Topic: "NZ's first Passive House"

"NZ's first Passive House" 

Some of you might be following the passive house blog that someone brought to our attention earlier.

http://passivehouse1nz.blogspot.co.nz/

Kudos for them for the great blog, perhaps there is some sponsorship involved from the suppliers.

I'm starting with a slight personal criticism, a little bit of a McMansion it seems to me. I'm siding more with our personal use of resources being a bit more modest given the seven billion souls currently on the planet but that's just me.

Construction seems relatively (and perhaps surprisingly) standard except perhaps for the Intello building wrap although ply sheathing isn't widespread.

R4 ceiling batts between ceiling joists. (thermal bridging?)
90mm stud walls with, I assume, Batts to follow. ( more thermal bridging)
Double glazed wooden windows.

Your thoughts customers?

Re: "NZ's first Passive House" 

Shouldn't have said the Intellos is a building wrap...more an internal membrane.

Re: "NZ's first Passive House" 

I wouldnt have used Pink Batts at all!!
Polyester would have been my choice ''Greenstuf/Novatherm''

R4 is plenty for Auckland in the ceiling imo segmented or otherwise

Re: "NZ's first Passive House" 

Although only a 90mm frame I think they will have a service cavity (perhaps 50mm) which may reduce this thermal bridging and also have some more insulation. They haven't shown this part yet.

Re: "NZ's first Passive House" 

Yes, the window surrounds do look as though they protrude inside by about said distance.

Re: "NZ's first Passive House" 

I have red a few articles about the project and been following the blog... certainly some great stuff!
The confusing thing is that many articles are saying that house is "certified" where it is not even finished yet... does it not need to be tested before it gets certified... Others have tried similar with the ehouse in Wanganui and did not achieve certification (so I hear).
Anyway, the blog also shows (as Lastmanever mentioned) that it does not take that much to do it and it is not a big difference to the homes that are built around NZ, but you need somebody who understands the problems and knows how to address them. Typical house will lose around 40% of its heat through transmission (walls, ceiling, floor, windows) and 30% though air leakage. Just addressing the air tightness will obviously make a big difference, but not many builders will know what to do to make things better. Most of that can be sorted by taping over the joints... Intello wrap is 160 UKP for 75m2 in UK (no idea how much for the same in NZ, but can't be hugely different), so a great product that addresses air-tightness completely.
Installing the windows in line with framing (not pushing those in the cladding and exposing everything but 5 mm to the outside air) would help too.
Thermal bridging can be addressed in many ways and not at a huge price...
The point is that it does not have to cost 3500NZD/m2.. you could get a great performance for a smaller investment that will return in a few years and live in healthy and warm home.

Maybe reviewing the BC and suggesting better approaches is what EECA should be doing, I think... or MB and CB could contribute a bit as well by requiring builder to at least familiarize themselves with some more up to date methods...

I hope the house actually gets certified and we get to read the actual energy consumption numbers in a year or so... I am expecting that the house will need none to very little heating/cooling...

Dejan

Re: "NZ's first Passive House" 

I believe the only practical test required on completion is a blower door test for air changes but likely there will be additional monitoring to ensure the models have hit the target for the Auckland climate.

Re: "NZ's first Passive House" 

Sure (calculated/simulated heating demand would have been done in the design phase)... There is also a primary energy use that will depend on the choice of appliances (easy fix :-)). These guys seem to know what they are doing...
Take the "Little Greenie" example... with 9.0 HERS stars and temperatures inside the house going towards 30 degrees when its sunny outside... Obviously a roof space is boiling.
From the monitoring report (page 12 in http://goldenbayhideaway.co.nz/images/build/Little-Greenie-Getting-The-Facts.pdf):

Internal Roof
Temperature
Located up in the roof above the insulation and next to the logger unit – this area was subject to some very high temperatures

... they have > R 7 over the ceiling and nothing under the roof... would have been much smarter to have one layer under the roof and another on the ceiling... fail.
Accurate obviously does not do the right thing by giving this house 9 stars... The temperature inside a house is extremely reactive to the outside temperature (check pages 13 and 14 graphs). It climbs and drops very quickly by 5-6 degrees... That thermal envelope is a failure (I blame the roof for overheating, but not sure how can they lose 5 degrees overnight with so much insulation everywhere)... This proves that the devil is in the details... a lot of insulation does not get a performance if it's not installed properly... and I believe the passive house will look much more stable... it should not lose more than 1-2 degrees over night...

