Lessons Learned from a Green Building Project

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

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.

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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.

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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, โ€œThe sticker is wrong.โ€ 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 โ€œwrongโ€ 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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Comments

2 Responses to “Lessons Learned from a Green Building Project”

  1. spacer Carpet on January 30th, 2010 1:11 am

    Don’t just check once, check everything that comes in the door. So many are only looking at getting their products out of the warehouse.

  2. spacer Mike O'Brien on February 1st, 2010 7:06 pm

    Hi, Bruce–

    Thanks so much for writing up your experiences. You’ve pointed out a major issue in green building, that is too frequently ignored in reports on new buildings.

    We had some similar experiences with our otherwise excellent and capable subs, with one exception. The electrician from Red’s Electric recommended that we do a walkthrough of the house with our electrical plan in hand to confirm that all fixtures, switches and outlets were correct. Over two hours, to my surprise we ended up making many changes to our carefully considered plan, and improved the electrical system quite a bit. That experience suggests that it would always be helpful to walk through an installation with the person who actually does the work.

    As just one example, we had not specified where to locate transformers for halogen track lights. He suggested places, and also managed to reduce the number of transformers and save some money in the process.

    One of the new guys did drill wiring holes through the bottom chords of several trusses before he was stopped; fortunately our code inspector allowed us to make in-place repairs or that would have been a mess.

    Best,

    Mike

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