House Venting Can Cool Your Energy Costs
(In Teresa Peschel’s “Fed, Safe, and Sheltered,” she talks about the best ways to efficiently heat and cool your house. In this essay, she has more advice on the best way to use vents and other openings to make your home comfortable.)
When you want to vent out your house, ensuring a complete air exchange that cools your house off, the obvious answer is to open your windows. However, your windows are just the start. Of equal importance, if you know where all your vent locations are, you can make sure you compensate for them during the winter. After all, heating the great outdoors gets expensive.
Winter has the opposite problem of summer: you want to keep your heat inside where it belongs and trap warming sunshine. Summers, well, you want to keep that sun outside and let in as much cooling night air as possible. The cooler your house is in the morning, the longer it will take to heat up during the day.
So let’s start at the top with your roof. Roof improvements, sadly, are not a do-it-yourself job unless you are already a carpenter. The attic sitting up on top of your house is not supposed to be a heated space. It is supposed to be close in temperature to the outside. It shouldn’t be 150° in the summer nor should it be cozy and snug in the winter and encouraging ice dams.
Heavy insulation between the attic and the interior spaces will keep you from paying to heat or air-condition your attic.
Once you’ve insulated, you’ve got to vent the attic. Your attic probably has one of those tiny, louvered windows at each gable end. They are a start but grossly inadequate to vent insulation-destroying moisture.
So the next passive step is to add roof vents. These come in two varieties: little cap units that help, some, and those big whirly-bird things that look sort of like a lump of ice-cream on a plain cone. Those are better. Both of these vents (use at least one for each roof section) can be installed without replacing the shingles.
Best of all is the ridge vent. This is a vent that runs along the entire roof-top, from gable end to gable end. Every roof ridge needs one. If you don’t have one, have them installed when you replace your shingles (with white shingles for still more cooling). Having a set installed when we re-roofed our house made our attic 30° cooler in the summer.
Along with the ridge vents, make sure your attic has soffit vents too. These encourage air flow, keeping your roof dry. Get plenty of them, under every eave. Make sure they’re not blocked with insulation. That will defeat their purpose.
Cooling the rest of the house
Once your attic is properly vented and thus cooler during the summer, you can use that to cool down the rest of your house. This is because warm air rises, so encouraging air to move up and out through your attic will help create enough of a draft to bring in still more fresh air through your open windows on the ground floor.
Your mileage will vary wildly as every house is different. You have to experiment and keep records.
My mother’s house is more than 150 years old. It has two stories plus a big attic with full-sized windows. She draws in cool air on the ground floor with fans directed inward, closes the upstairs windows, opens all the attic doors, and then blows stale air outside of the attic windows with big box fans. The fans, along with the design of the house, pull air up and out. She does this every night and it makes her central Delaware, un-air-conditioned house tolerable. Lots of trees that shade the house help, too. She’s learned that some windows must be closed to make this work. It is work for her, having to open and close windows and turn on and off fans.
Our house in South Carolina was a plain, rectangular 1950s vintage ranch. We had a variety of vents, including the whirly-bird kind, soffits, and a ridge-vent. My attic access consisted of a pull-down staircase. I couldn’t leave it open, maximizing the night-time airflow, as little kids would zoom towards the staircase, along with bad cats. I could leave it ajar which helped some.
Our current home has ridge-vents, gable-end vents, and soffit vents. We have three portions to our attic, only one of which is easily accessible. We have a doorway to the main attic awkwardly located in the stairwell. Bill constructed a summer door insert for this opening consisting of a frame of wood with screening stapled to it. When it starts to cool off, in addition to using the fans, I open the attic door and install the screen insert. Passive air movement helps drag air up and out through this portion of the attic.
The third portion of our attic is the highest point of our house. It is accessible only through a ceiling hatch located in the same closet. It is awkward and clumsy opening this hatch every night and closing it every morning but I could do it. I just don’t want to bother now. If my cooling costs rise, I’ll have to reconsider. This attic access could benefit from a fan that would blow straight up into the attic and thence outside. It would provide a strong chimney effect. Since our cats can’t jump into this portion of the attic, I wouldn’t need to insert a screen.
Obviously, you only want to vent your attic this way during the summer nights. Everything should be shut up snugly when you don’t want this improved air circulation.
Other Vents and Doors
The next set of vents to look for in your program are fireplace and wood stove vents. Your fireplace chimney is made to draw a draft; that is how your fire keeps burning. When you are heating or air-conditioning your house, keep those dampers tightly closed. But, when you are running fans overnight to bring in cooler air, open your fireplace damper and get another column of air moving. The hard part is remembering to do this, and most importantly, closing the damper in the morning so you don’t bring in hot outside air.
Do you have basement windows? Are they operable? They should also be incorporated into your cooling program. Basements are nearly always much cooler than the rest of the house in the summer so why not draw some of that cooler air upstairs where you can use it? If your basement is in two parts – unfinished and finished — you may have to leave doors open between the sections to keep the air circulating.
Circulating air in your basement will help it stay drier too, an added benefit.
Do you have a vent over your stove? Is running this vent worth the cost of electricity and the noise? I don’t use this vent because it hasn’t proved cost-effective.
What are your doors like? All of your exterior doors should have storm doors with screens. Then you can – depending on your area – use these doors for added ventilation. Interior doors can affect your cooling plan as well. If you keep doors closed at night, then air can’t circulate. If you are fortunate enough to have transom windows, get them back into operation. Transom windows were designed specifically to move air and light around while still providing some privacy.
Explore your house and look for all potential openings. Once you know where they are, see if they can be used for summer cooling. And once you’ve found them all, you can also make sure they can be properly sealed for the winter and keep your heat inside. People do discover concealed attic hatches that had been bleeding heat to the great outdoors, ajar basement windows, and improperly closed storm windows.
The hardest part with venting your house using my methods is that they take time and effort every single day. It is considerably easier to write big checks for heating oil and air-conditioning. But if you don’t want to write those checks, then you have to do the work yourself. Don’t forget to draft your children for free labor. They should learn how to keep a house more comfortable too. Then when they get houses of their own, they’ll be ready.