The worldwide discussion of anthropogenic climate change has accelerated since 2006, and many decision makers have become aware of the significant contribution of buildings to global carbon dioxide and other greenhouse gas emissions. Since energy use is the source of about 70% of GHG emissions and buildings represent 40-48% of the total energy use, then controlling building energy use and GHG emissions represents about 30% of the problem.1 In fact, a 2007 study by McKinsey (www.mckinsey.com/clientservice/ccsi/greenhousegas.asp) showed that controlling building energy use is the only method of reducing GHG emissions that is currently cost-effective—or is likely to be so in the future.
The Great Green Hope
The great hope is that ever-greener buildings can help lead us out of the current problem of excessive and growing carbon levels in the atmosphere, provided they in fact dramatically reduce energy use. Since these investments are cost-effective (i.e., have positive life cycle costs), there is no rational reason why they should not be made, since everyone is better off in the long run.
While green building and energy performance rating schemes have become firmly established in much of the world,2 researchers and practitioners are finding that building performance does not yet match up to the levels needed to avoid catastrophic climate change over the next several decades. In particular, research shows that many high-level green certified buildings in the U.S., the United Kingdom, and elsewhere are not delivering effective performance in reducing in energy use.3 Even for those that are delivering promised energy savings, the average improvement has been about 25% against the relevant reference standard (ASHRAE 90.1-1999, 2004, and 2007).
However, we already know that reductions in energy use must be far more than 50% to get average building energy down to reasonable levels. For example, the 2030 Challenge calls for all buildings in 2020 to use 80% less energy than 2005 levels and to be carbon neutral by 2030. Given that the AIA, ASHRAE, and USGBC have all signed onto these goals, it’s fair to ask: How well we are doing in 2010?
Since we must control absolute GHG emissions from buildings, it’s important to know how the best buildings in the world are doing to control their emissions. For a new research project, along with Ulf Meyer (currently a professor in the Department of Architecture, University of Nebraska, Lincoln), I am looking at the highest-rated green buildings in the world—LEED Platinum, BREEAM Outstanding, Green Star Six-Star, etc.—to see how well they are performing in actual operation. We’re especially interested in current design and construction practices, so the focus of this research is on buildings occupied since early 2004 and having at least one year of performance data by mid-2010. The results will be published in 2012 in our book, The World’s Greenest Buildings: Promise vs. Performance in Sustainable Design(Routledge, London).
Our intent is to review how far green buildings have come, based on actual measured performanceover at least 12 months of full-time operations, including both energy and water use. We will review those buildings rated at the highest level of each national rating system and then select 60-70 buildings from various countries, based primarily on lowest resource consumption, especially lowest energy use (in kWh/sf or kWh/sm), taking the building type into account.
We also want to present energy use in terms of both site energy use and source (or primary) energy use. That’s the only way to get at induced carbon emissions from building operations. We will profile each building selected in a case study format, using a common reporting format, although the presentation of each case study will highlight specific design and operational solutions.
In the future Building Teams will need normativedesign criteria, such as annual electrical consumption (kWh per unit area), fuel consumption, and water use (gallons or liters per occupant or per unit area), for use in building projects that aspire to the highest level of green building certification. Without such explicit goals, most designs will fall far short of the needed GHG emission reductions. To put it another way, we’re looking for buildings that are “positively good, not simply less bad,” in William McDonough’s memorable phrase.
The promise of green buildings
In his recent book Greening Our Built World, Gregory Kats points out the benefits of a major transition to green buildings. Kats assumes that by 2020 certified green buildings will represent 95% of all new construction and 75% of all major retrofits; such a scenario would produce a 14% reduction in CO2 from buildings in 2025 vs. 2005 and a net present value (NPV) of green building of $650 billion in the U.S. alone, representing about 5-10 times the initial cost premium.
This high promise makes it even more pressing that building owners, designers, and contractors take seriously the challenge of achieving high levels of building performance. My own experience as a participant in Building Teams over the past half-decade tells me that most teams are too preoccupied with just getting a building designed and built within a budget to aim at high levels of building performance.
I would, however, qualify that statement by saying that the response of design teams is entirely rational. Given current relatively low energy prices in the U.S., most engineers and architects implicitly limit building energy investments to a three- to five-year payback, which results in investments that achieve 15-20% improvements over ASHRAE 90.1-2007. The problem is this: aiming at relative improvements against a modest standard will never deliver the absolute reductions in carbon emissions needed from the building sector to combat global warming. After all, nature doesn’t care about relative improvements; it only cares about absolute levels of carbon dioxide in the atmosphere. And, as the saying goes, “Nature bats last.”
