There has been a large amount of publicity in all media of Australia lately on spruking the advantages of tile roofing over metal roof systems. At BPN (Building Product News) they have a classic example of this "New Roof Tile Research Highlights Energy Efficiency Performance" on 21st August 2012.
Many of the tile manufacturers have the same type of claims on their websites and even tile roof contractors advertising the fact the - "studies in the USA" & "testing at University of Newcastle" etc have proved the above statements of ENERGY EFFICIENCY!
Lets look at some of these claims by the Tile groups:
- Comparing (white) roof tiles and (white) metal roofing showed that roof tiles have significantly higher reflectivity than metal roofing, reflecting a total of 75.4 per cent of solar energy. This is 7.8 per cent more reflection than metal roofing which reflected a total 67.6 per cent.
- Concrete and terracotta roof tiles were found to cause the strength of energy being transmitted to dissipate significantly.
- The roof is one of the largest external facing surfaces of a home and the choice of roofing material has a major role in determining internal living temperatures and household energy usage.
1. Embodied Energy.
This is the base embodied energy of each roof system at time of manufacture. The less the MJ/sqm the better
|Timber frame, concrete tile, plasterboard ceiling||251 MJ/sqm|
|Timber frame, terracotta tile, plasterboard ceiling||271 MJ/sqm|
|Timber frame, steel sheet, plasterboard ceiling||330 MJ/sqm|
So here - the tiles win on average but only just.
2. Solar reflectivity.
This is simple energy reflected by the roof system and based on results from the USA?
Tiles (White) reflect a total of 75.4 per cent of solar energy.
Metal (White) reflect a total of 67.6 per cent of solar energy
So here we have the tiles ahead again on average but not much.
3. Re-cycle Capabilities.
The is simple again and roofing materials are measured in their ability to be recycled and here is a list of waste disposal in landfills in Australia.
|WASTE DESCRIPTION||WASTE QUANTITY|
WEIGHT % OF TOTAL
|Paper / cardboard||1|
|Garden / vegetation||3|
|Wood / timber||10|
|Textiles / rags||1|
|Soil rubble (<150mm)||34|
|Soil rubble (>150mm)||2|
|Clay-based [eg. bricks, tiles]||16|
|Other / unknown||11|
The tiles on average are 8 times less likely to be involved in recycling whereas the steel roofing is nearly 100% recycled.
Huge loss for the tiles as an unfriendly "green" product.
4. The Construction Stage.
With no actual statistics available on the impact of tile roof over metal roof installation - but any observation of a tile roof in progress - the on site disturbance is extremely waste intensive with large area of ground disturbance.
Tiles here lose again heavily as metal roofing is simply delivered, located & fixed. Also more time efficient.
Again no available statistics but metal roofing with a lighter frame requirement is much more efficent in transport costs to deliver than tile systems.
Another big loss for tiles over metal.
6. Construction Light or Heavy.
These two systems are at exact opposites - with tile roofing requiring extra heavy design structues from the footings up. The metal roofing system offers a much lighter overall building structure for support.
Huge loss again for Tiles.
7. Final Score
Metal Roofing 4 beats Tile Roofing 2.
The winner is metal roofing.
If a Life Cycle Analysis was done on two houses next to each other on the total "Green" acceptability - the metal roofing systems wins every time.
Metal Roofing is much more environmentally suitable for residential housing systems in general and this latest information by the Tile Groups is almost untrue when looked at in total context. Let's get the ASI etc to publish some data that reflects the true nature of metal roofing, its affordability, LCA favourable outcomes and generally more "GREEN".