ENERGY STAR reports that the typical American household spends approximately $2,000/year on home energy bills. With the cost of electricity, natural gas, and home heating oil rising dramatically, people are finding new motivation to make their homes more energy efficient.
Reducing home energy consumption is also an important part of the solution to global climate change. The typical home is a major source of U.S. greenhouse gas emissions, accounting for over twice as much carbon dioxide (CO2) annually as the average automobile. The Environmental Protection Agency estimates that average home energy consumption (for a house heated with natural gas) results in about 27,300 pounds of CO2 emissions annually--compared to 12,100 pounds CO2 produced by the average automobile. By taking steps to reduce their home energy usage, individuals can play a significant role in curbing global warming.
A good place to start is to get answers to basic questions about energy consumption. How much energy do I use right now? How is that energy produced? What is the environmental impact of the energy I use? What can I do to make a difference?
HOW MUCH ENERGY DO I USE RIGHT NOW?
Start by becoming familiar with the information contained in your natural gas and electric bills and then track your energy usage from month to month. This will make you more aware of just how much energy your home is consuming and more conscious of energy issues generally. It can also provide a big incentive to test various strategies to improve your home's energy efficiency and will help you monitor the impact of those changes.
Understanding Your Gas Bill
(A detailed discussion of the components of a Nicor Gas bill is available here.)
How do you know whether the number of therms you used is "reasonable"? The answer to this is . . . it depends. It depends on how cold it was outside.Your gas bill may give you this information if it reports the total number of degree days in that billing period. Or you can find degree day records for your area on Weather Underground. (Enter your location in the History Data section and then indicate the time period--day, week, month, year--for which you want weather data.)
Degree days are used to calculate the effect of outside air temperature on building energy consumption. Heating degree days (HDDs) are a measure that indicates how much colder the outside average temperature was compared to a baseline temperature of 65°F. (This baseline reflects the observation that houses generally require heating if the outside temperature is lower than 65°.) If the average of the high and low temperatures for a particular day was 35°, that would add 30 HDDs to the total for the billing period.
Similarly, cooling degree days (CDDs) are a measure of how much warmer the outside average temperature was than 65°F.
Dividing the number of therms used by the total number of degree days for that period provides useful information about the energy performance of your house. It reflects the temperature setting of your thermostat, the tightness of your house, and the efficiency of your home's heating system.
With this calculation, you can compare your energy consumption from month to month, and year to year, despite variations in the weather and the fluctuating cost of energy.
(The number of therms used also reflects the energy consumed in heating water and any cooking done with gas. Your summer gas bill will give you a rough idea of how much these uses contribute to your energy consumption year-round.)
Understanding Your Electric Bill
Most consumers pay a fixed per-kWh rate for their electricity no matter what time of day or which day they use it. In some areas, however, consumers may choose an alternative system called Real Time Pricing (RTP) and pay a rate based on the wholesale market price of power, which varies from hour to hour and day to day.
For much of the day, the "real time" price is lower than the standard fixed price, but at times of peak demand--on steamy afternoons in summer, for example--the price of electricity can soar. RTP customers can save money by reducing their electrical usage during these high-demand hours. (About 95 percent of participants in ComEd's RTP program, for example, saved money in 2007.) For the utility, lower peak demand decreases the need to operate more expensive "peaker" plants (to supplement the power from less expensive base load plants), reduces the risk of blackouts, and delays the need to build new power plants.
Another rate structure that rewards customers who cut usage during peak periods is Time of Use (TOU) pricing. With this system, the utility company establishes two or more tiers of prices, setting peak and off-peak rates for different times of the day, days of the week, and seasons of the year. During winter months, for example, the peak period may be early morning and early evening whereas in summer months, it may be midday through early evening, reflecting air conditioning usage. The higher rate charged during peak periods encourages customers to shift usage to off-peak hours.
(A discussion of the components of a ComEd bill and the utility company's various energy-saving programs is available here.)
WHAT ARE THE SOURCES OF THE ENERGY I USE IN MY HOME?
Most of the energy consumed in homes is produced by burning fossil fuels like coal, oil, and natural gas. When burned, each of these fossil fuels emits various greenhouse gases, principally carbon dioxide (CO2). But they differ significantly in the level of emissions that each gives off.
Roughly two-thirds of the carbon emissions related to operating a home is attributable to the electricity used in the home. This is due in part to the relative inefficiency of most power plants in converting the energy in the fuel they burn into electricity. It typically takes three or four units of fuel to produce and deliver one unit of electricity.
The other factor is the electric power industry's heavy reliance on fossil fuels--carbon-intensive coal in particular. More than two-thirds (71%) of the electricity generated in the U.S. is produced by burning fossil fuels, with nearly half (49 percent) coming from coal, 20 percent from natural gas, and less than two percent from oil. Non-fossil fuel sources account for the rest: nuclear power provides 19 percent, hydropower produces 7 percent, and the remainder comes from other renewable sources.
WHAT IS THE ENVIRONMENTAL IMPACT OF THE ENERGY I USE?
To answer that question, you will need 12 months of data about the energy used in your home. If you do not have a year's worth of utility bills at hand, you should be able to obtain your account history from your local utility companies.
For most Americans, driving ranks along with electrical usage at the top of the list of daily pollution-causing activities. (For others, air travel can be the biggest contributor to their greenhouse gas emissions.) Calculate and compare your vehicle's miles-per-gallon and greenhouse gas emissions at the Fuel Economy Website of the Department of Energy and the Environmental Protection Agency. Environmental Defense is another good source of information to help you choose a more fuel-efficient vehicle.
WHAT CAN I DO TO MAKE A DIFFERENCE?
There are lots of things you can do--many of them no-cost or low-cost steps--to cut your energy consumption and reduce your greenhouse gas emissions. Frequently mentioned action steps include the following:
More detailed lists of energy-saving measures can be found at these websites:
LINKS AND RESOURCES