Looking through (insulated) glass for energy savings

By Katie Schindall, MBA/MEM candidate, Yale University, 2009 Climate Corps fellow at Sodexo, member of Net Impact

Window film is cool stuff. Literally. It reflects the sun and insulates buildings. It is used to keep buildings cool on hot, sunny days, and to keep heat from escaping in cold climates.

According to an article published on FacilitiesNet in 2006, window film can reduce heat penetration up to 80 percent and improve insulation by as much as 32 percent for single-pane windows or as much as 23 percent for double-pane glass. Anecdotal evidence repeatedly notes increased employee comfort from the decreased solar glare and better insulation.

Given these benefits, several of this year’s Climate Corps fellows have been looking at the possibility of installing window film at our sites.

Our initial questions about good sources for information on performance have spawned a vibrant information exchange, with data and demonstrations all over the country. At one site, 3M is installing a sample section of window film to illustrate its impact on temperature. This demonstration should also provide an idea of what the film will look like and what the impact will be on the amount of light coming through the glass. Another Climate Corps fellow shared a model from her local utility that allows anyone with building information to estimate the cost and benefit of installing film at that site.

Why are we so concerned about the cost-benefit analysis?

Well, we’re MBA students, so that’s a start. But the bigger issue is that window film is expensive: I have seen estimates ranging from $3 to $12 per square foot (PG&E does a good job of providing some ranges).

This can stall the conversation in leased buildings where the tenant pays the energy bills. In long lease situations, this may not be a problem: 3M says it generally takes 2 to 6 years for the energy savings to pay back the initial investment. However, in situations like mine where there is uncertainty over how long the company will remain in the building and where there are a lot of windows, the return on investment will be critical.

We have had an initial assessment done for the buildings at my site, and I am eagerly awaiting the results. In the meantime, I’ll keep working on similar analyses for other options. As for most issues related to environmental sustainability, we will need to integrate several approaches to reducing our energy use if we want to be successful.

There are increasing rebates and tax incentives available to help defray the cost of window film; The Tax Incentives Assistance Project and the Database of State Incentives for Renewables & Efficiency are good places to start. Window film vendors – including 3M, Clear-Wall, Vista Window Film, and Llumar – also have information available. Please note: this is informational only and not meant to be comprehensive or seen as a recommendation of services.

This content is cross-posted at GreenBiz.com

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