Does precooling save energy? if not, is it worth it?

We were encouraged to precool our house to use less energy during peak demand (and pay electricity rates based on demand). But our house seems like it runs all night and morning to cool down enough to not run during the maybe 5 to 6 hours of peak time when it heats up without the AC running.

We have done air sealing and insulation, but need to replace our not so efficient 30+ year old furnace, which could factor into how long it takes to cool our house back down, but makes me wonder if we set it at 76 degrees all the time (maybe higher) if it would run less over all.

If so, which is more important, using less during peak demand times or using less overall?



  1. 0 Votes

    One commercial building was able to save a bit of energy, but they had a massive air conditioning system.  This link will bring up the PowerPoint of their experiment. 

    The energy companies are likely encouraging people to reduce use during peak times because of the strain it puts on their system, and if the system overloads, then no one gets AC.

    I would suggest trying your idea of staying at 76 degrees all the time, and see how much energy you use. If you feel that your AC unit is still on quite a bit, you could switch back to the precooling method.

    One thing that has helped in my west-facing room is heavy duty curtains that are meant to block out light completely.  They also help reduce sound and heat.  If you have sunlight coming into your home from large windows, you might consider that option to help stay cool as well.

    This precooling system is also available; however, I can’t attest to how well it works.

  2. 0 Votes

    The only truly significant way to save energy is to stop using the air conditioner. The AC only became commercially available about 50 years ago; thus, it is certainly not an indispensable part of modern life.

    In fact, the use of air conditioning is only making things worse, especially in a country (such as the United States) where 20% of electricity consumption goes towards cooling buildings and about 50% of electricity comes from coal-powered plants, which intensely pollute the atmosphere and make our world even hotter. Air conditioning use cannot conceivably be seen as anything more than one step forward towards cooling, and ten steps back toward increased needs for cooling (see first link below).

    There are better solutions to a comfortable home than air conditioning. Passive cooling is a set of ideas that, when applied, can cool your house without any energy input (after the initial building/retrofitting work). These mostly involve insulation, but also include ventilation, air flow, thermal mass, window placement and window shading. See the second link below for more information.

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