Tuesday, October 18, 2011

Energy Safari: Energy Efficient Life Sciences Building At Dartmouth

An LEED Building at Dartmouth: Conserving Energy

On October 11, the ILEAD Energy Safari Class visited the new Life Sciences Building at Dartmouth, to see Energy Conservation as well as Energy Production. As usual, Robert Hargraves has an excellent blog post on our visit.

Our tour was led by Joe Broemel, senior project manager at Dartmouth, and Ken Merrow, project manager at Trumbull-Nelson, a construction company. They were knowledgeable and very patient. They had to be patient, because we asked so many questions.

The building is beautiful, and one of its most lovely features is its careful management of run-off rainwater. Roof gardens help cool the building, and a rain garden (shown above right) is part of the run-off-capture system. Captured rainwater will feed the toilet water, the Reverse Osmosis/Deionized Water system that provides lab water, and cooling tower make-up water. The run-off system is expected to save one million gallons of water a year.

Another beautiful feature is the use of daylight lighting when possible. The labs have large windows, providing daylight deep into the lab space. Adjustable lighting makes up for cloudy weather, rather than the "lights on/lights off" format of most buildings.

I thought back to some of the labs I have worked in during my life: well, they just seemed squalid in comparison!

Air Exchanges

It was a truly gorgeous, energy-efficient building, but it seemed to be such uphill work to make it efficient.

For example most energy-efficient buildings have a tight building envelope, and aim at three air exchanges per hour for ventilation. This building also has a tight envelope, but the labs require twelve air exchanges per hour for safety. That twelve-exchange figure does not include the air exhaust demands of the fume hoods: each square foot of fume hood opening requires 100 cubic feet per minute of air flow to protect the workers.

The building deals with the air-exchange problem well, with an enthalpy wheel (air-air heat exchanger) to capture much of the heat from the air the building needs to vent. The enthalpy wheel is shown at left. (I am not sure how big it is, but it seems about two stories tall.) Enthalpy wheels are a relatively new technology, capable of recapturing 80% of the heat in outflowing air. They also control humidity, and they keep the indoor atmosphere pleasantly humidified. Indoor humidity becomes important in below-zero weather, when the dry air inside a building can lead to cracked skin and nosebleeds. I think enthalpy wheels can make an important contribution to energy conservation. They are used in other buildings on the Dartmouth campus.

Being Cranky About Cost-Effectiveness

However, somehow, I was not as happy with the whole thing as I might have been. All those air exchanges, for example. The building has a very tight envelope, but inside it has has fume hoods and rapid air exchanges in the lab space. I wasn't sure that the carefully built envelope and triple glazed windows were important, considering all the air exchanges. On the other hand, the enthalpy wheel at least mitigated the exchange problem.

Let me first admit I am being completely unfair. The Life Sciences Center is wonderful. It is well designed, and will be an ornament to the Dartmouth campus for at least a century. It has a pleasantly "organic" feel due to the roof gardens, the sweeping views from the large windows, and the use of local wood in the interior design. It's really a marvel.

So, what was my problem? I guess I wish more local buildings had simple efficiency retrofits, rather than this one shining example of every possible type of energy efficiency. If I think of the building as an experiment, then I love it. It shows what can be done. If I think like an energy-committee member (which I am), I can't help but worry about cost-effectiveness.

Still, the world needs shining examples as much as it needs insulated walls in modest homes. This building certainly is such an example, and I am very grateful for Dartmouth for arranging our tour.

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