Where do we stand today?
In the absence of the 2007 commercial buildings (CBECS) survey results, which the U.S. Department of Energy has not released, we must rely on the 2003 survey for data on average commercial building energy use.
As shown in Table 1, the average energy use in typical U.S. buildings in 2003, measured at the energy source, was about 500 kWh/sm/year. The newer ASHRAE 2007 standard would yield a source energy use of about 280 kWh/sm/year, while the ASHRAE 2011 standard is expected to result in a building source energy use of about 200 kWh/sm/year.4
Note that the ASHRAE standards are for “regulated” energy use, which includes heating, cooling, hot water, and lighting, but not all plug loads, while the CBECS database includes all building energy use. For comparison purposes, then, it’s important to add plug loads, which represent about 25% of total building energy use (LEED 2009’s standard default value). I’ve included in this table some “stretch goals” at which climate design engineers at Germany’s Transsolar are aiming—and, in fact, actually achieving.
Two things immediately stand out in Table 1. First, source energy use needs to be reduced dramatically in both existing buildings (via retrofit)—by 80% to meet “best in world” new building standards and by 50% to meet current new building standards. Projects such as the Empire State Building energy retrofit, which promises a 38% reduction in current building energy use, are clearly a step in the right direction, but still don’t meet even the 50% reduction test. Second, it’s apparent that energy use in new buildings needs to be reduced more than 60% versus the newest ASHRAE 90.1 standard to meet the goals at which German buildings are already aiming.
What is the state of U.S. design practice? In general, a green building with an EUI (energy use intensity, or energy use in kBtu divided by square footage) of 50 would be considered nearly a state-of-the-art design in the U.S., according to Steven A. Straus, of Glumac Engineers. That translates to a source energy EUI of about 110 (using a multiple of 2.2) and a source energy use of about 346 kWh/sm/year, about 3.5 times the Germans’ current design goal. I found similar outstanding results for a number of European buildings in research for my 2009 book Green Building Trends: Europe, so I know that it is feasible for U.S. and Canadian projects to achieve similar results.
However, certain factors have to be acknowledged: 1) the climate in Western Europe is fairly amenable to low-energy design compared to much of North America, with far less energy use required for latent cooling; 2) Europeans are prepared to invest more in their buildings, and are willing to accept slightly higher summer temperatures (up to 26ºC, or 79°F) in buildings on occasion; and 3) European buildings tend to have narrower floor plates, owing to regulations requiring all office workers to have access to daylight and views to the outdoors. This results in fewer internal cooling zones.
Why all this concern about numbers?As Charles Eley and others have pointed out (in “Rethinking Percent Savings: The Problem with Percent Savings and the New Scale for a Zero Net-Energy Future,” July 2009, accessible at www.newbuildings.org), current green building scoring systems, by focusing on relative improvement against a standard, are misleading in terms of where we need to go to reduce carbon emissions from existing and new buildings. A LEED Platinum building designed today, even if it achieved all the energy points in LEED 2009 (representing a 48% reduction from ASHRAE 2007 energy standards), would still have a source energy use of 187 kWh/sm/year, almost double that of a state-of-the-art European building.
There is yet another problem with giving credit to percent reduction. As Eley and his co-authors note, “Process energy, plug loads, commercial refrigeration, and other nonregulated energy uses were not included [in the ASHRAE and USGBC standards] because the codes did not establish a baseline for these end uses. In some building types like supermarkets and restaurants, the nonregulated energy can represent two-thirds of the total. Even in offices and schools, nonregulated energy typically represents approximately one-third of total energy.” Again, we must focus on total energy use, including the embodied energy of building materials, because as we continue to reduce base building energy use, embodied energy will become an even larger component of total building energy use.
What about cost?
At this stage in the evolution of building energy design, the best-performing buildings have double faÇades, thermally active slabs, radiant heating/cooling or ground-source heat pumps, natural ventilation, heat reclaim systems, and often cogeneration systems. They will also likely cost more up front. The cold reality is that it is virtually impossible to achieve major energy savings in new buildings simply with better windows, lighting controls, demand-control ventilation, and more efficient HVAC systems. Either you have to invest more money, or you have to undertake true integrated design that reduces overall mechanical, electrical, and plumbing system costs while radically improving performance.
There are projects that have succeeded with integrated design; for example, the Oregon Health & Science University’s Center for Health and Healing, in Portland, which was designed in 2003 and completed in 2006 and which, for several years, was the largest LEED Platinum project in the U.S. (www.betterbricks.com/casestudies.aspx?ID=1184). The project had a site EUI of 145, very good at the time for a complex medical building. MEP costs were cut by 10% (from the general contractor’s original MEP budget for conventional systems), or nearly $3 million in a $140 million project. The key: an involved (and very savvy) owner, a set of very aggressive goals, and an integrated design approach.
