Unexpected discovery from monitoring our gas usage: we have a leak!

For the past few weeks, I've been keeping a detailed spreadsheet of our electricity and gas usage.  My main aim is to figure out how much energy individual actions require (having a shower, running the dishwasher etc).

What I wasn't expecting to find is that we have a gas leak!  I noticed that our gas meter was continuing to turn even when everything was off.  I was a bit sceptical that we actually had a leak because we couldn't smell any gas.   I called British Gas who sent a gas engineer within an hour.  He confirmed that we do have a leak, turned off our gas and we're now in the process of getting this fixed.  If I hadn't been keeping a close eye on our meter readings then we wouldn't have found the leak.

The fact that the pipework in our house was leaking gas at a fairly swift rate (about 46 litres per day if my maths is correct) even though we couldn't smell it suggests that our house is still pretty draughty  (which is perhaps not too surprising because I'm currently renovating our living room and so all the livingroom's 12 airbricks are venting directly into the living space).

Geeky details:

Meter readings (everything was off during this period):

• 25/04/2010 01:29 = 5323.9810 m³
• 25/04/2010 10:02 = 5323.9975 m³

Gas used over this 8.5 hour period = 0.0165 m³

This is equivalent to:

• 0.0463 m³ per 24 hours
• 46.3 litres per 24 hours
• 16.905 m³ per year
• 0.51 kWh per 24 hours
• 187 kWh per year
• £5.61 per year (at 3p per kWh)
• 12 kg of natural gas per year (with a global warming potential equivalent to 300kg of CO₂ )

Conversions

• 1 m3 of natural gas = 0.714 kg
• 1 m3 of natural gas = about 11 kWh (varies a bit depending on pressure and calorific value)
• Global Warming Potential of methane = 25 (over 100 years; GWP of CO₂ = 1)

Update 26/4/2010: An excellent local gas engineer just popped round. He's identified the leak as coming from the interface between the pipework and the gas cooker.  The gas is back on to the boiler but fixing the connection to the cooker will happen later in the week.  So for the time being, we're cooking on (camping) gas!