Health risks associated with passive houses

[K78]

I've read a lot about the benefits of passive house design over the past few years on ebuild and other forums, but not much on any negatives.

 

My biggest concerns with passive house design have always been around air quality and internal temperature. I really struggle in stuffy environments. I even open windows in winter.

 

I was researching the above and stumbled across this. 

 

http://repository.tudelft.nl/islandora/object/uuid:88fd72b2-f7ab-45ea-a403-ce367801cf3f/datastream/OBJ/download

 

 

 

 

 

[ToughButterCup]

You are absolutely right to be concerned. I was  - until I spent a few days researching the issue, and visited  several passiv houses. 

 

@MrsRA and I always sleep in a draft: year round. Our Tomcat (Sid) will not use a catflap (we haven't got one) and so uses the windows. I work outdoors all day (on the build), and so loathe stuffy rooms. Sounds to me we are quite like you, therefore.

 

In the planning phase, at one stage I thought we'd go 'hardcore' and have a naturally ventilated passiv haus (instead of MVHR) and read several research articles on the subject. As a spin off from that exercise I read about how common it is for MVHR installations to be 'tuned' badly, switched off even, unbalanced and commonly poorly maintained - filter left uncleaned, that sort of thing. Air quality suffers as a result.

 

I have yet to choose an MVHR system, but in researching suppliers I have come to realise that there is a common conflict of interest: suppliers often both design and specify the system. And I have yet to find a supplier who is obviously competent at design. Maybe the sales reps I talk to -not one of whom is interested in design-  simply fill me with dread because they couldn't give a stuff about the customer; they just want to close a sale.

 

We went to Denby Dale passiv haus open day this time last year. What did we see? The owner chatting enthusiastically about how he leaves the window slightly open all night because he -like you,  like us- can't stand a stuffy room.

 

I think the answer is take great care tuning (balancing) the airflow, and, if needed don't be shy about keeping the window open a bit. Yes, it'll unbalance the airflow, yes it's counter intuitive.

But nobody has ever said passiv hauses have to have the windows shut all the time. Not even us Germans.

[K78]

The more I think about it. The more I think a passive house wouldn't suit me. 

 

I like wood burning stoves, have dogs and plan and to have aquariums again. My house design also has 2 large window/doors opening onto a balcony, so solar gain is also an issue. 

 

My house will still be well insulated. Just not to the extent of most on this forum. 

[Crofter]

Solar gain is a potential issue, but I have heard good things about IR-blocking films that can be applied to windows to make a big difference to how much heat is absorbed.

 

As far as I understand, all you have to do to turn a passive house into an active house is to open some windows.

But it's much harder to do it the other way around.

[Stones]

I don't understand the problem, all a passive house is, is a house that meets certain standards, the most notable one being the amount of heating input required. All of the concerns you have, air quality, solar gain etc could apply to a house built to less stringent insulation and air tightness standards. It's about how you choose to live in the house.

 

I like a fresh, well ventilated house, and far prefer the air quality offered using an MVHR than a house without, I just choose to mechanically ventilate at more than the minimum or optimum passive house level. If I want to really freshen things up I throw open the windows.

 

I like my house nice and warm in winter, and will happily heat it 24/7 at a higher temperature than than the prescribed design temperatures used when filling out PHPP.  So what if it costs a bit more?

 

At the end of the day, it's your house, and you do not have to be a slave to some predetermined rules unless you choose to.

 

 

[Dudda]

PHPP requires a minimum of 0.3 air changes while the regulations here in the Republic of Ireland require 0.4 but for the total floor area not the Treated Floor Area that PHP uses which is smaller. You can get a larger MVHR unit and have it run at a higher rate and as it's recovering circa 80-90% of the heat, the house will still be very warm but have a lot more fresh air. Might cost an extra euro or two a year but worth it if you're afraid of a stuffy house.

[Bitpipe]

We've been living in our (non certified) passive house for a month now and I've only got round to completing the MVHR installation today due to other works in the plant room.

 

So for the last few weeks we've been randomly leaving the windows, velux and big sliding doors open for ventilation and it's been fine - no need to have the heating on either even on the recent cold nights. Will be interesting to see what difference the MVHR makes.

 

Can't agree with Stones more, we have a highly insulted, airtight house that's been designed to minimise solar gain (blinds and orientation). No one dictates how we live in it though.

 

Solar gain is an issue whatever the standard of your house - our caravan suffered from excessive gain (was unbearable in the summer) and that was not passive by any standard

 

 

[ToughButterCup]

@K78, go and have a look (and feel) at the Denby Dale passiv haus open day. There are a good few others you can visit too. But the owner at Denby Dale is a really nice bloke - given the chance he will chat to anyone for ages and give you lots of technical info.

Nothing in the PH standard says you can't open the windows. It took me ages to accept that.

[Gone West]

My other half wasn't sure what living in a PH would be like so we stayed in a PH B&B for a few days. She liked it straight away. Hope this isn't advertising.

 

http://www.passivhausbandb.co.uk/

 

 

 

 

[Barney12]

Loving this thread!

