THE NORTHERN CALIFORNIA town of Morgan Hill has seen many changes throughout the years. It began as an agricultural community in what once was known as the Valley of Heart’s Desire because of the area’s rich farmland. Today, Morgan Hill fi nds itself enveloped by the technological revolution that created what we now refer to as Silicon Valley. The valley and town had to adapt to changing times and a changing economic base.
Once the center of Morgan Hill’s agribusiness, the Granary had fallen into disuse and stood only as a relic of a bygone era. It had been built in the 1940s in the center of town on a main, north/south railroad line and remained in operation until 1995. In 2003, Morgan Hill-based Weston Miles Architects Inc. saw potential in the old, unused building. Rather than tear it down and build something new, the firm perceived an opportunity to reduce, reuse and recycle. Waste could be reduced through adaptive reuse of the building. By using metal, a highly recycled and recyclable material, it was possible to take an inherently green idea to the next level.
EVERYTHING OLD IS NEW AGAIN
What began as a 9,000-square-foot (836-m2) existing building supplied 20,000 square feet (1858 m2) of usable space after the renovation. Two stories were added in one area and a third story was put on in another, taller part of the building. “We were really interested in keeping that history—a feeling of what had been here,” says Lesley Miles, AIA, LEED AP, principal with Weston Miles Architects. “For us, the Granary building was an icon of that time period. If you go down the Southern Pacific tracks out here, there are lots of these buildings. There’s a huge opportunity to develop sustainable buildings close to transit. They can be rehabilitated and made into really unique, exciting spaces.” Th e fi rm long has had an interest in sustainable design and construction, so giving new use to an old building held a great appeal for Miles and her partner, Charles Weston, AIA, NCARB, LEED AP. Th e process of demolition and subsequent construction of a new building is very energy- and waste-intensive, as well as expensive. More often, the idea of renovation and adaptive reuse is coming into vogue. The Granary provided a chance to put these ideas into practice and try new things along the way. The renovated building ultimately earned a LEED for New Construction Gold certification from the Washington, D.C.-based U.S. Green Building Council. “The metal aspects of the building really helped us,” Miles explains. “It also kept the costs down on the entire renovation project. In looking at doing a metal building, we realized there was an opportunity to do the most sustainable building we could build. Th e Granary allowed us to reuse 75 percent of the existing building structure and re-clad it. Th e neat thing about metal is it allows you to have a complete finish. It’s extremely green because, on top of having at least 25 percent recycled content, you don’t have to add another material to finish it.”
WASTE NOT
For the walls, it was decided to use a Galvalume panel. “It’s a galvanized product with an aluminum component,” Miles explains. “The finish has a subtle glow to it, but the aluminum gives additional rust-proofing. With galvanized metal, over time in places where it’s tweaked, eventually it will start rusting. Galvalume doesn’t have that problem.”
Installation of the metal was quick and smooth, adding to the effi ciency of the project. “Because we had an existing frame that we covered, we ordered all the sheets to size; it was like ordering a giant puzzle. There was absolutely no waste,” Miles says. “That was something we found out as we were going through the process and looking at things from a sustainability standpoint; if you have zero waste on your exterior finish material, it’s pretty amazing.” “The building is a prefabricated steel-frame building, so the vertical weight is taken by the frames and the lateral weight is taken by the cross cables,” Weston explains. “By code, we couldn’t add more lateral weight to the existing structure.” According to Weston, there was a fairly low-tech solution to this issue. “What we did was build a box within a bigger box, so the little box could carry its own vertical and horizontal load without touching the bigger box,” he continues. “On a normal prefabricated metal building there are girts from one metal frame to the next, and you directly apply siding to the girt. I couldn’t do that because I had this structural problem to overcome, so I took the girts out between each of the metal frames and put in a typical 2- by 6-inch [51- by 152-mm] wall and installed waterproofing and a nailing substrate on the exterior.
