In order to find out how many Gigajoules we use per year, we first have to separate the energy used to heat water, from the energy used to heat our house. In order to do this I looked at our old July and August natural gas bills.  In these months we don’t heat our house, so the amount of energy we use should be only from heating water. We don’t have a gas barbecue or gas dryer.

 

 To the right are my family’s natural gas bill amounts from July and August for the last seven years. In order to find the average per month, I first added these amounts together and divided them by fourteen.  To make calculations more accurate I removed the lowest five numbers, (shown by*), to account for time when we were on holidays and not heating water. 

 

 I then redid my calculations this time dividing by nine.  Now, with my monthly average of 2.63GJ I multiplied this by twelve to get the yearly average. I got the estimate of 31.56 GJ /year for heating water.  The rates Albertan’s pay per GJ fluctuate greatly.   In order to make my calculations appropriate for more people, I went to the Atco Gas South  History of Rate One: Adjustments For a Residential Customer in Calgary, (http://www.atcogas.com/Rates/Historic_rates/ South_Historical_Rates.pdf).

 

 I then calculated the average gas price for the past twelve months including delivery charge and GST.  The price was $8 per GJ, (using the above site).  Using this rate, I calculated that it would then cost us $252.48/year to heat our water with natural gas. 

 

 

 

 

Ellie Shifflett 

Grade 8, Cayley School

Last Edited May 1/07