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graeme m

Passive Certification?

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As we are getting to that point in the build. Should I be Certified (if you know what I mean).

Edited by graeme m

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My wife says she should have had me certified before we started!

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That's a question only you can answer :D. If you're confident with your calculations and don't need the certificate for selling then no. The only way to know for sure is to pay for certification, if you think it's worth a couple of grand.

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My reading  (time too short to make appropriate links to substantiate the point) is that the cost of certification exceeds its market value.

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My experience (which may not be typical) is that market value is, at least at the moment, negatively impacted by over-emphasising the low energy usage of a house. 

 

When we had our house valued a couple of years ago, the valuer knocked 5% of the value because, in his words, it was an eco house and that made it of limited marketability.  Given this, and the relatively high cost of Passivhaus certification (at least £2k, probably more when you add in the premium that every supplier is going to chuck on for providing the additional information) then I don't think it makes sense, unless you really want to proudly display the plastic plaque you get from the PHI.

 

Far better, in my view, to design the house to meet the same sort of performance level, and then keep the energy bills.  That way, when you come to sell (if you ever do) you can just make copies of the bills to show any prospective buyer the running cost.  I'm inclined to think that the low energy classification systems, be they AECB, SAP or Passivhaus, just aren't on the radar for most buyers, and some may well be put off by what they see as odd or complex features, like well-sealed windows, MVHR, minimal heating system provision etc.  Far better, I think, to just have a note on the sales particulars that says "this house costs £XX to run every year, and the vendor can provide bills as evidence".

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Isn't certification a bit like the government car fuel usage test.

What works in the lab does not always translate to the road.

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7 hours ago, JSHarris said:

I'm inclined to think that the low energy classification systems, be they AECB, SAP or Passivhaus, just aren't on the radar for most buyers,

 

I'm inclined to think that the only people these schemes are on the radar of are here.

Edited by Triassic

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1 hour ago, SteamyTea said:

What works in the lab does not always translate to the road.

They do base the certificate on the reality rather than the theory in the sense that they use the as built details to validate it. Only long term will you actually 'know' what is what.

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2 hours ago, SteamyTea said:

Isn't certification a bit like the government car fuel usage test.

What works in the lab does not always translate to the road.

 

Not really. The Passivhaus planning package (PHPP) does a pretty good job of modelling the real world. As with all models, it's at best as good as the data that's fed into to it.

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The architect has suggested I use a Passive designer his quote which was for everything and worst possible scenario was £15k. Like I say it included everything but it seems a lot to me £7k was set aside for Passive checking by Warm and airtesting etc. I could do a lot with that £15k

 

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At the end of the day its only a certificate and your name on a list. Will it make any difference to you long term , doubt it. Build it to passiv standards and just put that £15k towards the build costs. 

 

 

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5 hours ago, MikeSharp01 said:

they use the as built details to validate it

 

4 hours ago, jack said:

it's at best as good as the data that's fed into to it.

Sounds to me, but not looked at the methodology, that they started with a bunch of data, created a model that fitted, then checked it against the data.

Leaving a window open or a hot tap running would 'ruin' the model.

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2 hours ago, SteamyTea said:

Leaving a window open or a hot tap running would 'ruin' the model.

Yes but that is not the point is it. Even if the model has its flaws, and it does, it addresses the key issues consistently and levels the playing field with a set of reasonably transparent calculations and associated underpinning assumptions. Some things cannot be argued - the more air tight you make it the less heat it will loose. the more insulation you use the better the U value and so lower heat loss, etc. Connect this to those consistent assumptions about how much hot water a number of people will use alongside all the other assumptions and you have a model that is consistent. So if you want to leave the hot tap running you can that won't make it any the less a passive house just a wasteful one. 

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You'll always have your naysayers but facts are facts and the simple fact is, PassivHaus buildings have been proven to work as designed and in the real world.

