Having just built a house I am forming an idea of what my annual heating/cooling related electricity consumption might be. Liberally I'm looking at around 1500 kWh annually which will be overwhelmingly heating as I'm based outside Ballarat. The house is ~133m^2 with R5 ceiling,R9 walls and R2.5 floors and all heat is supplied via a heat pump with approx COP=3.
The home was rated at 6 stars using the NATHERS scheme however I have added some extras that weren't on the original plans. Using the NATHERS starband chart (http://www.nathers.gov.au/about/pubs/starbands.20121129.pdf) my consumption would put me at about 7 stars.
My question is, is it actually possible to achieve a 10 star build that ACTUALLY requires the heat energy NATHERS suggests.
For Ballarat a 10 star home uses 2MJ/m^2 which is 2/3.6 = 0.55kWh/m^2 which is 74kWh (for 133m^2) of heat/cool energy per annum. Assuming a similar heat pump thats 25kWh of heat/cool electricity per annum!! Really?
I understand that further north its not that hard to achieve a zero thermal input home due to a friendlier climate, but how do you achieve that kind of efficiency in colder climates? I have some pretty bad ass insulation, vast majority of glazing faces true north, windows are low U with moderate SHGC and have appropriate amount of thermal mass. If you do some basic heat diffusion calcs a conservative heat loss (during winter) is 1.0kW or 24kWh a day which will require at least 7kWh of electricity. And this assumes zero air loss.
Anybody have some success stories? Low energy consumptions in a cold climate?
Thanks