Looking for the most effective way to build a passive house

[Kate12]

We are new to this forum - currently have designs and a plot and want to build a passive home. We have researched different options and decided (maybe wrongly?) that we should definitely not go the traditional masonry route so are investigating timber frame companies. We are considering Baufritz but cannot find any feedback on them on BuildHub. Does anyone have any experience of them? 

[Gone West]

Hi Kate, welcome to the forum. We looked at Baufritz at a show around ten years ago when we were researching for our build. We liked the concept, but not the price so in the end did our own thing. We designed the look, construction type, insulation etc to give us the U factors we wanted for our PH. As others on here have done you can purchase a PH timber frame package complete with foundations which is a lot easier than designing it all yourself. Have a look at the various blogs on here detailing members PH builds and good luck with your project.

[PeterW]

Welcome ..!

 

Plot and plans are a good start - has the build been designed to be to passive standards ..?? If you’ve got plans it may be good to post them as it can give an idea of what’s achievable. 

 

Any construction method can be used to meet passive levels - it’s the detailing that causes the issues later on and this can happen with anything from blocks to timber frame or ICF. Sadly there is no golden bullet ..!!

 

 

[Bitpipe]

Welcome - we also had committed to a design with PP etc before stumbling onto this site (well, it's predecessor) and deciding to make our build meet passive standards - which we achieved, although it's not certified.

 

By luck we had more or less the right orientation and glazing design and didn't need to tweak things too much, mostly adding external blinds to minimise unwanted solar gain.

 

We also went down the timber frame package route as we were managing the build ourselves and got a full airtight, waterproof (once glazed and roofed) shell to passive standards from a single contractor which made the rest of the build pretty straight forward.

 

We mixed things up slightly by building a passive basement instead of a ground level slab, but the principals are the same.

 

One thing to consider is ensuring the follow on trades don't undo the work that has gone before them to make the envelope airtight - it's not hard to achieve but needs continuous attention to detail (and sometimes supervision).

[Alexphd1]

Hi and welcome. 

 

As mentioned above most build methods can be to passive level inc masonry but the devil is in the detail.

 

But first I would question if you really want the passive certification (not a bad thing), a lot of people on here have taken the fabric first approach and built to passive level of insulation and airtighness even using passive design principles for overheating in the summer but have not bothered with the certification.  Certification adds cost and time which most self builders run out of both! 

 

 

 

 

 

 

[Jeremy Harris]

We've also built to the PH standard, but opted not to go for certification, just because it was an additional cost that we didn't feel was going to add value.  We chose a timber frame package that included the passive slab foundation system and which was guaranteed to meet the PH airtightness spec, really to save a bit of hassle and to reduce the risk of one contractor blaming another if there was a problem.

 

I'd agree with the above, pretty much any build method could meet the PH standard, but some will need more attention to detail, specifically with regard to airtightness.  I believe that one reason there are a few PH timber frame options available is that it's a bit easier to get timber frame construction airtight than something like block and brick, but with patience block and brick could be just as good.  As yet it doesn't seem as if any of the package build companies are offering ICF as an option to meet PH spec, not sure why, as ICF should be as easy to make airtight as timber frame, at least for the EPS ICF systems.

 

[Bitpipe]

1 minute ago, JSHarris said:

As yet it doesn't seem as if any of the package build companies are offering ICF as an option to meet PH spec, not sure why, as ICF should be as easy to make airtight as timber frame, at least for the EPS ICF systems.

 

I got a quote from these guys early on as I was thinking of doing the basement in ICF so explored doing the whole house that way. 

 

https://thermohouse.co.uk/

 

 

[scottishjohn]

I agree with all that has been said above 

the term in the tile  "Effective"

Is that from a technical angle or cost --thats where views could diverge  

and is it a self build or contractor build .

I think you must make a hard decision on that early on  in the process 

an idea of  budget for the build as well as plans or size/type  of building 

 

[jonM]

We are in the process of building a house to passive standards but again will not be seeking formal certification. 

A key point for a cost effective build is to keep the form of the house fairly simple in order to achieve the necessary airtightness, so it may be worth optimising the existing design. It is not impossible with more complex designs, just more expensive. 

Detailing is absolutely critical and having someone on your team who has experience in detailing to reach passive standards would greatly increase the chances of a successful outcome be that a timber frame manufacturer, Architect or passive house consultant. 

The German "factory manufactured" firms such as Baufritz offer turnkey solutions which reduce risk but you do pay a premium. There are some UK based companies that will get you to a lockable shell guaranteeing a certain level of airtightness or your build team can take responsibility for meeting the required standards. 

Before thinking about build methods and companies, I would get the design looked at by a passive house consultant and modelled in phpp first if you have not already done this. 

 

[ToughButterCup]

Welcome @Kate12.

When you get used to the idea of Fabric First  (took us a while) then you need a way of evaluating the different ways of building.

In that task, PHPP is your friend.  You can change many of the parameters and look at the outcome(s). Once you get in to it, its great fun.

 

Buy it and run it yourself if you're comfortable with spreadsheets  or spend £200 or so to get someone else to do it for you. 

Anyway, best of luck.

