Article by: Amelia Lee Undercover Architect
Forward by: Amanda Robertson | 3 min read
I’m a big fan of the Undercover Architect www.undercoverarchitect.com In this article Amelia Lee looks at dark vs light rooftops and uncovers some interesting history plus raises some interesting environmental aspects. So if you’re planning to re-roof or build a new home, consider some of the colour and roofing options available that will assist in improving the sustainable environmental aspects of your home.
As an architect (that’s Amelia) she says, I’ve ALWAYS selected a light roof colour. Colorbond ‘Shale Grey’ is probably my most common go-to. I will play with gutter and fascia colours to get that darker trim to the home, but the roof stays light.
However, some council areas prefer darker roofscapes (Pittwater and Woollahra for example). And according to an article published on The Fifth Estate in 2014, 70% of roof tile sales in NSW were black or grey (and Victoria was similar).
In an article written by Perth architect, Sid Thoo, titled “Does roof colour affect the energy- efficiency- of my- house?”, the difference in solar absorption (and consequently solar reflectance) is outlined for the various Colorbond colours. One of the most popular colours, “Monument”, has almost 2 X the solar absorption of Shale Grey.
Using energy efficiency modelling, Sid explains how detrimental this higher solar absorption can be for the heat loading of your home overall.
Interestingly as well, in The Fifth Estate article, it cites research done by the Roof Tile Association of Australia, performed by the University of Newcastle, that found that light coloured tiles yielded “energy savings between 25-36 per cent compared to dark coloured tiles”.
The same article talks about the heat island effect … the impact of having a collection of homes together, all with roofs with higher solar absorption, and what that does to the local air temperature. Combine that with the lack of decent street trees and shade, and it’s making for hotter areas.
The argument for dark roofs has often been “we like it, but don’t worry- we’ll upgrade the insulation”. Which is an extra expense that will help you internally, but won’t deal with the external impacts of a higher solar absorptive roof. And the councils that argue for dark roofs often do so on the premise that they ‘blend in’ to the surroundings more effectively.
Strangely, tools like BASIX can (in certain climates) favour a dark roof over a light one to meet winter heating targets. They’re not perfect tools, and they don’t penalise the star-rating of a home that then adds a huge air-conditioning unit to cope with the summer heat the dark roof can bring.
The article In Review also has some interesting information on the limitations of the rating tools to ‘see’ colour in the roof.
There are some products that include coatings to reduce the solar absorption – however, generally, the light colours will still perform better than the darker ones.
With our climate only getting hotter though, it’s worth remembering that all our energy efficiency tools rate your home’s performance against historical – not predictive – data.
Choosing the colours and materials for your future home is worth thinking about early, and putting together as a total palette. Consider how your gutters and fascias can add colour and feature – they don’t have to be the same as your roof colour. You can then match darker gutters to a dark garage door and tie things together like that. Play with the range of colours available, and view the entire scheme together to get the balance and look you’re chasing.
Thanks Amelia. As a real estate agent I’m asked all sorts of questions about properties, especially if the property is in need of renovation, extensions and sometimes complete remodelling. When appropriate I always suggest to clients to work with an architect who they have a good affinity with and engage a quality builder, as good design and a quality build adds greater value to their home when it is time to sell.
