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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.
Some FAQ's regarding the fee system
Do you know...?
How to create H1 reports for additions and alterations
How to enter pod insulation R-values for concrete floors
Whether the DesNav Calculator can be used for commercial buildings
NZS4218:2004 or NZS4218:2009
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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:
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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.
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.
The short answer: Yes
The long answer:
The first question is always whether the building has to comply with the thermal targets of Clause H1 at all. The screen shot below shows the relevant section in Clause H1.
If the building does not fall into one of these groups, i.e. if it is not exempt then you have to comply with Clause H1. In that case the permitted compliance method depends on the building size and type.
The DesNav program tests compliance with NZS4218 Schedule and Calculation Methods.
So that means that you can use the DesNav calculator to show compliance with Clause H1 also for a non-housing building larger than 300m². If the building fails to comply you can either increase the insulation levels to meet NZS4218 (using the DesNav calculator) or instead you check whether it complies with NZS4243 (which is not part of the DesNav calculator).
Note that for some large non-residential buildings you also need to show that the lighting power density complies with Clause H1. Usually your lighting consultant will be able to do these calculations for you.
PS: I am also providing professional services to do NZS4243 H1 calculations. If you are interested you can send me the building plans to firstname.lastname@example.org and I can give you a quote.
I am sometimes being asked why the DesNav calculator still refers to an "outdated" standard NZS4218:2004 rather than to the new NZS4218:2009.
The reason is that NZS4218:2004 is still the "Acceptable Solution" called up in Clause H1 (page 9, 3rd edition from October 2011). Only when the reference to the Standard explicitely changes in Clause H1 will the new Standard become the Acceptable Solution.
To complicate the issue Clause H1 itself has since 2011 a number of "replacement tables" with minimum target R-values. These replace the minimum R-values in NZS4218:2004. Incidentally the values in the H1 replacement tables are largely the same as the values in NZS4218:2009.
But all the other requirements such as the maximum permitted windows and skylight areas, etc. must still be taken from from NZS4218:2004.
The BCA must therefore accept calculations based on NZS4218:2004 and the replacement R-values tables as "Acceptable Solutions".
The good news is that the DesNav calculator automatically takes care of the confusing situation when checking for compliance.
PS: The BCA can of course at its own discretion accept compliance reports based on NZS4218:2009 as "Alternative Solutions", but it is not obliged to do so.
No. Once you have paid for a report you can make as many changes to the project and download a new copy of the report free of charge.
Just be aware that if you create a copy of the project you would have to pay again for the report of the copied project.
No. Reports for projects that were created before the 19th of February 2015 remain free of charge.
The payment system is set up so that when you open the report page you have two choices, either pay by credit card or be invoiced.
If you select credit card it redirects to a separate ASB website where you do all the credit card stuff. Once that is done it returns to the DesNav page and e-mails you the report and a receipt.
If you choose the invoice option the DesNav website will send you the H1 report and together with it an invoice.
There is also a monthly invoicing system available that collates all invoices during each month. Please let me know if you would like to have an account set up for this.
I hope is convenient to you.