Energy Performance Score: The time has come.

January 29, 2010 · Posted in Construction, Real Estate · 3 Comments 

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.

Energy Performance Score Sheet

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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Lessons Learned from a Green Building Project

January 17, 2010 · Posted in Construction, Lessons Learned from a Green Building Project · 2 Comments 

Last month, we rounded out the fifth year living in our green home. It seems like a good time to look back at how it all worked out. I plan to write blogs on several topics, including actual energy performance vs expected performance, the value of simplicity, financial analysis, and the life span of air sealing.

You can see a detailed description of the house and all the green features in the Oikos Project Showcase. Here is the first installment. This one came to me even before construction was complete.

Lesson 1: Trust no one, check everything

Take nothing for granted. Despite the best of intentions and very clear drawings, a couple of features failed to make the trip from plans into the real world. One example is the ventilation system. The ductwork for our energy recovery ventilator (ERV) is completely snarled (see photo). On paper, everything looked great. The duct runs were short, straight and smooth. Reality turned out differently.

ERVs (and their cousins heat recovery ventilators) are uniformly designed so the duct connections leading to the outside of the building are on one side of the unit and duct connections leading to the inside are on the other side of the unit. This facilitates an orderly and efficient duct layout. Unfortunately, the installer cut holes to the outside so that the supply ran to one side and the stale air outlet to the other. No matter which way the ERV box was oriented, one of these ducts had to make an immediate 180 degree turn. That adds resistance equivalent to about 40 feet of straight duct. It’s true these two portals must be far enough apart that stale air can’t be sucked back into the fresh air inlet, but six feet of separation is generally considered enough.

The ERV installer didn't follow the plan for the ERV ducwork. It's a mess!

The biggest problem occurred with the duct that delivers fresh air from the ERV to the house. The designer and I carefully considered how this duct should run. A series of chases were designed and built to carry ducts through the building. The stale air exhaust duct and this fresh air duct would occupy the same chase to the ground floor bath. Then a smaller chase would cross a narrow hall to carry the fresh air duct to the ground floor bedrooms. It was clean and simple.

Instead of following the plan, a second fresh air supply run was added from the mechanical closet where the ERV sits to the ground floor bedrooms. That in itself wouldn’t be bad, except the two fresh air delivery ducts originate on opposite sides of the ERV, forcing the use of a T-fitting just a foot from the ERV housing. Air leaving the ERV immediately slams into this T.

Despite careful thought and planning, the guy on the site did it wrong. I’m sure there was a reason, but I’ll never know what it was. Is this a fatal flaw? No. The ERV delivers 80 percent of it’s rated capacity at full power. But some air flow is lost, and the electrically commutated blower motors (ECMs) certainly have to use more electricity.

The real point is that even people with the best intentions can’t get everything right all the time. The construction process is so fragmented that quality control procedures are essential. Quality control is the responsibility of the general contractor. In this case, I will share the responsibility, because I should have caught the problem earlier.

There is another short story that illustrates the need to check everything. Construction was started in April of 2004. You may recall that the ban on pressure-treated lumber using chromated copper arsenate (CCA) took effect that year. The ban meant that no products could be manufactured with CCA after January. However, product already sitting in warehouses could be sold. Well, we specified in the lumber order that no CCA lumber should be used. I happened to visit the site just after the ground floor framing had been completed.

The salesman said there wasn't any of it in the warehouse. Nevertheless, toxic CCA-treated lumber arrived at the site.

Pressure-treated lumber was required for the mud sills and the bottom plates of all the walls, because they sit on concrete. I saw a partially used stack of treated lumber and casually looked at a small tag that was stapled to the end of the each stick (see photo). The lumber yard had delivered CCA. I called the salesman. He said, “The sticker is wrong.” This response has become an alarmingly common reply. Since that day, I have heard many sales reps utter these words in defiance of clear evidence and common sense. If the label actually applied to a product is “wrong” how could we possibly know what is right?

The unused CCA lumber was replaced with something less harmful.I think the salesman was afraid that I would demand that the installed material be ripped out and replaced too. I didn’t think that was necessary.

There are hundreds of products and materials delivered to every job site. How many of these are wrong? Too often, installers substitute materials or make installation errors that are never caught. Green building is far more susceptible to this problem than typical construction, because green projects have more components that are out of the ordinary.

I’m confronted with this issue frequently in my capacity as a green rater for Earth Advantage Institute. While certification will not solve all the problems, it can reduce blatant errors and help to ensure that home builders and home buyers get what they pay for.

Bruce Sullivan

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