Thanks for the kind words, they are much appreciated.
I think one of the problems with approaching the design of a low energy house that some people have is that it can be hard to grasp what is important, in relation to the stuff that is far less important. Advertising has to take a share of the blame here, as there are always magic energy-efficiency widgets being advertised that promise the earth (but usually deliver next to sod all).
There are some basics that always hold though. Use a "fabric first" design, which means design the fabric of the house to be intrinsically airtight and well insulated, and forget initially about all the sub systems. Money spent on good insulation and airtightness is never, ever wasted, it will carry on paying a dividend throughout the whole life of the house.
Once the decisions have been made about the fabric of the house, then the heating requirement can be determined, and this, in turn, will determine the type of heating system (if any) that you need. A well designed passive house may well cost less to build than a conventional house and need very, very little heat at all. Even in the blustery conditions today we had enough solar gain to heat our house to just under 23 deg C, with no heating on since the night before.
The biggest energy requirement will almost certainly be hot water. It will probably at least equal, and perhaps be greater, than the heating requirement, It is well worth looking at a separate design for the hot water system, just because of the fairly large difference in requirement between heating and hot water.
I'd suggest only looking at ways of providing heating and hot water once you are close to the final design spec, and don't be lured by the ads for the latest bit of technology until you know how little heat you need.
Rather like Tony's house, we can heat our house in mid winter with a few conventional light bulbs if we wanted to. It sounds daft, but a 60W incandescent light bulb in one of our bathrooms might well end up making it too hot for comfort.
Edited by jsharris, 28 January 2015 - 09:46 PM.