Because it’s now generally cheaper to save fuel than to burn it, global warming, acid rain, and urban smog can be reduced not at a cost but at a profit… through energy efficiency. — Amory Lovins, The Negawatt Revolution, 1990
Worldwide energy use in residential and commercial buildings accounts for more than 15% of total greenhouse gas emissions (chart) and in some developed nations like the U.S. that percentage is significantly higher — as much as 40% (PDF). This is due in large part to huge inefficiencies in the way buildings are designed and constructed.
The good news is that retrofitting old buildings can result in lower utility bills, greater comfort, and significantly reduced greenhouse gas emissions. The Natural Resources Defense Council estimates that the U.S. could save more barrels of oil retrofitting the 8 million American homes that use oil as a heat source than could be produce by opening the Outer Continental Shelf for oil drilling. And retrofitting just 10 million coal-powered homes would eliminate the need for 12 (750 MW) coal-fired power plants (PDF).
Worldwide, according to the Greenpeace report Energy [R]evolution (PDF) by applying strict energy efficiency standards to the built environment we could eliminate the more than 60% of wasted energy and nearly 1,00 coal-fired power plants by 2050. The recent retrofit of the Empire State Building in New York City into a landmark green building is a case in point:
“Mining for energy savings” — in addition to being cheaper and less toxic than extracting fossil fuels — is a massive job creator. The 2010 report Efficiency Works (PDF) estimates that retrofitting just 40% of the residential and commercial buildings in the U.S. would create 625,000 jobs sustained over a decade, generating $64 billion in ratepayer savings per year, and mitigating 384 million tons of CO2 emissions.
The global market for environmental products and services is projected to double from $1.4 trillion per year at present to $2.7 trillion by 2020, according to Roland-Berger Strategy Consultants. Half of this market is based in energy efficiency which is a significant job creator. In Germany, for example, environmental technology is to grow fourfold to 16 % of industrial output by 2030, with employment in this sector surpassing that of the country’s major industries in the machine tools and automotive sectors. Investments in improved energy efficiency in buildings could generate an additional 2–3.5 million green jobs in Europe and the United States alone. The potential is much higher in developing countries.
There a five main targets for improving the energy performance of buildings — building envelope, heating & cooling systems, lighting & daylighting, efficient appliances, and water conservation.
The “building envelope” is the wrapper of a building that defines the line between indoors and outdoors. In older buildings that line can be very blurry. Single-pane windows, leaky doors, unsealed basements, poorly insulated roofs — all of these can mean wasted energy for heating and cooling. The Rocky Mountain Institute estimates that a typical U.S. home could reduce its energy use by more than 20%, preventing 5,300 tons of CO2 emissions per year (PDF) by creating an efficient building envelope.
In commercial buildings, window-wall systems are key to lowering operational costs and saving CO2. Incorporating insulated windows, low-E films window films, and design features like south-facing window overhangs (which block afternoon sunlight in the summer and allow sunlight in the winter) can result in dramatic improvements in building performance. New hi-tech developments like GlassX (pictured above) can actually change phase, absorbing heat during the day while allowing light to pass through, then re-releasing the heat at night.
Heating & Cooling
For the most part, the heating and cooling systems which make our buildings comfortable are out of sight and out of mind. But the furnaces, boilers, ducts, fans and pipes which supply hot and cold air to our buildings offer huge efficiency opportunities. The Rocky Mountain Institute estimates that a typical U.S. home could reduce its energy use by more than 10%, preventing 2,500 tons of CO2 emissions per year (PDF) by sealing ducts and using more efficient equipment.
In commercial buildings, the savings can be far greater. By taking advantage of passive ventilation, heat exchangers (which transfer heat from exhaust air to supply air, and thermal mass (which can absorb heat and re-radiate it at night) some systems can be entirely eliminated, resulting in energy savings of 40-70%.
Lighting & Daylighting
Lighting typically accounts for 20% of total commercial energy use and 10% of residential energy use (chart). Much of this energy results from the use of incandescent light bulbs, leaving lights on unnecessarily, and not taking advantage of natural daylighting. Using blinds and louvers to modulate natural daylight and providing light sensors that automatically turn lights on and off based on ambient light levels are two strategies that can greatly reduce total energy consumption.
The Energy (R)evolution report by Greenpeace (PDF) projects that through better lighting efficiency standards alone we could eliminate the need for 220 coal-fired power plants worldwide. The Rocky Mountain Institute estimates that a typical U.S. home could reduce its energy use by more than 6.5%, preventing 1,800 tons of CO2 emissions per year (PDF) by using efficient bulbs and turning lights off when not in use.
Electronic appliances account for more than 1/4 of total home energy use. Much of this energy is wasted by inefficient devices and “standby” losses — the energy consumed when devices are not in use but still running a current. The Rocky Mountain Institute estimates that a typical U.S. home could reduce its energy use by more than 7%, preventing 1,900 tons of CO2 emissions per year (PDF) by using efficient appliances and fully powering down electronic devices.
Programs like EnergyStar rate appliances for their energy efficiency, and new energy management devices like TED, which helps building owners monitor energy use, and the EcoStrip which powers off peripheral devices when not in use which, can result in savings of up to 1000 kWh’s per year.
In many parts of the world, a large amount of energy is required to collect, distribute and treat water and wastewater. According to the Natural Resources Defense Council, a full 4% of total U.S. energy consumption is attributed to water processing. In drier regions like California that number is significantly higher — a whopping 19% of total state energy use. Reducing water consumption by just 10% would be the equivalent of taking 1 million cars off the road (PDF).
Drip irrigation (which delivers water at the roots of a plant) and timing irrigation for the early morning hours can reduce evaporated water loss by as much as 40%. Fixing leaky plumbing fixtures and utilizing efficient fixtures like dual-flush toilets, waterless urinals, low-flow shower heads and sink aerators can further reduce consumption. In arid climates strategies like water catchment (used to harvest rainwater for garden irrigation), xeriscaping (using native drought-tolerant plant species), and water recycling (which reuses treated wastewater for non-crop irrigation) can help create an oasis in the desert without heavy reliance on energy-intensive municipal water supplies.
Quick Facts on Efficiency
- Investments in improved energy efficiency in buildings could generate an additional 2–3.5 million green jobs in Europe and the United States alone. The potential is much higher in developing countries [International Labor Organization]
- According to the U.S. Department of Energy’s Building America Program, an integrated, systems-engineering approach can reduce as much as 50% of the energy consumption of a new home – with little or no impact on the cost of construction. [U.S. Department of Energy's Building America Program]
- Studies show better sales in stores that utilize natural light. Retailers are increasingly using daylighting in an effort to harvest the associated sales benefits. [City of Bloomington]
- We could save more barrels of oil by 2030 through retrofitting the 8 percent of American homes that use oil as a heat source than we could produce by opening the Outer Continental Shelf (NRDC).
Creative Commons: Michael W. May
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