Submission: H1 requirements in housing and other buildings

BRANZ acknowledges the work undertaken by the Government to address issues that have emerged following the implementation of new insulation requirements in housing. Concerns raised by the sector include:

• the increased upfront costs of complying with the new requirements
• the lack of design flexibility to achieve compliance
• the belief that higher insulation requirements are causing some new houses to overheat in summer.

BRANZ welcomed the opportunity to contribute to the consultation and provide input on how Building Code Acceptable Solutions H1/AS1 and H1/AS2 and Verification Methods H1/VM1 and H1/VM2 could be amended to address these issues.

Our submission is summarised below.

Backing the intent of the changes

BRANZ agrees with the overarching goals of the proposed changes described in the consultation document, which are:

• maintaining adequate energy efficiency in buildings
• balancing upfront building costs and longer-term benefits
• removing barriers for designers to optimise insulation for energy efficiency in a building
• improving the consistency and certainty of compliance and consenting of buildings in regard to insulation requirements and energy efficiency.

Compliance pathways that support designing for year-round comfort

BRANZ’s response to the H1 consultation is founded on a key principle.

We believe that pathways to achieving compliance under H1 should encourage greater industry engagement with the outcomes of design choices – that is, engagement with the reality of what is being built. By promoting flexibility of design and assessment of performance year round comfort becomes an attainable goal for home occupants.

Our research has shown that, when designing for energy efficiency and comfort (including avoiding overheating during warmer weather), homes should be considered as a system and not a set of individual components. A number of factors, including orientation of the building site, the number and position of windows, shading, insulation, heating and cooling systems, and ventilation work together to govern how comfortable people will be in their homes at different times of the year.

The existing schedule method does not encourage this holistic view of design.

BRANZ supports the calculation method and a longer-term move to modelling

BRANZ therefore supports the proposed removal of the schedule method as a compliance pathway for H1 Energy efficiency as this move will pave the way for using modelling to achieve greater year-round comfort for home occupants.

The calculation method allows insulation to be reduced in some places and increased in others as long as the overall thermal resistance doesn’t drop below that of a reference building, however it does not consider year-round outcomes. The modelling method is more sophisticated and applies climate, occupant loads and other factors to assess energy use against a similar reference building. It has the potential to provide rich information about how a building is likely to perform – and therefore how occupants are likely to feel.

BRANZ views an initial shift from the schedule method to the calculation method as a necessary step before there can be widespread uptake of more sophisticated modelling tools.

However, we note that care will be needed if a blanket removal of the schedule method occurs. The schedule method may continue to have a role in rework, renovation and remediation projects, and when using or considering Alternative Solution compliance pathways.

Support needed for the sector to transition

The proposed changes will require skills uplift and behavioural shifts across the sector. For many, the changes will be a first step towards thinking differently and holistically about buildings. Although the calculation method is widely used already, there is still a need for support and education, so it is easily and consistently applied. The sector will also need support if a longer-term move to modelling tools occurs.

BRANZ recommends a gradual transition over 18 – 24 months to ensure the sector is ready, complexities have been adequately thought through and tools are fully developed and tested. BRANZ has the research, expertise and connections to international best practice to assist in this area.

Strategic and structural Building Code changes recommended

While acknowledging that this consultation was limited to the H1 Energy efficiency clause of the Building Code, BRANZ believes that if beneficial outcomes for occupants are also to be considered, several other Building Code clauses (e.g. E3 Internal moisture, G4 Ventilation and G5 Interior environment) will need to be reviewed jointly.

BRANZ recommends that MBIE invests in a strategic, planned approach to reviewing and, where necessary, updating related Building Code clauses. BRANZ has the research, insights and knowledge to support this work.

The issue of overheating is a poignant example of this need: Anecdotal and soon-to-be released research insights tell us that buildings are getting warmer inside. Solving the issue of some buildings getting too warm will require consideration of several Building Code clauses simultaneously and holistically. It will also require evidence to inform and support any future actions, including those that sit outside of the current Building Code (such as defining what overheating means).