BCA Section J DTS Method
One of the two methods to demonstrate compliance with the energy efficiency requirements of the BCA Section J is called Deemed to Satisfy or DTS method. This is the favored method by the majority of building designers due to its fast delivery speed, affordable fees and easy to follow process for both energy efficiency assessor and the clients of those services. On the other hand this approach has major limitations due to non holistic approach toward the energy efficiency performance of a building. The other method of compliance with the BCA Section J requirements is Alternative Verification Method JV3 or verification using a reference building.
BCA Section J DTS Compliance Method
Deemed to Satisfy Provisions
Deemed to satisfy provisions of the BCA Section J are a set of requirements that a building must satisfy in order to meet the energy efficiency commitments of the BCA. By nature DTS provisions are generic and do not consider each design scenario in its own scenery and circumstances but instead they set a framework of rigid provisions that a building must meet in order to satisfy the BCA Section J requirements based on its locality or BCA class and sometimes even non of these.
For example Part J1 of the Section J requires an external wall of a non residential development to have a certain level of insulation irrespective of the building type, space functionality and characteristics, external conditions and other specific situations. Very limited scenario specific evaluation is available in Parts J2 for glazing and J6 for artificial lighting. Because of this approach a BCA Section J DTS report is normally compiled where the architectural design of the proposed development is tolerant to some degree of modification. Due to its simplified compilation procedure a BCA Section J DTS report is the faster and much more economic solution to demonstrate a building's compliance with the BCA.
Section J DTS Assessment
BCA Section J DTS assessment can be considered a design review of the building elements related to energy efficiency versus the DTS compliance requirements of the BCA Section J. Each construction and service element which is addressed is evaluated separately and irrespective of its interaction with other building elements which contribute to energy efficiency performance of the building either positively or negatively.
Because of this approach the results of this method of BCA Section J assessment are sometimes not favorable for building designers or not even efficacious enough in practice. For example utilization of high performance windows above the DTS requirements of the section J contributes to an area's energy preservation performance and therefore a lower performing insulation would be sufficient to maintain the building within the compliance limits. This interaction is the main missing element in a BCA Section J DTS assessment practice which sometimes requires building designers to pursuit alternative verification method using reference building thermal simulation method instead to keep their original design while satisfying the BCA Section J requirements.
The positive side is that the DTS process is far less time consuming and expensive compared to an alternative verification method which makes this method the only reasonable choice for small to medium non residential developments.