Known for being economical in terms of space and sticker price, prefabricated homes are also boasting increasingly abbreviated build times. One modest-sized dwelling in Castlemaine, Australia took a mere 10 days to construct and garnered an esteemed sustainability marque from PassivHaus to boot. One of the world’s fastest-growing energy performance standards, ‘Passive House’ accreditation is doled out solely to homes operating on 90 percent less energy than traditional homes. For consideration, three eco-friendly parameters are paramount: thermal performance, airtightness, and ventilation. The most efficient homes use the sun, internal heat sources, and heat recovery for insulation, avoiding the need for energy-guzzling radiators even in the icy throes of winter. At just 419 square feet, the Passive House in Castlemaine, Australia (the first in the country to receive this certification) comprises a wooden frame with wool and fiber insulation and a facade clad in steel to confer a modern look. Further insulation comes from the triple-glazed windows and specially engineered seals protecting the windows and floors, which is made from an air-tight membrane called Intello. Keeping the interior snug and toasty year-round is an energy recovery system which, contrary to ordinary logic, funnels air into the house, heating it in the winter and cooling it in the summer at low running cost while also keeping moisture out. The system also tamps down heat transfer, giving the exterior of the house a u-value (heat transfer coefficient) of 0.261 watts per square meter. The lower a home’s u-value, the better its insulation. As a result, annual heating, electricity and hot water demands for the Castlemaine Passivhaus are a mere 11 kilowatt hours per square foot. Designed by Australian architectural firm CARBONlite, which specializes in prefab homes, the various sections of the Castlemaine dwelling were built off-site over a 5-day period. Once assembled on site, the exterior was erected and the building made wind and watertight that same day. The house has a mono pitch roof with an overhang to provide shade and minimize overheating during Australia’s scorching summers.
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Architects deliver a North American first with Warren Woods Ecology Field Station.When Belfast, Maine–based architecture firm GO Logic presented the University of Chicago's Department of Ecology and Evolution with three schematic designs for the new Warren Woods Ecology Field Station, the academics decided to go for broke. Despite being new to Passive House building, the university was attracted to the sustainability standard given the laboratory's remote location in Berrien County, Michigan. "We presented them with three design options: one more compact, one more aggressive formally," recalled project architect Timothy Lock. The third option had an even more complicated form, one that would make Passive House certification difficult. "They said: 'We want the third one—and we want you to get it certified,'" said Lock. "We had our work cut out for us." Thanks in no small part to an envelope comprising a cedar rain screen, fully integrated insulation system, and high performance glazing, GO Logic succeeded in meeting the aesthetic and environmental goals set down by the university, with the result that the Warren Woods facility is the first Passive House–certified laboratory in North America. Warren Woods' envelope begins at ground level, with a shallow foundation utilizing GO Logic's patented L-shaped EPS insulation around the edges, and a continuous air-seal layer between the foam and the slab. "The system allows us to pour consistent slab-on-grade without any thermal bridging," explained Lock. The sealing layer connects into the wood stud wall backed by graphite-impregnated Neopor insulation. The architects chose the insulation for its high R-value, knowing that they would need to compensate for the relatively large amount of surface area dedicated to the exterior wall. Pro clima one-way breathable building paper allows the building to expel moisture. GO Logic installed a rain screen of Eastern White Cedar vertical gap siding sourced from the Upper Peninsula "because of the aesthetic goals of the client," said Lock. "They desired a contemporary aesthetic but also [the look of] a Midwestern barn." The architects planned the interior space and allotted glazing judiciously, locating the laboratory on the north side of the building. Its position, under the cantilever over the entry, maximally reduces solar gain—an important consideration given the heat generated by the equipment inside. The classroom space, on the other hand, is positioned on the building's south side, punctuated by a long strip of Kneer-Südfenster glazing. "We are highly critical of windows that are available domestically," said Lock. "The big drawback with North American windows is that the tradeoff for a higher R-value is significantly reduced solar heat gain." Instead, the firm imports Kneer-Süd's products directly from Germany. "In Northern Europe they know how to get all the heat from the sun that they can," he observed. "We also love the way they look." The windows and doors are fully integrated into the air-seal layer using one-way breathable tapes from SIGA, imported (like the pro clima paper) through 475 High Performance Building Supply in Brooklyn. A custom-fabricated stainless steel accordion screen shields the classroom-side glazing from both intruders and the sun. "It's good for security—the university likes that," said Lock. "But the screen was also big for us to control the amount of heat that enters during the summer months and shoulder seasons." The idea, he explained, is that when classes are in session and the weather is nice, the occupants can throw open the doors. When only the laboratory is in operation, the closed screen will cut back on heat gain. In addition, the steel mesh "became something that was also a really exciting design feature," said Lock. "It had a great effect—not just cooling the space, but also softening the natural light."
