How window film can now enhance indoor air quality.

Today's indoor building management challenge includes dealing with high indoor temperatures, stale, under-ventilated and circulated air, moisture and mold growth, off-gassing of furniture and building components and the impact of such conditions on the productivity and health of building occupants.

Sick building syndrome not only threatens building occupants, it can result in litigation that threatens the bottom-line of employers and building owners alike. Ironically, many of the measures taken to increase energy efficiency such as "tightening" buildings to reduce both air infiltration and outflow have degraded a building's air quality.

Building managers must understand how light and heat through existing glass can impact a building's environment. Knowing how glass performs will make clear the role of window film in mitigating the ability of glass to negatively impact the indoor environment.

According to the California Energy Commission, 30% of a building's cooling requirements is from heat entering through existing windows. Yet, reducing heat in a building is usually considered to be an exclusive HVAC function.

As a supplement to HVAC, stopping heat at the window using heat-blocking window film, can not only reduce air conditioning operating frequency and cost, but can also placate many building occupants who believe "conditioned" air is less desirable to work or live in than non-conditioned air.

The most recent window film installation at Stanford University took place at Encina Hall in 1998. Some 6,212 s/f of spectrally selective window film was applied in June, 2003. Spectrally selective film blocks solar heat while simultaneously transmiting natural light. As a result of the film's installation, Encina Hall now enjoys an annual savings in A/C cost of $4,891.95.

Unfortunately, conventional window film blocks so much natural light it darkens building interiors often resulting in the need for additional artificial illumination that can often generate more heat. Ultimately, in many buildings this requires the use of more air conditioning which defeats the purpose of installing heat-reducing window film.

Not only does conventional window film block natural light resulting in increased artificial illumination, the denial of natural light to building occupants negatively impacts their productivity and well being according to studies conducted by the California Energy Commission, the US Department of Energy, and elsewhere.

Fortunately it is possible to select window film that will block significant amounts of solar heat entering a building without reducing desired levels of natural light. Spectrally selective film, such as the type used in buildings at Stanford University, the University of Colorado at Boulder and the headquarters of the American Institute of Architects in Washington, DC transmits natural light while blocking the heat that can exacerbate out gassing, mold formation and sick building syndrome.

The quality of the indoor air depends on selecting furnishings and building components that will not out gas and in preventing the formation of condensation and humidity in sufficient amounts to cause mold. Most significantly, a strategy to manage a building's environment must rely on an adequate HVAC system whose ability to reduce heat is aided by the simultaneous implementation of appropriate heat-blocking window film and other relevant methods to both save energy and enhance environmental quality. Only when a multitude of systems function in an integrated and orchestrated approach will positive results be achieved and maintained. In such a program window film will play an increasingly important role.