How Window Film Earns LEED Credits
1. Energy Performance Credits
Buildings that exceed the EPA ENERGY STAR rating of 60 required for certification can receive up to 10 LEED credits through additional energy efficiency improvements (LEED E&A Credit #1). The table below shows the LEED points that can be earned for an existing building based on additional energy efficiency improvements. Window film alone can provide from one to four LEED points in energy efficiency improvements, depending on the environment and the film installed.
2. Credit for Light Pollution Reduction
Light pollution reduction, also known as “Light Trespass”, is covered by Credit #7 under the “Sustainable Sites” goal. “Light Trespassing” occurs when lighting used within the building is visible at certain levels in the surrounding external environment. To qualify for this LEED credit, most of the internal light must fall within the building. Luminosity measurements are taken outdoors, with all lights off, and again with all the lights on. A LEED credit is achieved if the outdoor illumination level does not increase more than 10% than levels with the “lights on.”
Installing solar control window film will result in a lower amount of visible light transmission (VLT) through the windows. Window films have varying degrees of visible light transmission, and films with lower VLT ratings will greatly reduce light trespass from the building. When choosing a film, you can consider the amount of likely light trespass in advance and select specific films with a given target in mind. For example, Stainless Steel 50 can cut light trespass from a window in half.
3. Glare Reduction Credit
Under the Environmental Quality category (EQ #8.2), a credit can be achieved for “providing for glare control features for all windows where direct penetration of sunlight would interfere with normal occupant activities”. This is a goal that works in conjunction with the light pollution requirement in Sustainable Sites Credit 7 for “light trespass”. This requirement can be met by applying window films with a VLT low enough to meet occupant requirements for glare-free activity. For example, Stainless Steel 50, which reduces light trespass, will have the added benefit of glare
reduction. Applying this film can eliminate unwanted glare on computer screens and maintain an internal glare free environment, allowing you to pursue both “light trespass and glare reduction” credits in a single application.
4. Thermal Comfort
Improving and maintaining thermal comfort for one LEED Credit is an option under section EQ 7.1 of the certification program. The performance measurements are the same as those for the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 55-2004. ASHRAE 55-2004 is a thermal comfort standard that outlines requirements for documenting a space as appropriately thermally comfortable for the occupants. The credit can be met by demonstrating compliance with data logging temperatures (#184.108.40.206), or by survey, where at least 80% of building occupants must consider themselves comfortable in the building climate (#220.127.116.11). This includes mitigating “local discomfort” (#5.2.4) and reducing temperature variations with time (#5.2.5).
Solar heat transmitted through untreated windows is often the cause of local discomfort. Occupant complaints about excessive heat or hotspots can be completely mitigated by applying high performance, solar rejecting window films (as referenced in section #5.2.4). Solar control window film excels at moderating temperature variations over time, greatly improving thermal comfort (as referenced in #5.2.5).
5. Innovation Credits
There is also an innovation category for up to four extra LEED credits that you can apply for by making a case that a chosen building upgrade, not currently covered under the LEED for Existing Buildings standard, has improved the environment of the building.
There are two ways that window film can be used to apply for the innovation credits. One way is to apply for a credit based on the environmental benefits provided by blocking ultraviolet radiation through solar control window film. Window film blocks 99% or more of harmful UV A and UVB rays, which contribute to skin damage and skin cancer, and are the leading factor causing fading to interiors. A second eligible credit could be earned if fade reduction can be applied to reducing waste or improved building maintenance, as specified in the Materials and Resources section of the standard.