You might like to get in touch with Andy Pickard: http://www.ajpengineering.com.au/ He specializes in home energy efficiency advise and retrofitting particular to the Canberra climate and issues. We have a unique climate in this region - not just because of the extreme temperatures, but also because of how vapor behaves in our walls, which makes choosing the right insulation important :) Goodluck! Should be lovely after you've installed it! (I work at Jigsaw Housing, the collaboration of architect + builder + scientist, and we specialize in energy efficient homes. I also do casual private consultations for people that are just looking for a bit of design/efficiency advice that's not really worth taking to an architect for a full service.)

We couldn't have Polished concrete because our soil is clay and is prone to heavy cracking when dry. We are using tiles and the builder is using an adhesive that is flexible which will prevent the times from cracking. We have finally found a company fair price carpets in Adelaide that can help us with carpet. There is an Ro rating on underlay and carpets that helps us decide which is best. They talked to someone in Melbourne. All good so far. Thanks for your help

@wayne For hydronics talk to Gary Flood at the Enter Shop. They are in Melbourne but he has installers everywhere. http://www.enter-shop.com.au/ Alternatively Alex at AJs Plumbing http://www.ajsplumbing.com.au/ We generally do in-slab hydronics but have also done it inside a rammed earth wall (at our office so feel free to come and look) and underneath a timber floor (several times including in our office). Insulation is critical. In a slab make sure you insulate the slab edge as well as the underside. When we talk of hydronics we generally use heat pumps to create the hot water (it's free to run if powered by PV). You mentioned wetback stoves (wood powered heating). In my view timber is only a viable option in rural settings. In (sub)urban settings the particulate pollution is a serious health issue and there is a fair chance that at some stage woodstoves will not be permitted by urban Councils. You finished by talking of ducted air conditioning. Regardless of the technology used to generate the heat/coolth, ducted systems are inherently inefficient and, in my view, should be avoided at all costs. The heat pumps can be great but the principle of pushing heated air around requires pump energy (you have to move large volumes of air). Almost all residential installations have flexiduct (not rigid as in commercial offices), the ductwork (aside from a study showing 80% of them did not meet the Australian Standard insulation code) due to its flexi-nature has lots and lots of curves and bends all of which increase the need for pump energy. This is why is it not possible to get a rated systems as you can with a split system; it is totally dependant on installation quality. You also need to be mindful of condensation issues in ductwork as heated air passes through relatively cold roof spaces, again quality of ductwork can be a big factor here.

As Australias largest supplier of hydronic heating, we have been providing Australian homes with stylish, safe and comfortable hydronic heating and cooling solutions. As exclusive stockists of an extensive range of premium products, we ensure that all homes can enjoy the benefits of a low carbon, energy efficient system. We have just released an industry leading guide on Underfloor Heating, that contains information for both homeowners and installers, I believe the content within would be the perfect for many commenters on this post. If you're unsure on how to proceed with your project I recommend you take full advantage of our personalised consultation service, available for both homeowners and installers. Using the latest design software and coupled with the expertise of our Customer Service Team, you can rest easy knowing that we’ll design a bespoke solution that delivers superior comfort that is also environmentally friendly and energy efficient. If you would like a copy please email me on sophieo@huntheat.com.au, alternatively head to our blog to download a copy: Hunt Heating Blog