We built our first house back in 2015/6 and are lucky enough to be in a position to do it all over again. We're currently choosing between architects.

We're aiming for a four bedroom highly energy efficient home. Getting Passive House certification isn't a requirement, but we'd like to be approaching that level.

We are considering using the architect that we used last time as we know we have a good working relationship with them, they are local and they have experience getting challenging planning permission applications granted (we have a tricky sight). On the downside they have very limited experience with Passive Houses. They are currently designing one for another client. As they don't have anyone qualified in the office they are using a consulting firm for advice, PHPP modelling etc.. None of the contractors they work with have built a Passive House before.

One of the other architects we're speaking to has been Passive House certified since 2010. They have done multiple new build and retrofit Passive Houses. Clearly they know how to reach Passive House standard and have relationships with timber frame companies and contractors who have achieved it in the past too. On the downside we don't know how well we'd work with them (I'd rate the relationship with your architect as the most important one of the whole process as it can be a 3yr journey together) and they are based a bit further away lack some of the local planning knowledge and convenience.

Has anyone been in a similar situation? I think my main concerns are:
1. If you use a non-Passive House qualified architect can you effectively supplement with a Passive House consultant (there do seem to be a view about and most successful PH projects seem to have one)? Or do you really need to be going with a certified architect?

2. If you go with a timber frame company that has a Passive House option (e.g. MBC) when they create the structure will they include all of the designing out thermal bridges or do you need your architect to have done that?

RIBA do have a find an architect service, but it seems to be based on practices self certifying that they are suitable for your project and everyone says they are "eco" these days, but that can mean a wide spectrum of things.

I've also searched the Passive House website which is how I found my closest Passive House architect.

I think that you might mean low energy rather than energy efficient

Would you consider doing a scope and letting architects into a competition to do it? Or you could get them to price against that scope.

I would advise a building physics model to inform the design. (Overheating can be a problem but can be designed out or mitigated)

I would not build timber frame preferring masonry for maximum comfort, slow temperature swings, higher capacity to store heat and coolth. Storing these reduces energy use.

How low can you go?

Have you thought of a kit house from Germany a proven design and installed by them. Will be fairly quick build and accurately done. I used to subscribe to House building and Renovation magazine and there were often write ups of such projects in there. Might be worth a look see. I am very sceptical of UK trades having the skills to build an airtight. properly insulated house with no cold bridges. Whilst a plumber may be skilled in what he does it is unlikely he/she will have the knowledge to ensure that any holes made in in the walls will be adequately sealed.

My view is that PHPP is a bit limited on overheating but I am a bit out of date and so PH might have been updated,

I would recommend setting your own u-value targets less than 0.1 for main elements 0.7 for fenestration
PH and Building regs set standards but best to aim for much better than either of them

Hi Richard, I came across this picture from the Passivhaus Trust, illustrating how a triple glazed window loses less heat than a double glazed window does, but this is more than offset by the extra high-carbon materials embodied in the 3rd pane and the thicker frame. The triple glazing also restricts solar gains more. So overall, their double glazed option has better whole-life carbon than the triple glazed.

If you were just designing a PH using PHPP then the impact of those extra materials would not automatically be flagged up, so you might want an architect who is able to think this aspect through themselves. This picture has obviously shifted in the last few years, as triple glazing used to be the best option by default, so certain architects might be more up to date with developments.

I got the impression the PH trust are reflecting on how/whether to incorporate this into the PH standard. ."For most new build homes... embodied carbon ...is greater than the operational carbon over its lifetime. This demonstrates how critical it is ...that ‘zero carbon’ homes account for both sources of emissions, rather than only focusing on carbon emissions from [energy] use." (The current PH standard only focusses on impacts from energy use).

They make the point that designing for low heating load, means less materials would be used in the heating system

Embodied carbon is important but also very difficult to calculate fairly, because circumstances change rapidly. If and when window companies become carbon neutral, then there shouldn't be embodied carbon in windows (embodied energy, yes sure). Embodied carbon in products depends on embodied carbon in the energy used to make them and the materials they are made from and the processes used. But the use of double or triple glazing, as well as the types of glass and coatings to be used in various orientations and climate regions, has long been a subject of debate.

The Passivhaus Trust is the UK organization that markets and supports etc PH in the UK. The Passive House Institute is the organization that is responsible for the development of PHPP and the future of the standard.

There is an add-on for PHPP called PHribbon that can calculate the embodied carbon in a passivhaus design, as well as other things. It was developed in the UK but has been adopted by PHI.

Putting in plastic UFH pipes speculatively seems like an excellent way to increase the embodied carbon :)

I believe you need somebody who understands what is required (and has enough authority to be listened to) on site pretty much full time. It's amazing how fast things can go wrong if they're not stopped promptly, and rework is expensive.

I think ask this anti 3g must be coming from the uk window industry. 3g is volume product in central and Northern Europe. Window quality is higher for 3g and won’t need replacing for several lifetimes of dg here.

Back to the original question have you considered using your previous architect alongside getting input from a PH qualified consultant? I adopted this halfway house approach and it worked OK, as in the architect was happy to add in the detailing, but whether the builder will take any notice is a different matter...

Posted By: modernvictorianBack to the original question have you considered using your previous architect alongside getting input from a PH qualified consultant? I adopted this halfway house approach and it worked OK, as in the architect was happy to add in the detailing, but whether the builder will take any notice is a different matter...

If it is only about detailing it might just work.
I think it is far better to have the designer and PHPP calculator in one outfit. This ensures the PH aspect is embedded in the design from the get-go and not slapped on afterwards.

Independent qualified PH Consultant is a well-established thing, specifically to provide the necessary PH input to the vast majority of Architects who aren't PH Consultants themselves. Of course ideally all in one person, but for time being, the independent seems to be a workable strategy. As Dave says, hard to fudge - either the Consultant's advice is worked in, or you get a PH Fail.

As far as 'slapped on afterwards', you can tell your Architect from the start that he must develop the fundamental design in collaboration with the PH Consultant, including any non-optimal features that he (and/or you) choose to have regardless, which is always possible as long as compensated elsewhere in the design.