May 2, 2002

Sustainable design in the real world

Courtesy of McGowan Broz Engineers The Federal Aviation Administration’s new Terminal Radar Approach Control building at Sea-Tac Airport was designed to the LEED gold level. Currently entering construction, the 45,000-square-foot facility will direct air traffic approximately six to 35 miles from the airport.

Though every job and client gets our best effort, there is an unmistakable sense of calling about our green design work. And the resulting idealism is undoubtedly good for our clients and communities, not to mention our own professional well-being.

That said, what we really get paid for is to help owners decide just how a project will be green, then get that vision “into the ground.” It is nutsy-boltsy and unglamorous — but in the end, profoundly satisfying. Here, then, are a few of the challenges we’ve encountered, and how they were (or weren’t) overcome.

lEvolving standards

Though sustainable design is as old as human-built structures, the systemization of the underlying precepts is, relatively speaking, in its infancy. One of the most prominent standards used today is the U. S. Green Building Council’s Leadership in Energy and Environmental Design (LEED). Essentially a “checklist” approach to sustainable design, it’s a fine standard and represents much thought and effort by the many professionals who contributed to it. New as it is, however, there are a few gaps.

One of those gaps is in the LEED energy efficiency credit. In our design of the new Terminal Radar Approach Control (Tracon) facility at Sea-Tac Airport, we encountered an interesting question on process or “plug” loads — literally, electrical loads needed to accomplish tasks, and which typically plug into the wall (such as computers). Plug loads are of considerable interest to designers striving to achieve a high percentage of energy savings because:

• Plug loads generally arise from end-user work requirements and, as such, are not controllable by the building designer.

• Depending on the building, they can dominate total energy consumption.

• Their nondiscretionary nature can make it difficult to achieve good energy savings percentage-wise. (More about that below.)

The LEED standard actually evolved during our design of the Tracon facility. The version we started out with accounted for plug loads in its energy calculation methodology, but did not consider the fact they weren’t controllable by the designer.

However, the version in effect at the January 2002 design completion did consider this, by allowing the analyst to back them out of the final analysis. But what about the energy needed to cool those plug loads? You can make a good argument either way: either it should be included in the analysis because the energy will, in fact, be expended; or it shouldn’t be included because the plug loads themselves aren’t included.

It turned out that the newer edition of LEED was silent on the subject, and we ended up having to get an on-the-fly adjudication: the plug-related cooling loads stayed in. We are feeding this information back to the Green Building Council in hope of seeing it reflected in later editions.

What works?

As we continue to gain experience in “building green,” we’re getting a good feel for what is and isn’t feasible here in Western Washington. A good example is the aforementioned energy conservation credit. The LEED standard offers increasing credits for energy savings up to 50 percent above a defined baseline.

In reality, here on the wet side of the mountains you’re doing well to achieve 20 percent to 25 percent savings, though it obviously depends on the specific building and site.

Much of this is due to our temperate climate. We don’t get too hot, too cold or too muggy, so heat losses and gains through the building envelope are modest compared to many other parts of the country. So if you really want to go for big energy savings, try Fairbanks or Miami.

On the other hand, some measures are relatively easy to implement and pay back quickly. Water conservation in buildings is easily implemented through the use of modern, low-flow fixtures. This is doubly advantageous, as it minimizes the burden on both the water and wastewater utilities. Measures to improve indoor air quality, such as controlling vapor emissions during construction and use of carbon dioxide monitors, can be done at modest cost. There are numerous other examples of good payback.

Keep the faith

Designing green isn’t a chore, provided the design team (including the owner) addresses sustainability from the earliest conceptual stages. We’ve dealt with projects where sustainability was “tacked on” late in the game. The difficulties increase exponentially with time.

Finally, we recently completed a project where the bids came in too high to support the sustainable design provisions we had painstakingly designed in. For every one of those, though, we’re confident there will be another where the sustainable elements are implemented, fulfilling the promise of green design: creating buildings that don’t pose a burden on future generations.

Other Stories:

• When building green isn’t thinking green
  
• Why green buildings fatten your bottom line
  
• The future bodes well for green development
  
• Smart planning begets smart lighting