Re: "NZ's first Passive House" 

Hi Dejan,
Can you explain more about positioning the windows back into the insulated part of the wall instead of on the outside, cold part.
I can understand the theoretical advantages of putting the windows in the warm part of the wall, but I understood that windows , being a potential weathertight weakness are positioned on the outer edge so that any leaks end up drained into the drained and vented cavity. If a leak was to occur and the window was set back into the frame of the wall would this then present a higher risk of a "leaky" home?

Re: "NZ's first Passive House" 

If passive-haus design house can not be achieved in Auckland climate, then it shows the poor building standards in NZ. After all, Auckland climate is very different to German or Scandinavian places where energy efficiency is taken more seriously.

It would be a world of difference challenge to build a passive-house design in the South Island like in Christchurch or further south.

As far as i'm aware, the NZ building code does not specify air tightness in a house. To matters worse, if you did specify air tightness, it would be a hassle with city council approval in convincing them you will meet indoor air quality or address the issue of leaky house syndrome. After all, this is the key reason almost all houses built in NZ do not take the detail of 'air tightness'.

We've finished building last year here in Christchurch. I woke up this morning and the kitchen was at 20C. At night before going to bed it was 24C. Although we may not have the energy saving concepts that we see overseas, great effort was made to air tight the place (without causing attention to city inspectors).

I wouldn't put too much emphasis on mass amounts of insulation. The traditional method is building thicker walls but using the same insulation. I would much rather use close celled spray foam and achieve better performance than a 140mm thick wood framing.

It's also interesting that the weakest part of the house is the windows in terms of insulation. A lot of emphasis is put on the WALL but little detail on the ceiling and roof. I'm not aware that heat is lost sideways as much as heat is lost through the draftyness of the whole building envelope.

Re: "NZ's first Passive House" 

In a thermally efficient and correct design the windows MUST be in line with the insulated part of the wall. This is not possible with NZ style aluminium windows but normal practice with the European style windows. The window installation with the vented cavity in the NZBC 'acceptable solution" is designed for aluminium windows with potential leaks and condensation but nonsense for modern fit for purpose joinery.
Therefore the European designed windows are the way to go for energy efficient building.

Re: "NZ's first Passive House" 

I'll reiterate, it is of no great feat to achieve a house that requires little or no supplemental heating in areas were climates do not vary in temperatures greatly. ie. It's a lot harder to achieve 20C inside when the temperature difference outside is 25C or greater.

In Canada, you could be looking at a 50C temperature difference on it's coldest days.

Does insulation matter? Definitely. But all the insulation in the world doesn't do justice when 'air tight construction' isn't addressed.

Regarding the Eco-ply Barrier product. Air tightness can not be achieved by taping the joins. The size and shape of the roof would be a bigger cause as the wind blows down through the ceiling between the drywall/Gib board (wall cavity).

Re: "NZ's first Passive House" 

SBO

The roof/ceiling/wall junction is just one of the problem zones in NZ building design

Re: "NZ's first Passive House" 

"In a thermally efficient and correct design the windows MUST be in line with the insulated part of the wall. This is not possible with NZ style aluminium windows but normal practice with the European style windows. The window installation with the vented cavity in the NZBC 'acceptable solution" is designed for aluminium windows with potential leaks and condensation but nonsense for modern fit for purpose joinery.
Therefore the European designed windows are the way to go for energy efficient building"

I have been advised by NK Windows in Christchurch that "We are not able to install set back into the wall due to the New Zealand building code."