 

Our most recent entry in the Passive House Plus magazine is one example, one we did the entire feasibility study, certification, tool box talk etc. on.

 

In my view the certificate isn't exactly necessary but you may always live with the question "is it really Passiv Standard". The standard has certainly moved building efficiency and building standards forward dramatically, unfortunately not all builders grasp the concept. Even when building towards the standard.

 

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23 minutes ago, craig said:

You'll always have your neay Sayers but facts are facts and the simple fact is, PassivHaus buildings have been proven to work as designed and in the real world.

 

Our most recent entry in the Passive House Plus magazine is one example, one we did the entire feasibility study, certification, tool box talk etc. on.

 

In my view the certificate isn't exactly necessary but you may always live with the question "is it really Passiv Standard". The standard has certainly moved building efficiency and building standards forward dramatically, unfortunately not all builders grasp the concept. Even when building towards the standard.

 

 

The simple and straightforward answer is that it is not at all difficult, challenging or expensive to build a house that meets or exceed the now pretty old Passivhaus standard, and there is little merit (other than bragging rights) in going through the very expensive certification process, in my view.

 

As an example, I knew sod all about building, architecture, energy efficient construction etc, before embarking on our self build.  I did some home work, learned a fair bit in the process, used no consultants or experts, and ended up with a house that exceeds the Passivhaus energy performance standard.  It wasn't hard to do, didn't cost the earth, and frankly there was nothing technically difficult about it at all.  The major issues were making sure that everyone working on the house paid attention to the detailing, nd overcoming a load of prejudices and plain old disbelief.

 

There's nothing magical or mystical about building a low energy house, that's comfortable to live in, although there seem to be a host of "experts" intent on convincing the unwary that the only way to achieve this objective is to pay others lots of money...................

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I think that the PassivHaus standard is the best that we have available to us at the moment - it is specific and measurable.  "As built" performance can be compared with/evidenced against "designed" performance to make sure that the building has been built to the required standard.  Compare that with the big developers throwing up houses, rigging it so that they meet building regs (e.g. siliconing all the gaps, air tightness testing, getting a pass, and then removing the silicon before decorating) and then only being required to prove that a sample of their houses meets regs.

 

Right now, my view is that the PH industry seems to be populated, in the main, by people who care about what they are doing - architects who want to design to the PH standard, certifiers that do a thorough job of certification, builders who care about air tightness etc.....  It's not (yet) been invaded by the get rich quick merchants that we have seen around the RHI technologies.

 

As Craig says:

 

38 minutes ago, craig said:

In my view the certificate isn't exactly necessary ......

 

It really is up to the individual whether they want certification or not.  I don't think it adds to the value of the house, at the moment.  An alternative, perhaps contentious view, is that paying for certification helps to maintain and build an industry which is generally going in the right direction.

 

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11 hours ago, Cambs said:

Right now, my view is that the PH industry seems to be populated, in the main, by people who care about what they are doing - architects who want to design to the PH standard, certifiers that do a thorough job of certification, builders who care about air tightness etc.....  It's not (yet) been invaded by the get rich quick merchants that we have seen around the RHI technologies.

 

Spot on.

 

I've seen, I've read, I've been involved with projects that are planned as PH, built as PH and failed. Every bit of data entered into PHPP, on site checks, air tests performed and so forth. It's not as easy as you think @JSHarris to achieve the standard.

 

Only one house I know has achieved certification, that was not planned as PH and was tested and certified after it was built.

 

Edited by craig

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1 hour ago, craig said:

 

Spot on.

 

I've seen, I've read, I've been involved with projects that are planned as PH, built as PH and failed. Every bit of data entered into PHPP, on site checks, air tests performed and so forth. It's not as easy as you think @JSHarris to achieve the standard.

 

Only one house I know has achieved certification, that was not planned as PH and was tested and certified after it was built.

