IAONZ supports BRANZ HEEP2 findings: progress has been made, but the retrofit job is not done yet

The HEEP2 findings provide important evidence for New Zealand’s building, energy efficiency, housing and public health sectors. They confirm that progress has been made over the past two decades but also show that many New Zealand homes still do not consistently achieve healthy, comfortable indoor temperatures.

For IAONZ, the message is clear:

The job is not done yet.

New Zealand must continue improving the thermal performance of existing homes. Heating, ventilation, cooling, moisture management and occupant behaviour all matter, but they cannot replace the need for an effective thermal envelope.

Insulation remains a minimum starting point for warmer, drier, healthier and more energy-efficient homes.

Why HEEP2 matters

The HEEP2 report shows that indoor temperatures have improved since the original HEEP study. This is encouraging and likely reflects better heating technologies, improvements in the housing stock, retrofit activity, and changes in how households heat their homes.

However, the report also shows that many homes still fall below recommended healthy temperature thresholds, particularly in bedrooms and during overnight and early morning periods.

This is important because bedrooms are where people spend many hours, often at the coldest part of the day. If bedrooms are still frequently below healthy temperature levels, then the retrofit challenge remains significant.

HEEP2 also highlights emerging summer overheating risks. This reinforces the need to think about homes as complete systems, where insulation, airtightness, ventilation, shading, heating and cooling all work together.

Insulation first does not mean insulation only

IAONZ supports a whole-of-house approach to better home performance.

Effective heating is important. Ventilation is important. Moisture management is important. Summer cooling and overheating management are becoming increasingly important.

But these measures work best when the thermal envelope is performing properly.

A home that is poorly insulated, draughty, or has weak envelope performance will be harder and more expensive to heat, harder to keep comfortable, and more vulnerable to poor indoor conditions.

That is why IAONZ continues to support retrofit programmes, practical training, quality installation, and evidence-based insulation assessment.

The retrofit message for New Zealand

The HEEP2 findings support a clear national retrofit message:

We have made progress, but we have not finished the job.

New Zealand still has homes where insulation is missing, incomplete, damaged, poorly fitted, or no longer performing as intended. In some homes, insulation may be present but not sufficient for current expectations of comfort, energy efficiency and building performance.

Continuing to improve ceiling, underfloor and wall insulation, along with draught reduction and appropriate ventilation, remains a practical and necessary part of improving New Zealand’s housing stock.

This is relevant to public programmes such as Warmer Kiwi Homes, but also to private retrofit decisions by homeowners, landlords, builders, designers and property managers.

Quality installation matters

Insulation products only deliver their intended performance when they are correctly selected, correctly installed, and protected from avoidable defects.

Gaps, compression, folds, missed areas, moisture damage, poor coverage, or unverified substitutions can reduce the real performance of the thermal envelope.

That is why IAONZ continues to promote quality installation, installer training, evidence-based sign-off, and practical industry guidance.

IAONZ position

IAONZ supports the HEEP2 findings and encourages government, industry and the wider housing sector to treat the report as further evidence that home performance improvement must remain a national priority.

In IAONZ’s view:

• the thermal envelope remains a foundation for better home performance
• insulation retrofit work across New Zealand is not complete
• quality installation is critical to achieving real-world outcomes
• heating, cooling and ventilation strategies work best when the building envelope is performing well
• retrofit programmes should continue to prioritise insulation as a minimum starting requirement
• homes should be considered as systems, not as isolated components

The HEEP2 findings reinforce what IAONZ has consistently advocated: better building performance requires both good products and good installation, supported by practical training, quality assurance and ongoing investment in New Zealand’s existing homes.

The job is not done yet. Insulation remains a minimum starting point for healthier, more comfortable and more energy-efficient New Zealand homes.