That's a very good question.
When we established those targets, we were modelling what it would take to reduce carbon emissions from the building sector by 2030. That was our target. I'm not talking about homes, but larger buildings over 25,000 square feet. We looked at approaches and technologies, particularly in the existing building sector, that would take us to that goal. With the net-zero carbon buildings I talked about earlier, that's a kind of an additional reduction that's possible.
What we found is that there are really four strategies. One is to recommission buildings, which is operational. The second one is deeper retrofits. When a building is being retrofitted, you have a deeper retrofit of a building. Then, it's the renewable energy used. Then there's fuel switching, when you go from a fossil fuel to put, let's say, a whole building on hydroelectricity, which is very clean in Canada, in British Columbia, Quebec, and so on.
We modelled that, and it would take 100,000 buildings that are over 25,000 square feet—that's the size of the buildings—and you would have to do recommission work to 80% in deep retrofit to build 60% of those buildings over the next 14 to 15 years. It's possible, but it requires investment. This is already happening, but it requires investment. Without the retrofit of existing buildings, we are not going to achieve our carbon reductions.
If you look at the carbon curves, where we're currently going and where we need to go in a very short period of time, there is quite a significant gap. Without saying that this is invoking a sense of high urgency, I think it is a case where we need to take very targeted action to reduce carbon emissions, not just from buildings, but from the transportation sector, from the production of energy, from the industrial sector.
However, without the existing buildings and paying attention to that, there's not an opportunity to reach that target. It's a sizeable amount of carbon that's emitted from current buildings. That doesn't even include our 12 million or 13 million homes that we have in Canada on top of that.