September 2, 2010

Green building laws and energy efficiency standards could help reduce CO2 emissions

Worldwide, buildings consume massive amounts of energy. The United Nations Environment Programme has reported that 30–40% of all primary energy produced worldwide is used in buildings. In 2008, the International Energy Agency released a publication which estimated that existing buildings are responsible for more than 40% of the world’s total primary energy consumption and for 24% of global CO2 emissions.

The picture in the United States is strikingly similar. In 2009, the residential and commercial building sector was responsible for over 50% of total annual U.S. energy consumption and 74% of total U.S. electricity consumption. A report by the U.S. Energy Information Agency (EIA) estimated that 60% of the nation’s electrical production is utilized to operate commercial buildings, which include those used for education, mercantile, office, storage, and warehouse purposes. By any measure, buildings are responsible for using much of the energy produced today.

In addition, energy consumption is rising. In 2007, DOE projected that energy use in the United States will increase by approximately 19% by 2025. But that is only half of the problem. Not only does this country use a lot of energy, it does so inefficiently. America uses twice as much energy per unit of economic output as Germany, and nearly three times as much as Japan.

Fortunately, there are many ways to improve a building’s energy efficiency. Simple measures such as weatherstripping, maintaining entry door closers, and installing storm windows as a low-cost alternative to replacements are usually the low-hanging fruit in weatherization. In addition, adding insulation materials to new and existing frame construction buildings is a proven and relatively inexpensive way to improve building energy efficiency with respect to heating and cooling. New innovations in insulation can reduce the energy used in manufacturing insulation and allow insulation to be recycled or biodegradable. Mineral, fibrous, and cellulose-derived materials are now available for insulation purposes.

Another large user of energy is a building’s heating, ventilation and air-conditioning (HVAC) system. Properly designed and installed HVAC systems can reduce the amount of energy used for heating and cooling a building. An HVAC system includes a heater, air conditioner, and fan in one system and operates at a partial load nearly all the time. The design of the HVAC system as a whole-system mechanism saves energy by monitoring airflow and keeping the indoor temperature fairly constant. An HVAC system must have a correctly designed distribution system to minimize the amount of airflow (and thus energy) necessary to heat and cool the building. In addition, allowing building occupants to individually control heating and cooling in their living or working spaces is an effective way to reduce energy use.

Electric lighting consumes about one-quarter to one-third of the energy in a typical commercial building. Lighting also generates heat, so reducing the amount of energy consumed for lighting through effective and efficient lighting also reduces the size of a building’s air conditioning plant. Building information modeling (BIM) are computer programs that allow building design and construction teams to draw and test the building’s operating systems, such as electricity or hot water, in one computer model. Modeling buildings with BIM can aid in quantitative energy analysis, connecting complex systems and allowing more precise analysis for better energy use.

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