NaTHERs Weatherboard Advice
All Assessors trained in the Cert IV in NatHERS assessment have been trained to offer advice for you particular situation.
In NSW most assessors only work on new projects, not so much on retrofitting old houses, but the principles are the same.
We could assist by thermal modelling your existing house which looks at both heating and cooling, looking at the amount of energy that is required to heat or cool your house throughout the year.
It seems that you are having a problem with heating especially in the winter months.
The first recommendations are usually the most cost effective.
1) install draft seals to all doors and operable windows to avoid direct heat loss. If this is not obvious then you could get a pressure loss test done where your house is pressurised by air, and an assessor walks around with a smoke producing tool to see where there are any drafts occurring, as the smoke will find its way towards the gaps in your external fabric construction.
2) install dampners to ceiling vents such as exhausts to bathrooms / kitchen.
If a sealed house has been achieved already, I would suggest thermal modelling, this would allow us to rate your project as it stands, then start adding additional insulation such as anticon blankets (roof) and thicker bulk insulation in the ceiling. Also it is possible to insulate underfloor if you are on suspended timber construction.
Last resort and most expensive is to retrofit new insulation in your external walls, but your cladding or gyprock will have to be removed, and this step is usually not undertaken.