Verification using a reference building

The NCC is a performance-based code, requiring all new buildings to meet minimum performance requirements.

The NCC is a performance-based code. It requires all houses to make efficient use of energy, particularly the energy required for cooling and/or heating.

One way to verify that the relevant Performance Requirement is met, is to compare the design with a reference building based on the elemental Deemed-to-Satisfy Provisions.

This method involves using software to perform two modelling runs.

The first models the building complying with the minimum DTS Provisions of NCC Volume Two.

This is the reference building model, providing the cooling or heating load targets for that building.

The second run models the building using the actual design elements proposed, remembering that these still need to comply with the NCC requirements for insulation, thermal breaks, and building sealing.

Heating and/or cooling loads are calculated for each model, and if the proposed building loads equal or are less than that of the reference building, then it complies with the requirements.

Let’s step through an example of using this method. It’s made up of six steps.

Step 1 is selecting a calculation method.

The software program used must be validated, and be capable of assessing the heating and cooling load by modelling

... the building fabric

...glazing and shading

...air infiltration and ventilation

...and the other elements included in V2.6.2.2 part (d).

House energy rating software accredited or previously accredited under the Nationwide House Energy Rating Scheme, or NatHERS, are not permitted for this method.

Step 2 is to model the reference building.

In this model, include the mandatory parameters as listed in Table V2.6.2.2.

Step 3 – Calculate the reference building loads.

Step 4 – Model the proposed building.

Certain building aspects in this model must be the same as in the reference building model…

… but this time, include the specific design features proposed for the building.

Step 5 – Calculate the loads for the proposed building.

And lastly, in Step 6 compare the reference and proposed building's heating and/or cooling loads.

If the proposed building has a heating or cooling load which matches or is less than the reference building, then compliance is verified.

If not, make design adjustments and repeat from Step 4, or use a different Assessment Method.

This Verification Method is clearly outlined, with worked examples, in the Handbook: Energy Efficiency NCC Volume Two.

The handbook and other resources are available from the ABCB website.