Are they wrong?

Re: "NZ's first Passive House" 

Of course it can be done and has already been done in New Zealand.
The building code has just an aluminium window solution which has a limited use for the European systems. In dealings with NK I always found them little helpful. Every 2nd sentence I heard was: "we don't.... and we can't...

Re: "NZ's first Passive House" 

Hi passivehousenz, may I ask, given your pseudonym, if you are associated with Passivehouse in NZ or the Auckland project?

Re: "NZ's first Passive House" 

Hi Passivehouse,
So, would you have any recomendations for window suppliers that are more helpful?

Re: "NZ's first Passive House" 

Nik - in the grand of schemes, NK Windows is correct. The issue isn't about getting a house that can have set back windows in line with the wall insulation or not but rather, being able to 'work' with the local city councils and the NZ building industry that have a rigidness of building things different. I don't blame them after what the leaky house syndrome has brought about (radical changes with huge consequences).

I'm in Christchurch and know the difficulties dealing with city council when it comes to use of non-standard materials. It's not a matter of 'we don't or can't do' but rather, it's all about the cost. Builders don't want the hassles and the gov't doesn't want to be left with mistakes that may haunt the building industry in 20 or 30 years time. More over, the home owner doesn't want their $ wasted in an unreasonable manner.

I've got Homerit PVCu tilt/turn windows in my house and they're not aligned with the wall insulation. In terms of energy savings (or heat loss) - I can't see it being a huge factor. The window wood reveals are spray foam insulated all around if the air cavity between the brick cladding and the timber framework present a problem of robbing heat.

As for NK, their quote was 20% more than my Homerit quote delivered. Their SGU glazing was considerably a lot more expensive than the Viridian glass units I wanted.

Re: "NZ's first Passive House" 

Homerit uses aluminium window detailing for UPVC.
This is technically incorrect and their and most other profile extruders would never give their approval to install windows this way..
The Councils give a tick because they don't have a clue about anything else than aluminium.
The building code has no provision for UPVC joinery and therefore it is always an alternative solution regardless of flush or recessed installation.
The building code also stipulates that the guidelines of the system providers must be taken into consideration and adhered to.

Re: "NZ's first Passive House" 

Please elaborate why 'technically' the PVC framing is incorrect when it's installed in place of how an aluminium joinery framing will be? Look at all the other PVCu extrusion window suppliers and how many are not recessed installation in NZ.

In the grand of schemes, what benefit are you getting at by having the window in-line with the wall insulation?

If I had it my way, my 1st choice of PVCu windows would be the ones from Canada. Triple rubber seals, built-in inside fly screens, and integrated PVCu reveals (none of this wood crap) to ensure real air tightness. Are their windows in line with the wall insulation? No they're not.

I ask these questions because i'm sure city building engineers will have the same question before issuing consent. As i've indicated before, overseas designs have hurt the NZ building industry and there's good reason to question what is different and what has proven to work here. Direct fixed polystyrene cladding on the exterior is one of them that doesn't work in NZ.

BTW, is it a marvel that Homerit is the only brand that has BRANZ appraisal? (not that BRANZ means anything as they've been wrong so many times).

Re: "NZ's first Passive House" 

PVC has different technical properties such as themal expansion rate. It is a bit like using the design of a steel bridge to build a concrete bridge.
UPVC has no issues with leaking corners and cavity condensation. Therefore there are quite different considerations involved.
UPVC windows can be installed flush or recessed and both ways it must be done correctly.
Homerit is a fabricator using a variety of profiles. Their BRANZ appraisal is just for the VEKA stuff they use and if your doors are higher than 2 m they are already out of the scope of the BRANZ appraisal.
Further the BRANZ appraisal has no reference to durability testing. NK and Eurowindows are more trustworthy as they provide durability tests (carried out in NZ) and other testing of their systems has been done by more reliable institutions than BRANZ.
It is not the original overseas designs that has hurt the building industry ( because they were never used) it is the shortcuts they applied to it thinking they were smarter and can do things cheaper.