 

I'm just waiting for the passive house police to come along (and to be frank I've seen a few posts from current and past forum members along these lines).

 

So don't forget some of the important rules:

 

1. Kill the cat, cat flaps will not be tolerated.

2. Remove or reduce all windows. I know you've bought a plot with a view but seriously saving on your energy bills is way more important than a view.

3. Make sure you go paperless for ALL bills etc. There is no way you are having a postbox. 

4. Bury your partner under the patio. Far too risky that they may open a window. 

5. Kill the dog. Can't think of a reason why other than enjoying yourself cannot be tolerated. 

 

OK, I'm having a bit of fun BUT you are going to drive yourself to the edge of insanity doing this self build lark, nothing is more stressful. SO BUILD YOURSELF A HOME NOT A HAUSE! 

 

 

[joe90]

I know I am going to " suffer" from solar gain in my passive principled new build but after a holiday to the south of France where we both loved the heat I am looking forward to it. Seriously though my south facing " sun space" in the middle of winter and the shoulder seasons can be a lovely place to be when its wet or chilly outside.

[jack]

56 minutes ago, PeterStarck said:

My other half wasn't sure what living in a PH would be like so we stayed in a PH B&B for a few days. She liked it straight away. Hope this isn't advertising.

 

http://www.passivhausbandb.co.uk/

 

We did the same a couple of years ago.  Adam and his family are lovely, and he's extremely knowledgeable (having co-written the Passivhaus Handbook).  Worth the cost of staying just to pump him for info!

 

11 hours ago, K78 said:

The more I think about it. The more I think a passive house wouldn't suit me. 

 

I like wood burning stoves, have dogs and plan and to have aquariums again. My house design also has 2 large window/doors opening onto a balcony, so solar gain is also an issue. 

 

My house will still be well insulated. Just not to the extent of most on this forum. 

 

I wonder whether we need to agree on what you mean by "Passivhaus".  As you know, technically it's a (very!) detailed standard that a house can be built to meet.  Everyone talks about airtightness and insulation, but there's a lot more to it than that if you want to go for certification.

 

It sounds like what actually concerns you is a house having high levels of airtightness and insulation.  

 

On airtightness, as others have said, there's absolutely nothing to stop you keeping your windows open whenever you want to.  We've only this week started closing windows in our Passivhaus-level airtight house - we typically leave loads of windows open upstairs through the shoulder seasons, and only close them in summer once the temperature outside gets higher than what's inside.

 

The thing is, building airtight gives you options.  If we have an extremely cold, wet and windy period and you need to keep windows closed, then you'll still have great air quality.  If we have a hot period, you can close everything up, leave your MVHR on summer bypass, and hopefully keep the internal temperature low relative to the heat outside.  If you don't build airtight, you don't have these options.

 

Regarding insulation, even a building insulated to current building regs will overheat if it isn't designed with proper regard for solar gain.  Get it right and your house won't overheat.  In our case, we have around 500mm overhangs on most southern and western windows.  We have a 5m long, 2m high slider to the south that gets quite a bit of sun through the middle of the day, because we don't yet have any external shading in this area.  We also have external blinds on most southern and all western windows.  We had a few days over summer where it was warmer inside than I'd have liked it, especially upstairs, but I'm doubtful having less insulation would have made much difference to that.

 

13 hours ago, K78 said:

I was researching the above and stumbled across this. 

 

http://repository.tudelft.nl/islandora/object/uuid:88fd72b2-f7ab-45ea-a403-ce367801cf3f/datastream/OBJ/download

 

 

That article repeatedly refers to things like poor positioning of vents and poorly designed systems that make fan noise noticeable even on the basic setting.  If your MVHR system is designed and installed properly, there's no way you should hear anything meaningful on the basic setting.  You might hear it a bit on boost, but that would be the case with a regular extractor.  Same with vent positioning and flow rates - these are within your control.

 

If you don't want to build to PH standards, that's cool.  I personally think they're a little over the top in terms of the energy requirement, in particular.  But don't compromise your one opportunity to build a really comfortable house based on misconceptions like not being able to open windows if you want to, or that adding more insulation is what causes overheating.

 

Edited to add: I now wouldn't live in a house with a dog unless we had MVHR.  I'm very sensitive to smells, and our house has absolutely no dog smell about it, despite us having a very energetic springer who goes paddling in the local stream twice a day when we take her for a walk.

[Dudda]

1 hour ago, Barney12 said:

1. Kill the cat, cat flaps will not be tolerated.

 

Not any more cat lovers.

https://passivehouseplus.ie/news/product-news/urban-front-integrates-passive-pet-flap-in-oxford-passive-house

 

[Nickfromwales]

I knew we should have patented that concept  

"This time next year, Rodney, we'll be millionaires".......??????

[Barney12]

1 hour ago, Nickfromwales said:

I knew we should have patented that concept  

"This time next year, Rodney, we'll be millionaires".......??????

 

OH but Nick. Money can't buy you happiness. However a little pussy on the kitchen table can.

