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Better Ventilation Is A Breeze

I plan to keep my air-conditioning costs as low as possible without being terribly uncomfortable. What can I do to improve natural ventilation in my house while reducing heat through windows and doors?—Nick Z.

Air conditioning can account for a significant portion of utility bills even in so-called “cool” regions of the country. Not every region has below-zero temperatures during the winter, but most areas easily top 90 degrees for many days during the summer.

I am glad you mentioned not being “terribly uncomfortable.” No matter how much heat you can block from windows and doors, and how effective the ventilation is in a house without air conditioning, an air-conditioned house with a reasonable humidity level will usually be more comfortable. With proper ventilation, I have to air-condition very little to stay reasonably comfortable during Cincinnati summers.

Direct and indirect heat coming in windows and doors increases the temperature inside homes significantly. Even the most energy-efficient windows and doors have an insulation R-value much lower than the typical house wall. There are also gaps around doors and windows that, even though sealed with weatherstripping and caulk, allow in some hot, humid outdoor air.

Benefits of ventilation
Because you can’t stop all the energy gain at windows and doors, you might as well make maximum use of ventilation through them. This can be cross-ventilation from window to window on the same floor, or through-ventilation from a window to an upper vent.

The wind blowing over your house creates higher pressure on the upwind side and lower pressure on the downwind side. Open windows on the downwind side completely. Open them only halfway or less on the upwind side. This combination may reduce total airflow somewhat, but it increases the speed of the air coming in.

For through-ventilation, open windows on the upwind side of your house. If your windows are exposed to the sun, install sun-control screening. The dense weave blocks more than half of the sun’s heat, but you can still see through it. If you don’t like the appearance of screen doors, consider installing a retractable screen, for use only in hot weather

EFFICIENCY IDEA
Awnings shade doors and windows

Adding awnings is a good method to reduce heat coming in through windows. The proper size of the awning depends on the latitude angle of your area and its orientation to the sun. An awning contractor should be able to help you determine the proper size.

Installing an awning over a door helps reduce heat gain by blocking the sun’s rays from heating the door or shining in an open screen door.

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