Meeting the energy efficiency requirements of the BCA
There are various routes to compliance with the energy efficiency requirements in the BCA that come under two broad headings – Deemed-to-satisfy provisions and alternative solutions.
Deemed-to-satisfy provisions (officially known as acceptable construction practice in the BCA), cover two compliance pathways:
- Elemental provisions (known previously as deemed-to-satisfy or DTS); or
- Energy Rating Method
DTS Provisions represent a ‘recipe book’ solution where the required performance of each design element (Walls, Floors, Roof, etc.) is described in detail.
Although occupant comfort is not a primary goal of these requirements, an essential aspect of energy efficiency in a residential building is to ensure that the building is constructed in a manner that improves the comfort level of occupants, to the extent that they feel less need for artificial heating or cooling. This can be achieved by creating a thermally effective building envelope. Creating a thermally effective building envelope also means that when artificial heating or cooling is needed, the envelope will be more effective at retaining the conditioned air due to the barrier between the internal and external environment. The intent of the DTS Provisions is to ensure that the construction around conditioned spaces has sufficient levels of thermal performance to ensure energy is not used unnecessarily. The measures are intended to achieve this outcome by requiring certain elements to have minimum levels of insulation, either through adding insulation, such as batts or reflective insulation, or through the inherent thermal qualities of the building material, for instance the thermal mass of a masonry wall.
The Deemed-to-Satisfy Provisions for energy efficiency prescribed in the BCA contain a range of practical, commonly used and cost effective building solutions such as insulation in roofs, walls and floors, glazing of low solar heat and conductance characteristics, shading, energy efficient air-conditioning plant and energy efficient lighting.
A “Deemed to Satisfy” Report or DTS Report is essentially a checklist and the accompanying BCA glazing calculator which demonstrates your buildings meets the prescribed requirements for each of the building elements for your climate zone as specified by the BCA.
This Method is a quicker and less expensive alternative to the Energy Rating Method. However, this method has no flexibility and each of the building elements have to meet the minimum requirements separately. For example you cannot add more ceiling insulation to compensate for lack of wall insulation. Also this method doesn’t tell you how your house is performing in terms of energy efficiency.