The HERS Index was developed by Residential Energy Services Network (RESNET). A HERS Index of 100 represents the energy use of the “American Standard Building” while an index of 0 (zero) indicates that the building uses no net purchased energy…a lower value is better.
A projected HERS Index is based on the proposed or intended design prior to construction. A confirmed HERS Index is based on field verification and performance testing during and after construction.
Our projected HERS Index was 31. With a slightly smaller 4.9Kw versus the originally planned 5.17Kw solar PV system, our confirmed HERS rating is 32, which means our home is approximately 68% more energy efficient than the HERS reference home (American Standard Building).
We are doing things to lower our energy consumption beyond what the HERS computer software can capture. These include harvesting daylight from our many windows and solar tubes by not turning on lights and allowing the cool evening Colorado air to come in our windows at night during the summer months.
Our First Xcel Energy Bill indicates we are on the right track.
At the time we submitted information for the CRES 2011 Denver Area Solar & Green Homes Tour, our testing had resulted in a confirmed HERS Index of 38. Francisco Reina, Lightly Treading, Inc., since determined the Heat Recovery Ventilation (HRV) air flow had inaccurately been recorded. The vane anemometer originally used was not designed for low flow (residential) use. The second reading was taken with an Alnor 6200 Lo-Flo balometer.