This stage also serves as a model for on-going monitoring of the systems and the basis for a proactive preventative maintenance program once upgrades have been installed on the more complex mechanical systems. Frequent review may uncover additional opportunities for energy savings. The building envelope can yield tremendous opportunities for additional load reductions on the mechanical system. Installing window film, weather stripping to seal windows and doors, roof and wall insulation, and energy-efficient office equipment can further contribute to significant reductions in heating and cooling loads. Window film is a metallic-based polymer film that is attached to the inside glass to reflect solar heat gain away from the building.
Many films also have a higher insulation factor that retards the loss of heat in the winter.
Additionally, improved insulation will further retard the loss of heat in a building. By completing the load reductions in stages 1-3, the savings opportunities are increased due to the reduced load on the mechanical systems. This stage is the culmination for the previous load reductions in stages 1-4. Heating and cooling for most buildings is accomplished by chillers, boilers, or packaged direct-expansion systems. Most of the load reductions obtained through the previous four stages benefit the cooling side.