Environmental Engineering Reference
In-Depth Information
ter heating, lighting, cooking, and refrigeration, uses which frequently have been targets of energy
efficiency standards, accounted for just over 60 percent of commercial delivered energy demand
in 2009 and are projected to fall to 55 percent of delivered energy in 2035 (USEIA 2011b).
Lighting is a significant consumer of energy in commercial buildings. More electricity is con-
sumed by lighting than any other individual end use. One-fifth of total site energy is consumed
by lighting in commercial buildings (EESI 2006a, 1). Nearly all commercial buildings have some
type of lighting (91 percent). The majority of those without lighting are warehouses and vacant
buildings. Standard fluorescent lamps are widely used—85 percent of commercial buildings use
these lamps. Nearly half of buildings (47 percent) use incandescent lamps and just under one-third
(30 percent) use compact fluorescent lamps. Lighting is generally the most wasteful component of
commercial use. More efficient lighting and elimination of overillumination can reduce lighting
energy use by approximately 50 percent in many commercial buildings (USEIA 2011b).
Lighting continues to have the largest and most cost-effective energy-saving potential in existing
commercial buildings. Improvements in refrigeration systems and components are the second-
largest source of savings potential. A reasonable range of economic savings potential in existing
commercial buildings is between 10 and 20 percent of current energy use. Building sensors and
controls—excluding those associated with lighting—have the potential of reducing commercial
building energy use by an additional 5 to 20 percent (Belzer 2009).
Traditional windows waste about 30 percent of the energy used to heat and cool a building. Ad-
vanced dynamic window technologies, or “smart windows,” could save more than 1 percent of the
nation's annual energy consumption, or more than $10 billion in annual energy costs (Risser 2011).
For example, Pleotint LLC has developed a glass film that uses sunlight to prevent excess heat and
light from coming into homes and buildings, increasing comfort and reducing the amount of energy
needed for heating and cooling. Pleotint's “thermochromic” technology harnesses the sun's heat to
cause a chemical reaction that automatically darkens window tint as the sun gets hotter. Pleotint
estimates these self-tinting windows could pay for themselves in five to seven years through reduced
energy costs (Risser 2011). SAGE Electrochromics has created SageGlass, which uses a small electric
charge to switch between clear and tinted, depending on heat and light conditions. These “electro-
chromic” windows can be programmed to respond to specific temperature and sunlight levels or
can be regulated manually by the click of a button. SAGE estimates its tinted-window technology
can reduce a building's energy consumption substantially (Risser 2011).
The industrial sector represents production and processing of goods, including facilities and
equipment used for manufacturing, agriculture, mining, and construction, accounting for about
30 percent of total U.S. energy consumption in 2010 (USEIA 2011a, 38). Since 1990, a growing
share of U.S. output has come from less energy-intensive services. In 1990, 68 percent of the total
value of output came from services, 8 percent from energy-intensive manufacturing industries, and
the balance from non-energy-intensive manufacturing and the nonmanufacturing industries (e.g.,
agriculture, mining, and construction). In 2009 services accounted for 76 percent of total output
and energy-intensive industries only 6 percent. Services are expected to continue to play a growing
role in the future, accounting for 79 percent of total output in 2035, with energy-intensive manu-
facturing accounting for less than 5 percent of output (USEIA 2011b). U.S. agriculture has almost
doubled farm energy efficiency in the last twenty-five years (Morris and Grubinger 2010).
From 1949 to 2010, primary energy consumption in the United States tripled. A sharp reversal of
this historical trend occurred in 2009, in part due to the recession. Real gross domestic product (GDP)
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