Think Brick Sustainability Blog

Energy efficiency – especially when sales are struggling and there is a greater focus on cost cutting – is a key area of opportunity for businesses and households alike because it saves money. (And is definitely a motive behind the Federal Government offering free ceiling insulation to 2.7 million homes across Australia).

Since initial reports in 1999 the Australian Government has been concerned with energy efficiency in households and has subsequently inserted minimum energy efficiency regulations into the Building Code of Australia (BCA) that apply to new houses.

These regulations are focused on improving the energy efficiency of the building envelope (ie the walls, roof and floor) and architects and builders have two methods of complying with the regulation:

1. computer simulation using energy efficiency software, or
2. having a minimum total R-value in the envelope.

The first of these methods is, generally speaking, a good way to determine energy efficiency because it accounts for the many factors that improve energy efficiency (eg thermal mass, insulation, orientation & design features such as appropriately located windows). The second method, however, is limited in its effectiveness because it relies only on R-value (or thermal resistance, the measurement for insulation).

Relying on R-value alone is problematic because, as has been demonstrated by both the University of Newcastle and independent computer simulations by Energetics Energy Consultants, the same R-value in similar houses produces very different energy consumption results.

For example two identical houses located in Brisbane, both with the same design features, can reduce its heating and cooling energy consumption by up to 17% by orientating the house to the North instead of the South. Likewise, the same house plan in Brisbane, with the same design features and similar R-values (R=1.4) on a North orientation, can improve its performance by nearly 26% by using insulated double brick instead of insulated weatherboard.

These results were obtained by Energetics using the computer simulation program DesginBuilder and similar results exist for nearly all parts of Australia.

The University of Newcastle have similar conclusions from the full-scale test modules under free floating conditions. In that experiment , the best performing building performed 14.4% better than the highest R-value building despite 18% less R-value. If R-value was the best measurement for energy efficiency, one could reasonably expect that similar R-values would produce similar results, and likewise, that the highest R-value would produce the best performance. In both of these experiments, conducted by different, independent researchers and consultants, neither of these situations holds true.

An ‘easy’ solution to correct this discrepancy might be to eliminate the second method of complying with the energy efficiency regulations (achieve a minimum R-value), however, it is not this easy because this method reduces red tape and makes it easier for builders to comply with the regulations. As such, the Government would struggle to remove the second method of compliance for fear that it would further increase the costs of building houses.

It is for this reason that the brick industry is proposing to the Federal Government that the research by the University of Newcastle be extended. Based on the interim results there is a very real chance that an alternative to R-value for the second method of compliance could be achieved. Such a change would take some time to implement, but in the interests of streamlining development and reducing red tape, this time and investment is justified.