Achieving Energy Efficiency – Case Study – Sunshine Coast Granny Flat Part 4


Welcome back to the final series in this 4 part case study where we discuss and analyse our Sunshine Coast granny flat build. This time, we will investigate the energy efficient build materials that were used in the case study. The materials selected in any build will go a long way to contributing towards the energy efficiency rating. Unfortunately, an often overlooked component during the design and build process. Why do the materials have such a big role to play in achieving energy efficiency? Read on to learn more.

Searching for energy efficient granny flat building materials? Enquire with the Sunshine Coast building experts.

What are energy efficient build materials?

In the modern day and age of construction, it is important to note that there is such a wide range of building materials on the market. The fair majority won’t be considered energy efficient, unfortunately. Sustainable and energy efficient building materials will have two main benefits.

Firstly, via procurement and production – being renewable or utilising less energy to produce.
Secondly, the ability to contribute towards the thermal comfort and energy consumption (meaning that you will use less power trying to heat and cool).

There is no real simple, one size fits all solution when it comes to choosing energy efficient build materials. The best options will come down to the build location, local climate, size of the build, and use of the material.
Following the three simple R’s can be simplified way of narrowing the options down.

Reduce – Build a smaller footprint, paying attention to material sizes in order to create less waste.

Reuse – Where possible, reuse materials.

Recycle – Choose materials that can be recycled, whether that be from wastage during the construction or in the future.

Given that we have explored the design brief, build location/climate & the design response in our previous posts, we are better able to explain why our final selection of materials does contribute towards the overall energy efficiency rating.



We believe in insulating all of our builds. Utilising a combination of wall batts, roof blanket and wall wrap.

Insulation Batts – Walls
Insulation Batts are made from fiberglass or mineral wool. Insulation Batts are primarily used to insulate all walls in our granny flats. The wall batts utilised are guaranteed to reduce energy used for heating and cooling, leading to a decrease in energy consumption.

Roof Blanket
The particular brand of Roof Blanket we installed is called the Space Blanket. The Space Blanket is designed to manage heat gain and heat loss. This type of insulation is a specialist under-metal roof insulation. The space blanket is made with soft Earthwool® insulation and is laminated with an anti-condensing facing foil. The soft wool is made with upto 80% recycled glass and with ECOSE ® Technology – a sustainable bio-based binder containing no formaldehyde. When being manufactured, the soft wool gets spun into shape – much like fairy floss, creating millions of air pockets.

Wall Wraps
The wall wrap we select is called the ThermalBreak7 ™. The ThermalBrake7™ will contribute to the overall R-value by forming a reflective air cavity with an unventilated air space. Combined, this can deliver upwards of R1.0 to the thermal performance of the wall or ceiling, especially with good performance against downwards heat flow in Summer conditions


Windows not only allow for natural light but can increase natural cross-flow ventilation. The windows installed in our display granny flat have low-e glass. Low-e glass comprises of a thin coating over the glass to reflect radiant heat, and reduce heat loss in winter.

The Window to Success

Roofing & Cladding

COLORBOND® steel was selected for the roofing and some walls. Made in Australian laboratories, COLORBOND® steel is designed for our local climate.

There are further benefits, including thermal efficiency and sustainable performance. This material features Thermatech® solar reflectance technology. Thermatech® technology is designed to reflect more of the sun's heat on hot days, which can mean less dependence on air-conditioning, plus reduced heat stress 

Jenelle's Weekender - Colorbond Cladding

Cabinetry & Appliances

We chose to work with Australian manufacturers and local suppliers to ensure longevity and sustainability. These suppliers included – Laminex & Dulux. Sustainable practices are at the forefront of these companies production plants – limiting the use of water and electricity. They use water based resins and cleaning systems which reduce the level of toxicity and pollution.


If you would like to learn more about our energy efficient build process, make an enquiry with our friendly team. Our display granny flat provides just a small example of what is possible to build. 

Contact us for more energy efficient granny flat build material ideas. Trust your local Sunshine Coast builder.