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Passive house

Posted 16 Aug '11 01:43 AM

A better more reliable way than passive solar. http://www.passivehouse.org.nz

Re: Passive house

Posted 16 Aug '11 03:24 AM

Great article to read on passive building. Common sense stuff, too. Please tell me what the difference is between this and passive solar? Thanks, Leo

Re: Passive house

Posted 16 Aug '11 04:04 AM

Passive solar relies on sun, large windows and thermal mass but the thermal envelope is often compromised. Some claim that the solar gain is enough to compensate for a poor thermal envelope. I don't agree with that and would always give a passive house the preference. It has correct orientation as well and larger windows on the north side, thermal mass is nice but not a must BUT a passive house has a thermal envelope which doesn't stop where the windows start and therefore it is warm day and night and less dependant on a regular sunshine pattern

Re: Passive house

Posted 16 Aug '11 05:17 AM

My God, Guess What, if we ever learn to harvest negative energy we can build a negative Power Station, hook you up to it, and all our future power needs will be met.

Re: Passive house

Posted 16 Aug '11 08:06 AM

Must be the cold .........or the education?? ...perhaps both ????????

Re: Passive house

Posted 16 Aug '11 08:06 PM

Proof Ze Germans have no sense of humour.

Re: Passive house

Posted 16 Aug '11 08:56 PM

You don't know my nationality....You know nothing really.... Looking at you would probably make me laugh my head of.............but your posts are rather boring...

Re: Passive house

Posted 17 Aug '11 02:24 AM

Hey guys, let's try to keep things a bit friendly. This kind of tit for tat slinging off when there is a difference is really uncool!

You both have a point of view, nobody is right and nobody is wrong. It is all about an exchange of ideas.

If this sort of thing keeps up you will find that you are the only few left using this forum. It has happened to other forums before.

Re: Passive house

Posted 17 Aug '11 04:18 AM

Fully agreed. I find the best way to handle some posts is just to ignore them. The passive house article and explanation have been helpful to me and a kiwi friend here who is already planning a new build one day. He build a house 10 years ago, is freezing and had no idea how to make it warm at the time. He and his wife lay a wake at night because of the roar of the Wellington wind. His next house will indeed be different! Leo

Re: Passive house

Posted 17 Aug '11 07:27 AM

Everyone should be able to expouse a point of view on a forum such as this, that's the point. I found the forum searching for an NZ site on energy efficiency and green building. A a local forum, of course, is so much more useful because of local knowledge, experience and trade information.

It seems to me, though, that there are a few, and Guess What stands out, who want to bludgeon every one else into submission with extreme views such as everything European is great and the whole New Zealand building industry is crap as is all New Zealand housing. That is not an environment for people coming on and talking and asking about any issue or problem thay have.

It also seems to me not to take into account the way housing technology has been evolving around the world or have knowledge and regard for the social history of New Zealand explaining why we have developed and grown in a particular ways.

Re: Passive house

Posted 17 Aug '11 08:22 AM

This is a discussion and debate forum not a hug forum. LME has hi-checked the passive house topic I started with his nonsense comments. I will not comment on his or her comments anymore. Fact is that currently taxpayers money is used to fix serious shortfalls in the building methods which resulted into cold, unhealthy and expensive to run homes. I want to encourage debate and change to work for better outcomes and higher standards. The social history is not relevant for issues we have to solve now. And the issues are too big and too costly. So we can't afford to wait until the wheel has been re-invented. Especially if proven know how is readily available for free. Yes, I am tired to see taxpayers money used to bail out the mainstream building industry which seems to be very resistant and in denial to anything deviating from their set ways. Tradition has a place but can become a dead end road.

Re: Passive house

Posted 17 Aug '11 10:22 AM

I wasn't really talking about hugging any bunnies but facts such as Central Heating not been widespread in NZ houses...more a reason for the perception of houses being cold than lack of insulation I would have thought.....but then I could rabbit on.....

Re: Passive house

Posted 17 Aug '11 08:07 PM

Back to GW's original point. I have a question - are the two mutually exclusive? Passive solar focuses on heating naturally and retaining that heat, surely to do the latter properly and effectively requires careful attention to the thermal envelope? Or is it that PS designers tend to get caught up with the ideal of no artificial heating via thermal mass that they don't concentrate enough on the thermal envelope? I guess what I'm saying is that it seems to me that there is (or should be) a lot of crossover between PS and PH design. Also, due to the reasonably high (at least in some parts of the country) sunshine hours that NZ receives, that the ideals of PS design surely have a part to play?

Re: Passive house

Posted 17 Aug '11 09:06 PM

Most PH designs I've seen have quite prominent windows on the sunny side and they are definitely going for solar gain. They use a computer program to configure the houses so, presumably, this is part of the calculations and the triple glazed windows can allow solar gain while retaining inside heat.

