Not really happy flyer, just because I don't agree with your wildly optimistic figures doesn't mean I'm a closed book. In fact quite the opposite. How though, do you expect to give your customers honest and accurate advice if the figures don't stack up? Do you expect them (or us) to believe you just because you said so? That's not how I operate, rather I like to give them some solid figures to dwell on and decide whether its want they want or not.
Simple zoning doesn't work for other reasons, for example zoning bedrooms independently to living space is fine until you have children that go to bed at 6-7-8pm. Most wouldn't put the kids to bed in a cold room to save a few quid, you might?
complicated zoning costs a fortune and I still don't see the benefits as a retro fit with un insulated intermediate floors, losing heat from downstairs to upstairs, educating the customers to close all the doors etc most don't even turn the lights off when they leave a room!