However, such examples are few and far between, because, in my opinion, most Building Teams in the U.S. simply don’t know how to cooperatively design and construct buildings to get high-performance results.
That’s why it’s so important that Building Teams set BHAGs (“Big Hairy Audacious Goals”) at the outset of each project. These BHAGs should challenge the entire team to meet average local costs for the specific building type, while achieving energy use 50% below the new ASHRAE standard and simultaneously preserving user comfort, health, and productivity. Seen in this light, it’s clear that primary responsibility for choosing the right design and construction team, for charging them with a specific set of BHAGs for the project, and for managing the process to achieve truly integrated design must fall on the shoulders of the building owner.
In my 2008 book Green Building through Integrated Design, I investigated how more than 20 Building Teams used some form of an integrated design approach to achieve LEED Platinum certification without spending significantly more money (in some cases, none) compared to conventional delivery processes. These successful projects shared certain commonalities. Typically, there was an early decision, usually in conceptual design stage, to achieve LEED Platinum status, followed by an early stage eco-charrette to discuss integrated design options, with an involved owner driving the process the entire way to completion. Beyond those similarities, there were almost as many approaches as there were projects—there was no single approach to securing high-performance results. The underlying factor was always the intention to do so.
Implications and goals for Building Teams
Here are three new goals to establish for your next project:
1. The site EUI for building design will be 25 (25,000 Btu/sf/year) beforeconsidering the contributions of onsite or purchased renewable energy. (Pick a number based on CBECS data for the specific building type, but make it suitably aggressive.)
2. The project will be carbon-neutral in terms of site energy use, either through onsite renewables or through purchased renewable energy.
3. The overall building cost will be equal to or close to regional averages for similar building types and sizes.
What might happen if these three goals were set in stone at the outset of a project?
• Every member of the Building Team would have to be fully committed to the energy goals before agreeing to participate in the project. This would be similar to an IPD “contract” signed by Building Teams engaged in integrated project delivery, such as that developed by the American Institute of Architects (http://www.aia.org/contractdocs/AIAS077630).
• An integrated design process would be essential to the success of the project. Building Teams would have to learn how to make it work.
• Every Building Team member would share in the risk of failing to achieve the project objectives, instead of being able to blame other members for deficiencies.
• Building Teams would begin to learn how to achieve high-performance results on a conventional building budget. Just about the only way to do this is to cut mechanical, electrical, and plumbing system costs through integrated design.
These appear to me to be worthwhile goals and aspirations, not achievable without a considerable stretch from existing Building Team practice. These goals are even a stretch from existing green building practice, but are necessary for us all to do our part in the battle to limit global climate change from human activities. That cause is important enough for me to say: If it doesn’t perform, it can’t be called green!
So now it’s up to you, the Building Teams. What do you think should be our goals, and how do you propose to achieve them? BD+C
Jerry Yudelson is the author of 12 books on green buildings, green homes, green development, and water conservation. He leads the consultancy at Yudelson Associates, Tucson, Ariz., and can be reached at www.greenbuildconsult.com. His latest book, Dry Run: Preventing the Next Urban Water Crisis (New Society Publishers), was released in June.
Table 1. U.S. Buildings’ Average Energy Use, Compared with ASHRAE and German Practice
Building Type Source EUI Site EUI Percent electric Source energy use (kWh/sm/yr)
Office 166 76.3 64 523
K-12 school 153.2 74.7 64 483
Retail store 158.3 72.2 67 499
ASHRAE 2007 375
ASHRAE 2010 267
“Good German Practice” 150
“Best German Practice” 100
Source: eawag.ch/medien/bulletin/20090123a/index_en.
Review of 2003 CBECS Study data, info.aia.org/nwsltr_cote.cfm?pagename=cote_a_0703_50percent. Note: EUI is in 1,000 Btu/sf/yr; 100 EUI is equal to (29.3 kWh/100 EUI) x (10.76 sf/sm) = 315 kWh/sm/yr. ASHRAE 2007 data based on a personal communication with Paul Ehrlich, PE, Building Intelligence Group, July 2009. “German Practice” data is based on a personal communication with Thomas Auer, Transsolar, September 2010. Projects are KfW Bankengruppe buildings in Frankfurt: Ostarkade (for “Good German Practice”) and Westarkade (for “Best German Practice”).
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