Energy Efficiency

The objective of the BCA is that the building fabric must meet minimum energy efficiency requirements. The building fabric and the building services combined must meet minimum energy efficiency requirements. The fabric of the building is not likely to be changed for the life of the building and yet features within the building services are often replaced after 10 years. Poor building fabric performance cannot be justified by compensating with additional heating and cooling. The simple message to the industry and consumers is that you spend less on energy if you improve the performance of the building fabric.

In WA, there will now be two methods whereby compliance with these new performance requirements of the BCA can be achieved for housing:

• By applying the Deemed-to-Satisfy Provisions of the BCA Parts 3.12.1 to 3.12.5; or
• By lodging an alternative solution using an appropriate assessment method eg energy rating assessment tools.

The Deemed-To-Satisfy Provisions of parts 3.12.1 to 3.12.5 of the BCA requires the design to be fully specified to comply with the BCA prior to the plan being submitted for approval.

MAJOR POINTS OF CONSIDERATION

• Passive solar design: extremely important design issue.
• Insulation and appropriate R-ratings: concrete slab edge; walls and ceilings.
• Air leakage: around fireplaces, windows and doors.
• Design features: ceiling height – north facing windows in living areas.
• Floor type: slab on ground, suspended slab or timber.
• Zoning: ability to segregate areas.
• Glazing: double or tinted% facing to the north Disadvantage of % facing south or west.
• Thermal mass: the floors and internal walls – trombe thermal mass walls.
• Size of eaves: differing widths for the various aspects.
• Cross ventilation design features: Reduces residual heat in summer – added benefit of diminishing fungus and bacteria in carpets and curtains.
• Common walls: especially in multi-unit/townhouse developments.