Now that we’re in the prime heating season, homeowners are looking for ways to maximize their energy use and money in their pockets. In this edition of Under the Lens, we examine one common practice and how it may not be as effective as you think: closing vents in unused rooms.

Back in the day when homes were heated by wood or — gasp! — coal, closing off rooms was almost always a smart move. The heat for the house came from one centrally-located stove, and the goal was to keep as much of the heat as possible concentrated in specific areas. Today’s modern systems are different; while the heat is still generated in one spot (your furnace), it’s piped directly through your ducts to each room. Since there is usually only one system, or “zone,” in the house, blocking vents in one room impacts how the entire system works.

So what’s the problem with closing off vents? Since your heating system is designed to operate at a certain level, shutting down some pathways increases the air pressure in the ducts. This leads to more hot air being wasted, as it escapes through leaks in the system. As more vents are closed, the pressure gets higher and even more heat is wasted. (It’s also worth noting that if you close off a large number of vents and the pressure gets too high, your furnace can start to overheat – causing a safety concern, and potentially damaging your equipment.)

What that means is that instead of saving on your heating bills, you could actually be using the same – if not more – energy than before. This may seem counterintuitive, even false, but research out of the Lawrence Berkeley National Laboratory backs it up.

Here are energy-saving best practices for winter:

• Install (and use) a programmable thermostat. When asleep or away from home, turning back your thermostat 10°–15° for eight hours can save up to 10% a year on heating and cooling bills.
• Replace your furnace’s air filter. A dirty filter restricts air flow, which forces your furnace to work harder and use more energy.
• Have a professional fix leaks and insulate your duct system. According to the U.S. Department of Energy, typical systems lose 25-40% of the energy put out by a central furnace, heat pump, or air conditioner.
• Open curtains on south-facing windows during the day to allow sunlight to heat your home, and close them at night to keep the heat in.
• Turn down your water heater’s temperatue. Water heating can account for 14%-25% of the energy consumed in your home.
• Speaking of hot water, insulate accessible hot water pipes, especially those close to your water heater. For tips, visit energysavers.gov and search “insulate hot water pipes.”

By Tyson Cook, Staff Scientist