How to “Recool” Your Home (and Why You Should Do It)
If you have some sort of air conditioning in your home, you are among the lucky ones – at least it seems so until the electricity bill comes up. If gigantic utility bills are making you sweat, there’s one strategy you can try that may seem counterintuitive at first but can keep your home cool and manage your bills on the hottest summer days: hypothermia.
What is hypothermia?
Subcooling or pre-cooling is a strategy designed to keep your home at a comfortable temperature while reducing energy consumption, and there is evidence that it actually works if you take the time to plan it properly.
If, like most people, you’ve set your HVAC system to operate primarily during the hottest hours of the day and then switch to lower settings during the cooler hours of the night, you may be involved in what scientists call “not properly”. This is because when an HVAC system is turned on in a home that is already quite hot, it must work very hard (and use a lot of expensive energy) to pump the heat out. Subcooling or pre-cooling changes the strategy.
The idea is to run your HVAC system at its highest settings at night when it’s coolest outside and the sun isn’t baking your home. Try to lower the temperature in the house to a very low temperature – about 60 degrees, if you can do it. As the sun rises and the outside temperature rises, your home becomes warm and cold and will stay that way for a long time, allowing you to put your HVAC system on low. During the day, set the thermostat to the most comfortable temperature for you, say 74 degrees. It will take a long time for your home to warm up to this point if you take a few steps (covered below), and your HVAC may not work at all.
Hypothermia has two huge potential benefits:
- Low costs. If your utility plan has different rates during peak and off-peak times, you can save a lot of money because you’re running your energy-hungry HVAC system during off-peak times when rates can be significantly lower. Some people report that this technique can cut their utility bills by up to 25 percent .
- Less wear. If your house is already 90 degrees when you turn on the air conditioner, you will have to work very hard to cool the room. The compressor, fan and other components will be trained. Running it at night when temperatures are much cooler means it won’t be subject to as much wear and tear, so your system can last longer and require less maintenance.
There is plenty of evidence that hypothermia can work both in terms of saving you money and protecting your equipment. But the success or failure of hypothermia depends on two factors, one under your control and the other not: the design of your home and taking a few extra steps to make your home the best thermal battery it can be.
How to keep hypothermia at home
Simply put, if your home is old or was not built with any energy efficiency in mind, hypothermia will be more of a challenge. That’s not to say it won’t work for you, but you’ll have to work a little if your home isn’t well insulated and doesn’t have features like a reflective or coated roof.
But even if your home was built with the most energy efficient materials and designs, subcooling still depends on a few best practices to be successful:
- Variable rates. Electricity bills should include peak and off-peak hours. If you pay the same flat rate for electricity regardless of the time of day, hypothermia won’t save you money. This is because the idea is that your air conditioner runs at night when electricity is cheaper, and runs less (or not at all) during the day when it’s more expensive.
- Programmable thermostats or window units. It’s not an absolute requirement, but having programmable units allows you to set them up and forget about them, as well as guarantee the most efficient operation (and no chance of forgetting and getting a greenhouse or an even higher energy bill).
- Close these windows. Keep all windows closed to prevent hot air from entering, and lower curtains or blinds to keep the sun from heating up the interior. This may make your house look like a cave, but it will be a cool cave.
- Reduce heat sources. The sun and that swampy air outside is one way to turn your home into a stove, and the other way is your real stove. Once you’ve cooled your home, you’ll need to avoid heating things up from the inside, which means limiting the appliances you use during the day. In other words, don’t bake chicken for dinner because you’re just pumping more heat into your home. Other heat-generating appliances that should be avoided include the clothes dryer and dishwasher.
- Get used to the cold. Hypothermia means that your house will be quite cold at night, but you will have to avoid doing anything that could jeopardize this, such as turning on heaters. You may feel ridiculous in winter clothes in the midst of a heat wave, but when your energy bills drop significantly, you’ll be glad.
Hypothermia takes some discipline and planning, but it can lower your energy bills by keeping your home at a comfortable temperature all day long. Your mileage may vary depending on the characteristics of your home (and your tolerance for getting cold at night), but if your utility bills are skyrocketing, it’s worth a try.