This stage also serves as a model for on-going monitoring of the systems and the basis for a proactive preventive 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. Measures such as window film, weather stripping to seal windows and doors, roof and wall insulation and purchasing more energy-efficient office equipment can further contribute to significant reductions in heating and cooling loads. Window films are a metallic-based polymer film that is attached to the inside glass, reflecting solar heat gain away from the building.
Many films 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. The average building ventilation system is 38 percent larger than necessary. Considering that ventilation systems can account for up to 30 percent of the energy use in a building, there is a huge potential for savings in reducing ventilation systems that are too large. By completing the load reductions in stages one through three, the savings opportunities are increased due to the reduced load on the mechanical systems. This stage is the culmination of the previous load reductions in stages one through four.