demonstrate that combining super insulation (such as straw bales with R-values of R-30 to R-45), thermal mass (adobe floors and natural plaster), and solar PV can allow homes to remain cool without air conditioning even when outdoor temperatures exceed 100°F.

APA

RMI (2020). How to Stay Cool while Saving Energy. https://rmi.org/resources/how-to-stay-cool-while-saving-energy/

Chicago

RMI. How to Stay Cool while Saving Energy. 2020. https://rmi.org/resources/how-to-stay-cool-while-saving-energy/.

Wikipedia

{{cite report |author=RMI |title=How to Stay Cool while Saving Energy |date=19 August 2020 |url=https://rmi.org/resources/how-to-stay-cool-while-saving-energy/ |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{rmi2020how, author = {{RMI}}, title = {{How to Stay Cool while Saving Energy}}, institution = {RMI}, year = {2020}, month = aug, url = {https://rmi.org/resources/how-to-stay-cool-while-saving-energy/}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }