Hello All,
Can you please share your thoughts on the German 'Passiv House' principles especially:
1. North facing
2. Highly insulated and an airtight house
3. Thermal mass (would rammed earth internal walls be enough or should we have an insulated concrete floor in north facing rooms?)
4. energy recovery ventilation?
If we had heat recovery or energy recovery ventilation would that mean that cross ventilation is not as important as the house should be airtight?
Are many people building this way in Victoria?
I am thinking it will be difficult to get a builder to build a 'Passiv Haus' home?
Any advice or comments greatly appreciated.
Thanks, SM.
'Passiv Haus' Homes & energy recovery ventilation
(36 posts) (15 voices)-
SM
MemberPosted Tuesday 24 Jul 2012 @ 12:53:02 pm from IP # -
Hi SM
1. Yes (I see you have turned it around).
2. Yes, but we don't need to insulate against minus 30 degrees.
3. Thermal mass is important away from the coast and away from the tropics.
4. Heat recovery ventilation is unnecessary here (See No. 2.) but most Australian houses leak air like a sieve, so that must be fixed. You will have to hassle your builder.Posted Tuesday 24 Jul 2012 @ 11:11:28 pm from IP # -
SM
There are other relevant threads on this site, but some are not easy to find:
"Low-energy houses"
http://www.ata.org.au/forums/topic/3
"Energy Efficient House"
http://www.ata.org.au/forums/topic/2192
"How important is thermal mass in a building?"
http://www.ata.org.au/forums/topic/2188
"Thermal mass"
http://www.ata.org.au/forums/topic/1004
There are others, and this list is a year old.Posted Tuesday 24 Jul 2012 @ 11:24:51 pm from IP # -
SM
MemberThanks for your reply Catopsilia.
So what level of insulation shouls we be aiming for in northern Victoria?
We are trying to figure out which is a better option:
1. Having a H shaped sinle storey house (one room wide)with all communal areas & office & bedrooms north facing thus allowing for heat gain in winter and also allowing cross ventilation. However this maybe be an expensive buid and require a lot of corridor space, insulation & windows. And we are not keen on the idea of concrete floors in the bedrooms.
or
2. A more conventional shaped rectangular house with communal areas & office north facing. Some bedrooms, bathrooms and utility areas south facing but using heat recovery ventilation. ? then cross ventilation is less important in the design. This would mean less external building area to insulate and less windows so it would be more economical.
Opinions please......Posted Tuesday 24 Jul 2012 @ 11:28:44 pm from IP # -
"... so it would be more economical."
Go for economy wherever you can. Every innovation is much more expensive than you think.
Posted Tuesday 24 Jul 2012 @ 11:38:24 pm from IP # -
scott drew
MemberSM, do some more research. you are well on your way if you have read the German passive house. Have a search for some Aussie stuff too. On a train right now so don't have access to my bookshelf, but will get back to you with some titles I have read.
As above too, don't forget Victoria isn't as cold as Germany.
Also, bedrooms really don't need to be north facing. When in bed you rug up anyway. Communal and living areas should take priority, heated bedrooms are a 'nice to have' in a passive house not usually must have.
Posted Wednesday 25 Jul 2012 @ 1:15:04 am from IP # -
SM
MemberHi Scott,
Thanks for your reply. Yes this is all part of the research as we are in the planning stage. Good point on the bedrooms. As i am sure you are aware it can be tricky to get independent advice on these matters. I am trying to find someone who has built a house in Victoria on the German Passiv haus principles to find out what we need to do and what not to do. We just want to get as much right as we can. The idea of an airtight house and energy recovery ventilation appeals as it sounds like it can take care of itself with minimal maintenance and no requirement for us to open & close windows at the correct time of day. We plan to install solar to offset the cost of running this system.
I would love to hear from someone who has installed heat recovery ventilation.
Thanks SM.Posted Wednesday 25 Jul 2012 @ 2:04:10 am from IP # -
Jeffbloggs
MemberSM
There are a couple of things to consider when designing a house.
1. North facing is ok, but remember the sun is never stationary, it follows an arc during the day that is at least 140degrees. Just north facing, doesn't account for good eave shading either, the sun also changes by season in angle as well. It is difficult to achieve "real" overall design in a non-moving, non-sun following passiv-haus design. I would recommend a hybrid active-passiv house design.Predominately always think of de-coupling systems. ie from collection to usage. There is much to be gained from doing this. One example is windows that can follow the sun when you want (winter), and block the sun when you don't (summer). This for instance can be achieved by installing automated roller shutters.
