October 13, 2005

Fight Rising Heat Costs

Homeowners can cut heating costs if they take a few simple steps, North Dakota State University Extension Service engineer Ken Hellevang says.

He recommends homeowners seal openings in the walls and ceiling with weather stripping or caulking to reduce air leakage.

“The largest heat loss from a home occurs due to air leakage,” he says.

A well-sealed house will have an air leakage rate of about 0.5 air changes per hour (ACH), while a poorly sealed house may have an air leakage rate that exceeds 1 ACH. The difference will increase fuel use by about 500 gallons of propane or 460 therms of natural gas for one heating season. A therm equals 100 cubic feet, or 1 ccf, of natural gas.

Homeowners should check between the sill plate and foundation at the base of the wall, and around windows, pipe penetrations and electrical outlets. Look for openings, and feel or use a lighted stick of incense to check for drafts.

Hellevang also advises homeowners to do the following to reduce heat loss:

• Install plastic over windows. Windows with sliding parts typically have higher air leakage than windows that seal by compressing the weather stripping.
• Install weather stripping around doors and use a storm door.
• Use approved enclosures or seals for recessed lights. Recessed lighting is the most common location for air leakage through the ceiling.
• Seal fireplace dampers. Use a chimney cap, fireplace plug or draft stopper.

The difference in heat loss from 120 square feet of double-pane (R-2) and triple-pane (R-3) glass window during a heating season can increase fuel use by about 50 gallons of propane or 46 ccf of natural gas. Adding plastic to a double-pane window increases the R-value from 2 to 3, and reduces air leakage and condensation on the window. Closing draperies will reduce heat loss at night, but it also will increase the amount of window condensation.

Hellevang cautions homeowners not to cut off all leakage because homes need some air exchange to remove indoor moisture, odors and pollutants. He recommends a minimum ventilation rate of 0.3 ACH.

Homeowners can monitor the amount of air exchange by watching how fast odors dissipate or measuring the relative humidity. They can use an electronic relative humidity meter or observe the amount of condensation on windows to monitor the relative humidity. The relative humidity should be below about 50 percent during the fall and reduced to between 30 percent and 40 percent for most of the winter.

If condensation runs off the window onto the window framing, homeowners can use ventilation to reduce the humidity level. Using heat recovery ventilation, which is a heat exchanger installed with the furnace or air conditioner, will reduce heat lost during mechanical ventilation by 60 percent to 80 percent.

Inadequate insulation in the basement and around band or rim joists is the second largest cause of heat loss, Hellevang says. The band or rim joist is the exterior portion of the floor framing. The recommended minimum insulation value is R-10 for a basement and R-19 for band or rim joists.

A poorly insulated basement may increase fuel use for a heating season by about 100 gallons of propane or 92 ccf of natural gas. The difference in fuel required to heat a 1,500-square-foot house with a ceiling insulated to R-38 versus R-19 also is about 100 gallons of propane or 92 ccf of natural gas per heating season.

“Adding more insulation to the ceiling or attic and to the basement or rim joist will have a quick payback at today’s fuel prices,” Hellevang says.

Here are some other tips:

• Lower the home’s thermostat setting and use space heaters as needed in parts of the house. Each 1-degree reduction can save 2 percent to 3 percent in fuel costs
• Close heat registers in rooms that can be cooler.
• Use a programmable thermostat that turns down the heat when the home is empty but has the house warm when the occupants return. That can reduce heating costs from 5 percent to 10 percent.
• Turn the heat down at night. A 10-degree setback may reduce heating costs up to 5 percent.
• Have a professional service the heating system annually.
• Change the filters on a forced-air heating system regularly.
• Do not vent a clothes dryer into the home to save energy because this will put excessive moisture into the air, which could cause condensation and other moisture problems.

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Source: Ken Hellevang, (701) 231-7243, kjh-eng@ndsuext.nodak.edu
Editor: Ellen Crawford, (701) 231-5391, ecrawfor@ndsuext.nodak.edu

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