Energy & Atmosphere (LEED EA Category)

The Energy & Atmosphere category can be a little confusing.  USGBC has created alternate paths to earning points for Energy & Atmophere.  Our Home Provider only supports the path that requires a rating using the HERS Index.  According to the government’s Energy Star website, a HERS Index is

a scoring system established by the Residential Energy Services Network (RESNET) in which a home built to the specifications of the HERS Reference Home (based on the 2006 International Energy Conservation Code) scores a HERS Index of 100, while a net zero energy home scores a HERS Index of 0. The lower a home’s HERS Index, the more energy efficient it is in comparison to the HERS Reference Home.

Each 1-point decrease in the HERS Index corresponds to a 1% reduction in energy consumption compared to the HERS Reference Home. Thus a home with a HERS Index of 85 is 15% more energy efficient than the HERS Reference Home and a home with a HERS Index of 80 is 20% more energy efficient.

Our preliminary HERS Rating is a 69.  Our rating could have been lower if it wasn’t for the number of windows and lights in our home.  When performing the preliminary rating (which is based off of plans and a conversation about design and use of the home), our Home Provider also gave us a list of things we could do to get a better rating.  We have agreed to incorporate better insulation in a few areas and to upgrade our windows in the front window tower.  But upgrading the tankless hot water systems would cost significantly more so we chose not to do that, neither did we choose to reduce the window-to-wall ratio.  We have a ratio of 30% now, and to get a six-point decrease in our HERS Rating we’d have to reduce it down to 22% – given the fantastic design of the house, that just wasn’t feasible (although we did go through the exercise to see if it was possible).

One more point to make about the HERS Rating:  they take into account not only how the house is being built (windows, doors, insulation type, HVAC type, construction methods, etc), they take into account the heat gain of the items in the house.  So every appliance or component that emits heat is measured – refrigerator, stereo, computers, etc. – because the heat that they generate has to be countered with cool air, which requires electricity, which is energy, which is what we’re trying to use less of.

While the EA Category for us focused primarily on the HERS Rating, there are a few other areas where we could gain points.  We obtained points for our hot water distribution system.  While we didn’t upgrade to the super-duper tankless heaters, we are using tankless throughout the house.  And we got points not only for the tankless heaters themselves, but for the fact that the heaters are located close to the faucets they serve (no more than ~30 linear feet).  The idea being that when you turn the hot water on in the shower, you don’t waste water or energy waiting for hot water to travel the pipes to the shower head.  We also get a point for insulating all hot water pipes 90 degree bends…apparently that’s where hot water pipes lose most of the heat of the water.  We also got points for refrigerant management.

To get a good sense of the practices that you will end up using regardless of whether you use a HERS Rating or not, look at the alternate path in LEED.  The following categories are addressed, and we could have gotten a good number of the points in that path.  Let me know if you have any questions about these categories:

  • Insulation
  • Air Infiltration
  • Windows (we struggled with windows and I’ll blog about them separately)
  • Duct Tightness
  • Space Heating & Cooling
  • Domestic Hot Water
  • Lighting
  • Appliances
  • Renewable Energy 

Pointwise, the EA category is our weakest, again mostly due to the amount of windows and lights in the house.  We may earn a few more points if we get a better final HERS Rating, but the category will still be our weakest.

Energy & Atmosphere expected points:  18 out of a possible 38.