Andy Warren
Submitted photo

Ah, summertime in Arizona. A time for cooling off in the backyard swimming pool, barbecuing with family and neighbors and planning our seasonal escapes to cooler climates. It’s also the time when living in an energy-efficient home can mean the difference between receiving a monthly electricity bill that’s manageable and one that causes your blood to boil.

The energy efficiency of new and existing homes is measured by an industry standard called a HERS rating. HERS stands for Home Energy Rating System. Often compared to a car’s MPG (miles per gallon) rating, a HERS score can tell a potential buyer a lot about a home’s energy performance. Here are three things every homebuyer should know about a HERS score:

Why it’s important

The HERS rating provides a quick snapshot of the home’s energy performance. If you’re buying a new home, a favorable HERS score can help you anticipate the cost of future energy bills. If you’re a seller, a good rating is a handy marketing tool that could lead to your home commanding a higher resale price than a less energy-efficient alternative down the block.

How it works

The Residential Energy Services Network (RESNET) has created an index where a home built to the codes generally in place when the index was created (about five years ago) would score a 100, while a typical resale home can often score around 130 (or much higher or lower, depending on when and how it was constructed). Factors taken into account include energy consumed by heating and cooling systems, water heaters, lights and appliances.

Each one-point change on the HERS Index’s 150-point scale represents a 1 percent change in energy efficiency. For example, a home with a HERS Index score of 60 is 40 percent more efficient than a standard new home. Like in golf, the lower the score, the better.

What makes a low score

Constant, industry-wide improvements in HERS scores have emerged through a variety of factors, ranging from more energy-efficient appliances and light bulbs to the use of high-performance building materials. This multipronged effort toward greener building has evolved over the past several years as homebuilders increase their commitment to both their customers and the environment.

A low HERS score has become a coveted symbol of quality. Find out more about HERS by visiting the Residential Energy Services Network website at

• Andy Warren is president of Arizona homebuilder Maracay Homes, part of the TRI Pointe Homes family of builders. He serves on the board of directors and as an executive committee member with the Greater Phoenix Economic Council and is a past board member of the Home Builders Association of Central Arizona. He is also a member of Greater Phoenix Leadership and an active member of the Urban Land Institute.

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