Window Films: Low Hanging Fruit for Efficiency Gains

One of the easiest and most cost-effective ways to drive energy efficiency in buildings is improving the efficiency of their windows.

This is an area that is generating a lot of research and development. This week, The Energy Department’s Advanced Research Projects Agency-Energy (ARPA-E) announced $31 million in funding for 14 projects in the SHIELD (Single-Pane Highly Insulating Efficient Lucid Design) program.

The press release points out that single pane windows, which are common in industrial and commercial buildings, provide little insulation. Developing materials that can cut heat loss in half — the goal of the project — is preferable in many cases to costly replacement.

There is little downside to window film and other approaches that increase the efficiency of installed windows. Much is gained, and often the work and expense required is minimal. Michael Mancini, the Director of Marketing for Madico, offered a list of window film benefits at Facility Executive. First and foremost is saving money:

Up to 30% of any building’s cooling and heating load is through windows. Installing window film reduces the stress on a facility’s HVAC system. Many films block up to 80 percent of the sun’s heat, helping to cut cooling costs. Professionally installed window film can also reduce a facility’s heating needs in the winter by helping to maintain interior warmth. Over time, window film goes a long way in conserving energy for facilities of all sizes.

Mancini offers other reasons, such as window film’s shatterproof qualities and the protection it provides from UV radiation. For an energy manager, however, saving money by increased efficiency is the key.

Another sign of the government’s interest in improving window efficiency is ongoing research at the Lawrence Berkeley National Laboratory in Berkeley, CA. Earlier this year, the lab said that it is working on a heat-reflecting polymer that can be painted onto windows.

The goal is ambitious: The lab wants to make it possible to simply paint on a substance that will increase energy efficiency. The team working on the project – which received a $3.95 million award from ARPA-E – is headed by the University of Colorado Boulder. Caltech and Materia also are involved.

Research is not only leading to new products from the government. Earlier this year, 3M Thinsulate introduced 3M Sun Control Window Film, which takes the concept a step further than protecting inhabitants from excess heat and UV rays. It does that – but it extends the benefits to structures in cooler climes by reflecting interior heat away from the window and back into the building. By reducing drafts near the windows, the film helps keep the interior warm during the winter.

Window films and similar retrofit approaches are one way to reduce the waste that is flowing out through the sides of buildings. They are the least intrusive. Of course, rip and replacement of old windows with new has a higher upside, but the costs and inconvenience of going this route are far greater.

The evolution of the Internet of Things (IoT) is impacting everything – and windows are no exception. Sensors built into new windows or retrofit onto those already installed offer new dimensions in energy efficiency. Of course, such initiatives – whether done within a broader IoT project of not – include significant costs and broad planning.

Increasing the efficiency of windows seems a bit mundane. But it is a matter of scale: Buildings have lots of windows. Increasing the efficiency of each even a little bit can add up to big savings.

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