I think we've come up with conservative numbers that are used in Alberta, which are coal-based in terms of the CO2 emissions. What we've done is to take a simple look at how much energy can be taken out of the lighting system from a building. The average would be one watt per square foot, or 10 watts per square metre, 10ยข a kilowatt hour, and 3,000 hours per year.
Now this isn't anything more than a broad brush to give us a sense of what the starting point might be and whether it is worthwhile pursuing. The numbers are going to vary from province to province, but it could be part of a more significant study.