Re: "NZ's first Passive House" 

I've looked at the NK windows and didn't like how the wood reveals are butted up against the face of the PVC sash profile (unless they've changed). The Homerit have the wood reveal around the perimeter of the sash.

If BRANZ's reputation is flawed, then why is it widely accepted nationwide with city councils? While on the same token, other independent testers don't seem to have the same welcome of acceptance despite their tests are more thorough? Political?

But forget the windows. What we have in NZ is an entirely different building system compared to what we see overseas, where homes are built more for air tightness and the reliance on mechanical ventilation with HRV. After all, these passivehaus / R2000 type homes were born out of countries that experience far greater weather extremes than what we have here. I don't think it's an issue that shortcuts are being made when adopting those principles.

There's the issue of cost that overshadows the whole concept of going passivehaus / eco-design building. Assess the carbon foot print of a new house in NZ vs. a new house in Canada or in Ireland.

For example in NZ many people may be happing in a new home with winter heating bills that may be around $200/month. A passivehaus in the same location may net $50/month or less. But look at the cost to achieve this $150/month difference? The issue i'm getting at is the difference in savings may not be that considerable in NZ compared to say if that house was in Canada sitting next to a high carbon use centrally heated house where average heating bills are like $500/month (but this figure is deceiving as a kW/hr in Canada is like 7 cents). So the passivehaus house in Canada may have a monthly power bill of $50 there but when you compare the high price of electricity in NZ and what the carbon foot print of a new NZ house consumes, it's no wonder going to the extreme of taking a building system from those places and implementing it here in NZ doesn't seem that beneficial in terms of payback or resale value.

Then you have the issue of high material costs in NZ because the materials used are non-standard (but standard use overseas - ie. HRV in Canada).

Re: "NZ's first Passive House" 

Very interesting windows with the wood reveals fitted to the sash ;-)

Re: "NZ's first Passive House" 

passivehouse

have you read the technical info on the NK & EuroWindows websites?

''Provided that the NZ licensees EuroWindows Ltd, manufacture a similar window unit with identical design, components and workmanship,similar compliance performance would be expected.''


The European lab is not accredited for the AS test method

The NZ test reports do not carry accreditation

Quote from you

"... more trustworthy as they provide durability tests (carried out in NZ) and other testing of their systems has been done by more reliable institutions than BRANZ."

Yeah Right!

What's the point in testing in NZ if don't test the products made in NZ?

Re: "NZ's first Passive House" 

I think a lot of the bad reputation of BRANZ came about in it's early years by accrediting one too many flawed building products. Prior to BRANZ was BEAL which was part of the NZ gov't building authority. Though highly political, the split-up of BEAL came quickly when monolithic cladded houses were showing up to be rotting NZ houses (my guess way back in the early 90s). Stripping BEAL and independently forming BRANZ was a way the NZ gov't could get out of liability (or blame as no director back then took responsibility) of any prior mistakes. But in recent years, the NZ tax payer still had to foot part of the bill for the leaky house syndromes.

The issue about 'trustworthy' is a tough sell nowadays in the NZ building industry. Even products like Carter Holt Harvey's Eco-Barrier plywood sheathing still isn't proven for use in building houses. I'm not aware of a similar product used overseas say in N. America. The concept is to powder coat 1 side of the sheet to serve as a vapour barrier and also serve as a replacement of the traditional Tyvek house wrap. If the method of achieving air tightness of a house by using their tape to seal up the joints between each sheet is a good way, then not on my dead body. When you want to do air tightness, you've got to do the WHOLE building envelope (specifically the roof/ceiling parts).

Regardless of testing, a lot of trust is put on the manufacturers to produce the same product as what was tested. CHH for eg have been caught mis-labeling their pinus timber as a higher grade than what it should be (resulting in inferiorly built houses) Ie. stamping MSG8 when it should be MSG6.