Integrated Strategies’ Extended Benefits
- Aug 26, 2013
AIA/COTE Winners Pursue Synergistic Combinations of Green Building Strategies
By Brad Berton, Contributing Writer
This year’s winners of the American Institute of Architects Committee on the Environment’s Top Ten Green Projects awards leave little doubt that commercial property designers continue pushing the sustainability envelope—sharpening its cutting edge along the way.
While protecting and enhancing the environment is a fundamental component of the AIA/COTE criteria, there is also considerable emphasis on integration—not only of architectural solutions but also of each project and its community and ecology.
And the designers do indeed deliver, with many expertly integrating wide-ranging design, engineering and technological solutions that reduce demand for utility-supplied electricity and water. Several endeavors have successfully reduced net grid-energy consumption by coordinating on-site renewable juice generation with leading-edge daylight harvesting techniques and other demand-reducing strategies.
Take the new San Francisco Public Utilities Commission headquarters. In addition to on-site solar and wind production, numerous mechanisms combine in pursuit of the often conflicting consumption-reduction strategies of maximizing natural light while minimizing solar heat gain.
The 277,500-square-foot urban office tower designed by KMD Architects in partnership with Stevens & Associates also ambitiously strives to re-use not just its gray water but nastier black water as well.
Winning project teams likewise reduce carbon footprints and other environmental impacts by looking to a given site’s existing street-level resources and those from above and below. This might mean redeveloping abandoned brownfield properties, recycling leftover building materials and tapping geothermal energy in addition to solar and/or wind resources.
Lake Flato Architects and its client Rio Perla Properties pursued several of these strategies in converting an abandoned San Antonio beer storage facility into a modern mixed-use property. They re-used 83 percent of the Full Goods Warehouse’s original shell, then erected the Lone Star state’s biggest roof-mounted solar PV array.
Full Goods likewise illustrates increasingly creative and sophisticated efforts to reduce demand for potable water—in its case re-using the brewery’s beer vats to capture rainwater that can irrigate the site’s landscaping.
No doubt the nation’s green-minded architects and engineers will continue devising increasingly effective methods for retaining and re-using rainwater as well as waste water in order to reduce demand for outside potable water, observed Paul Schwer, president of sustainability stalwart PAE Consulting Engineers.
Meanwhile, amid the ongoing quest for net-zero energy and water requirements, ever-improving technologies along with falling costs should allow for more and more on-site energy generation, Schwer added.
Integrating Energy Solutions
Indeed, as one might expect from a facility in the sustainabilty-minded Pacific Northwest housing public-servant engineers, Seattle’s Federal Center South Building 1202 synergistically integrates multiple forward-looking efficiency strategies to achieve “net-zero-capable” status and a 100 Energy Star score.
As ZGF Architects Seattle office design partner Allyn Stellmacher explained, the facility’s primary hydronic HVAC system combines chilled perimeter beams with a custom-designed “radiant wave chilled sail” network of S-shaped fixtures suspended from ceilings.
Compared to chilled floor or ceiling beams, the sail system offers efficient radiant cooling while also absorbing heat without requiring a lot of air flow, Stellmacher added. This combination of technologies ultimately provides plentiful cooling capacity while saving on energy otherwise required for high-volume air fans.
Air is ultimately exhausted passively through the atrium roof, allowing a high-efficiency heat-recovery system to simultaneously condition incoming outside air as necessary before routing it into the under-floor distribution system.
A couple other new-wave technologies also assist in reducing heating and cooling loads at the striking facility housing the U.S. Army Corps of Engineers. The HVAC system taps geothermal energy, as water-carrying tubes inserted into 150 of the structure’s 230 structural steel piles feed the perimeter hydronic beams.
And a rooftop tank filled with salt-based phase change materials passively absorbs heat from interior air while liquefying (“melting”) as the air temperature climbs, then releases it while solidifying (“freezing”) at night and on cold mornings. Add it all up and Building 1202 uses about one-fifth the energy seen with a typical air-conditioned office building in the region.
Likewise, that modern office building housing public utility professionals in sunnier San Francisco logically features sustainable energy systems reflecting the occupant’s power provision mission. Combining nearly 700 solar PV panels on multiple rooftops, with the turbine tower sited on a north façade designed to accelerate wind, renewable on-site generation should provide 7 percent of the SFPUC headquarters’ power needs.
The facility’s new-age integrated building management system efficiently coordinates operable windows with floor-level cooling circulation, among numerous other control and monitoring functions. The BMS designed by Smart Buildings L.L.C. monitors some 13,500 data points, accessed via 450 dashboards.
The anticipated combined benefit is that the SFPUC home office should exceed California’s strict new Title 24 energy efficiency requirements by 55 percent.
Speaking of PV, that big Full Goods array is designed at over 200 kilowatts—or nearly 27 percent of the property’s power needs. The project also reflects the modern movement away from air ducts, featuring efficient and flexible “ductless minisplit” HVAC systems serving multiple, individually controlled spaces through single exterior units.
Meanwhile, demand-reducing features of Fix Development’s more boutique-size “radical green” Clock Shadow Building in Milwaukee include a 27-well ground-source heating and cooling system, along with a building envelope engineered for exceptional thermal performance.
Beyond designing a roof with a high-insulation R-value of 40, the Clock Shadow team integrated water retention and thermal strategies via the extensive rooftop “production garden.” As roofs in Milwaukee’s climate represent “the most critical surface for insulating,” the team boosted the R-40 value further with the additional four to 12 inches of soil, explained Dan Beyer, principal with Continuum Architects + Planners.
In addition to hosting regular rooftop farmer’s market events, another radical feature at Clock Shadow is the nation’s first so-called “regenerative” elevator drive, which produces juice on its descents.
Designing for Daylight
As the COTE honorees likewise illustrate, cutting-edge approaches continue reducing energy required for artificial lighting. For instance, integration of multiple design, material and operational strategies minimizes the energy required to light the SFPUC building’s workspaces. Indeed, illumination consumes hardly half the juice needed in a typical Class A office building, noted KMD senior associate Michael Rossetto.
Its daylight harvesting strategies are particularly bountiful. Automated interior and exterior shading systems track the sun’s trajectory. And various forms of light shelves and even highly reflective exposed concrete surfaces strategically bounce daylight into “open office” interior space configurations. Of course, energy-efficient artificial lighting fixtures, featuring dimming ballasts, are likewise integrated with the shading mechanisms.
In stark contrast to the rectangular footprint of the structure it replaced, Building 1202’s design team devised an oxbow-shape atrium configuration and narrow 60-foot floorplate that interact to daylight 90 percent of the new building. Meanwhile, exterior sun-shading, adjustable internal window treatments and clerestory glazing combine to help control solar heat gain.
When artificial light is required, strategically spaced, custom-designed linear fluorescent fixtures efficiently illuminate the facility’s wide-open layout. The combined strategies create an overall lighting power density of 0.6 watts per square foot—representing a savings of 30 percent over the Seattle Energy Code specification.
Certainly, such achievements make considerable contributions to the sustainable built environment. As such, they live up to COTE’s dedication, as its Web site states, to providing “healthy and safe environments for people” and “preserving the earth’s capability of sustaining a shared high quality of life.”
Read this article in its original format in the August 2013 issue of CPE.