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Energy Performance Score: The time has come.

Buying homes is a very emotional process. It’s no wonder that so many people buy energy pigs with lipstick. They look nice, but swill energy. Few people think about how much electricity or natural gas they will have to buy to stay comfortable after purchasing the pig.

Most folks shopping for homes labor under the misconception that new homes use less energy than old homes. There is a certain logic here. New homes tend to have more insulation, better windows and more efficient heating systems. Why, then, do older homes often use less? Take the state of Oregon, for example. I recently learned that the average home in our state uses about 78 million Btus (mmBtu). Based on energy models, we expect a “typical” new home to use about 98 mmBtu. I’m talking about total energy consumption for space heating, water heating, lights, appliances, everything.

After the shock wore off, I started to think of reasons. First, existing homes tend to be much smaller. In Oregon, the housing stock includes homes that are up to 100 years old and most of them are small – between 1,400 and 2,000 square feet. By contrast, the average size of new homes is 2,400 square feet and some are much larger. Size matters.

This brings up and interesting distinction between “efficiency” and “consumption.” Large houses might be called efficient, if they use a less energy per square foot of conditioned floor area than a smaller house. However, the smaller house would consume less energy. Which is more important? Consumption is more important – without a doubt.

Here’s another example. When we built our current house in 2004, we bought a new refrigerator. Comparing the actual energy consumption of several models, I noticed that a 22 cubic foot ENERGY STAR model was expected to use more electricity than an 18 cubic foot refrigerator without the ENERGY STAR label. The larger, more efficient, model would use more energy than the smaller, less efficient, one

There’s been some debate among energy nerds about a term known as Energy Utilization Index (EUI). This term expresses building efficiency as energy per square foot of conditioned space. Some nerds also argue that climate must be factored in, so that those unfortunate enough to live in cold areas are not burdened with guilt for using more energy. Climate matters, too.

As we move into the age of carbon footprints, we need to focus on consumption. It’s the bottom line. Consumption is what you pay for. Consumption generates greenhouse gases and toxic pollution. Consumption must be the yardstick that we use to set energy targets and measure our progress toward those targets.

Which brings us back to helping homebuyers choose houses. Technically speaking, it’s not high efficiency we want to sell, it’s low energy consumption. There are a number of proposals floating around for labeling systems that rate a home’s energy performance and then slap that rating on a label in order to communicate the information to home shoppers.

The system I prefer is called Energy Performance Score, because it shows consumption directly. Using the example of Oregon homes, the average home that consumed 78 mmbtu would have an EPS of 78, while the new home that consumed 98 mmbtu would have an EPS of 98. Simple, huh? The EPS value is the building’s total energy consumption in Btus without all those pesky zeros. Like a golf score, lower is better. When you get to zero, you have a zero energy building.

The EPS score sheet shows the energy consumption, greenhouse gas impact and estimates energy costs.

EPS wasn’t the first energy rating for homes. The Home Energy Rating System (HERS) created and administered by RESNET goes back to the late 1970s. The HERS rating is the standard energy rating approach for residential buildings. It is recognized by government agencies and lenders as the basis for energy efficient mortgages.

While HERS has been available for decades, it has two flaws. It ignores both climate and building size. A 4000 square foot house in Maine could have the same rating as a 2000 square foot house in Arkansas even though the actual energy consumption was starkly different.

In addition to the energy consumption score, the EPS process generates a carbon score based on the amount of electricity and natural gas used and the carbon released in order to bring that energy to the home.

I should emphasize that EPS and HERS are projections using computer models, not measurements of actual consumption. The number of people in a house and their behavior will have a big impact on the monthly consumption. This is impossible to model accurately with a computer. What they do model is the structure and equipment of the building that enable occupants to achieve low energy use. Without good energy bones, occupants are unlikely to achieve the desired results.

So, my preference is the EPS system. (And, it has nothing to do with my day job at Earth Advantage.) A metric based on consumption is simple and direct. It gives builders, real estate brokers, lenders a clear way to communicate the actual energy consumption of homes. It gives homeowners an idea of where they stand and motivates them to improve. It allows society to set measurable goals for performance. It drives the housing market to build better houses.

If you agree that we need a clear metric to express the energy consumption of homes, you can give the idea a big boost by voting on Change.org. Ideas with the most votes may get the ear of the White House. The page titled We Must Change Energy Behavior – An MPG Rating for Your Home explains the EPS procedure and gives more great reasons why we should move forward with this idea – whether or not it gets an audience with the Obama Administration.

The EPS value should be published in real estate advertisements, included in multiple listing services and printed on standard appraisal forms. Every home placed on the market should have an EPS number just as every car on the lot carries an EPA mileage sticker.

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