Building Retrofit: Simplified Lighting Energy Savings Estimator
Buildings account for approximately 40% of all energy use in the U.S. and electicity is the largest energy source for buildings. In fact, increasing demand for electricity by buildings was primarily responsible for the 58% growth in our nation’s net electricity generation from 1985 to 2006. In part because a majority of electricity is generated by burning fossil fuels, buildings are responsible for the largest share (approximately 40% in 2005) of U.S. carbon dioxide emissions. Increased demand of electricity by buildings has also resulted in higher electricity expenditures, which rose from $144 billion in 1980 to $238 billion in 2005 as measured in constant 2005 dollars
Given that both residential and commercial building energy use represents an increasing share of U.S. energy consumption, it is imperative that buildings become more energy efficient. While the growth in the total number and size of houses has increased total energy use by the residential sector, the sector has made strides in increasing the energy efficiency of our nation’s homes. From 1985 to 2004, the energy intensity of the residential sector decreased by 9% as measured by energy use per household. In contrast, commercial building energy intensities have trended upward over time. To reverse this trend, we must change how commercial buildings use energy. According to the U.S. Department of Energy, lighting accounts for 25% of the commercial building sector’s total primary energy use. Therefore, installing energy efficient lighting can reduce a commercial building sector’s electricity costs and carbon dioxide emissions.
An efficient lighting strategy includes use of natural daylighting as well as energy saving artifical lighting sources. However, existing building design might limit the amount of available natural daylight therefore placing more importance on the type of articial lighting used in the building. Most fluorescent light fixtures that are older than ten years use T12 lamps. Replacing these outdated T12 lamps with newer high efficiency T8 lamps will reduce a commercial building’s energy consumption. As compared with T12 lamps, T8 lamps use approximately 40% fewer watts, produce approximately 40% less heat (which reduces air conditioning needs during warmer months), and output 10% more light. Moreover, according to the U.S. Environmental Protection Agency, T8 fixtures have a 2-4 year simple payback. An energy saving alternative to incandescent light bulbs are compact fluorescent light (CFL) light bulbs. Switching from incandescent bulbs to CFL bulbs has many benefits including reducing electricity usage by 65% to 80%, reducing operational costs because CFLs last eight to ten times longer than incandescent bulbs, and generating less heat thereby reducing usage of air conditioners.
The Building Retrofit: Simplified Lighting Energy Savings Estimator provides an estimation of the energy and cost savings, as well as the potential reduction in carbon dioxide emissions and coal consumption that can be achieved by switching to higher efficiency lighting.