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Efficiency

How to Keep Your House Cool Without Air Conditioning

By Al Buss, Vernon County Energy District

It’s 5:30 in the afternoon on July 3rd, outside it’s a sweltering 94 degrees and humid. Inside our house is 76 degrees and comfortable, without any air conditioning.

It is possible to live comfortably without A/C, we’ve done it for years. That’s a lot of money saved. The cheapest energy is the energy we don’t use at all. Experimenting and finding what works can save quite a bit of money.  

Half of our house is a log house built in the 1850’s and the other half is timber frame built in the 1920’s. In other words ours is not a brand new super tight, super insulated house. We have done a fair amount of insulating and sealing but it’s an old house.

The strategy is to cool the house down as much as possible at night and then keep it cool during the day. It’s simple enough.

Usually around 8:00 pm we open most of the windows. Downstairs we’ll open the lower half of the window but usually have one or two windows with the upper sash lowered. This way the cool air can come in the lower part and warmer air can escape out the open upper sash. 

We do the opposite upstairs. Most of the windows we open the upper sash but leave one or two windows with the lower sash open. Since warm air rises this helps let the warmer air out of the upstairs windows while the cool air flows in the downstairs windows. 

Usually we don’t use a fan because there’s enough of a breeze to move air through the house. If there’s no wind we may use a box fan or two to help. We do this only when it’s not predicted to be below 70 degrees overnight.  

In the morning we close up all the windows to seal in the cool night air. It doesn’t seem to make much difference what time we close the windows as long as it’s before it starts getting warm outside. I’ve noticed that anytime before 8:00 am is fine. We also close up all the blinds except one on the north side of the house. 

We also close up all the inside doors. In our house closing the doors helps to keep our living room cooler than the rest of the house. 

During the day we avoid doing things that create heat. Cooking, coffee makers, dishwashers, clothes dryers, incandescent lights, TV, stereo and computers all create heat.

A well insulated house will stay cool much longer than a poorly insulated house. Insulation in the attic helps to keep the heat from the roof radiating into your living space. A few years ago we added 12” in our attic bringing the total to 20”. It has made a big difference both keeping cool in summer and warm in the winter.  

Tight seals on windows and doors are also important, both to hold cool air in the summer, and heated air in the winter. Caulk and weather stripping are inexpensive ways to increase comfort and save energy dollars.

The thermal mass of your house also helps. Plaster walls have more thermal mass than drywall so it takes longer for them to warm up keeping the house cool longer. Keep in mind it also takes  them longer to cool off once they are warm which can make it harder to cool the house after a long stretch of very warm weather. 

Shade trees on the south and west side of the house help too. If you plant trees it’s best to choose deciduous trees that lose their leaves in the winter. That way the sun will help warm the house in winter when the leaves are off and you want the heat.

There are usually three or four nights a summer when the temperature doesn’t get low enough to cool the house. Some people’s houses are not well insulated enough to make it through the whole day closed up. When either of these happens the house can start to feel, “stuffy.” 

One mistake people often make is to put a fan in a sunny window and blow in hot, outside air. It may feel better on the skin but it’s actually heating up the inside of the house.  To ventilate, it’s better to open windows on the shady side and place a fan facing out to exhaust out the hot air. A 20” X 20” box fan works well for this, place it right up next to the screen.

We have a digital indoor/outdoor thermometer so we can see what kind of results we are getting. In the past I would watch the temperature and only open the windows when it was cooler outside and close them when it got warmer. After trying this I’ve come to the conclusion that opening up around 8:00 pm and closing up anytime before 8:00 am works just as well.

Our house may not be quite as cool as it would be with A/C however it’s still comfortable. When we are doing something outside on these hot days it is always a relief to come inside.

Cost: $0
Savings: $100-$150*
CO2 reduction: .64 – .96 metric tons*
*per year