Introduction to Energy Efficiency

Let's look at a summary of U.S. Energy Sources and End Uses as illustrated in the chart below. On the left of the chart, it lists primary energy sources such as oil, natural gas, coal and nuclear, etc. Then end use consumption are listed including transportation, industrial, residential and electric power generation. On the right side of the chart, energy efficiency for each end use consumption is listed. For example, the energy efficiency in the transportation is about 15%, electric power generation is about 35% efficient. Across all the energy end use consumption, no single sector is over 50% efficient! Energy cost money, waste energy means wasted money. For example, Illinois State University monthly energy bill is about $1 million! Since energy efficiency is less than 50%, it means half a million dollar is wasted per month.

US-energy-source-end-uses.png

As you will learn in the next few modules, improving energy efficiency is very doable! There are major energy efficiency opportunities in common industrial/commercial energy use with great pay-back and significant impact on pollution reduction. Primary industrial/commercial energy use include:

1. Lighting

2. Heating and cooling

3. Motors

4. Air compressors

We will discuss energy efficiency opportunities in 1 and 2 above areas. In this lesson, we will focus energy efficiency opportunities in lighting.

Why Lighting?

Because lighting consumes most energy in a building! The figure below illustrates the energy intensity (KWH/ft2) by end use according to the Energy Information Administration (EIA) report in 2011. EIA is a division of US Department of Energy.

Commercial Buildings Primary Energy End Use Splits (2011)

http://www.c2es.org/docUploads/rc-9.png
Source: DOE,   2011   Buildings Energy Data Book,   Section 3.1.4, March 2012.   http://buildingsdatabook.eren.doe.gov/ .

The commercial sector encompasses a variety of different building types, including schools, hospitals, restaurants, hotels, office buildings, banks, and stadiums. According to US Department of Energy, a t an estimated cost of $38 billion a year, lighting represents the largest source of electricity consumption in U.S. commercial buildings. Even in residential buildings, lighting consumes 10% of the total energy use as shown below.

Residential Buildings Primary Energy End Use Splits (2011)

http://www.c2es.org/docUploads/rc-8.png
Source: DOE,   2011   Buildings Energy Data Book,   Section 2.1.5, March 2012.   http://buildingsdatabook.eren.doe.gov/ .

Have I Grasped the Key Facts Here?

 

According to US Department of Energy, lighting represents the largest source of electricity consumption in US commercial buildings

 
 

 

Lighting consumes 10% of the total energy use in residential buildings as compared to 20% in commercial buildings.