It may come as a surprise, but most schools and classroom buildings are unoccupied more than 80% of the year! This assumes they are open 9 months a year and 9 hrs each week day. This leaves a lot of time when energy might be wasted by things being left on when they shouldn't. Plus corrections made during unoccupied times won't draw any complaints from the occupants.
Improvements that can save money during these times include automatic temperature set-up or back, turning down or off water heating equipment, and making sure indoor and outdoor lights are used appropriately and only as needed. But be careful. In some buildings turning off the indoor lights may increase the heating energy use.
Use the pie charts shown here as a guide for how a typical school uses electricity and natural gas. Notice lighting and HVAC are almost 90% of the electric use, and space and water heating comprise about the same percentage of natural gas use. A small improvement in a large energy user will probably create more savings than a large improvement to a small energy using system. So it just makes good sense to focus first on the lighting, HVAC and water heating systems.
One quick way to get a feel for the school energy use is based upon its square footage of conditioned space. Use the table below to estimate some ball park annual energy costs for facilities of various sizes. Furthermore, the table gives a feel for how much savings potential might be in two systems if 20% savings were achieved.
Take a moment to think about the numbers. A small school in the 50,000 sq. ft. range might spend $50,000 annually on energy. If there were a project that could cut their lighting portion of their energy budgets by 20%, they could save between $6,000 and $7,000 each year. A larger building in the 150,000 sq. ft. range spending $150,000 annually on energy could have $20,000 savings from a similar measure. In many cases, these measures have just a one or two year payback, so it's worth investigating. Those savings keep on coming in future years and can be used to make the school a better place to learn.