Net zero energy, LEED Platinum project raises the bar on eco-friendly office design.For its new headquarters in Los Altos, California, the David and Lucile Packard Foundation put its building budget where its mouth is. The philanthropic organization, whose four program areas include conservation and science, asked San Francisco-based EHDD to design a net zero energy, LEED Platinum building that would serve as a model of cutting-edge green building techniques. “They wanted to achieve net zero in a way that was replicable, and that showed the path forward for others to follow,” said project manager Brad Jacobson. “It was not just a one-off thing, not just a showcase.” The building’s facade was fundamental to its success as an example of sustainable design. “We were surprised at how significant the envelope is, even in the most benign climate,” said Jacobson. “Pushing the envelope to really high performance made significant energy and comfort impacts, and could be justified even on a first-cost basis.” EHDD began by considering the building’s siting. Because the street grid in Los Altos is angled 40 degrees to the south, orienting to the street would result in a long southwest elevation. The architects asked daylighting consultants Loisos + Ubbelohde what penalty this would entail. “They said you have to keep all solar gain out of the southwest facade; if you do that, the energy penalty will be in the realm of less than five percent,” recalled Jacobson. “But you really have to do an excellent job on sunshading. That was our mission.” EHDD designed deep overhangs over much of the facade’s southwest face, and added balconies and shade trees for additional protection. Where the glazing remained exposed, they installed external movable blinds from Nysan that operate on an astronomic time clock. “The blinds worked really well,” said Jacobson. “We were surprised how easy they were to commission and get working, and how relatively robust they are.” Thermal bridging was another area of concern for the architects. EHDD worked with Atelier Ten on thermal modeling of the wall, and discovered that any metal stud wall would sacrifice performance. They opted instead for wood stud construction, and switched to 24 on center framing to reduce thermal bridging through the framing structure. For insulation, the architects added one-inch external mineral wallboard from Roxul. On advice from structural engineers Tipping Mar, they installed FRP plates to separate external elements like balconies from the main structure. Because of the building’s location, EHDD did not initially consider triple glazing for the Packard Foundation offices. “We wrote it off at first,” said Jacobson. “We thought, that can’t be cost effective in this climate.” But Integral Group’s energy analysis convinced the design team otherwise. The improvement in comfort allowed by triple element windows from Serious Materials (now Alpen HPP) was such that the architects were able to eliminate a planned perimeter heating system, resulting in an estimated savings of twice the cost of the glazing upgrade. “It’s a really good envelope,” said Jacobson. “We did heat sensor testing of the building, and you can really see that it’s working as it’s supposed to. You don’t see the studs, and the windows are not leaking a lot of heat, so that’s been a real success.” The architects clad the building in local and sustainable materials, including FSC-certified western red cedar, stone sourced from within a 500-mile radius, and architectural copper. “Architectural copper is a really interesting material,” observed Jacobson. “It’s actually about 80-90 percent recycled because it’s valued. It doesn’t need refinishing and it patinas nicely. For a building being built to last 100 years, it has a good shot at never needing to be refinished or replaced.” Jacobson summarizes his firm’s approach to the design of the Packard Foundation headquarters as “Passive House light.” “At the same time we were doing a Passive House for a climate science researcher we’d worked with in the past,” he said. “We were working on both and learning from each. It’s a different type of building, but a lot of the same principles apply: good air sealing, eliminating thermal bridging, and pushing the envelope further than you think makes sense.”
Santa Fe, New Mexico–based architecture firm WAMO Studio recently moved into a cool new office—a former walk-in ice cream freezer. The repurposed space, formerly used by Taos Cow Ice Cream to store frozen treats. The 550-square-foot freezer offers a sleek and industrial space with sheet metal walls and industrial-strength insulation. After a few adjustments, WAMO has transformed it from a frigid container to a viable workspace. Partner and architect, Vahid Mojarrab, described the space to the Santa Fe New Mexican as “a perfect fit” for the husband-and-wife architecture company, which specializes in energy-efficient and high-performance design. Mojarrab and his wife, Carol Ware, had been searching for office space for their joint venture since he split from his former architecture partnership earlier this year. When a friend from Taos Cow mentioned a vacant freezer for lease on the ice cream company’s property, WAMO Studio realized the conversion easily: cutting holes for three windows and a door, removing the freezer’s compressor, and adding a heat pump for temperature control. Mojarrab is excited to reveal that the unit is about 50 percent more energy efficient than a common office space because of the insulated sheet metal construction that served its original purpose. Finding a way to recycle current architecture while improving its energy efficiency is something he believes affects the inhabitants of a building as well as its proprietor. “[E]ventually, the tenant pays for it,” he told the New Mexican. “At the end of the year, your landlord comes to you and says, ‘Your utility bill is so high I have to raise your rent.’” The rest of the Taos Cow property, including two separate walk-in freezers, is still dedicated to ice cream storage. With the majority of the original structure, including the freezer door, intact, the office of WAMO Studio blends inconspicuously into its surroundings. WAMO Studio is dedicated to environmentally conscious and site sensitive architecture. They are currently focused on Passive House certified endeavors.