Some equipment loads are deferrable in that they
can be turned off for a short interval and then turned
back on with no appreciable impact on operations. Water
heating and cooling are two examples, but even
space heating can be deferred for periods of up to thirty
minutes with no perceptible effect on thermal comfort.
During extreme weather outside air can be reduced for
short periods in order to improve heating or cooling
efficiency. See the discussion of warm-up and cool-down
cycles which follows.