A Home Energy Rating, completed by a Certified Home Energy Rater, is a
comprehensive evaluation of the efficiency of a home which is not specifically
related to the occupants or the structure alone.
The evaluation results in
a written report which includes the rating of the home, generally given as
both a numerical and “star” score. Knowing your home's energy
rating is similar to knowing the fuel efficiency, or miles per gallon rating
of your car. It is, in effect, the fuel efficiency of your home.
Having a rating completed, based on the standards of the Home Energy Rating
System (HERS), will provide you with a comprehensive report that:
provides detailed information on each area of your home and its energy use
provides detailed heating and cooling load calculations for equipment sizing
gives insight as to what areas of your home would benefit the most from improvement
shows how your home compares to those built to the International Energy Code, and
is transferable to subsequent occupants of the home.
What is Involved?
All ratings are REQUIRED to
start by the rater providing you with a copy of their
The disclosure statement shows you any outside
interests the rater might have in providing you with a home
energy rating. Those interests might disclose that the rater
also works for an insulation company or a window company,
companies that might benefit by providing improvements to your
home as a result of your rating.
If the rater does not provide you with a copy of
their disclosure statement, ask for one.
Raters are required to provide a disclosure statement to each
client by their HERS Provider, and by the
Energy Services Network
the national governing body of the Home Energy Rating System.
The next steps in providing a Home Energy Rating are for the
rater to take pictures of your home, and to make detailed sketches
that include floor plans and outside elevations.
The information developed from these sketches includes the
square feet (area) and cubic feet (volume) of the homes
“envelope,” and the location and square feet of
the windows and doors; and
the locations and types of various items such as vents, ducts,
lights, and heating, cooling, and hot water equipment.
Other items, such as shading from trees and adjacent buildings or
overhangs, and the orientation of the home with respect to sunlight
are also considered. All of this information is important and
is needed to obtain an accurate rating.
A rating will generally include completing a blower door test
to evaluate the home's air infiltration. The blower door consists
of a calibrated fan and several pressure gauges, or a digital
pressure sensor which are used to test the air infiltration
The air infiltration rate is the amount of air that can
enter the home through cracks and gaps around doors, windows,
trims, moldings and penetrations. The blower door is used to
pressurize the home, making it possible to measure the amount
of air that is escaping or entering. The pressure created by
the blower door is typically 50 pascals, or roughly ¼
inch of water column, and is equivalent to having a 15 mile
per hour wind blowing past the outside of your home (the blower
door does not create any appreciable wind inside your home).
This measurement is termed the air infiltration rate, air exchange
rate or air changes per hour and, depending on the tightness
of your home, can have a sizable effect on your heating and
The rating might also include a duct
blaster or pressure pan test of the ductwork. This duct blaster
or pressure pan test can determine how leaky the ductwork is
and how much, if any, of your conditioned air might be escaping
to the outdoors. Blower door and duct testing, and in some
cases a visual inspection of the insulation during construction,
is required for certain ratings, such as for *ENERGY STAR®
homes and for certain tax credits.
Other issues which affect the energy use of the home, and must
be documented for the rating are:
the type and amount of insulation in the walls, floors,
ceilings and other areas;
the size and efficiency of the heating, cooling and
water heating equipment;
the insulating value, or U-value, of windows and doors
in the home;
other types of energy using equipment;
the number of occupants in the home and
how the energy using equipment is controlled.
After the information is gathered and
all relevant testing completed, the Rater inputs the information
into the Home Energy Rating System approved rating software
program. The program then calculates the home's energy usage
If the owner has the actual energy usage history
for the house (copies of electric, gas, and/or other utility
bills for one or more years), the real usage and costs can
be compared to the results of the software for accuracy.
It is important to note that the results of the Home Energy
Rating will vary from actual use due to variations in energy
usage by occupants.
What Does the Rating Mean?
The cost of heating a home is the
largest cost of home ownership after the mortgage. An efficient
home can save on your utility bills and provide you and your
family with greater comfort for years to come.
The homeowner will receive a detailed
report which will help to show the home owner where they will
benefit the most from energy efficiency improvements. The
rating consists of a star and a
numeric rating. The numeric rating is associated with a
percentage of the energy the home would use compared to a
home built to minimum energy code standards. The more efficient
the home, the lower the number (percentage) and the more stars
of the rating score. The following chart provides general
information regarding the overall efficiency and the numeric
and star rating scales.
Extremely Efficient and ENERGY STAR®
Very Efficient and ENERGY STAR®
Extremely Poor Efficiency
Homes in these categories show
the greatest need for improvement,
using 250% to 500% (2½ to 5 times) more energy than the
a home built to minimum energy code standards.
Your HERS Report
The HERS report will pinpoint specific areas
of your home which are wasting energy and money. By comparing
improvement costs to possible benefits, a home owner can
determine which improvements will be the most cost effective.
Most raters will be able to help in this decision making
process, and may provide a report outlining which improvements
they expect will result in the most savings for the least
How Should I Prepare My Home for the Rating?
The Rater will have all of the necessary
paperwork and tools required to complete the rating.
You should make sure that the Rater has clear
access to the basement, attic, crawlspace and all energy using
If there is a fireplace or wood burning stove, the ashes
should be removed to avoid the possibility of blowing onto
Once again, you will notice very little air movement
in the home due to the effects of the blower door, usually
no more than a slight draft in areas of high leakage
The rater will need to close all exterior windows and doors,
and open all interior doors to perform the blower door
*Note that for ENERGY STAR® ratings, a separate thermal
bypass check list must be completed on new homes.
This will require an inspection of the insulation prior to the
application of the interior wall finish.
If available, you should also have the actual energy usage
history for the house including the real usage and costs.
This would consist of copies of utility bills for a typical
year or up to three years if available. This is not a
necessary part of the rating, but does help with evaluating
possible improvements. You should also talk to your rater
about any specific areas of the home you are concerned about,
or possibly prepare a list of energy items that most interest
How Much Does the Rating Cost?
The cost of a rating can vary depending on the degree of
complexity, travel distance, size of a home, accessibility,
whether the rating is for an existing or new home, and of
course, the pricing structure of the individual rater.
The simplest rating may only involve a physical inspection
to check insulation levels, equipment efficiency and other
readily available efficiency factors, and then to make minimum
recommendations for possible energy savings. The most complex
rating would include a blower door test for infiltration,
a duct blaster test for duct leakage, physical inspections
during different phases of construction, completion of ENERGY
STAR® checklists, HVAC load calculations, participation
in design decisions, multiple software input changes to
compare possible designs and submittal of calculations and
verification of compliance with requirements for ENERGY
STAR®, energy codes or other efficiency programs.
Because of wide variation of rating complexity, costs will
also vary from a minimum of $250 to $2,500 or more.
It is recommended that perspective customers check with
community service agencies, utilities and other providers
of energy efficiency programs, as some may provide these
ratings for free, or at a reduced costs. Regardless of
possible incentives, the customer should always check pricing
from multiple providers to compare like costs.
Who Can Provide the Ratings?
For a list of certified HERS raters
across the nation, please visit the
STAR® website; or the Residential Energy Services
Network (RESNET) website under the
consumer information link.
Questions or comments regarding the
quality or actions of raters, or the program itself, can
be directed to: