Question 1

What is an H1 report, and when do you need one for consent?

Accepted Answer

An H1 report is an energy-efficiency assessment that helps you show your design meets Clause H1 of the New Zealand Building Code. You’ll need one for new or altered residential or commercial projects. We assess the thermal performance of your building envelope, including insulation, glazing,  roof, wall and floor construction, and solar heat gain. Send your plans early, and we’ll tell you the most practical compliance path.

Question 2

How long does an H1 report take?

Accepted Answer

Most H1 reports are completed within approximately 3–5 working days depending on project complexity and how complete the documentation is.

Simple projects may be completed faster, while larger architectural homes or townhouse developments may take longer if multiple revisions are involved.

Fast turnaround is one of the biggest advantages of early H1 coordination because it helps avoid consent delays and redesign pressure later in the project.

For urgent projects, we can also provide same-day H1 reporting where possible. This is especially useful for projects facing consent deadlines, the build has already started and the wrong material has been installed, or situations where builders and architects need quick answers to keep the project moving.

Question 3

Which H1 compliance pathway should we use, calculation or modelling method?

Accepted Answer

The best H1 pathway depends on the design of the building.

The H1 calculation method is generally suitable for:
simpler homes
standard glazing layouts
conventional construction systems
straightforward compliance pathways

The H1 modelling method (H1/VM1) is usually better for:
architectural homes
townhouse developments
high-glazing homes
complex roof forms
large window areas
custom designs
Customers who want to optimise build cost savings

Many projects that fail under the calculation method can comply using the modelling method without requiring architectural redesign.

This is especially common where clients want:
less insulation
larger glazing areas
improved natural light
cleaner architectural detailing

We always get our H1 reports to comply while maintaining the original architectural intent.

Question 4

What information do you need to start an H1 report?

Accepted Answer

To begin an H1 report, we typically require:
architectural plans
elevations and sections
window and door schedules
insulation specifications
wall, roof, and floor build-ups
project location or climate zone

For preliminary H1 reports, early design information is often enough to begin optimisation before consent drawings are complete.

We use EnergyPlus-based thermal modelling for H1 compliance reports.

Question 5

When should we start H1 compliance to avoid redesign later?

Accepted Answer

The earlier H1 compliance starts, the easier and cheaper compliance usually becomes.

We recommend starting during preliminary or developed design so issues can be identified before documentation is finalised.

Early H1 compliance helps identify:
overheating risk
excessive solar gain
poor glazing performance
inefficient insulation strategies
thermal bridging issues

Late-stage H1 can sometimes force unnecessary upgrades if optimisation opportunities were missed earlier in the design process.

Question 6

How can H1 modelling reduce construction cost while staying compliant?

Accepted Answer

H1 modelling allows the building to be assessed as a complete thermal system (both heating and cooling) rather than relying only on heating, which is what the calculation method does.

This creates opportunities when modelling to:
reduce unnecessary insulation upgrades
optimise glazing performance
reduce overheating penalties
minimise the need for expensive construction changes
reduce reliance on high-cost thermally broken joinery in some projects

Reducing overheating penalties is often one of the biggest opportunities for cost savings because overheating can drive additional insulation or glazing requirements.

Careful glazing optimisation and passive performance analysis can significantly reduce compliance cost while still achieving strong thermal performance.

Question 7

What parts of the design have the biggest impact on H1 compliance?

Accepted Answer

The biggest factors affecting H1 compliance are usually:
glazing size and orientation
window thermal performance (non thermally broken vs. thermally broken frames)
solar heat gain coefficient (SHGC)
thermal bridging in wall framing
roof insulation
slab edge detailing
overheating risk
shading design

Large north & west-facing glazing areas are one of the most common causes of overheating and failed H1 modelling compliance.

Modern H1 requirements now assess how a building is likely to perform in real-world conditions, including thermal bridging, glazing performance, overheating risk, and actual heat loss, rather than relying only on insulation product ratings. This leads to more comfortable, healthier, and energy-efficient homes while encouraging smarter design decisions instead of simply adding more insulation such as what was happening with the schedule method.

Question 8

Do I need thermally broken windows in New Zealand?

Accepted Answer

Not always.

Many homes can comply with H1 requirements without thermally broken joinery, particularly when the glazing design, ventilation strategy, and thermal performance of the building are carefully optimised.

However, thermally broken windows are generally recommended because they reduce condensation risk and improve thermal comfort compared to standard aluminium joinery.

Even thermally broken joinery can still experience condensation under certain conditions, especially in homes with poor ventilation or high indoor moisture levels.

A good continuous ventilation strategy is often just as important as the window frame type when managing condensation and indoor comfort.

Question 9

What happens if the architectural design changes after the H1 report is issued?

Accepted Answer

If the design changes after the H1 report is completed, the report may need to be updated.

Changes that commonly affect H1 compliance include:
glazing size changes
insulation changes
wall construction changes
orientation changes
roof geometry changes
floor area changes

Minor changes can often be updated quickly, while larger design revisions may require the thermal model to be redesigned to match the updated plans.

We regularly work directly with architects, builders, and homeowners throughout the design process and can provide as much support as needed during revisions and consent.

Question 10

Do you work directly with architects, builders, and homeowners?

Accepted Answer

Yes. We regularly work with:
architects
architectural designers
builders
developers
homeowners

Some clients only require the final compliance report, while others want ongoing support throughout the design and consent process.

We can provide as much involvement and technical support as needed during design development and council coordination.

Question 11

Can a failed H1 report be fixed without redesign?

Accepted Answer

Yes. In most cases, failed H1 compliance can be resolved without changing the architectural design.

This is especially common for projects that initially fail under the schedule or calculation method due to:
large glazing areas
architectural complexity
overheating penalties
insulation trade-offs

Thermal modelling often allows the design to be optimised in ways that maintain the original architecture while still achieving compliance.

We regularly help projects comply where previous H1 assessments were unable to achieve compliance without redesign.

Question 12

How much does an H1 report cost?

Accepted Answer

The cost of an H1 report depends on:
floor area
project complexity
number of units
glazing complexity
modelling requirements
level of support required

Architectural homes and townhouse developments generally require more detailed modelling than simple residential projects.

Frequently asked questions on NZBC H1