Building Energy Efficient Log Homes

Wouldn’t it be great if new homes came with a sticker on the window that guaranteed their energy performance like cars do? But predicting a new home’s operating efficiency isn’t as easy as taking a test drive. "Two homes can have the same exact design yet have far different heating and cooling costs," says Mike Gingras, owner of Seven North Log Homes in New Haven, Vermont. A builder/dealer for Real Log Homes of nearby Hartland, Mike has designed and crafted Energy Star-rated homes for nearly 20 years.

Log homes are particularly wellsuited for energy efficiency, thanks to "thermal mass"—a natural property in the logs that helps to keep a home’s interior temperatures comfortable, no matter what it’s doing outside. Here’s how it works: Log walls collect and store energy, then radiate it back into the home. You can increase energy efficiency by simply adding more thermal mass (say, by upgrading the diameter of your logs). "Today we can build log homes to be 15 to 20 percent more energy efficient than conventional homes," says Mike, who recently built a 6,300-square-foot home with 10-inch diameter logs. That house now costs about $2,200 to heat and cool each year. (A conventional home of just 2,500 square feet averages about $1,700 a year in the same market, he says.

If you’d like to further capitalize on your home’s energy efficiency (and who wouldn’t in this era of rising fuel costs?), Mike suggests this approach: "You have to think of your home as a total system." That means coming up with a heating and cooling strategy before you build — then, making sure the home is sealed properly during construction. "We can build log homes today that are super tight," adds Wayne Cohen, director of dealer development at Alta Log Homes in Halcottsville, New York, which also offers Energy Star-rated log homes. But making a log home tight takes experience, so you should be selective about the builder you choose. "Increased performance takes detailed work during construction," explains Peter Rosi, a builder for Jim Barna Log Systems in Brookston, Indiana. He says builders must pay special attention when sealing the area where the foundation meets the first course of logs. Other tricky spots are the log-to-log connections and the place where the roof system meets the log wall. Here are some other ways owners can make all the right moves when designing and building energy efficient log homes.

Look Outside

A log home in the Southwest desert needs a far different heating and cooling strategy than one set along the coast of Maine. So understanding your climate is the first step in designing an efficient home. How do you sort it all out? The solution is REScheck, developed by the Department of Energy to simplify compliance among state and regional building codes. REScheck classifies regions of the country into climate zones and recommends heating and cooling systems, window U-values, insulation amounts and a host of other information for each climate. You’ll find more at: http://www.energycodes.gov/rescheck

BLACK OUT. Many regions are prone to power outages from high winds, freezing rain or snow. Take a hint from homebuyer Richard Holcomb, who opted for a propane-fired generator to ensure uninterrupted power for his vacation log home in Blowing Rock, North Carolina.

POWER WALK. Your selection in HVAC systems will also be influenced by fuel costs and availability.If you’re building your home off the grid, you will have to employ alternative technologies, such as wind and solar power, to supply your energy needs. You may need to augment with a propane-powered generator for more energy.

Glass & Ceilings

WINDOW TREATMENTS. Simply orienting your home to catch the sun’s rays can reduce your energy bill by up to 30 percent, says Orlo Stitt of Stitt Energy Systems in Rogers, Arkansas. Although it’s best to face windows directly south, they can be oriented up to 30 degrees away and lose only 5 percent of energy savings.

SEE CLEARLY. Another energy-friendly option: Choose windows with a “low-e” coating that blocks ultraviolet rays. To compare, look at each product’s U-value rating, ranging from 1.2 to .2. The lower the number, the better the energy performance.

MASS APPEAL. Logs aren’t the only material that can radiate heat into your home — or help keep it cool. Installing tile floors in front of south-facing windows does just that.

HIGH SOCIETY. The volume of your home can affect your heating needs, as can the number of windows and doors. Cathedral ceilings, in particular, take more energy to heat and cool.

MANAGE OVERHEAD. Upgrading your roof insulation to a greater Rvalue is the easiest way to save energy. Consult your builder and REScheck to determine the maximum R-value your roof system needs for your climate. It will range between R-38 to R-48 in most climates.

Be Cool

Most home owners choose central AC these days — and most manufacturers offer "size" calculators on their Web sites to help predict your home’s AC needs based on interior volume (square footage and ceiling heights) and climate.

CHILL OUT. In January, the Department of Energy raised the minimum Seasonal Energy Efficiency Ratio (SEER) for CAC units (and heat pumps) from 10 to 13. This 30 percent increase will get you better efficiency, but will also cost you more up front as unit sticker prices go up $400 to $1,200.

BIG FAN. Other air conditioning options include window units, ceiling fans and attic fans, as well as evaporative coolers (or swamp coolers) that are only used in low-humidity areas).

The Heat Is On

You’ll find a wider range of choices for heating systems. (Again, use REScheck to determine HVAC size). Here are your overall heating options.

FORCED AIR FURNACES. Powered by either propane or natural gas, these units deliver warm air through floor registers. To compare performance, look at the AFUE (Annual Fuel Utilization Efficiency) rating noted on a yellow tag on the side of each unit.

HIGH VELOCITY FORCED AIR. With this unit, the air delivered to a room enters at a higher velocity (typically 2,000 feet per second) for better temperature control and comfort.

BASEBOARD SYSTEMS. This traditional heating method uses hot water or electric power to warm your home.

RADIANT HEAT. You have your choice of electric or hot-water systems, typically installed within the floor (but panels can also be mounted on walls or ceilings) to offer high comfort and energy efficiency.

GEOTHERMAL HEAT PUMPS. Here, heat pumps use the earth or groundwater as a heat source in the winter and as a heat sink (drawing out hot air) in the summer.

HEARTH PRODUCTS. A toasty fire and a winter night go together like butter and popcorn. And hearths are considered the “heart” of many homes.

COMBO SYSTEMS. Many experts recommend combining two or more heating systems for ultimate comfort. Mike at Seven North often suggests radiant heat for the basement, paired with a high-velocity forced air system (to provide both heating and cooling) for upper levels.

Breathe Easy

Since log homes are sealed “super tight,” consider a triple approach for maintaining indoor air quality.

AIR-TO-AIR EXCHANGERS: Attached to a forced air system, these units use highly conductive metal or other materials to remove the energy (heat or cooling) from outgoing air — then transfer up to 80 percent of the energy back inside with fresh incoming air.

HUMIDIFIERS: In the winter, indoor air humidity can drop to as low as 5 percent, drying out your lips, skin and respiratory system. A whole-house humidifier ($400 to $800) will keep you less reptilian.

VENTILATION FANS: Bathrooms equipped with humidity-sensitive controls remove steam and unwelcome odors. Electric can cost $100; solar-powered: $400. Creating a healthy and comfortable indoor environment is a science — and adding or subtracting one method can affect the entire system. Don’t go it alone. Log home companies, designers and builders with Energy Star experience can analyze what’s best for your home—and help you get the best bang for your buck.

For more information on heating and cooling your log home, check out the April 2006 Affordable Log Homes issue of Log Home Design.  

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