“VERY URBAN” is the title of this shot of the formerly-known-as-WaMu tower by photocoyote.
It’s technical, and doesn’t sound like much–a U-value of 0.35 for window systems in commercial buildings–but it’s got the architects at at least one major Seattle firm, Callison, and the people at another company you may have heard of–Vulcan?–riled up. The change comes as the city of Seattle adopts the 2009 Washington State Energy Code (WSEC), and adds its own tweaks, before “going live” with it on July 1 of this year.
While the state code allows up to 40 percent of a commercial building to be “glazing area” (i.e., windows), Seattle would apply more stringent heat-loss requirements to buildings with 30 to 40 percent glazing area: a U-value of 0.35.
A low U-value tells you that a window (or the whole window system, including the sash and frame) provides greater insulation, keeping heat from traveling in or out. In commercial real estate, this can mean substantial savings in heating and cooling costs over the life of the building.
The DPD’s John Hogan says that on average window area makes up 25 percent of the gross wall area in non-residential construction, so 30 to 40 percent is on the high side. (The optimum for energy efficiency, he says, is 15 to 30 percent.) Thus, the lower target U-value of 0.35 for the view-tastic model.
Vulcan’s Hamilton Hazelhurst says the lower U-value represents a “huge financial cost that would be impossible to justify in terms of cost/benefit.” As an instance, he points out that the Amazon SLU project has a U-value of 0.38. Doesn’t seem like much of a difference. But Hazelhurst claims that to achieve the one percent in energy efficiency you’d get from moving to 0.35, the payback on the cost of $1.2 million would take 387 years. He also says, chillingly, if the code update had been in effect, it’s likely Amazon would have built elsewhere.
UPDATE: Hazelhurst adds more detail–Amazon had specifically requested operable windows, but “the minimum U-values [for opening windows] currently available from manufacturers is 0.45.” So Amazon would have been faced with a choice: windows that open, or SLU. Given Amazon’s keen interest in operable windows, it’s not clear whether they would be SLU tenants, or ensconced on the Eastside.
In Seattle’s temperate climate, the architects and developers say, it’s not cost-effective to extract these minute gains in energy efficiency. The city seems unconvinced that the cost is in fact prohibitive, but does appear to be open to another low-tech energy-saving solution: windows that open. If you can open a window instead of running air-conditioning, that’s a real energy savings, and it’s something that Seattle’s middling heat waves allows.
The next Construction Codes Advisory Board (CCAB) meeting is May 20. Should be interesting.