Sometimes the most efficient air conditioning system is not having one at all.
To curb energy consumption, architects with projects in temperate cities – Seattle, Portland, San Francisco – have started to design buildings without mechanical air conditioners. These buildings will have heaters in all likelihood, but not air conditioning (see Can Greentech Make Housing Cheaper and Green Buildings No Subsidies Needed).
"There are only five days a year you need cooling in Seattle," said Amanda Sturgeon, an architect and senior associate at the firm Perkins + Will, who recently designed a building without a mechanical conditioner.
In some cases, architects are putting in air-side economizers, i.e., computer-controlled windows that open to let in cooling breezes (see The Solar Window). The General Services Administration building in San Francisco uses openable windows on 12 of its 18 floors that let in cool breezes at night that, ideally, keep the offices cool in the daytime. There is no mechanical cooling in the open office areas.
This shift comes courtesy of two trends. One, building developers and contractors have latched onto green buildings as an economic opportunity. Designing a building to LEED Silver or Gold standards – the environmental building standards promulgated by the U.S. Green Building Council – only adds around 2 percent to the overall cost or less, according to various contractors, architects and researchers. Designing to the LEED Platinum standard can add only 6 percent if carefully planned. The trick, say Sturgeon and others, is to exploit as many passive, design-centric techniques for scoring LEED points before moving on to the potentially more expensive, equipment-centric ones like biomass boilers or new types of lighting systems.
That small additional cost, however, is compensated by the higher rents, better property valuations and other factors that LEED-certified buildings produce. Chipmaker Advanced Micro Devices says its über-LEED Lone Star campus in Austin, Texas has become a recruiting tool. Webcor, the large California builder, gets a substantial portion of its revenue now from green projects. Jeanne Clinton, the Clean Energy Advisor to the California Public Utilties Commission, argues that green building has a negative cost because owners realize a profit from any investments relatively quickly.
The second trend is that air conditioning is a great place to start. Running and managing buildings and the appliances inside them gobbles up around 39 percent of the energy consumed in the U.S. – that's higher than transportation, which consumes close to 26 percent.
Air conditioning and heating consume about 40 percent of the power in buildings. Put another way, heating and cooling gobble up 16 percent of the power in the U.S. Despite the decline in fossil fuel prices prompted by the economic downturn, most experts believe electricity prices will continue to rise over the coming decade.
Homes and offices aren't very efficient when it comes to mixing hot and cool air either. Jim Lee, CEO of Cimetrics, which analyzes energy efficiency for military bases, large universities and others with fairly large real estate holdings, says clients regularly can save 10 percent to 20 percent on energy and related maintenance costs by fixes that don't require retrofits. In some government buildings, the savings can climb to 40 percent. Most of the savings Cimetrics can offer comes from fine-tuning the heating and cooling system, in part because only a small percentage of buildings have linked their lighting systems to networks in a way that Cimetrics can analyze it.
"The way we heat and cool buildings in this country is absolutely ridiculous," Lee said. Eighty percent of the buildings in Chicago are outfitted with electrical heating, which is less efficient than other systems. Why? "They were built in the ‘80s when electricity was damn near free," he said.
Some startups, such as IceEnergy and Cooling Corp., which recently spun out of UC Davis, have released devices that can trim air conditioning costs. But Sturgeon says that going without has a bit more appeal because of the long life of air conditioning systems.
"It will be in there for 50 years," she said. "Are [building owners] willing to take a risk?"
New versions of the LEED standards coming next year as well as future building codes will further put pressure on the air conditioning industry. In the 2009 version of the LEED standards, buildings will get far more credit for energy efficiency and green power than in the past.
In the new standards, a building can get one point for being 12 percent more efficient than a baseline and 19 points being 48 percent more efficient, said Sturgeon. Under the current standards, buildings can get three points maximum for getting five percent of their power from renewable sources. In the new standards, it rises to seven points if a building can get 13 percent of its power from renewable resources.
Several states are also expected to adopt LEED recommendations as part of their building codes. California has already set a mandate that, starting in 2020, new homes will have to be net zero-energy. The net-zero energy will be attempted to be applied to commercial buildings in 2030.