High Reflectivity Film
Because of high reflectivity film’s permanence, the DOE suggests using it in climates with short winters. The film reduces heat gain the entire year, including in winter months, which might actually benefit from solar heat.
Silver, mirror-like film works better than more transparent film. High reflectivity film works well on very large windows, like on the garage here, where cool temperatures are desirable.
Ideal locations: East- and west-facing windows.
Best uses: Reducing solar heat gain all year round.