Understanding Electric Usage
Contact the Energy Coach (by email): firstname.lastname@example.org for answers to your electric or energy questions, or call the Co-op and speak with the Coach directly.
kWh 101. Although we may all associate electric usage with COST (as in: “my electric bill is $75″), in order to understand why an electric bill is what it is, you need to examine HOW MUCH electricity your household uses. Residential Co-op members use electricity in units called KILOWATT HOURS (kWh).
Q. How many kilowatt hours does the average Co-op household use daily?
A. The average kilowatt hours used per DAY, based on more than 10,000 residential Co-op households is around 18 kilowatt hours (kWh). This does not mean all Co-op households use around 18 kWh/day; rather there is a range in average, from single digits per day, to some households who use 40 or 50 kWh per day.
Electricity is a flow of energy; kwh/day is a measure of the rate of use or flow rate. To manage COST one needs to understand where the energy is flowing, and at what rate of use. Some electric loads are “driven” by occupancy or season of the year; others run year-round. Electric loads are also differentiated by their voltage (typically either 120 volts or 240 volts); voltage also implicates how a member can directly measure any load’s impact (kwh/day).
In examining your electric bill what you should consider is: (1) what is your most recent AVERAGE DAILY usage (KWH/day), and (2) how does this measure of your household energy intensity vary (or not) over time.Cost is driven by usage; usage is measured in kwh/day or rate of use.
The first way to review this is to look at the most recent AVERAGE DAILY KWH usage on your Co-op bill. Bills are driven by (1) average usage and (2) cost per KWH. The cost per kwh also impacts the total bill; WEC provides 200 kwh/month of low cost electricity; all additional kwh’s per month are priced higher than the first 200. The kwh/day rate of use then also impacts the cost per kwh; lower usage means a relative lower cost per kwh.
Q. My neighbor’s house is bigger than ours/ they have more kids than we do/we’re gone all day, and the neighbors are not/ etc, yet our bill is more than theirs. Why?
A. Although each home is different, there’s little correlation between house size and electric energy intensity ( as measured in AVERAGE DAILY electric usage (KWH/day). Rather, electric usage depends on (1) what equipment you own, and (2) how you use it (“duty cycle”).
Q. I’ve heard that it makes sense to switch from electric hot water to another hot water system. Is this true?
A. Typically, yes. The key is to understand (1) the nature of what the energy is being used for, and (2) some idea of the amount of energy being used. Electricity makes good sense for residential loads such as lighting, refrigeration, entertainment, and numerous relatively smaller end uses. There are ways to make sure that these types of electric end uses are reasonable and technically efficient.
There are four typical residential energy uses through which we consume energy primarily as HEAT. These four residential energy end uses are: (1) space heating, (2) domestic hot water, (3) cooking, and (4) clothes drying. Generally, if the need is “HEAT” then it makes sense to look for equipment and fuels to generate the heat on-site, rather than through using electricity to provide HEAT.
Typically in Vermont one can purchase the equivalent amount of HEAT for less money than directly through the equivalent amount of kilowatt hours of electricity. However, it does not make long term sense to make energy decisions only on the basis of relative operating costs; rather, it’s important that such decisions take account of the long term effect of both equipment and fuel choices. This is done by “life cycle costing” or looking at the long term relative total costs, and not just today’s fuel cost.
One uncertainty in making long term energy decisions is what will future fossil fuels cost? And exactly because of this uncertainty the better option today is to reduce the total amount of HEAT used, regardless of whether from fossil (non-renewable) or renewable sources.
In order to compare today’s fuel costs between various options, one needs to take current price and convert into an equivalent unit cost for a unit of HEAT; this conversion then allows comparison of fuels, shown as their cost per million BTU’s (a unit of heat measurement), or “$/MMBTU”. In Vermont this calculation can be found @ the DPS website:
Q. How can I make my home more energy efficient?
A. This is a simple question with potentially complex answers. First, examine your electric usage, in AVERAGE DAILY KWH, to determine your relative electric energy intensity. IF your average usage is 10 KWH/day, then there’s less savings (energy or dollars) opportunity in this area. IF your household electric usage averages more than 18 KWH/day (for example), there may be any number of ways to lower usage and cost.
An energy efficient building is one which uses less overall energy, regardless of source. A low energy building is a high performance building. Building energy performance can be measured, and evaluated between buildings, by various means. There are now national standards for building performance, and a net work of trained contractors to asses and remedy today’s buildings to meet or exceed these performance standards.
Most members spend more money on space heating and hot water than on electricity. In Vermont, it is in the space heating and overall thermal integrity of your home that the greatest money savings opportunities typically exist. To learn more, visit, HOME PERFORMANCE WITH ENERGY STAR.
Members may be concerned with the price of a particular fuel, per gallon or per kilowatthour or per cord. All of these costs are important, but more important, for the long term is HOW MUCH of a fuel or energy source is used. See “the energy iceberg”.