2. Insulate, insulate insulate! What you don't loose, you don't have to make. This is where the most energy can be saved. Think of windows as holes in the wall. DG if you want to stay warm.
3. As mentioned in point 1 de-couple. In the case of thermal mass think of it as a latency device, or heat storage battery. If you don't charge it you can't use it, if it's "flat", you will still be cold in winter and warm in summer. Thermal in this case doesn't mean that it will stay warm without "charging" from somewhere, all it will do is smooth heating/cooling loads to avoid peaks, nothing more nothing less. I would recommend a hydronic type thermal mass as is also used in German passive houses. Water has up to 3x the thermal mass of brickwork/concrete, and can easily collect and distribute heat through pipes, which no solid thermal mass can do.
4. Heat/Energy recovery ventilation (HRV) system will only reduce the losses you would normally experience when the house is not well sealed, and from ventilation through windows. This means that with a HRV the house will not have to replenish heat/cold from ventilation ie having better air quality. The HRV can be simple and price effective if you consider the ducting design in the house design ie short ducting etc and because you can reduce the window sizing required. With HRV you can also employ the same ducting for both cooling and heating from the hydronic thermal store, or reverse cycle air-con/heat pump. This reduces cost further. but as with the thermal mass, it is not a energy/temperature source, and will only reduce the losses from ventilation.
Overall the right combination of design and systems will yield the best results, "energy plus" type housing takes the "passivhaus" design to the next level however, in that it is optimised to produce more energy than it consumes. Hope this helps.
Regards
JBPosted Wednesday 25 Jul 2012 @ 11:29:48 am from IP # -
Jeffbloggs
MemberHi SM
No probs, someone should benefit from what I learnt the hard way!On your other two posts you mention size and shape. In regards to insulation benefit and shape one should always consider that the exposed surface area of any shape, ie a H shape house versus a square box house, increases the less "spherical" or boxy it gets. If you look at German Passiv houses, you will see that they are nearly all double storey and square or slightly rectangular, to increase northern exposure. The reason for this is that they have the greatest interior volume, or space, compared to their external surface area. If you reduce you external area, you also reduce your areas of heat loss/gain, and by doing so even reduce your building costs through reduced wall and roof areas. This also reduces the effective thickness of insulation you can use in relation to the external area.
Think of the high surface to volume ratio of a car radiator, which is designed to distribute heat out of the water coolant. Now imagine how good a radiator would function in a insulated box. It simply would not loss much heat at all. A sphere shape has the best surface to volume ratio of all shapes, but is impractical and therefore expensive to build. Square and boxy is the go for housing. You can still add architectural "features" if you want to break up the design.
A simple comparison:
Rectangular single storey 200m² floor area, W7m x L28m x H3m = 413m² surface area
Square double storey 200m² floor area, W10m x L10m x H6m = 340m² surface areaThat's 73m² less roof and wall area that you need to build, maintain, insulate and shade. Or over 20% more surface area for the same internal volume building. The cost reduction in itself will pay for the added double storey cost, but your house is 20% better off for the rest of it's life simply because of the shape. If you are planning on insulating your slab for hydronic floor heating etc, then the second storey floor doesn't require further insulation either. You can also build double storey using SIPS panels for the floor instead of concrete, further reducing the use and cost of concrete. Another benefit of going double storey is more exterior space on the ever reducing residential lots.
German passive houses also incorporate the thermal hydronic store in the centre of the house to reduce thermal losses, by using the house itself as insulation. BTW your idea of automating the HRV ventilation is one we have adopted in our house designs as well. These relatively simple "active" components have a big impact on consumption. There are quite a few aspects which need to be considered in house design. You can contact me via PM if you want more specific help/links on the design side. Let me know how you go.
Regards
JBPosted Thursday 26 Jul 2012 @ 8:13:21 am from IP # -
johnmath
Memberhave you contacted http://www.passivhausaustralia.com.au/ ? They are based in SA, but probably have a network of collaborative partners.