[PeterW]

3 hours ago, jack said:

I wonder whether we need to agree on what you mean by "Passivhaus".  As you know, technically it's a (very!) detailed standard that a house can be built to meet.  Everyone talks about airtightness and insulation, but there's a lot more to it than that if you want to go for certification.

 

Its a trademark ! You do have to be very careful and I'm sure that there is a thread over on ebuild about someone having to retract their "status" to Passive House as its not one that has the certificate..

[joe90]

That's why on my post above I put "passive house principled new build". I don't see the point in paying for a certificate as I have nothing to prove to anyone, I just want a comfortable cheap to run house and I have a conscience regarding pollution.

[Barney12]

3 minutes ago, joe90 said:

That's why on my post above I put "passive house principled new build". I don't see the point in paying for a certificate as I have nothing to prove to anyone, I just want a comfortable cheap to run house and I have a conscience regarding pollution.

 

Not to mention the fact that all the evidence seems to suggest that the lovely certificate of a Germanic persuasion will mean your house is worth LESS if you ever need to sell.

(and before someone comes along and says "I'm never going to sell my self build" could I please borrow your crystal ball please!!)

[joe90]

I believe that showing my bills to a future prospective owner will prove more than a certificate ( but I will never sell it honest ?)

[joe90]

P.S. forgot to say we started my build thIs week ( although we are still waiting to hear from the Secretary of State regarding our appeal to build what we want ?)

[gravelld]

39 minutes ago, Barney12 said:

 

Not to mention the fact that all the evidence seems to suggest that the lovely certificate of a Germanic persuasion will mean your house is worth LESS if you ever need to sell.

(and before someone comes along and says "I'm never going to sell my self build" could I please borrow your crystal ball please!!)

 

I'm interested in this evidence. Have some statistically significant numbers been released?

[K78]

1 minute ago, gravelld said:

 

I'm interested in this evidence. Have some statistically significant numbers been released?

 

Many surveyors will down value a property if it isn't conventional uk construction. Such as timber frame with timber cladding. 

 

If if a passive house is built with from brick and block with a cavity, I doubt it would be a issue. 

 

I was was talking to a developer who has just built and sold 4 detached timberframe houses clad with render board. He said every surveyor made a initial negative comment about the render board finish, but weren't concerned once he mentioned they had NHBC guarantees. 

 

I personally hate NHBC. But for people who think they might have to sell in the near future, they are probably worth it. 

[jack]

49 minutes ago, gravelld said:

 

I'm interested in this evidence. Have some statistically significant numbers been released?

 

I don't think there is any, at least relating directly to PH certification.  I think there's just anecdotal evidence that some surveyors will downvalue anything holding itself out as an "eco" house.  I believe Jeremy Harris had that experience.  I seem to recall someone else saying that PV can reduce the value of a house even if it's still going to have a cashflow associated with it for the balance of the FiTs contract.  Here's feature that could give a windfall of thousands of pounds over the next 20 years.  How much value do such people place on that feature?  Negative thousands of quid!  Bizarre.

 

1 hour ago, PeterW said:

Its a trademark ! You do have to be very careful and I'm sure that there is a threadover on ebuild about someone having to retract their "status" to Passive House as its not one that has the certificate..

 

I don't believe the word Passivhaus by itself is a trademark.  From memory they only have a trademark on the logo.  There may be a question over whether the word "Passivhaus" is confusingly similar to the logo.

 

Even if it is a trademark, to infringe you'd have to be using it in the course of business.  A private individual can therefore describe their house as being of "Passivhaus standard" or "designed using Passivhaus principles", because that description isn't in the course of business.  A developer, on the other hand, can't use such a descriptor when selling their houses unless they meet the standard AND have the certificate from the PH institute.  The latter would effectively be a license to use the trademark. 

 

Irrespective of the TM position, you may be committing fraud if you're holding out that your house meets a standard when it doesn't (edited to add:) and you get some sort of financial gain from that assertion.

Incidentally, the PH Institut had a big falling out with their US branch a couple of years ago.  From memory the US branch ended up getting the rights to their US trademarks.  It was all pretty nasty!  

[gravelld]

@K78 What you say makes sense, but it also sounds a little FUDish. I'd like to see some numbers.

 

I remember when we were last in the market. One nice place we found didn't have NHBC. We were of the opinion that you take a risk with any house. But then the vendor... the vendor! chipped in saying the previous purchase fell through because of it, and the mortgage company refused to mortgage it. It was that which sewed doubt into our minds. We would've gone for it anyway (our mortgage company was fine) but by then someone else had their offer accepted.

Edited October 7, 2016 by gravelld

[gravelld]

3 minutes ago, jack said:

 

I don't think there is any, at least relating directly to PH certification.  I think there's just anecdotal evidence that some surveyors will downvalue anything holding itself out as an "eco" house.  I believe Jeremy Harris had that experience.

 

Yes, Jeremy's anecdote sprang to mind when I read the post above. But that ain't evidence.

 

If there's one thing I've learnt in business, whenever money is involved: don't trust what people say they will do, look at what they actually do.