In my own experience (single-glazing) I find it easy to maintain a good overnight temperature in the house with good insulation otherwise etc but the outside temperature may stay low for a long time in the morning, a few degrees slowly rising. The house temperature, responding to the outside continues to slowly decline and opening up the house to the sun, while pleasant, only increases the rate of drop. It is not until later in the day when the outside temperaure has risen that you really get the benefit of sun heat inside.

Re: Passive house

Posted 17 Aug '11 09:08 PM

One doesn't exclude the other. But the thermal envelope is the most essential part, thermal mass is nice to have and of course the orientation is essential for natural heating. But if the orientation is not so ideal a passive house still works. Some passive solar designers seem to count too much on thermal mass and neglect the thermal envelope without taking into account that there are cold days and nights with no sun. Energy efficient building and single glazing don't match very well.

Re: Passive house

Posted 17 Aug '11 09:16 PM

http://www.passivehouse.org.nz/PH_definition I think the definition in the link above explains it very well. Yes solar gain is taken into account. I think the key here is that by calculation a passive house is one that only requires 10W/m2 or less of active heat source to maintain a temp of 20degrees 24hr/day in all areas of the home! There appears to be much more emphasis on insulation levels and airtightness than with passive solar. The importance of insulation seems be becoming more generally understood in New Zealand, however the importance of airtightness is rarely discussed or considered!

Re: Passive house

Posted 17 Aug '11 09:40 PM

Just a quick comment.

The definition is good but assumes a moderate to cold climate (rightly so for our part of the world). The execution of PH needs to be tied to the location. A PH build in NZ would be quite a different design to one build for Kenya, for example.

Good site and info though - the rationale, concepts and application need to be promoted to the wider public and construction industry rather than just preaching to the environmentally converted. How that is achieved is another issue entirely.

Pete

Re: Passive house

Posted 17 Aug '11 09:44 PM

Nikoftime, Is the 10W/m2 a typo from you or is it on the site? The Passivhaus Institut in Germany specs <15W/m2. i.e. possibly 50% more heatloss. That NZ figure seems very stringent.

Pete

Re: Passive house

Posted 17 Aug '11 09:53 PM

Regarding Pete's previous comment, cars now have to rate their efficiency. And when petro prices are high, people are not buying petro guzzlers. I suppose the time is coming when energy ratings for homes will be compulsory. Then people will know how much the house will cost them in energy usage. When this will eventually happen, I have no idea. But it will sure change the building industry in a hurry. Leo

Re: Passive house

Posted 17 Aug '11 10:00 PM

Quote: "This is a discussion and debate forum not a hug forum. "

EXACTLY. Discussion and debate, not sarcasm and belittling. My request to ALL posters is to address the topic and not to make personal attacks or put-downs.

Re: Passive house

Posted 17 Aug '11 10:09 PM

"However, you will use this fireplace only in inland areas or if you either like it really cosy or are very fond of gazing at the flames. You will not need it to keep a Passive House warm in most NZ locations." From the passive house air tighness page.

I wonder how many people would support this statement after the last 5 days of chill.

Must do some work and stop reading the PH site !!!!

Re: Passive house

Posted 17 Aug '11 10:50 PM

"Is the 10W/m2 a typo from you or is it on the site? The Passivhaus Institut in Germany specs <15W/m2. i.e. possibly 50% more heatloss. That NZ figure seems very stringent" Hi Pete, the 10W/m2 is from the passive house site. I have noticed this difference before. I guess the 15W figure is the strict limit of a passive house but 10W is a better figure to aim for. I quoted the 10W figure as we were discussing the New Zealand Passive house website. Perhaps the author recommends 10W as, in theory, it should be easier to achieve for most parts of New Zealand compared to most parts of northern Europe! Although the difference between 10 and 15 is significant it still provides an example of what can be achieved, especially if you compare to a typical NZ new build house which would likely require around 80W/m2 to maintain the 20degree comfort level (Perhaps the underfloor heating specialists can give a more accurate figure!)

Re: Passive house

Posted 18 Aug '11 02:45 AM

Wow, 10 w/m^2, that's really low. Around here the winter max is 12 and min 2, average 7, so I need to maintain a 13 degree temperature difference. If the PH is 10 x 20 x 3m, the surface area is 580m^2 and I am allowed 200 x 10 = 2000W to heat this house. I am not allowed any solar gain because it might be cloudy (or indeed snowing). So I need an average R-value of 13*580/2000 = 3.77. If I want 20% of the wall area to be windows at R0.75, then the walls, floor, and ceiling need to be R5.1. That would need about 250mm of polystyrene under the floor plus no thermal breaks.

Does anyone here have such a house?

Re: Passive house

Posted 18 Aug '11 03:07 AM

We are in the early planning stage of such a house with walls and roof about R 5.5.

Re: Passive house

Posted 18 Aug '11 04:01 AM

Hi Guess what Are you using the intello product and if not what method are you proposing to ensure airtightness? what windows are you proposing to use, as Robert has identified it seems difficult to find windows in NZ with a lower u value than about 1.3 (R of 0.77)?
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