H1 Update 11.21

The changes became effective as of 29^th November 2021. There is a transition period where you can still use previous editions until 2^nd November 2022.

Windows in Climate Zones 1 and 2 (Auckland and surrounding areas) will be allowed to have slightly lower R-values until 2^nd November 2023 but there are many solutions already available at the higher performance.

Yes, any retrofit work will also need to comply (considering just the areas that are altered or the building as a whole).

Small buildings are all housing (including apartments). And anything else less than 300 sqm.

Large buildings are non-residential and >300 sqm.

There are a huge amount of variables in trying to asses the net value of this change. Estimates are the heating bills will be 40% less for housing and 23% less for commercial but those are based on a number of assumptions and may not apply to all typologies. Some estimates of increased costs were included in the consultation document.

If you were looking for the quickest shortcut to compliance, installing a heat pump for heating and complying through an energy model would produce the biggest bang for buck. Modelling is the only way to account for the improved efficiency of heat pumps, the schedule method does not accommodate this.

We’re speculating that MBIE has chosen to leave residential wall R-values at R2.0 to avoid further issues with interstitial condensation. BRANZ Research has shown many common NZ walls are not robust with respect to managing moisture and increases in insulation compound this. Typical 90mm timber stud walls with batt insulation are already close to failure when it comes to preventing interstitial condensation.

This update has placed a greater emphasis on the framing ratios when calculating construction insulation values. When you consider that current average framing ratios have been found to be around 34% (BRANZ ER53) with some reaching as high as 55%, the current typical assumptions of 18% of construction R-value will likely need discussion with this latest update.

We expect changes to ventilation and heating to come with the next code update, at which point further wall R value increases would be expected.

It is worth noting the substantial increase to commercial buildings. Previously, this was R0.3 which could be accomplished by an uninsulated wall. Now, commercial buildings have a sliding scale that increases with colder climates and exceeds the residential requirements in every climate zone. As a reference, we suspect the residential code will follow the same model and targets in the next code cycle along with improvements to heating and ventilation (projected 3-5 years).

We agree, most simple buildings could have an energy model created by architects with sufficient training. We recommend that PHPP and ECCOH are the best tools for the job as they provide a robust analysis with relatively simple inputs. ECCOH is a simpler version of PHPP (Passive House Planning Package). As with all models, you need to understand the inputs and outputs to ensure you’re getting a useful answer. There is a general requirement that the modelling software be compliant with BETEST or ASHRAE 140. If you’re looking at some software look for that compliance aspect.

That being said, many of these external modelling professionals have very quick turnaround processes and that will continue to develop over 2022 and beyond. You might expect a range of $1,000 for a simple building and upwards of $50k for large complex ones. Given that modelling produces a more accurate picture of performance and quite likely will result in overall cost savings (due to optimised design) this could be money well spent.

At some point yes, but Oculus and others in the industry will be providing a set of standard details in early 2022 that will demonstrate how these H1 updates can be easily and efficiently applied.

Another useful tool is the High-Performance Construction Details Handbook put together by our friends at the Passive House Institute of NZ (https://passivehouse.nz/hpcd-handbook/)

A Certified Passive House still needs to demonstrate how it complies with the building code. We anticipate that the simplest compliance path for a Certified Passive House is via H1/VM1 which just needs the reference building included in a PHPP model.

NZS3604 is under review at the moment and we hope would be updated to reflect these changes, but Oculus will be providing a set of standard details in early 2022 that will demonstrate how these H1 updates can be applied.

Another useful tool is the High-Performance Construction Details Handbook put together by our friends at the Passive House Institute of NZ (https://passivehouse.nz/hpcd-handbook/)

Yes, all new buildings that are consented will need to comply with the building code, whether they are rented or owner-occupied. Any retrofit work will also need to comply (considering just the areas that are altered or the building as a whole). The Healthy Homes Standard would be over and above this requiring a suitably sized heating device not yet required in the code.

NZS 4211 is under review which deals with air infiltration of windows. This update includes changes to air infiltration.

Most would need a refresher on how to calculate construction R-values. If you haven’t been doing this calculating new ones may take some time. To assist, Oculus will be developing some common ways to comply with these new values to give you a starting point.

Window performance is largely the biggest change to the residential space. The combination of window frame performance, glass selection and actual sizes of windows in a house is an area not previously understood. Most window suppliers will have standard guides to help and can offer you a project specific R-value calculations free of charge.

Roof space air leakage is now a huge concern with cold roof construction. With the reduced drying effect that comes with more insulation, there comes a greater risk of condensation. To combat this, air tightness at the ceiling level either through airtight drywall (and sealed penetrations) or a separate layer is critical.

You can also take an introduction course in Passive House design which is an excellent introduction to the basics of building science and high-performance buildings https://www.phanz.ac.nz/2018/05/certified-passive-house.html

The first option is the Calculation method. This allows you to compensate for an element rated below the Schedule method with a higher performing element elsewhere. You can also use the modelling method (H1/VM1 and H1/VM2) to demonstrate compliance where the R-values in H1/AS1 are difficult or impractical to achieve.

While the Acceptable Solutions and Verification Methods have changed, the Building Performance Index (BPI) has not changed. This technically means the older versions of H1/As1 and H1/VM1 could be used as Alternative Solutions but that not a loophole we suggest using, as it will likely be eliminated soon.

There is no specific target for airtightness but it is explicitly required to prevent uncontrolled air leakage. It’s not clear what this means but the key is to attempt to form a continuous air barrier around all details and around the whole building. It really doesn’t take a lot of cost or time to make a pretty air tight building. Blower door testing after construction helps diagnose gaps and educate installers.

The new requirement for residential roofs is R6.6. This is an installed construction value which includes reduction for framing and thermal bridging.

Here are some of the nominal (i.e. just the material) insulation thicknesses:

• Glass / polyester / mineral fibre batts – R6.6 is roughly 320mm of insulation
• Polyisocyanurate (PIR) – 120mm
• Rockwool semi-rigid insulation – 225mm

To account for the thermal bridging, you might need to increase this by 25-75% depending on the bridging. This would leave something like:

• Glass / polyester batts – 400-600mm
• Polyiso – usually continuously installed – 120mm
• Rockwool rigid insulation – usually continuously installed 225mm

We think 400mm of batt insulation is going to be an awkward, difficult installation and think warm roof with rigid foam products are going to be preferable. This alleviates the condensation and air control problems and potentially much cheaper and easier to build overall.

There are several products from most manufacturers on the market which can fulfill this function.

It is expected a code update in the coming years will address heating and ventilation. In the meantime, it is critically important to the performance of these assemblies to include both heating and mechanical ventilation. The operational costs of running a whole house ventilation system is less than a $1 per day. While natural ventilation can be useful as a complement, it is not a reliable means of ventilation year-round.