In the middle of the winter, it’s easy to find the drafts in your home. Sealing drafts can improve your energy efficiency, but there are some important considerations to think about. Building contractors talk about the “thermal envelope.” If you haven’t heard the term, it refers to the “tightness” of a building’s enclosure. The tighter the enclosure is, the less air travels between the building’s inside and its outside.
Energy efficiency requires ventilation improvements
Gaps can naturally occur between the foundation and the home’s structure. They also commonly occur in the attic, where the roof joins the walls. Windows, doors, vents and other openings degrade the thermal envelope. These hidden openings enable air to travel freely between the home’s exterior and interior. That means your warm air in the winter, and cool air in the summer will dissipate. This raises the cost of your heating and cooling bill, and admits unwanted moisture into your home.
Conventional wisdom said that these gaps helped to control the growth of mold and mildew. That is true. But it also means that older homes are draftier, leakier and cost more to heat and cool. If you decide to seal drafts in your home (which will decrease your energy usage), test your home’s ventilation! You may need to add supplemental ventilation to avoid moisture build-up and other problems.
Your water heater can’t go it alone
One of the big targets for energy efficiency is upgrading the furnace. Older furnaces aren’t energy efficient, so they consume a lot of fuel. Traditional furnace designs vented the by-products of combustion out the chimney. (“By-products of combustion” = carbon monoxide.) Newer heating equipment may instead vent flue gases out of the side wall of the home. This may have implications for your water heater and you!
A furnace is a big piece of equipment, and it can create a generate a big draft in the chimney. This air movement enables the flue gases to escape the chimney. If you have a gas water heater, it may also vent out the chimney. It probably leans on the furnace to create enough draft to expel its products of combustion safely. If you upgrade your furnace but leave your water heater standing, your water heater may not be able to generate enough draft to clear the chimney of noxious gases.
This can set up a dangerous situation known as back drafting. Back drafting allows the nasty, noxious gases to pool in the chimney, or worse, escape into the house. This can cause carbon monoxide to accumulate in the house. Major danger!
There are a few solutions for discouraging back drafting when your water heater is the last man standing. Your heating and cooling professionals will want to line your chimney when they upgrade your furnace. This reduces the inner size of the chimney and allows the water heater to create a better draft. You could also upgrade your water heater to a “power vent” model. A power-vented water heater mechanically creates draft in the chimney to avoid carbon monoxide buildup.
Heating and cooling professionals can help!
Air sealing, insulating and upgrading your heating and cooling equipment all save money, but they change your home’s environment. It’s very important to avoid the unintended consequences that can come about from tightening your thermal envelope.
At Boston Standard Plumbing and Heating, we can help you choose the most efficient heating and cooling options. We can also help you ensure that your home remains safe and comfortable, while also saving you money!
Call us at (617) 288-2911 to schedule an appointment today!
Photo Credit: David Singleton, via Flickr
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