I'll take the second part of your comment first.
I'm not sure we know what the cost is or what the cost benefit is, because we're treating CO2 like a free good, and as long as we treat it like a free good we actually don't know whether this is a net win or a net loss.
But on your first point, your idea of retrofitting is very analogous to the idea that I put in our brief on green taxes, which is an environmental investment tax credit. That would simply be the same cost as could be applied to the refit industry as well. Or you could do it directly through government programs that have been done in the past. I have a bias in favour of using the tax system, because we have the whole structure for tax administration there already. That's why we provide GST rebates through the tax system, because it actually encourages people to pay their taxes and take advantage of the tax machinery that's already in place.