Energy Saving Tips – How and Why to Close Foundation Vents

Foundation vents have a direct role in influencing the energy efficiency of your home.

by Don Ames

Energy saving tips – open in summer and closed in winter, that’s the way it should be to help conserve power, control your power bill, and support a healthy underfloor environment.

A  foundation vent is a little window into an unknown world.  A world that is part Hercules, because the structures within hold up a small personal planet -  a world that is part zoo, because of the all the little crawling creatures that reside there that we don’t even want to know about - a world that is part warehouse, because of all the mechanical, electrical, insulation, and plumbing structures that we simply can not do without. Take care of your underfloor space and it will take care of you.

Foundation vents are the subject of this instant savings tip. If you live in a cooler climate and live in a house with a crawl space, open the foundation vents during the warm summer months to add ventilation through the underfloor space and close the foundation vents in cooler winter months to stop the cool air from blowing through and cooling the floor and the house.

The heating system will not have to work as hard if it doesn’t have to fight a cold floor. Keeping the vents closed in winter helps keep the floor, the heating ducts and the water pipes a little warmer and, in the case of the water lines, a little less likely to freeze.

The size and number of foundations vents, especially in newer homes, have been carefully calculated to provide adequate ventilation. The building codes discribe the net free opening requirements for an underfloor area based on floor space and air volume. Adequate ventilation keeps the space dry and reduces the growth of mold, mildew, and the ever popular, dry rot.

Most foundation vents consist of three parts that are connected together into one unit.

1.  A plastic rectangle, open from side to side, that fits into the concrete foundation stem wall.

2.  Small mesh metal screen that connects within the center of the vent to restrict the opening to just air passage and not rodent passage. ( cats are rodents )

3.  Plastic flappers that are attached and hinged on one edge that can be pulled down to uncover the vent opening and allow air passage, or raised up to cover the opening and restrict the passage of air.

Closing the foundation vents, getting ready for cooler weather and saving energy.

1.  Drop by your favorite hardware store and pick up some styrofoam foundation vent covers. Cost you about $1.00 per vent. In the fall, stores will have sales on vent covers so keep looking.

2.  Count your cat population. If one or more of the metal screens has been broken or removed, be sure the felines are not using your underfloor space as a hideout. Cats, heating ducts, and insulation do not go together very well. Cats will destroy insulation and heating ducts as they try to get at the warmer air within.

3.  Grab a small hand brush or paint brush to clean out the vent openings. Leaves, twigs, dirt and spiders have to go so the vent flapper will close completely.  The vent will have some sort of small clip built into the vent body to hold the flapper closed. Don’t worry if the clip no longer works and the flappers just fall open. That’s one advantage of using the styrofoam vent covers, they hold the plastic flappers closed.

4.  Take the styeofoam covers and with a utility knife, carefully trim the covers, as needed, to fit snuggly in the vent opening. A good snug fit will seal the opening - hold the plastic flapper covers shut, and keep the styrofoam covers in place when the wind blows. It’s a little unhandy to find the pipes under the house are frozen and the wind has deposited your styrofoam vent covers all over the neighborhood.

With the vent covers closed, the underfloor space is protected from the cool and windy outdoor environment. The underfloor area is allowed to warm up, because of the warm heating ducts and warm water pipes that are in the space. The floor will be warmer, the thermostat can be turned down a degree or two and the furnace does not have to work so hard to warm the house. Power conservation has been awarded with a more comfortable and energy efficient home.

When spring arrives and the weather warms up, remove the styrofoam vent covers and open the vent flaps so air can pass through the crawl space once again. Store the styrofoam covers in the garage where they will be ready to be used again next fall.

Hope this article was interesting and helpful, come back to Detect Energy for more energy saving tips, but hurry, I won’t leave the light on for you…Don Ames