I think, transforming the whole building sector to zero carbon is really important. We have to start it now, because as you know, buildings last a very long time. It's very important.
I would say that, when it comes to homes, it is a bit more challenging because there is a different economic model. Developers have a different economic model. You really need to look at things like district energy systems, systems that tie homes together and supply them with clean, carbon-free sources of energy.
On the building sector, I think there's a better model there. As we said, we have a standard. We already have a number of buildings that we have certified under that standard as zero carbon right now, so we can do this right now. Some of them—actually, two of them—are private sector buildings, commercial developments that have found a way of doing that to get a good return on their investment. This is already happening.
I think the codes play a very important role in that as well, particularly for the residential sector because of the different economic model. As far as I know, there are plans under way to develop a near net-zero code by 2021 or 2022 for Canada, as well as a retrofit code by around the same time frame. I cannot overemphasize the retrofit code, because all net reductions in carbon between now and 2030 have to come from existing buildings.
Any new buildings, no matter how effectively you build them and how low-carbon you build them, will add carbon to the atmosphere through the building materials and through the carbon that is emitted through construction. It's the retrofit of buildings over the next 10 to 15 years that will reduce carbon emissions from the buildings. These are the net reductions.