 

 

 

Yes it is, it's a doddle.  I've run our as-built house configuration through PHPP, and despite being an all-electric house it still comes in within the PHI standard.  I used an off-the-shelf passive house foundation and frame supplier, and that dealt with all the building-related technical and quality issues, so my main input was in design and modelling, plus systems specification.  It wasn't in any way technically difficult or demanding work.  The hardest part for me was the artistic element of the architectural design - the technical stuff is easy, the art and design doesn't come naturally to me.

 

FWIW, our chosen frame and foundation system supplier offered a thermal-bridge free construction method and guaranteed PH airtightness level as a part of the package.  We came in at around 2/3rds of the max allowable  PH permeability at the very first air test, no remedial work or additional air testing was needed.

Edited by JSHarris

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2 hours ago, JSHarris said:

Yes it is, it's a doddle. 

 

You're a retired government chief scientist with degrees in chemistry and... another (which I can't remember, sorry!) You worked in technical management at a high level for many years. You've had highly technical hobbies across a wide range of disciplines all your life.

 

You're retired and have a lot of time to spend learning all this stuff, along with a brain that's capable of processing and retaining information far better than the average punter.

 

Respectfully, you may have found it a "doddle", but I suspect many may find it otherwise.

 

Also, certification is not just about airtightness, insulation and 15kWh/m2/year. It covers everything from undue thermal bridging (which ours has, despite being an MBC house - we missed this until it was too late, although a passivhaus consultant would have spotted it immediately), to MVHR efficiency and sound, to a hundred other little details. Yes, with planning it shouldn't be a struggle to meet certification if things are planned properly from the beginning, but I defy the average person with a job to do this without help and significantly increased costs.

 

Someone above mentioned £2000 for certification. Looking at this flowchart, I think it's very optimistic to assume that the consultants' fees alone will be less than double that for a typical project.

 

My rough calculations were that certification would add around £8-10k, and possibly as much as twice that, to the cost of our build. For example, if you don't use PH certified components in certain areas, it can be difficult or even impossible to get certified. An example of this is MVHR - if you use an uncertified product, you have to down-rate its stated performance by (from memory) 15%. That could easily mean the difference between a PHPP pass and fail. So you buy a PH-certified MVHR unit as we did when we were still considering certification, and pay at least a couple of grand more than would otherwise have been the case. 

 

I really liked the idea of certification. I believe it focuses the house-builder on details that they might otherwise ignore as being unimportant (specific performance numbers - eg, airtightness and annual space-heating energy) or too hard (modelling thermal bridges). I just couldn't justify the additional costs at the time, given that it didn't have any impact on the value of the house. It may be that in the longer term, the more general market will allocate a positive value to certification. 

 

Also, the Passivhaus is one of the ugliest logos I've ever seen, in any context, and there's no way I'd hang one of their plaques in my house.

 

4 hours ago, craig said:

Only one house I know has achieved certification, that was not planned as PH and was tested and certified after it was built.

 

Was that this one @craig?

 

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@jack, Point taken, but I never rose to the dizzy heights of the Chief Scientist (in reality CSA, the Chief Scientific Advisor), I was just a senior principal scientist before being kicked into management.

 

Arguably, the main issue is the divide between architecture and engineering.  I doubt that your build would have had those thermal bridges where the steels go through if the design, from an architectural standpoint, had considered the engineering challenges involved.  In the recent past (as in over the past 50 to 100 years) we have allowed architecture and engineering design to diverge, at least for dwelling design, and they have become almost entirely separate disciplines.  The classic case is where the architect designs something, with little or no thought as to how the desired thermal performance is going to be achieved, and then metaphorically chucks it over a wall for an engineer to sort out how to actually build it and make it perform.

 

In our case, I knew nothing about architecture, so started from the desired performance, and then made compromises in order to get the house to look a bit nicer.  This is, I believe, the complete opposite of the process that most houses go through at the design stage.  The main benefit was that I started with a baseline performance (basically just a sealed, well-insulated box), and then worked back from that to get something that looked reasonable and could be built without compromising the performance too much.  My target was to meet or exceed the PH performance criteria, right from the start, only because it seemed to be the only proven methodology around.

