Grab the Low-Hanging Fruit
Designers, contractors, and facility managers seek opportunities in existing and new buildings to mitigate climate change.
The bad news about our global climate keeps coming. Almost every week it seems there is a new discovery about ice pack melting faster than expected, ocean chemistry changing, or ecological systems suffering disruptions. Some of these discoveries involve troubling positive feedback loops (“positive” here is not a good thing), such as methane emissions from melting permafrost in Siberia and accelerated arctic warming due to the loss of reflective surface ice. If there is any sign of hope in this predicament, it is that we are still discovering many things we didn’t know, so perhaps some of the yet-to-come surprises will be beneficial.
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The world’s policymakers met in Bali this past December to begin crafting a successor to the Kyoto Protocol. They grappled with how much warming is tolerable, a question that leads to estimates of what concentrations of CO2 and other greenhouse gases in the atmosphere we can live with and what it might take to keep us within those limits. When it comes to the question of what can we do about it, reducing the amount of energy we use to operate buildings consistently emerges as a critical piece of the puzzle.
The 2007 series of reports from the Intergovernmental Panel on Climate Change (IPCC), which provided the scientific basis for the Bali proceedings, looked at all major sectors of the global economy and concluded the buildings sector is both the largest culprit and the largest opportunity in terms of cost-effective savings. Specifically, the panel estimates that, globally, this sector can reduce emissions at very low cost three times more than reductions that are easier to make in the transportation sector.
As the urgency of dealing with carbon emissions grows, the focus on buildings shifts from new construction to existing buildings. That’s because, in the short term, operations of new buildings represent a small part of overall building-sector impacts. To reduce emissions substantially within 10 years or less, we have to deal with the existing building stock immediately.
Fortunately, when one takes a close look at most existing buildings, there is a lot of low-hanging fruit in potential energy savings. Unless a facility is continuously fine-tuned and managed for energy savings, the second law of thermodynamics—entropy happens—demands its efficiency will decline over time. The emerging field of retrocommissioning is all about finding places where something broke and was never fixed properly, or a control setting was overridden to solve a short-term problem, leading to a long-term energy hemorrhage. Before even considering upgrades to systems and equipment, savings of 10 percent to 15 percent are often typical, according to a 2004 study by Evan Mills, Ph.D., of Lawrence Berkeley National Lab. Add in the cost-effective retrofit opportunities, such as those that can be financed by energy service companies in the model promoted by the Clinton Climate Initiative, and greater savings are possible. But there is no getting around the fact it is more cost-effective to make a building efficient the first time rather than retrofit it after the fact. So over time the opportunities in new construction are increasingly important, especially since half the buildings we’ll be occupying in 2030 don’t exist today.
Seizing that opportunity, the U.S. Department of Energy set a target of making net-zero-energy commercial buildings viable in the market by 2025. To find out whether that’s feasible, researchers from DOE and the National Renewable Energy Lab projected out to 2025 the evolution of currently known technologies and practices. Based on those projections, they predict that 62 percent of the commercial buildings built in 2025 could offset all the energy they use with integrated photovoltaics. Single-story buildings and those with low-energy intensity such as warehouses are the best candidates for reaching this goal.
To pull that off, however, the buildings will have to reduce their energy demand by an average of 59 percent from the ASHRAE Standard 90.1-2004 baseline. There just isn’t enough roof and wall area on most buildings to mount enough photovoltaics to meet a conventional building load, even if it made sense financially. The IPCC report noted energy savings should be easier in rich countries than in developing nations, because access to technology, reliable information, and financial resources are all more constrained in the latter.
A report on achieving carbon reduction in buildings from the U.K. Green Building Council analyzed the problem differently but emphasized the same basic principle: We should reduce energy demand first and use passive measures second before investing in renewable energy generation to meet any remaining loads. California has codified this philosophy in its New Solar Homes Partnership, which requires a home beat the state’s stringent Title 24 energy code by at least 15 percent to qualify for a financial incentive on a photovoltaic system. Future versions of Title 24 will require net-zero-energy use in homes by 2020 and in non-residential buildings 10 years later.
Architects and engineers are getting the message about the importance of energy efficiency, but all too often they generate solutions based on throwing expensive technology at the problem. It’s both cheaper and more effective to deal with fundamentals of thermal performance instead, but few designers are equipped or inclined to devote the needed attention to details such as the integrity of a building’s thermal envelope.
Ultimately, it will take progress in all sectors to reduce carbon emissions and head off the most extreme effects of climate change. Within the building industry, both quick fixes to existing buildings and more sophisticated solutions for new buildings are needed. While there are technical obstacles to be overcome, the real barriers seem to be social and political. Do we have the will to make it happen?
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