Posted Friday 27 Jul 2012 @ 1:09:48 pm from IP # -
proftournesol
MemberThis is a timely topic for me as I'm planning much the same thing in NE Victoria: a 2 storey 20-24 square well insulated north facing 2 storey house that is well sealed. The temperature range is -5 to 40 degrees so rather extreme for Australia. Site and cost dictate an elevated light weight house without thermal mass but we are also considering HRV as in winter the house will remain basically shut and air-tight for months (apart from entry and exit of course). It seems that adding a geothermal ground loop adds something to the cost but also gives a few degrees of heating/cooling. My question is what sort of additional heating would people recommend? I don't fancy spending all day seeking/chopping wood and worry about the interior air quality anyway. Solar hydronic looks like it works very well in summer, less so in winter! We will also have grid connected PV but would like to be net energy self-sufficient.
Posted Monday 26 Nov 2012 @ 5:47:10 am from IP # -
cool at home
Memberhttp://Www.yourhome.gov.au (technical manual) is ALWAYS worth a look. Free (online), accessible and comprehensive. It will answer many of the questions raised here, like appropriate levels of insulation for different regions, best use of northern sun and the dreaded windows as holes in your insulation. Too often people flick past this and spend time and money seeking out info readily available here.
No, I didnt write it (wish I had) and I'm not on commission - just a huge fan having used it in our build.
Posted Wednesday 28 Nov 2012 @ 8:41:44 am from IP # -
trip
MemberHi SM,
We are currently getting our passively designed house designs completed, and while we didnt go full passivhaus, it was decided with our climate being warmer than europe we wouldnt need to. We are still having a HRV installed and the house in theory should not need any if much external heat sources. I will pm you our architects name and website. He has designed passivhaus places back in europe where he is from. I will be able to contribute more once the house is built.
thanks
Posted Thursday 6 Dec 2012 @ 1:01:30 am from IP # -
SM
MemberHi Trip,
Yes please pm me your architects details- I am very interested. Yes I agree that if your house is well enough insulated and sealed then the theory is you should need much or any additional heating. There is an option of ducted heating and cooling through the HRV as the ducting is already in place. Have you considered this?
Will you do the blower test to check how we'll sealed your house is?
ThanksPosted Thursday 6 Dec 2012 @ 2:15:39 am from IP # -
proftournesol
MemberWe are thinking about going down the ducted heating/HRV route as well, probably with a Zehnder HRV unit. Who does blower tests in Victoria?
Posted Thursday 6 Dec 2012 @ 3:44:29 am from IP # -
tom
MemberWe were considering an air exchanger, but the only one with low enough power consumption (ie << 100W) was the Zehnder. Got quoted at $11K for supply and installation.
As we will be having ducted reverse cycle air con/heating anyway, we've decide the $11K is not worth it, and we will see if we have moisture/air quality problems first. And if we do just run the air con unit in dehumidify mode for a bit each day or open a window for a while. If we need to open a window or run an exhaust fan longer than normal, I can not see how the cost over 50 years will be anywhere near $11K.
The Zehnder is the bee's knees. Ducts are in the walls, runs around 40W depending on setting and size and is Passiv Haus certified. Other units are above 100W to run and require bigger ducts and vents in the roof, but prices are down below $5K.
For reference our house will be 8.3 stars and will be well sealed - rendered phenolic foam panels, foam sealed around windows and all penetrations. Double glazed windows, ...
Posted Thursday 6 Dec 2012 @ 8:44:42 pm from IP # -
johnmath
Membertom said: we will see if we have moisture/air quality problems first. And if we do just run the air con unit in dehumidify mode for a bit each day or open a window for a while.
I would not expect you will have an issue unless you unintentionally introduce one yourself.
Our house is pretty well sealed. If we inadvertently run the range hood without opening a window first or door it draws air down the combustion heater flue even with the damper closed, which of course smells of ash.
We take our shoes off outside - who knows what we've stepped in. We don't bring synthetic materials into the house any more than we need to. Do people realise that many materials like cotton sheets, for example, are treated with chemicals to make them crease free, and the chemicals used are implicated in cancer and other health issues? We buy natural organic fabrics where possible.
In our experience humidity and air quality inside isn't an issue. We like fresh air and have the place open when we can and overnight for passive cooling in summer, etc. We air dry most of our washing inside all year around. Windows that are not double glazed suffer from condensation in winter - no big deal. Interestingly, a draft proof house is much more dust free inside and easier to keep clean.
