The key building energy systems electrical loads are lighting, office equipment, heating and cooling systems. Most of the electricity is consumed in the lighting and cooling systems, however space and water heating can also be significant. 
Some of the key issues to consider in building energy use are the building's:
- Construction materials (glass areas, etc.) and orientation to the sun,
- Occupant use and maximum occupancy characteristics (especially time of day),
- Lighting levels and lamp source efficiency (which affects cooling loads),
- The time and seasonal value of fuel and power use in building design alternatives,
- Availability and price of water for potential cooling system use.
Most school facilities are designed for 20 or more years of use, so high quality construction should be emphasized. Since schools do not pay taxes, system design economics should reflect life cycle cost analysis for the best taxpayer value. And, not surprisingly, these life cycle costs have shown that the lowest equipment installed cost (i.e., lowest first cost) does not result in the lowest total cost (also called the lowest life-cycle cost). This is also why the higher first cost of geothermal heat pump systems is often considered an excellent investment over the life of the system in these applications.