 

If we were to adopt a similar process for all new builds, by merging the architectural design, technical design and cost engineering, with the emphasis on the latter two, then we'd undoubtedly have better performing new houses.   If self-builders adopted this approach then I'd argue that it would be pretty easy to achieve PH performance, at little or no additional cost.

Edited by JSHarris

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58 minutes ago, JSHarris said:

Arguably, the main issue is the divide between architecture and engineering.  I doubt that your build would have had those thermal bridges where the steels go through if the design, from an architectural standpoint, had considered the engineering challenges involved. 

 

True, but I don't want to live in a world where no-one ever designs an overhang because they're scared of the impact it will have on whether something can be certified. It would have been perfectly possible to reduce the thermal bridge in our case given some thought and a slightly higher budget for a thermally broken structure at those points. Alternatively, if we hadn't been so obsessed about trying to keep things box-like to minimise the surface-area to volume ratio, we could have extended the rooms underneath out under their associated balconies, thereby doing away with the need for steels passing through the insulation layer.

 

An experienced PH consultant would quickly have picked up these issues and been able to explain the compromises of each approach. I have a much better feel for this sort of thing now than I did at the time it would have helped me!

 

1 hour ago, JSHarris said:

If self-builders adopted this approach then I'd argue that it would be pretty easy to achieve PH performance, at little or no additional cost.

 

 

Undoubtedly, but that isn't the same as a PH-certified (or certifiable) house, which is what I was talking about. 

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I am with Jeremy on this.  Just good basic (as in no harder than 'A' level) engineering is all that is needed to design a thoroughly good thermal envelope.

It is very easy to get bogged down in detail at the very start, then go looking for solutions along the way.

Often when looking at solutions there is a conflict of opinions.  These conflicts usually take the view that you are starting from the wrong place.

So rather than be negative, why don't we start an 'official blog' about basic engineering.  When I say basic, I mean really simple, the kind of thing that a 12 year old could understand.

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22 minutes ago, SteamyTea said:

I am with Jeremy on this.  Just good basic (as in no harder than 'A' level) engineering is all that is needed to design a thoroughly good thermal envelope.

It is very easy to get bogged down in detail at the very start, then go looking for solutions along the way.

Often when looking at solutions there is a conflict of opinions.  These conflicts usually take the view that you are starting from the wrong place.

So rather than be negative, why don't we start an 'official blog' about basic engineering.  When I say basic, I mean really simple, the kind of thing that a 12 year old could understand.

 

I'm afraid that what you consider 'basic' is somewhere between rocket science and outright witchcraft for the majority of the population.

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No it isn't.

I think this is part of the problem.  People get put off 'science' at school because it is so badly taught.

Most is really easy.

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A large part of the problem is where we're starting from in terms of what the general population and builders know and want (edited:) are willing to pay for.

 

Since starting our project, several friends have undertaken significant building works. None have actually built houses, but one took a bungalow back to bare walls and added another storey, and two completed roof-off renovations including extensive extensions. All involved all-new windows and doors, and replacement insulation. I talked to all of them about insulation and airtightness, and all shrugged and said that their architect/builder was doing the "building regs" stuff. I encouraged them to go for better windows, but they weren't "in the budget".

 

I encouraged one to at least add extra insulation to their loft bedroom, given that they were unsatisfied with how hot their current loft was during summer. Nope. Not willing to spend the money, don't have the ridge height, and in any event they're installing an air conditioner!

 

Builders are even worse. We've all seen how disinterested many of them are in even following the rules they're supposed to follow. Most won't offer better standards even if they've capable of achieving them, because the buyers of their services value those standards at approximately zero.

 

So all this talk of technical capability within the industry is theoretical unless and until it's backed up by law and oversight, imo. Until then, people will do what they've always done.

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