Sure. I'll start, and then Malcolm can complete.
We have an approach. It's an approach used by our colleagues, the General Services Administration in the U.S., NASA and Harvard. It's an approach that looks, for example, at the energy retrofit area where you take a building at the front end, you cost in a detailed way the upgrades, and the savings that are going to emerge from those upgrades through a life-cycle cost analysis. That gives you up front when you are taking those decisions the costing that you need to be able to do that and calculate the greenhouse gas emissions.
In addition, we track greenhouse gas emissions by individual buildings in government. We have a methodology that is used by other leading international organizations.
Malcolm has been instrumental in helping that development. Maybe he can elaborate on this.