The acronym H.E.R.S. is now being seen with increasing frequency. It stands for Home Energy Rating System.
The Gainesville Alachua County Association of Realtors is now including the ability to record the H.E.R.S. index (now recognized by the Department of Energy) as well as virtually all other modern GREEN features for a residential dwelling in the Multiple Listing System (MLS) as it directly relates to the efficiency of the dwelling. Efficiency relates to performance and performance relates to cost of ownership and indoor environmental quality and it all relates to value.
In a recent Gainesville Sun article (read it HERE) there was reference to and an abbreviated explanation of H.E.R.S. that likened it to the fuel efficiency of an automobile in miles per gallon. I would like to elaborate on that to assure full understanding.
Think of the home (the building) from a performance standpoint and kind of like a car and it's fuel MPG rating (i.e. city and highway). Thought of another way what is the cost of home ownership or same as....what it will cost you at the pump to operate the car.
The H.E.R.S. number is an "index"(on an E-Scale) of the overall efficiency (performance) of a dwelling taking in to consideration the type of construction, the subsystems (windows, flooring, doors, roofing, insulation, etc.) and the engineering (climate control, Plumbing, Electrical, etc.). The integrity of the envelope is also measured in terms of balance and leakage of air within the envelope. Keep in mind that I am not a certified H.E.R.S. rater and one of those folks can give a much better technical explanation but you get the picture.
The single overall H.E.R.S. index number for a dwelling is relative to the "American Standard Building" and in our case here in Florida the standard building is in accordance with our local building code. This makes sense. A building in north central Florida is built to perform in terms of energy efficiency in a much different way than say.....a dwelling built somewhere in Minnesota.
An existing dwelling that has been upgraded from a performance standpoint and that has a H.E.R.S. index of 90 is 10% more efficient that a new home built to code and 40% more efficient than the average existing home which would normally measure at around 130.
The gain in efficiency (performance) equals a corresponding gain ($$ savings) in the cost of ownership. The gain in performance also equates to a gain in the comfort level and environmental quality (indoor air quality).
According to the Residential Energy Services Network (RESNET):
- 130 is the average existing home HERS index, built to older, less efficient codes and using less efficient appliances
- 100 is a new home index built to standard regional home building codes and is the baseline for the index
- 70-85 is the index range for new homes certified by the Environmental Protection Agency's Energy Star program
- 0 A "net-zero" home designed to balance all of the energy it takes from a utility with an installed rooftop solar array with the capacity to generate the equivalent electricity usage back to the utility grid
The Residential Energy Services Network (RESNET) has provided a nice interactive graphical tool that helps represent what the HERS index is telling us. You can take a look and operate that tool HERE.
I am available for further discussion.