3 April 2012 – US green building expert Jerry Yudelson does not mince words. Nature does not care about relative improvements in building performance; it only cares about absolute carbon dioxide levels in the atmosphere. Time to get real, and audacious he says in this extract from his forthcoming book The World’s Greenest Buildings: Promise Vs. Performance in Sustainable Design which he will discuss at ARBS, the airconditioning, refrigeration and building services trade exhibition in Melbourne from 7-9 May.
Worldwide concern over anthropogenic climate change has accelerated since 2006, and if energy use is the source of about 70 per cent of greenhouse gas emissions and buildings represent 40 to 48 per cent of the total energy use,[i] then controlling GHG emissions attributable to building energy use represents about 30 per cent of the total solution.[ii]
Green buildings and climate change
Green building and energy performance rating schemes exist in much of the world,[iii] but researchers and practitioners are finding that building performance does not yet match up to the levels needed to avoid significant climate change over the next several decades.
Even for those green building projects in the US that are delivering promised energy savings, the average improvement is about 25 to 35 per cent against the relevant reference standard.
However, we already know that reductions in energy use must be far more than 50 per cent to get average building energy down to reasonable levels.
For example, meeting the 2030 challenge would require all new buildings by 2020 to use 80 per cent less energy than 2005 levels and to be carbon-neutral by 2030.[iv]
Given that most of the US design and construction industry has all signed onto these goals, it’s fair to ask: How well are we doing?
To understand the status of today’s green buildings, one must look at actual measured performance over at least 12 months of full-time operations, including both energy and water use. My research looks also at energy use both in terms of site energy use, even though source (or primary) energy use is the only way to get at induced carbon emissions from building operations.
In the future, building teams will need to employ normative design criteria, such as annual electrical consumption (kilowatts per hour per square metre), fuel consumption per sq m, and water use (litres 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 need buildings that are “positively good, not simply less bad,” in architect William McDonough’s memorable phrasing, buildings that actually produce more energy than they consume.
The promise of green buildings
In his book, Greening Our Built World [v], Greg Kats points out the benefits of a major transition to green buildings in the US.
He assumes that by 2020 certified green buildings would represent 95 per cent of all new construction and 75 per cent of all major retrofits; this scenario would produce a 14 per cent reduction in carbon dioxide from buildings in 2025 versus 2005 and a net present value of green building gains of $650 billion in the US alone, representing about five to 10 times the initial cost premium.
Worldwide, it’s clear that a movement toward green construction and operations of this magnitude would provide gains of several trillion dollars.
How can we make this transition happen? Given current relatively low energy prices in the US, most engineers and architects implicitly limit building energy investments to a three to five-year payback, which results in investments that achieve 15 to 30 per cent improvements over American Society of Heating, Refrigerating and Airconditioning Engineers 90.1-2010, the currently applicable standard.
The problem is this: aiming at relative improvements against a “practical” standard will never deliver the absolute reductions in carbon emissions needed from the building sector to combat global warming.
After all, Mother Nature doesn’t care about relative improvements; it only cares about absolute carbon dioxide levels in the atmosphere. And Nature is the ultimate arbiter of human activity.
Where are we today?
My research into building performance revealed two important truths. First, source energy use needs to be reduced dramatically in both existing buildings (via retrofit or renovation) – by 80 per cent to meet “best in world” new building standards and by 50 per cent to meet current new building standards.
Second, it’s apparent that energy use in new buildings needs to be reduced more than 60 per cent versus the most recent 2010 ASHRAE standard to meet the goals at which the best new German buildings are already aiming.
What is the state of current US design practice? In general, a green building with an annual energy use intensity or energy use in thousands of British Thermal Unit per square foot of 35 to 40 would be considered nearly a state-of-the-art design in the US.[vi]
That represents a source energy use of about 200 kWh a square metre a year, about twice Germany’s best current design goal.
Why all this concern about numbers? The bottom line is that 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.[vii]
A LEED Platinum (or six star Green Star) building built today, even if it achieved all the energy efficiency points in LEED 2009 (representing a 48 per cent reduction from ASHRAE 2007 energy standards), would still represent a source energy use of 187 kWh/sq m/year, well above a state of the art European building.[viii]
What about cost?
At this stage in the evolution of building energy design, the harsh 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.
Even at this late date in the evolution of green buildings, most building teams simply don’t know how to co-operatively design and construct buildings to get high-performance results, without spending a lot more money.
That’s why it’s so important that building teams set BSAGs (“big, scary, and audacious goals”) at the outset of each project. These BSAGs should challenge the entire team to meet average local costs for the specific building type, while achieving energy use 50 per cent or more below the newest prevailing standard and simultaneously preserving user comfort, health, and productivity.
Seen in this way, it’s clear that the building owner must bear primary responsibility for choosing the right design and construction team, for charging them with a specific set of BSAGs for the project, and for managing the process to achieve truly integrated design.
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 a green building!
[ii] See David JC MacKay, Sustainable Energy – Without the Hot Air, 2010, downloadable free at www.withouthotair.com, Chapter 1. This is the best work I know for getting it right about energy use and the potential contribution of renewables.
[iii] See, for example, Jerry Yudelson, Sustainable Retail Development: New Success Strategies, 2009 (Berlin and New York: Springer), pp. 189-205, for a discussion of eight of the world’s leading rating systems, including LEED.
[iv] https://architecture2030.org/2030_challenge/the_2030_challenge, accessed September 20, 2010.
[v] Gregory Kats, Greening Our Built World, 2010, Island Press, Washington, DC.
[vi] Personal communication, Steven A. Straus, Glumac engineers, July 2010.
[vii] This discussion is ongoing in the building community since 2009. See for example, Charles Eley, et al., “Rethinking Percent Savings: The Problem with Percent Savings and the New Scale for a Zero Net-Energy Future,” Architectural Energy Corporation, July 2009, accessible at www.newbuildings.org.
[viii] For LEED 2009 requirements for new construction projects, see https://www.usgbc.org/DisplayPage.aspx?CMSPageID=220, accessed September 20, 2010.
US-based Jerry Yudelson, who runs Yudelson Associates has been involved in green building design and consulting services, renewable energy systems, environmental remediation products and services for 25 years.