Habitat Studio & Workshop and I have been bouncing back and forth on the energy model for this house. In his mind, you need to aim to be under 10,000 kWh of total energy use to get a house to net zero. The theory being that it would be feasible to add enough solar power through passive heat gain and PV modules to balance your energy needs. Well, we're workin' on it. We're at about 12,000 kWh at the moment. We still have to fine tune some details. I have been working on this since last December ! and energy modeling is to help you design the appropriate building envelope, size of windows, heating system, etc. It has been useful in making decisions about where to spend money on insulation.
I have to say I'm somewhat frustrated with the energy modeling software [Hot2000] that we have been trying to get work to give us reliable numbers. A few weeks ago, we were getting really odd numbers. It turned out that we had to toggle OFF a separate thermostat for the basement. Now we're getting somewhere. If you want to see our Hot2000 house report, you can click here!. I also have to thank Conrad Nobert of Green Edmonton blog fame for his thoughts on this too.