Alterations

Questions, comments and suggestions about the Design Navigator H1 Compliance calculator

Alterations

Postby Dave » Tue Oct 27, 2009 10:16 pm

Hi Albercht. I am designing an alteration to a dwelling and using the Navigator for H1, what I have done is treated the room extension plus the room (Lounge) as one unit. Using Pink Batts The new roof R value 4/The old ceiling R value 2.2/The internal walls R value 1.8/New walls R value 2.8/Floor R value 1.3 this has worked ok. My concern is that the internal walls do not Have any insulation so there should be a R value for this situation that can be used within the program?
I have also designed an entry for the same dwelling and part of the entry opens into a dining area, the entry is 5.5 wide so the wall has 3 metres deleted (South wall 3m/East wall 2.4m/North wall 2.5/West wall 2,4) This also works
Would appreciate any comments with what I have done………….Regards. Dave
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Re: Alterations

Postby Albrecht Stoecklein » Wed Oct 28, 2009 8:29 am

Hi Dave,

The rule is quite simple: you can ignore any internal walls. Even if there is just an opening, i.e. you created one larger space where previously there was one smaller room only, you only need to show compliance for the extended parts and simply ignore the fact that there now is an opening between the added part and the existing part. So in the Design Navigator you simply don't enter these (internal or even non-existing) walls. So in your example you did even more than was required.

Up to now this has been a bit of a grey area, but the new NZS4218:2009 effectively allows you to take this approach. (Note that the NZS4218:2009 is not yet the Acceptable Solution for H1, so the BCA does not have to accept it, but it is an Alternative Solution, and I think most forward looking councils should be happy with it.)

I appreciate that this is a bit of a legal rather than a technical approach, i.e. it makes technically not a lot of sense to insulate an added parts of an extended large open area which still contains uninsulated walls, single glazed windows, etc. Therefore I would in practice upgrade the existing external building elements in this open plan area to current NZBC level as well.

Hope that helps

Sunny regards

Albrecht
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Re: Alterations

Postby Dave » Wed Oct 28, 2009 11:02 am

Hi Albricht. I don’t seem to be able to get it to comply when I delete the two walls, I then gave them a R value of .44 which is what I selected from a drop-down list in the program the heat loss was not quite below the maximum when I gave it 1.8 it was well below, so how do I get it to work it’s likely that I am doing it wrong. I am also registered as David Law so could have a quick look for me………Many thanks. Dave

PS. R Values for internal walls within a standard insulated home greater than .44 would allow this extension to comply to H1 I am assuming that R .44 is for a wall next to an un-insulated garage so a wall within a standard insulated home (pre H1 2008) would have a greater R value, if I submit the compliance report showing the walls as insulated the then the council will require it to be done. This is assuming that I have filled out the report correctly.
:? :? :? :? :? :? :?
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Re: Alterations

Postby Albrecht Stoecklein » Wed Oct 28, 2009 8:22 pm

Hi Dave,

I had a look at your project (id 11650). The simple reason for the failure to pass is that single glazed window in the wall. That increases the heat loss of your proposed building to be slightly higher than the reference building's heat loss.

The reason why the building complies when you include the internal walls is a bit more tricky: Because the internal walls include no windows the glazing area for the whole extension is only 15.8%. However, for designs with less that 30% glazing the Calculation Method requires for the reference building to use 30% glazing and 70% wall area. So by default your building will do better because the difference of 14.2% is insulated wall with an R-value of about R-1.8 in your proposed building whereas in the reference building this area is double glazed window with an R-value of only R-0.26.

But I don't think this rule was actually intended for an the alteration scenario like yours.

There is a Codewords Article which covers your case: http://www.dbh.govt.nz/codewords-32-6

Example - no upgrading

If a new room is added to the side of an existing house, then the extension (ie, new floor, roof, walls and windows) will need to comply with Clause H1. The existing parts of the house that are untouched have the same performance (ie, thermal resistance) in this example after the alteration as they did before. The thermal resistance of the altered house is at least as good as it was before the alteration (in fact the overall thermal resistance has probably improved given that the new extension will comply with H1), and therefore no upgrading is required.

Note that parts of the existing thermal envelope that are enclosed by the alteration (eg, the side of the house onto which the extension is built) will cease to be part of the thermal envelope in the altered building.


So in your case you would have to improve the insulation somewhere in the extension or use double glazing for the one window.

I hope this helps.

Sunny regards

Albrecht
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Re: Alterations

Postby alexx_2010 » Sat Dec 19, 2009 5:45 pm

From my point of view i think you should improve the insulation in the extension and use double glazing for many windows.
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Re: Alterations

Postby Dave » Mon Dec 21, 2009 8:19 am

Hi everyone. Finally got to grips with it and the council has accepted the plans my problem was the house faced South and just increased a couple of windows with double glazing ........Dave :o
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Re: Alterations

Postby Albrecht Stoecklein » Mon Jun 10, 2013 9:01 pm

Update on Alterations and Extensions:

You enter the project (i.e. the whole building) in the DesNav calculator including the alterations and any extensions.

But for any existing unchanged components (walls, floors, etc) you are allowed to assume that they are already compliant, i.e. have R-values according to the Replacement Table 1 on page 24 of Clause H1. So even if the existing walls are for example un-insulated you would still be allowed to enter an R-value of R-1.9 for these (in Climate Zone 1). Similar for roofs, floors, windows and skylights.

For any modified or new parts of the building you have to enter their actual R-values.

If the DesNav calculator shows that the building complies with the Calculation Method you can submit the DesNav H1-report to show it complies.

NZS4218:2009 is not the Acceptable Solution (The Acceptable Solution is NZS4218:2004), but most BCAs will accept it as an Alternative Solution. In the DesNav project comment box you should explain that you followed that approach described in NZS4218:2009 Appendix D3.

Sunny regards

Albrecht
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Re: Alterations

Postby Peter » Wed Feb 05, 2014 5:10 pm

Hi Albercht

So what about the windows in any existing unchanged walls, do you add these in or ignore. And, if adding, what R value is given

regards Peter
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Re: Alterations

Postby Albrecht Stoecklein » Thu Feb 06, 2014 6:09 pm

Hi Peter,

Yes, you include all the windows in the existing walls. But you are allowed to assume that they have R-values of R-0.26, i.e. double glazed, irrespective of whether they are in fact double or single glazed.

The whole idea is basically that your existing house already complies, and you only have to show that the alteration also complies. But you can't do the calculation for the alteration alone, because it may mean that your alteration may have a 100% glazing area (in case your alteration consists of adding a new window). If your building has 100% glazing you would never be able to show compliance.

To avoid that issue you do the calculation for the whole house, but are allowed to assume that the existing unchanged part already complies. In that way the glazing area has a realistic value, i.e. the percentage of glazing of the whole house.

Hope that makes sense.

Sunny regards

Albrecht
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Re: Alterations

Postby Peter » Fri Feb 07, 2014 1:38 pm

Hi Albrecht

Thanks. Yes, perfect sense. i thought it may have to be .31 but the .26 gives me a margin of 1 for the heat loss. i have not tried it but i assume omitting the windows would be the same as allocating 1.9?

Regards,

Peter
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