H1 Compliance Calculator

Christmas and New Years Special


Need an H1 report in a rush?

Have your H1 calculations done by us. For a short while we offer to do your residential H1 calculations for you. Prices start from $200+GST and turn-around times are usually three days or less.


Just send me your plans (as PDF files) together with your preferred insulation type (designnavigator@gmail.com). I'll have a look at them, let you know whether I need more details and and will give you a quote.

I hope this takes a bit of the pre-Christmas pressure away and you will enjoy a relaxed and wonderful Christmas and New Years break.

Sunny regards

PS: In case you are wondering: We can also do H1 calculations for commercial buildings.

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This website calculates compliance with insulation targets of NZBC, Clause H1 as of 10 October 2011. It calculates compliance with the New Zealand Standard NZS4218:2004, Schedule and Calculation Methods, using the R-value targets from NZBC/H1 (October 2011) and for compliance with the Building Performance Index (BPI).

The Calculator should be used in conjunction with the Energy Efficiency Clause H1 of the New Zealand Building Code and NZS4218:2004, which can be purchased from Standards New Zealand.

You can create as many Design Navigator projects as you want free of charge. Once you have finished a project and download a completed H1 report a fee of 26.40+GST applies. Payment can be made via invoice or credit card. Please contact me if you want to have an account for monthly invoices set up.

Notice: The Internet Service Provider will need to shut down the Design Navigator website for maintenance on 04/03/2015 between midnight and 04:00 AM.
The website is currently experiencing some server issues. Please check in later.
The server crashed late morning on 21 March 2014. The ISP has recovered the database, however some projects created on the 20th and 21st March might be corrupted or deleted. There was another crash on 25th March that may have also corrupted some data. Sorry about this.

There currently is a bug in the Design Navigator H1 calculator, which is probably caused by changes which the ISP implemented recently.

Projects cannot be saved if they include a *previously* created construction R-value calculation table (view screen shot). The bug does not seem to occur for projects with *newly created* construction R-value tables.

You can still modify old projects and print the reports. You can also save projects, but before you do that you have to replace the old construction R-value tables with newly created ones, even if they are for the same detail.

I am working on fixing the problem.

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Click here to use the H1 calculator without saving and printing of projects.

Note: I am regularly adding further improvements to this calculator. I am always trying to conserve any previously saved projects but suggest that you keep printed copies of the compliance reports so that you can reproduce the results should the database records be damanged.

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Training Videos

Introduction tutorial:

Tracing scanned floor plans:

Home This tool was created by Design Navigator Ltd.

Additions and Alterations

The easiest way to show compliance for additions and alterations is to show compliance for the whole building rather than only for the changed parts. That means you enter all external floors, walls, roofs and windows whether they are existing or new.

The trick is that for all existing unchanged parts you can assume that they apply with the Schedule Method R-value targets (Replacement Table 1 in NZBC H1), irrespective of whether they in reality do. So you would for example enter for all existing windows an R-value of R-0.26, even if they are single glazed.

If the R-values of the existing parts are known and higher than the Schedule Method R-values then you can even use these R-values.

Only for the new and changed parts of the building you use the actually proposed R-values for these elements.

Any walls or other elements that used to be external, but are now internal elements will be ignored as usual.

This method follows the approach in NZS4218:2009 Appendix D3. Note that this version of the Standard is not an Acceptable Solution (that is still NZS4218:2004), but most BCAs will accept this approach since there is no alternative method recommended in NZS4218:2004.

There is also a message trail on the issue on the DesNav message board.

The H1 Replacement Table 1 R-values are:

Zone 1Zone 2Zone 3
Glazing (vertical)R-0.26R-0.26R-0.26
Glazing (skylights)R-0.26R-0.26R-0.31

Slab Pod Insulation Systems

Pod insulation systems consist of insulation pods (usually polystyrene) placed underneath the slab. Concrete channels separate each pod and provide structural stability.

The R-value of pod insulation systems is quite complex to calculate and the literature is conflicting.

Two relevant references are a BRANZ article published in the BUILD magazine in 2011 (BUILD 123 April/May 2011, page 26) and the Firth RibRaft Design Solution Brochure.

The BRANZ article is based on thermal computer simulations and found that "...for a traditional slab-on-ground floor without insulation ... the thermal resistances of the (pod insulated) floors are similar for a building with 100 mm deep walls." For 250mm deep walls the simulations found an R-value increase of 20% compared to an uninsulated slab.

The Firth Design Guide on the other hand refers to NZS4214:2006 and lists quite significant R-value increases due to the RibRaft system. It should be noted that the referenced Standard does not specifically cover pod insulation systems and only deals with total slab insulation and slab edge insulation.

Because of these conflicting resources I recommend to either ignore any benefits of the pod insulation systems in the DesNav calculations and treat the slab as uninsulated or to use a "custom R-value" and enter the BRANZ or Firth R-values manually and add a corresponding reference to the consent application.

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