With more than 80 percent of American homes having some kind of air conditioning or heating system installed, it’s easy to take that technology for granted. However, these systems don’t always function the way we expect. In those situations, we have to cope with the climate the way our ancestors did, in the days before these modern conveniences existed.

Coping without heating or air conditioning is an inconvenience no one wants to deal with, but it’s something everyone needs to be able to do. Fortunately, staying comfortable, even without your HVAC system, is a matter of following some relatively simple guidelines. With these tricks in mind, you can keep from feeling too hot or too cold, even if your HVAC system is on the blink for more than a day.

For example, keeping cool in the summer without air conditioning means dressing for the weather, drinking plenty of cold water, and avoiding the use of heat-generating appliances — unless necessary. For additional cooling, you can take a lukewarm bath or shower before bed, or stay in your basement during the hottest hours of the day.

Staying warm without your furnace is possible if you stick to only a few rooms and block the doors to the unused rooms with heavy curtains or blankets. Dressing in layers of warm wool clothing and blocking drafts under doors with rolled-up towels and blankets also helps you stay comfortable even when it’s cold inside your house.

Modern conveniences such as HVAC systems have certainly made life easier. However, knowing how to live without them will make life easier for those brief periods when they aren’t working. Or, you might want to live without them voluntarily to save a little money on your energy bills. Either way, these tips can help you stay comfortable without your HVAC system.