Net-Zero Buildings…Within Limits

Editor’s Note: Renewable energy sparks debate and discussion well beyond the industry itself. Given this broad and rich cultural context, Defining Renewables offers thought leaders from outside the industry an opportunity to express how they view and think about renewable energy. Our contributors this issue are Craig Briscoe and John Breshears with the architecture firm ZGF Architects LLP.

Architectural design has changed such that a pleasing form is no longer sufficient as a generator of a building’s design. Increasingly the natural forces of the sun, rain and wind are determinants as we try to harvest light, water and air when needed by the building and reject them when they are not required. But modern buildings (and occupants) need more than these raw forms of energy for comfort and productivity. Converting some of this raw energy to electricity or heat has become a must.

The cutting edge of the architectural community has embraced “net-zero” energy buildings as the loftiest goal in sustainable design. As a result, renewable energy in the form of photovoltaics and small wind turbines (mostly in concept, with few actual examples in practice) is increasingly common on and around buildings. What this focus on net-zero produces is a limited energy supply which yields the requirement for a very low-energy building.

Our own recent work includes a wind turbine installation on Twelve|West, a mixed-use high-rise in Portland, Ore. which is home to our new offices (lead image). We felt at the beginning of design that turbines properly positioned on and above the roof to harvest maximum winds would also be aesthetically successful; that our eyes which have evolved looking at landscapes shaped by wind and water might naturally appreciate structures positioned according to the flow of natural forces. Design is an iterative process and as a starting point we had drawn a series of turbines on the building where we felt they looked appropriate. The fact that after long study with aerodynamicists we ended up with a turbine array in roughly the same place was a pleasant confirmation of this hunch.

While it’s certainly not evidence of the ultimate value of building-integrated wind, the turbine installation at Twelve|West is an outstanding aesthetic success. The turbines have quickly become a landmark and a unique part of the life of the city. The behavior of the turbines makes the speed and direction of the wind–an invisible force–visible to people who might not otherwise notice or care what is going on above their heads or see any connection between their own actions and resource consumption. We can’t quantify putting people in touch with a small part of the natural world, but it is rewarding nonetheless.

Perhaps the greatest potential for architecture to contribute to a renewable energy economy is by creating buildings that use vastly less energy, whether from the grid or from on-site sources. We continue to form and engineer buildings with passive or very low-energy systems for lighting, heating and cooling.

Further, we are always looking for new ways to “engineer the user” or building occupants to use less energy as well. Through a combination of such advanced strategies, including a sizeable solar thermal array, Twelve|West is predicted to use 45 percent less energy than a similar building built to typical standards.

Building-integrated renewables are a visible demonstration of the limitations of renewable energy technology and, by extension, the need to conserve. To convey this message though, the design professions need to be honest about the limited nature of most renewable energy sources integrated into large buildings. We’ll start: the turbines on Twelve|West should produce less than 1 percent of the annual electrical load of the building.

Determining the real potential of building-integrated wind is tricky. There are prominent experts who dismiss the notion entirely and other experts who are intrigued by the idea and allow that there may be potential in certain applications. The fact is we don’t have enough data or experience to dismiss the idea outright and the technology for harvesting wind on a small scale is really in its infancy.

It seems to us that on-site renewable energy will be part of an overall group of renewable energy options for society. In Oregon the divide between east and west, rural and urban, has expanded to include disputes over the impact of utility-scale wind. The windy eastern end of the Columbia River Gorge is home to a wind farm boom unprecedented in all but a few states while the population centers of Portland and the Willamette Valley are hundreds of miles to the west. Some rural residents, oddly situated amidst the conservative “property rights” movement which bristles against the restrictions of the Gorge National Scenic Area to the west, are now asking why their valley views should be marred by wind turbines making electricity for city dwellers. The simple answer, of course, is that their views are where the wind is.

A more productive answer is that the transition to renewables will require generation remote from population centers as well as within the urban environment.


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