What Does a Home Energy Rating Really Mean?

The home energy rating, also known as the HERS index, is a standardized score that tells you where your home stands in the range of energy efficiency compared to an identical reference home. The HERS index is useful for developing effective plans to make improvements and upgrade efficiency, as well as for use when considering the purchase of an existing home. It’s also a marketing tool for home sellers to emphasize the energy efficiency of the house to potential buyers.

The Rating Process

HERS begins with an efficiency inspection by a HERS rater trained and certified by RESNET, a non-profit organization that sets standards for home energy rating.  The visual part of the inspection involves a close-up look at these factors:

• Building envelope characteristics, including the number of doors and windows, amount and type of insulation and condition of ductwork
• Air conditioner, furnace and ventilation system types and manufacturer’s efficiency ratings
• Types of major appliances
• Number of lighting fixtures and type of bulbs
• Evidence of moisture intrusion such as roof leaks or walls
• Any visible health or safety issues

The diagnostic phase uses specialized technology to quantify these efficiency factors:

• The extent of air leakage in the structure and the location of leaks is determined by a blower door test.
• Air loss from ductwork is evaluated by a duct pressurization test.
• The level and effectiveness of insulation is tested with infrared visualization.
• The safety and efficiency of furnace, stove and other combustion-related appliances is checked by a combustion analyzer and carbon monoxide detector.

What the Results Mean

The HERS index figure is calculated by comparing scores on aspects of the inspection to a reference house, which is an ideal new home of the same square footage that serves as a baseline. Scores above 100 indicate less efficiency and below 100 indicate greater efficiency. A home with a score of 75 indicates your home is more efficient than the reference house, while a score of 125 indicates less efficiency.

For more about obtaining a certified home energy rating for you house, contact Stack Heating & Cooling.

Our goal is to help educate our customers in Cleveland, Ohio about energy and home comfort issues (specific to HVAC systems).  For more information about home energy Rating and other HVAC topics, download our free Home Comfort Resource guide.

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