In addition to uniting the programmatic blocks, the supersize roof accommodates a photovoltaic system. “That’s the genesis of the design,” says Joe Lear, a principal at Davis. “But unless you have multiple sources of renewables, a net zero energy fire station is very difficult to achieve.” The project did not meet that target, but the photovoltaics, in combination with a low energy use intensity (EUI), mean that the station is well on its way to achieving net zero carbon, if the client decides to purchase emissions-free electricity.

The building’s EUI, estimated at 56.2, is less than half of what’s typical for public-safety facilities. It was achieved through a combination of highly insulated walls and roof, LED lighting, occupancy sensors, and a variable air volume (VAV) rooftop unit with a heat pump. The roof’s sheltering overhangs, combined with a municipal commitment to plowing, made it possible to dispense with electric snow-melting cable in the station’s apron paving. As a result of these conservation measures, the 207-kilowatt PV system is expected to turn Boulder’s 300 or so sunny days a year into about 65 percent of the all-electric building’s energy needs.

Some of the 89 steel members in the station that were salvaged from a deconstructed hospital are visible in the apparatus bay. Photo © Thomas Ellis

Prioritizing embodied as well as operating energy, perhaps the most innovative aspect of the building is its reuse of over 25 tons of salvaged structural steel. During the schematic-design phase, the client alerted the project team to the possibility of reusing framing from the deconstruction of a hospital, which the city also owned. That may sound like a straightforward proposition, but it wasn’t simply a matter of unbolting the hospital framing and delivering it to its new jobsite. During design development, there was some uncertainty as to whether the two projects’ schedules would align. To hold open the possibility of reuse, the structural drawings provided specifications for both new and salvaged members. “It’s a little bit of a change in thought process to say, ‘Well, here’s what I have available to me, and how is that structurally equivalent to what I would choose from scratch,’” says Chris Kendall, a principal at KL&A, structural consultant for both the hospital deconstruction and the new fire station. Organizing the various framing members to form an orderly composition—without, for example, mismatched depths in the exposed beams—also took some doing, says project architect Josh Perrin. “We rearranged things to maximize the steel usage while trying to create visual consistency within a structural bay,” he says.

KL&A also specified and managed a careful process of deconstructing, cataloguing, stockpiling, and testing the material. Fire retardant and other coatings were removed. Each piece was given its own cut sheet, including a picture, dimensions, and additional detail. Shop drawings were generated, and the framing members fabricated—cut to length, with leftover bits and pieces from their previous service selectively removed, and bolt holes drilled—for their new application. Ultimately, the design was able to reuse 89 salvaged pieces (32 percent of the original stockpile) for an embodied-carbon savings of 25,000 kilograms. (The city is offering the remaining steel, in any quantity, for $1.)

The additional labor associated with salvaging the steel meant that cost savings on the material were insignificant, coming in at about $6,000, according to Kendall. The real value lay in reducing the project’s embodied carbon, advancing the city’s ecological mandate, allocating the steel budget to local jobs, and putting a resource to good use. “We’re using 80-year-old material for a new hundred-year building,” says Lear. “We’ve more than doubled its life.”

Click diagram to enlarge