How to Conserve Energy with Retractable Patio and Window Awnings.

For example, in Boston, awnings can reduce the need for cooling up to 33%

According to a study conducted by the American Society of Heating and Air Conditioning Engineers, solar radiation through glass is responsible for approximately 20% of the load on an air conditioner. Outside shade products like awnings prevent the solar radiation from penetrating through the glass and substantially increase energy saved when compared to film and tinted glass alternatives. According to the American Society of Heating and Air Conditioning Engineers, a fabric awning reduces heat gain by 55-65% during the period of the day when the sun shines directly on southern facing windows/glass doors. For western exposure, the reduction in heat gain is 72-77%.

Table 1: Equal Window Orientation

A new study, released in August 2007, found that awnings can provide significant savings on cooling costs and on peak electrical demand by reducing solar gain through home windows/glass doors. The study, Awnings in Residential Buildings: The Impact on Energy Use and Peak Demand, was funded by the Professional Awning Manufacturers Association (PAMA) and conducted by the Center for Sustainable Building Research at the University of Minnesota.

In the first phase of the study, awning impacts were measured in seven U.S. cities across various climates, including, Minneapolis, Boston, Seattle, Albuquerque, Phoenix, St. Louis and Sacramento. The study revealed that in all cities for all window orientations tested, there are significant energy savings in cooling costs and peak electricity demand as a result of using awnings. The range of energy saved varies, depending on the number of windows, types of glass in the windows and window orientation. The table above shows the savings with the majority of the windows facing the South side. To see the full results by city and by window orientation CLICK HERE.

Awnings not only save money for home owners but also contribute to a reduction in demand for energy, thus directly reducing the impact of global warming from greenhouse gas emissions.

According to Michelle Sahlin, Managing Director of PAMA: “When numerous homeowners reduce their need for energy, there is less demand for energy at the times of peak usage, resulting in overall savings to utility companies and the public from a decreased need to supply generating capacity.”

The energy savings benefit of retractable awnings extends beyond the summer season. The ability to retract the awnings in the winter (as opposed to fixed roof structures) allows the solar radiation to penetrate through the windows/glass doors, contributing to the heating of the house and reducing heating costs and energy.

In Europe, retractable awnings are used for many years to significantly reduce air-conditioning use in the summer. In the US, the demand for retractable awnings has grown significantly in the last decade and is expected to continue and grow as energy costs soar and as the awareness for the negative impacts of global warming increases.

References
1. “Awnings in Residential Buildings – The impact on Energy Use and Peak Demand” by John Carmody and Kerry Haglund, Center for Sustainable Building Research, University of Minnesota and Yu Joe Huang, Lawrence Berkeley National Laboratory, August 2007.
2. The Professional Awning Manufacturers Association websites, Roseville, Minnesota, February 2008.