How Does My Thermostat Impact My Cost?

When working on a conservation project, it is often useful to have a “rule of thumb” to describe how the set-point on an air conditioned facility impacts the cost.

A good rule of thumb is: 4% increase in energy cost for each 1°F.


Your are working with an office complex that has their temperature set at 72°F. They are curious how much energy they might save if they raise their temperature from 72°F to 74°F.

A good estimate would be an 8% reduction in their energy costs.

The actual calculation of the exact number is quite a bit more complicated, but for temperatures in the “comfort zone”, this is a pretty good estimation.

Now go impress your colleagues with this calculation that you can do in your head!

- Paul Hullar