I built it as in normal construction and installed the metal on that. So there are two shells, essentially.” Building on their interest in keeping the original historic appeal of the Granary, Miles and Weston kept the original metal roof system on the building, leaving it exposed on the building’s interior. In places where the original roof had rusted through, Weston replaced it with original metal wall panels.
The team then re-covered the existing metal roof with a new metal roof. “We used a 6-inch [152-mm] light-gauge metal stud to build a cavity and put the new roofing on top of it,” Miles explains. “We blew in insulation, which was 96 percent recycled newspaper, and filled the cavity. That worked out great. We designed the building to be very energy efficient, but it still ended up using 25 percent less energy than we thought it would.” Th e 14,341-square-foot (1332-m2) roof has energy-effi ciency qualities of its own. “It has high emissivity and high reflectivity, so it is a cool roof. There is a coating,” Miles says.
SEE THE LIGHT
The roof also supports a photovoltaic array, another of the many green features of the adaptive-reuse project. “We waited a year and a half before we put the PV on the roof because we wanted to examine our energy usage and design it properly,” Miles says. “We were able to design solar panels for a much lower wattage than we thought. It’s 16 kilowatts, which is about 40 percent of our average annual energy use.” Operable windows provide a great deal of natural light to the building’s interior. “What was great about using metal is that we could provide a number of openings,” Miles explains. “One of the things we looked at was designing the window system to look like an old-fashioned industrial sash with the operable window in the center. That was quite a challenge.
The windows are low-E, and 50 percent of the year our inside-to-outside ambient temperature is close enough that we can open the windows and not use our mechanical system.” The site surrounding the Granary also came into play. “All around the building was concrete and hard-packed gravel from years of trucking,” Miles recalls. “We took that up and planted an orchard of 45 apricot and French prune trees, which are original to the valley. We used pervious concrete for parking; it acts as a giant sponge when it rains and releases the water gently to the aquifers. Th is is particularly appealing in our area, which is historically dry.” Weston Miles Architects moved its offi ce into the renovated Granary building in 2005. There are three other businesses in the building, and a pizzeria is about to move in. “From a simplicity and sustainability standpoint, reusing the building shell made a lot of sense,” Miles says.
“One of the reasons we bought the building is because everyone who was looking at it wanted to demolish it. That would have been such a shame.” Miles also insists there is a bottom-line cost advantage to going green. “There’s a tendency for people to say that building green is more expensive, but we found that by designing in a sustainable manner, we really thought about the materials we used and how we could limit the number of materials,” she explains. “By doing that, we were pleasantly surprised by the ultimate cost.”
In the current economic climate, the business case for green grows even stronger. “Right now the economic stimulus package and the current grant on the books allows companies to get up to $1.80 per square foot off their taxes by making their buildings more sustainable, so there’s a real opportunity for people to do projects like this,” Miles says. “Unfortunately, we completed the first phase of our project before this tax credit, but when we installed our PV last year, we were eligible for sizable tax savings, as well as a substantial grant from [Sacramento- based] Pacific Gas & Electric. I think there will be more opportunities like this in the future.”
Panel Discussion
The Granary in Morgan Hill, Calif., was designed by Weston Miles Architects Inc. and constructed by the firm’s in-house construction business, Weston Construction Inc., Morgan Hill, www.wmarchitects.com. Ahearn, Knox & Hyde Inc., San Jose, Calif., performed the structural-engineering work for the building. The team reused an existing 1940s Kansas City, Mo.-based Butler Manufacturing (www.butlermfg.com) steel building system, installing new metal roof and metal wall panels onto the structure. McElroy Metal Inc., Bossier City, La., manufactured 17,700 square feet (1644 m²) of Multi-cor panels for the building’s walls. The 26-gauge Galvalume Plus panels have achieved UL 790 for Fire Resistance and UL 2218 Class 4 Impact Resistance. McElroy Metal also manufactured 14,341 square feet (1332 m²) of its 24-gauge Mult-rib PVFSR roof panels with a dark bronze fluoropon coating. The panels have been tested according to UL 580 Class 90 Uplift and UL 2218 Class 4 Impact Resistance. For more information, visit www.mcelroymetal.com.