Big is an understatement, that's huge!! But based on that size, your energy usage is not actually that bad per sqm and you are comfortably in an A2 BER rating. Your GSHP is clearly working very efficiently so my suggestions above might not be as impactful knowing the size of the house. No harm in reducing stats while maintaining comfort but your main issue is that you have so much space to heat.House is 500sqm
That is how I would read it, you should only look at the 20m level for domestic wind turbines so maybe at 5m/s it is a feasible option for you.great map - if I am reading it correctly the windspeed for our location is 5m/s at 20m.
It might also be worth looking at historical MET data and windspeeds at your nearest weather station to understand the seasonality of the windspeed. My understanding is that it is fairly consistent throughout the year with a slight increase over winter months. This at least makes it a better fit to work with a heat pump as opposed to using solar PV.