 

 

[JanetE]

We have a timber frame house build to passive standards by the same company that @JSHarris used which is MBC.  Like you are planning, we are not passive certified. They laid the foundation installed the ufh heating pipes at the same time and supplied and erected the timber frame, and guaranteed air tightness.  The house passed on the first test. We decided to go to a company that would do the whole package as the interface between different contractors is often a major stumbling block. We did visit a few different timber frame company builds before opting for them, and realised that the fewer contractors involved the less chance of problems. Which you will find from the experiences of some of the members on this forum.  We have nothing but praise for the quality of their work and have now been living in the house for a year. It is such a comfortable space, no draughts and always pleasantly warm all through the winter and not too hot in the summer. If you have a look at @TerryE 's blog you will see some more information. 

This forum is an amazing source of very useful information.

Good luck with the build.

[Kate12]

Thank you to all of you for making us feel so welcome and your replies which are tremendously helpful.

We’ll certainly look at the PHPP software.

Good question on what I mean by effective - I do mean from a technical angle and from all the replies, it sounds like while all building methods could achieve it - a timber frame produced off site stands a better chance.

 

I’m keen to use someone who does more of a package to avoid the arguments between contractors. I’ve seen both MBC and Fleming mentioned on here. Is there anyone else anyone would recommend? 

Thanks again to everyone. 

 

[Jeremy Harris]

PHPP is very good, but it can be a bit daunting initially.  If you just want to get a rough (within about 10%) idea to start with, as to how changing things like wall, floor, roof, door and window U values affect things, or how much impact MVHR makes, then I wrote a simple heat loss spreadsheet to try and help answer these early "what if?" questions.  The file is an ordinary Excel file, but the forum software doesn't like files with .xls extensions, so download this, then rename it to change the .txt to .xls (I can promise it's safe, and has no macros etc): Heat loss calculator - Master.txt

 

This simple heat loss calculator takes no account of solar or incidental heat gain, exposure level of outside surfaces, etc, it simply calculates the heat loss for any particular fabric standard and temperature differential.  We, and others here, have found it does a reasonably good job or predicting performance though, and although definitely not a substitute for PHPP, it is a bit easier to use, so ideal when you are just looking to get a feel for what sort of performance you are likely to get for any particular fabric build standard.

 

If you want to have a look at the effect of floor insulation specifically, with underfloor heating, then I also put this spreadsheet together (same as above, rename the extension after saving the file): Floor heat loss and UFH calculator.txt

[Dreadnaught]

1 hour ago, Kate12 said:

I’ve seen both MBC and Fleming mentioned on here. Is there anyone else anyone would recommend? 

 

When I was reviewing timber frame suppliers, I looked at MBC (Ireland and Gloucester), PYC (in Wales near Welshpool) and Touchwood Homes (Hertfordshire). Eden (Cumbria) was on my long list but I did not approach them in the end.

[Bitpipe]

Useful exercise to send your planning drawings to all of these TF firms for an estimate and then check to see what's included in the price.

 

Some can seem expensive (or cheap) but when you factor in plant hire (i.e. crane), slabs, internal walls, floor decking, u values etc then you'll be able to compare apples to apples a bit better. 

 

Some of the cheaper quotes I received wanted me to provide full fall arrest systems (i.e. airbags etc) ...

[TerryE]

7 hours ago, Bitpipe said:

Some can seem expensive (or cheap) but when you factor in plant hire (i.e. crane), slabs, internal walls, floor decking, u values etc then you'll be able to compare apples to apples a bit better. 

 

Another couple who use the forum recently came to visit our house and to discuss issues and ideas.  One comment they made was that the whole issue of choosing a TF and evaluating various quotes was very much an "apples and oranges" comparison. 

 

You need to discus very carefully with putative suppliers what is in scope of supply and what is not, and have a clear shared understanding of who is responsible for what.  Our slab and TF ended up as about 25% of our total build cost.  (By way of comparison, we also had to have a local stone skin on our house; this looks beautiful, but this also ended up costing more than the supply and build of the slab, TF, insulation and certified airtightness.)

 

One of the reasons that I feel the the PHPP is total overkill is that the simple calculation method that Jeremy, I and many others used is that it gives an answer accurate to 10% or so and is transparent enough to allow you to do and understand the various design trade-offs.  IMO, the major risk / error here is between the nominal as-designed, and the actual as-built.  One of the reasons that we finally chose a TF twinwall / passive slab approach (even though this was slight more expensive and 100mm deeper profile than U-value equivalent single frame approaches is that this pump cellulose approach and the corresponding wall profile are very airtight by design and has very low associated Ψ values, to the point that the supplier contracts to deliver to a U-value and airtightness specification. This gave us a high degree of confidence that the as-build performance would be as designed.

Edited February 10, 2019 by TerryE

[joe90]

I have not used PHPP but built ours to passive principles. One thing I don’t think PHPP does it take into account local conditions (please tell me if I am wrong over this). @JSHarris found he had less of a heating load and more of a cooling load because of a sheltered valley location, we on the other hand are on flat land near the coast and reckon the constant (almost) South westerlies wash an amount of heat from our structure .