Posted Thursday 6 Dec 2012 @ 11:50:34 pm from IP # -
tom
MemberWe struggled with the need or not for an air exchanger. Have read well sealed houses have moisture and air quality problems, but our builder, who has built a lot of sustainable houses, says he hasn't put one in yet. He had one client in 20 years who had an issue, and they went on holiday for 6 months and came back to mold everywhere.
I think they're hard to justify the cost to buy and run. Good ones use 40W, bad ones user over a 100W continuously. They might recover 80-90% of the heat, so you've effectively now unsealed your house and need to spend more to keep it uncomfortable. So the 40W is likely to me more like 200W including extra heating. 24 hours a day. So now you have to either pay for an extra 5 or so KWh a day of stick up extra solar panels. Plus the purchase cost of the unit. And all this so the air doesn't get stale?
Anyway, I do ramble on.
Posted Friday 7 Dec 2012 @ 1:49:28 am from IP # -
proftournesol
MemberThe Ovens Valley gets bloody cold for 4 months a year, and overnight and in the early morning for maybe 10 months a year. I'm just not sure that I want to have the house 'locked down' for that length of time, after all the reason why we are moving to the country is that nice fresh air! HRV seems the easiest way to get fresh air without high energy use keeping that cold fresh air heated.
Posted Friday 7 Dec 2012 @ 8:19:57 am from IP # -
Jeffbloggs
Memberproftournesol
A HRV will only keep the energy for longer so over a period of a few days the temperature in the building will decrease to the same level as a house without HRV. There are also different types of HRV ventilation, of which some can harvest the heating effects of the sun on the house roof to keep the building warmer without heating.Posted Saturday 8 Dec 2012 @ 7:17:07 am from IP # -
proftournesol
Memberyes, we won't have it as our only source of temperature control, probably a wood pellet heater for heating
Posted Saturday 8 Dec 2012 @ 9:05:34 am from IP # -
ML
MemberHello all
I am wondering if anyone has any updates on their builds with the "build tight ventilate right" approach using heat recovery systems? We are in the detailed documentation phase of our plans and are aiming for this and to use a heat recovery system. Waiting for a quote on the zehnder comofoair.
I'd also be interested in knowing what you used for any artificial heating and coolling you required, and what windows you used ( I have been told that only air infiltration <1 on wers data will be acceptable for a "tight build" .
Thank you.
MLPosted Tuesday 19 Feb 2013 @ 10:09:48 am from IP # -
tom
MemberMy update is that my builder is having second thoughts about the need for an air-exchanged after chatting with one of the green living guys at the MBA. Apparently quite a few well sealed and insulated houses are starting to have mold problems.
Also having second thought myself. Have to decide soon, as our frame and trusses are up and they're doing the flat part of out roof today, and rough-in for the Vacuum tubes tomorrow. The build is flying along and will need to decide pretty soon.
So far the only unit I'd touch would be Zehnder. Biggest unit will do 150m3/hr on 27W. That would do 0.28 air changes per hour for us, just a tad below the 0.3 Passivhaus recommendation.
Has anyone here installed one of the Zehnders, or have their own quotes?
Posted Thursday 21 Feb 2013 @ 1:32:30 am from IP # -
ML
MemberThanks for replying. We are using our heat exhange system to circulate our artificial heating and coolling through the house as well as for air quality. Hopefully it will achieve what we want. Our quote should be through soon for the zehnder comfoair 550 through air 2 energy. I will let you know.
We are at the stage of planning the air tight build part of the "build tight, ventilate right" equation and figuring out what additional heating and coolling we should allow for.Posted Thursday 21 Feb 2013 @ 3:42:02 am from IP # -
tezz
MemberCame across this tonight. Spoiler alert, lots of product names, but all Euro.
http://www.ecologicalbuildingsystems.com/workspace/downloads/RynartCaseStudy2010.pdf
Done to an extreme?Posted Wednesday 27 Feb 2013 @ 12:54:58 pm from IP # -
NeilD1968
MemberHi, just wondering if anyone has looked at Zehnder alternatives like (maybe) the Daikin HRV units, and/or has experiences to share.
A2E has told me it will cost a whisker under $14K for a Zehnder 550, and I'm having a hard time seeing the value in that given my site is bayside Melbourne.
Thanks,
NeilPosted Thursday 27 Jun 2013 @ 3:38:46 am from IP #
