Energy efficiency in Buildings - Roofs

From this year we are looking into 'Energy efficiency' in buildings and how to apply it. Being what it is, some people still battles with that idea. As a plans examiner I have to narrow down the possible 'ifs' and the “not’s”...

To put this in perspective, the minimum requirements and that also applies the 'deem-to-satisfy' rule.

So my question would be: “What is the minimum requirement to insulate a roof?”

I have people still up to date specifying 'asbestos roof sheets' although this material has been substituted by various products which one is fibre-cement roofing.

Coming back to insulating roof spaces, we have learnt that a R-value of 3,7 must be achieved throughout the roof design to prevent solar heat gain within the building. This can only be achieved by a combination of two products namely 'Think Pink Aerolite & Reflective foil also known as Sisalation".

These products can be found on the following links: http://www.isover.co.za & http://www.sisalation.com
For those specifying the product, make sure its the correct one as you take responsibility for what you specify.
See below pictures taken when installation took place.

Think pink aerolite being installed above the ceiling boards.

Sisalation being installed to the underside of the rafters.