Widespread research links windows to three of the most important factors in occupant comfort and productivity, including access to daylight and views, thermal comfort (temperatures that are not too hot or cold), and visual comfort (good lighting that is free of glare).
Commercial window attachments – such as shades, blinds, external shades, shutters, and awnings; and secondary windows – enhance these positive effects on occupant comfort. That’s important, because when people feel more comfortable, they perform better. Studies have documented significant improvements related to occupant comfort across a number of industries including retail and education as a result of increased daylighting and optimized thermal comfort.
In addition to helping boost productivity, various types of window attachments can also improve the performance of the glazing systems themselves by:
- Managing solar heat gain
- Insulating the window system to reduce air movement
- Correcting glare
- Reducing cooling and/or heating loads
Such effects are critical for a sustainable future, because windows account for a huge amount of energy use. A 2010 study by the DOE linked commercial windows to 1.88 quadrillion BTUs of heating energy use and to 3.86 quadrillion BTUs of cooling energy use – or nearly 9% of all energy use by commercial buildings. Window attachments can offer an affordable and effective option to reduce that use in both new construction and in retrofit applications.
When considering window attachment systems, ratings such as AERC certification and other standards from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and the National Fenestration Rating Council (NFRC) can help design teams specify performance criteria. Other tools, including free software from LBNL such as COMFEN, Berkeley Lab WINDOW, EnergyPlus, and RADIANCE, can help evaluate alternatives and illustrate benefits. Manufacturers who offer commercial solutions – including several AERC member companies – also provide extensive resources to support design of window attachment systems.