A couple of months back, I wrote about how preservationists’ job descriptions have changed, and that increasingly we must be active participants in the larger conversation about sustainable buildings and communities. During the last year, the National Trust for Historic Preservation’s Green Lab (PGL) has been doing just this – identifying and engaging in policy and research projects that have the potential to transform the way cities and states approach the greening of our existing buildings and communities. In recent posts, I’ve written about the PGL's innovative work on outcome based codes, which is spearheaded by Consulting Director Liz Dunn, and our groundbreaking research on the value of building reuse. But the PGL has been gaining traction on a number of other fronts as well.
By way of a little background, the PGL’s work generally falls into three categories: pioneering new policy solutions to promote building reuse, neighborhood reinvestment and green retrofits; identifying and promoting existing best policy practices related to sustainability and preservation; and undertaking research to help better understand the value of building reuse, as well as best practices for retrofitting older and historic buildings. We’re in the midst of updating the PGL website to give you a more complete picture of our efforts, but in the meantime, Liz and I want to provide an update on our work on district energy, and the role these systems can play in helping bring down carbon emissions from existing buildings.
Why District Energy?
Wisdom has it that it’s pretty feasible to reduce emissions in existing buildings by around 50% with conventional approaches to energy efficiency -- but anything much beyond that requires the use of renewables. That means that many existing and historic buildings simply cannot achieve substantial energy reduction targets or reach “net zero” without the help of renewable energy sources.
Yet many existing buildings, especially those that make up our “urban villages” (think Main Streets!) are too small in scale or were designed in such a way that they cannot take advantage of all the dramatic energy efficiency measures of on-site renewable energy options available to new buildings. Furthermore, building owners find it challenging enough to pay for essential efficiency measures like insulation, lighting upgrades and better energy management tools -- an investment in a waste heat recovery system or a bio-mass facility is usually well beyond the means of a single building owner.
And only focusing on the individual performance of buildings may not represent a community’s optimal investment in clean, renewable forms of energy. Buildings are part of a community, and resource sharing is a common element to communities, from shared public spaces to water to electricity grids. There is a growing school of thought that cities and building owners increasingly will be compelled to look to district-level solutions to meet their clean energy needs.
That’s why the PGL is interested in district energy systems, which are local neighborhood utilities created to deliver heating, cooling and hot water to a collection of buildings. Such systems have been in use in the U.S. since the last century. Today there are about 6,000 such systems in place in North America, though most are used for institutions such as hospitals and universities. District energy is far more prevalent in Europe and Japan – for example, the entire city of Stockholm, Sweden is served by two district systems.
The PGL is partnering with the University of Oregon's Center for Sustainable Business Practices to develop a white paper that includes case studies and policy and financing recommendations for how district energy systems can be integrated into existing neighborhoods of older and historic buildings with multiple owners. The paper is intended as a primer for communities that are beginning to look at district energy as a possible strategy, and face common barriers, capacity constraints and learning curves, and who need guidance in identifying the policies and programs needed in their own situations to foster district energy system development.
We’re close to having the White Paper complete, and will be sending it out for peer review shortly. Look for the completed paper and more info later this summer on PreservationNation.
Patrice Frey is the deputy director of the sustainability program at the National Trust for Historic Preservation.
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