The American Institute of Architects’ Portland Chapter moved into their new home in 2008. It is a renovated older building in an historic district of the city of Portland. While it does not showcase high-tech strategies, its focus on reuse and demand reduction through age-old techniques makes it a notable example of a common-sense approach to sustainable design. Although only “off-the-shelf” components are used, the building has earned the highest rating of the USGBC’s LEED certification program.
Photo courtesy of Holst Architects
The 10,000 square-foot single story brick building was once a dilapidated livery stable, and is thought to be the oldest surviving structure in Portland’s now-thriving Pearl District, a former industrial zone. The new AIA headquarters occupies 5,000 square-feet, and its design achieves profound savings of energy and water, while providing a superior environment for the staff and users of the building. The building houses the Chapter’s administration, gallery, and expanded community gathering spaces.
Following are notable green building strategies employed:
- Site Selection
The location of the building is within walking distance of downtown Portland, and within one mile of the greatest concentration of architects in the city – the building’s users. It is located directly on a streetcar line. Bicycle racks are provided. Minimizing the building user’s transportation needs and encouraging public and non-automotive means of transportation reduces energy use and pollution.
Adaptive reuse is a basic and important green building strategy. The reuse of an entire building saves energy, land and materials; and helps preserve our heritage. This example shows how a building that housed horses in older times can be transformed into convenient, comfortable and stylish accommodations for people in the 21st century.
- Energy Conservation
Energy-saving measures include natural ventilation and operable, energy efficient doors, windows and roof vents. Sensors are installed on the windows that turn off the building’s mechanical HVAC system when the windows are left open. This ensures that no energy is wasted if the building envelope is not closed. Windows and skylights are used to the greatest extent to maximize natural daylight and reduce electrical lighting needs.
The south wall of the building, facing the sun, is fitted with an open steel “garden wall” frame that serves as a trellis for climbing vines that shade the building in summer, helping to keep the interior cool. The south-facing windows are well shaded from the high summer sun. Lower in the sky, the winter sun will reach in beyond the windows to warm the interior, and shine on the brick walls, which will absorb the radiant heat from the sun’s rays. These are “passive solar” design strategies.
Users of the building are careful to reduce energy demand by adapting to a larger range of comfort for indoor temperatures – setting thermostats lower in winter, and higher in summer. Improved insulation in the roof and walls also help to conserve energy by limiting heat loss and heat gain in winter and summer, respectively. Finally, an innovative mechanical system with air ducts under the floor delivers even ventilation and conditioned air more efficiently that conventional forced-air systems.
The building uses 38% less energy than a comparable non-green building. Energy cost-savings are 57%.
- Water Conservation
The building achieves significant savings of water by harvesting rainwater, which is collected from the roof, as well as the roof on an adjacent building. The water is piped to a tank in the basement, from where it is pumped for use in flushing toilets and urinals. The use of potable water by the building has been reduced by 88%!
The “garden wall” trellis also serves to conduct some rainwater from the roof to the small and lush garden area below, providing natural irrigation.
- Regional Influences
There are several excellent examples of how regional influences guided the design process.
Because the Northwest region of the U.S. enjoys plentiful, cheap and clean electric power, an early decision was that the building would be all-electric – it would not use gas or oil for heating or for making hot water. A large proportion of electricity in the region is generated by hydroelectric plants -- a relatively clean and renewable energy resource – so the use of electricity rather than gas or oil actually reduces the building’s carbon footprint. This is not so in most other areas that rely on fossil fuels for electricity. (A benefit of the building’s “all electric” design is that it may easily incorporate on-site solar or wind powered electricity generation in the future, which would contribute to all building systems year-round.)
Regional climate is of course a large consideration in the design of any building. The temperate climate of the Northwest means that natural ventilation can play a large role in maintaining interior comfort for much of the year. In other areas the weather is too cold or too hot much of the year for this to be beneficial.
Another characteristic of Portland’s climate is ample rainfall. In this case, the rainwater harvesting system on this low-rise building is able to supply virtually all the water needed to flush toilets and urinals. This would not be possible in dryer climates; although rainwater harvesting in the driest areas can take on critical importance due to the general shortage of wate
The AIA Portland’s Center for Architecture building is a fine example of simple green building that uses existing resources in simple ways to achieve superior results for the environment as well as the city, the neighborhood, and the users of the building.
Courtesy Holst Architecture, Portland, Oregon
Photos courtesy Michael Mathers, except as noted