ZGF Architects, LLP
Project Size (sf / site acreage):
500,000 GSF / 23,000 SF site
ZGF Architects, LLP
Hoffman Construction Company
ZGF Architects, LLP
KPFF Consulting Engineers
Air Quality Consultant:
David Evans and Associates
Building Envelope Consultant: RDH Building Sciences; Mechanical Sub: Total Mechanical; Electrical Sub: Dynalectric
Gerding Edlen, City Center Parking, and ZGF Architects, LLP
The project is located within the existing urban core, taking advantage of the current public transportation infrastructure, and is hoped to be a catalyst for new development in Portland’s west end. The existing site was a surface parking lot and a low-rise commercial building, neither of which had any stormwater attenuation strategies in place or any habitat potential. The designed building includes approximately 6000 sf of green roof area, planted with native and adaptive species that have been demonstrated to thrive in the climate and soil types at the roof level of this high-rise residential tower. Much consideration was given to climate and microclimate in design. The design of the green roof was fine-tuned to match climactic conditions, but even closer consideration was given to wind analysis in the effort to make rooftop wind turbines an effective strategy. The ownership group has invested in a detailed analysis of the urban wind environment by Sander Mertens, a wind energy specialist in the Netherlands who has focused on wind patterns in urban environments. Airport wind data was analyzed to account for the impacts of surrounding development and natural features such as the Willamette River and the West Hills. Wind energy experts from Aeronvironments, the creators of the Gossamer Albatross, came to Oregon to test a scale model of the top third of the building for wind patterns, utilizing the wind tunnel at Oregon State University. The outcomes of both of those studies are reflected in the design of wind turbines and towers for the rooftop of this project. The degree of careful, detailed consideration of site conditions taken on this project
Toward Zero Energy:
The 12th and Washington mixed use tower utilizes energy efficiency strategies to reduce consumption of energy by over 44% beyond ASHRAE 90.1-2004, and exceed the 2030 Challenge benchmarks for this project type. Some of the efficiency measures include: thermal mass, daylighting and occupancy sensors, low-flow fixtures for reduced domestic hot water demand, high-efficiency equipment, heat recovery, fan-assisted night flush of the office floors, chilled beams and hydronic baseboard heat in the office floors, and CO2 sensors for ventilation demand control in large volume spaces. This reduced load is met with two forms of renewable energy: 1,360sf of flat plate solar hot water collectors, and an array of wind turbines gracing the North edge of the tower’s roof. Throughout the design process, collaborative and strategic research relationships have been used to maximize the energy efficiency and renewable energy production of this building.
Local and Sustainable Materials:
The steel and concrete structure of this building is designed to provide thermal mass that will help provide a flywheel effect for indoor temperatures, but it also allows for the most ubiquitous materials in the building to come from highly recycled and local sources. Other materials which have received great focus due to volume or degree of occupant interaction include: high recycled content and urea-formaldehyde free MDF cores for solid core doors, casework, and painted trim; 96% recycled locally manufactured gypsum wallboard throughout the building; bamboo veneers for doors and casework; bamboo flooring; salvaged wood; FSC-certified wood; and linoleum flooring.
Water efficiency is achieved through a combination of conservation and stormwater reuse. Due to the state of Oregon’s restrictions on reuse of stormwater in residential applications, reuse had to be kept to the toilet flushing of the commercial floors of retail and office occupancy. The building has a 50,000 gallon storage tank in the underground garage, part of which is dedicated to fire suppression, with the remaining 22,000 gallon tank devoted to reuse in irrigation and toilet flushing. This system, which gathers and filters runoff from the rooftops as well as condensate from the mechanical system, is projected to reuse 286,225 gallons annually, utilizing 59% of the rainfall to the tower’s roof surface. 100% of the green roof’s irrigation needs, and 90% of the office’s flushing demands, will be met by the volume of non-potable water collected from the building. The Systems Development Charge (SDC) from the City of Portland’s Bureau of Environmental Services will be cut by 30% as a result of the reduced combined sewer contribution. That savings, at $204,840 covers 91% of the first cost of the system, vastly reducing the simple payback period for this investment. With hundreds of millions of Portland’s dollars being spent on its “Big Pipe” project, making this kind of investment is fiscally and environmentally responsible.
IEQ and Comfort:
Daylight, views, operable windows, underfloor air, radiant heating and cooling, CO2 monitoring, and low-emitting materials throughout this mixed-use tower combine to make a healthy living and working environment. In the case of this highly transparent tower, great care had to be taken to modify the opacity of the envelope while not losing visual access to the outdoors and daylight. The office floors and residential units are designed to as to allow access to views and daylight to over 90% of all regularly occupied spaces, while not allowing excess solar radiation to create unnecessary cooling loads. While many individuals are seeking out an urban lifestyle in downtown high-rise developments, they don’t want to compromise their ability to connect to nature. The rooftop desk amenities are accessible to office and residential occupants at different levels of deck. The penthouse level of the residential part of the building has shared event spaces that overlook the roof deck, green roof, stormwater planters, wind turbines, and the expansive views of the surrounding city, hills, river, and mountains.
Collective Wisdom and Feedback:
Teaming Gerding Edlen Developers with ZGF Architects and Glumac has made for a very successful partnership, and one that is continuing on several other projects that have started since the inception of 12th and Washington. The collective experience and wisdom of the individuals at the design table made for an exciting Integrated Design Process. In an era when the aesthetic of the highly glassy, transparent tower reigns supreme, such a project presents energy efficient design and energy modeling challenges. With a prescriptive-based code, exceeding a particular percentage of glazing requires utilizing a whole-building modeling path. This requires a significantly increased amount of time in reducing glazing strategically as well as modeling carefully so as to capture the nuanced balance between light and heat. The design of the rainwater reuse system presented some obstacles. With a huge supply of rainwater, particularly in the winter months, it was hard for the design team to not push for reuse in the residential toilets. The Oregon state plumbing code does not allow reuse in that application without jumping through many prohibitively difficult hoops. This project could have achieved far greater volumes of reuse than was achieved, even with the same storage capacity as designed. The sense of the design team was that a huge opportunity was lost.
In addition to providing further density and job growth to the immediate area, the extensive use of local and regional materials will also contribute to Oregon’s economy. The significantly reduced contribution to the combined sewers is a great contribution of the development group to the region, whose water quality is seriously compromised by combined sewer overflows and the resulting pollution. The research conducted into wind power in urban environments, particularly as integrated into a building’s architecture, engaged researchers from around the world, and will provide a valuable resource for designers nationally and internationally. With its wind towers providing an iconic beacon for a renewable future, the 12th and Washington building will be an important new element of Portland’s skyline. It will provide an easy to grasp message about Portland’s private and public commitment to eliminating our impact.