Enhancing the Thermal Performance of the Building Envelope
Did you know about 30 percent of a home's heating energy is lost through windows? One surprisingly simple solution can lower that total energy loss by 40 percent
In cooling seasons, about 76 percent of sunlight that falls on standard double-pane windows enters to become heat.
Architects understand the importance of the building envelope, which is composed of vital elements such as the roof, walls, water-resistive and air barrier, sheathing, floor, doors, windows, and glazing. Together, these components embody the thermal mass within a structure, which can absorb, retain, and emit thermal energy, regulating the indoor thermal behavior of the building. But then you have windows — 10 to 15 of these gaping holes in an average home — interrupting that carefully constructed building envelope.
Window treatments, while often an afterthought in the design and specification process, can contribute to the performance of the building envelope in some pretty surprising ways:
Insulation: About 30 percent of a home's heating energy is lost through windows. In cooling seasons, about 76 percent of sunlight that falls on standard double-pane windows enters to become heat, according to the Department of Energy. Window treatments with insulative properties can help regulate temperature by reducing heat loss in the winter and heat gain in the summer. The insulating effect of window treatments can help reduce the load on HVAC systems and improve overall energy efficiency. Cellular shades, for example, have a honeycomb structure that traps air and provides excellent insulation.
Air Leakage: Air leakage around windows can significantly impact energy efficiency and indoor air quality. Properly installed window treatments can help reduce air leakage by sealing gaps and improving the air barrier. For example, window shades can be installed with side channels or tracks that prevent air from flowing around the sides of the shade.
Solar Heat Gain: Solar heat gain can cause discomfort and increase cooling loads, which means higher energy consumption. According to an article by Green Building Adviser unobstructed south-facing windows gain more heat than they lose, even in mid-winter, in almost all U.S. climates. Window treatments, such as blinds or shades, help control solar heat gain by reducing the amount of direct sunlight, and thus heat, that enters a space.
Cellular shades are a perfect example of a simple solution that can be integrated into an architect’s holistic approach toward enhancing the thermal performance of the building envelope. They have the potential to reduce heat loss through windows by 40 percent or more. This translates to approximately 10 percent savings in heating energy. During cooling seasons, these shades can effectively diminish the infiltration of undesired solar heat through windows by up to 60 percent. Consequently, when properly installed with a tight fit, they can curtail the total solar gain to just 20 percent.
Factoring window treatments into the building envelope design presents an opportunity to enhance the thermal performance of a structure. Architects who consider the integration of window treatments as an integral part of their design can unlock the potential for energy savings, improved occupant comfort, and a more sustainable built environment.
A&I proudly offers a robust line of cellular shades that offers energy efficiency, sound absorption, light and temperature control. To learn more, see samples, and download spec sheets, visit our cell shades page.
