December 14, 2017

Winter is here. You will start seeing more and more white frost on roofs and snow everywhere.

Cold, frosty mornings are a great time to assess your attic's thermal fitness and compare it with other homes in your neighborhood. Frost on a roof is a whitish haze. Snow… well, you know what snow looks like.

After a frost or snow, go outside in the morning, or when it's overcast, and compare your roof to others’. (Bright sunshine can quickly melt exposed roofs, confusing the assessment.) The best attic thermal protection maintains a full surface of white frost or snow on shingles and is the last roof to melt.

If that’s yours, the attic floor is holding in air and heat. You are warm and cozy with less heater run-time. So, lower energy bills.

Instead, is your roof the first to melt frost or snow, then go dry? You may be paying your local utility to turn ice crystals on shingles to water and then turn water into vapor, heating the sky above your house.

Why is snow melting quickly on my roof?

Heat escaping an attic through the roof causes the heat plant (boiler, furnace, or plug-in portables) to run double-time. Where you see a fast melt or completely dry areas, you are seeing very specific heat losses. Likely there is a cold room or cold draft somewhere below, solved by a portable heater or sweaters. 

Even if you have insulation in the attic, heated air can escape upward through actual holes and crevices in the attic floor. Outside air can be pulled in through basement walls, finding a pathway up through walls and rooms and then out through the attic. 

This upward air flow filters through insulation, which gets quite sooty. Look for grey, dirty attic insulation indicating where air escapes. 

Adequate air sealing and insulation in attics and basement walls are key. Almost every house can use more air sealing. Invest in reducing heat and cooling losses and you will: 

  1. Reduce energy costs during both winter and summer;
  2. Enhance comfort throughout the house; and
  3. Improve indoor air quality and health.

Determine your investment potential by getting a Comprehensive Whole-House Energy Audit. Utility customers across the nation have access to incentives and rebates to have an energy audit done on their home. A three-hour energy audit, which includes a blower door test, will yield results that will guide you through the best combination of energy investments for your home. What’s more, certain utilities will assist with the cost of doing these upgrades. Check the Database of State Incentives for Renewables & Efficiency (DSIRE) website to see if your state has any coverage.

That's free money to save energy. Your share of the cost is back in your pocket within two years. And you continue to save money for decades!

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Frank Lee, Guest Poster

Frank Lee is an advisor with the City of Baltimore’s Office of Sustainable Energy.