Many years ago I took part in a school project that involved doing an energy audit. We measured various heat loss parameters for the main building and took meter readings over a period of time.
So I thought I’d do the same thing for my house. I’ve not yet worked out the details of how to calculate heat-loss values for the different parts of the building, but have started to monitor (and graph) my electricity, gas and water usage (now that I’ve a water meter). This Excel spreadsheet template is a first step at monitoring resource usage over time.
It’s possible to also calculate the equivalent CO2 usage but this isn’t straight-forward for electricity (depends upon generation method, transmission losses for your area etc.). I have included a calculation for gas, however. See the Resurgence pages for information on how to calculate CO2 emissions for various energy sources. Their calculators cover a large range of energy use but offer quite a course resolution (typically one year). My spreadsheet offers as detailed a look at resource usage in your home as you wish 
