Wednesday, August 13, 2008

Energy Star Raises the Bar for Home Builders

By Dan Morrison
A couple of interesting announcements at Building Science Summer Camp came from Sam Rashkin, the National Director of Energy Star for Homes: New standards that raise the bar and a new program for the best builders in the country: Advanced New Home Construction.

The new Energy Star specs include the following:
  • Thermal-breaks in walls -- When studs touch the inside surface and outside surfaces of a wall, they cut the R-value of a wall significantly.
  • Installing HVAC systems correctly -- EPA calls it “best practice installation;” Poor installations slash of the efficiency of an HVAC system by 35% (or more!)
  • Efficient water distribution, particularly for hot water. Hot water sitting in a tank waiting to be used, it cools. These standby losses at the tank are significant, but according to Energy Star, the standby losses in the pipes can be the same amount.
  • Better lighting, appliances, and plug-load management -- these loads account for over half of electricity use in homes : (major appliances: 24%, lighting: 18%, miscellaneous: 14%).
  • Size limits on Energy Star homes. The Home Energy Rating System (HERS), which scores Energy Star homes, inadvertently penalizes small homes by making it easier for very large homes to meet the energy efficiency requirements (not sure on the size limit yet, awaiting Sam’s answer).
  • Moisture control -- because tight houses have less drying potential, durability details must be well thought-out

These updates lay the groundwork for another EPA program: Advanced New Home Construction which will push the energy envelope 50% past 2006 International Energy Conservation Code. To get there, builders will:

  • ‘Super insulate the walls -- 50% more R-value in an air tight wall with perfect insulation and no thermal bridging.
  • Install ‘super-efficient’ high-performance windows which can block nearly 85 percent of solar heat gain while delivering R-8 thermal resistance (typical Energy Star windows block 70% solar heat and deliver R-3).
  • Install air-tight air handlers with high-efficiency variable-speed fans. HVAC systems often leak 35% of the air they transport. Half of that leaks out of the air handler. And today’s fans gobble up 70% more energy than necessary. Sealed air handler units are currently available and super-efficient fans are about three years away.
  • Install super high-efficient HVAC equipment -- SEER 18 (rather than 13) for air conditioning, >9.0 HSPF (rather than <8)>
  • Install solar domestic water heating system -- most solar water heaters can handle 50% to 90% of the water heating needs of a household.

The Advanced New Home Construction program is not open to all builders; it has requirements for participation. As such, EPA is looking for “the nation’s most energy efficient builders seeking recognition as environmental leaders” to join the Advanced New Home Construction program.

To learn more about the program, go to next September.

--Dan Morrison is managing editor of

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