Home Energy Monitoring - Level 1

The very first thing that you should do if you are interested in saving energy in your household is to get a handle on exactly how much energy you are currently using. You can go about determining your energy usage in one (or more) of several different ways. The simplest, cheapest and most straightforward way to do this is to just look at your energy bill (electricity, natural gas, etc) and obtain the energy reading from the bill.

• Advantages: Cheap (free). Easy
• Disadvantages: The reading may be an estimate. The time between readings is usually at least a month, sometimes more.

There are many different units for energy, and the units of energy on your bill are going to depend on the type of energy (electricity, natural gas) and your utility (different companies may use different units).  In BC, Fortis and BC Hydro use the kilowatt-hour (kWh) and Terasen Gas uses the Gigajoule (GJ).  The kWh is a pretty standard unit for electrical companies around the world, but the unit for natural gas varies from region to region (other units used are therms, BTUs and even cubic meters or cubic feet of gas).

Fortis BC (Electricity) Example

Here is a recent Fortis Bill:

Note the circled section on the right hand side.  This shows the meter reading, the calculation for how much energy (in kWh) was used for the period, a calculation for the average energy usage per day and a comparison to the average energy usage per day in the previous year.  As you can see in 2010, I used about 1 kWh/day more than I did for the same time period in 2009.

If you have your bills from the past, you can look at the energy usage on those as well and even enter all of the readings into a spreadsheet so you can get an idea of how your energy use changes from month to month and even from year to year.

Here is a spreadsheet that I created from the last two years of electricity usage:

Feel free to download this Excel spreadsheet and use it for your own energy monitoring.

Now that all of the data is plotted, I can make some observations on my energy use from month to month and year to year:

• Daily usage is fairly constant throughout the year, only varying by a 3 or 4 kWh/day
• Usage went down in the summer in 2009, but not in 2010.  This is probably due to me losing the battle over the air conditioner during summer 2010 (she likes a cold house)
• Winter time usage is higher than spring and fall.  This is probably due to the fact that we need the lights on longer in the winter.

Terasen Natural Gas Example

Using my past gas bills, I also created a spreadsheet and graphed energy usage over the course of 2009 and 2010.  For natural gas, I went with total monthly usage instead of average daily usage like I did with the electricity bills.  Note that the spreadsheet that you can download above includes both electricity and gas.  Here are the bar graphs for 2009 and 2010 for my natural gas usage.

Some things to note when looking at the gas usage graphs:

• gas use is way up in the winter time (obviously because it is cold, and the furnace is on more often)
• February use is less than March use in both 2009 and 2010.  I should look at weather reports for those months and see if March was actually colder than February.
• Gas use is way down in the summer, but not zero because my water heater uses natural gas.

Summary

Before doing any energy retrofits and changes in your house, I strongly suggest that you first get at least a basic idea of how much energy your house currently uses.  You can do this by looking at your utility bills and then plotting your monthly data in a spreadsheet.  The plots will allow you to better visualize the data so that you can see trends in your household energy use.  Based on these trends, you can make some educated guesses at what things in your house use the most energy and why.  Then, once you have completed this Level 1 Home Energy Monitoring, you can put some conservation and efficiency plans in to action and see how much you can save.