Narrowing the performance gap

Building the Denby Dale Passivhaus: continuity of insulation in the roof space

Continuity of insulation in the roof space at Denby Dale Passivhaus

Here are some recent thoughts that I submitted as a contributor to a Good Homes Alliance working group “to discuss the issues, experiences and potential solutions, related to the performance gap – from the perspective of the site workers and site managers etc”. The comments might prove useful in response to the recent debate about on site workmanship on Twitter and elsewhere.

The populist view of the ‘cowboy builder’ breeds a climate of mistrust between the public and the industry, and within the industry itself. Would it not be advantageous for all, if the construction industry was respected in the same way as say that British motor engineering now is? Where becoming a builder/site worker was not the last resort when leaving school at 16? However upskilling site workers is only part of the story.

Motivation is as important as knowledge to closing the performance gap. Mutual respect for everyone’s area of expertise, the acknowledgement of risk in undertaking innovative  design and, crucially, acknowledgement of financial risk,  between all members of ‘the team’ is absolutely crucial for good workmanship and building performance. (The team includes everyone from client, designer, QS, contractor,  and tradesman to site labourer, and not necessarily in that order). A site worker will, in my experience, always respond positively when asked for an opinion on their own field of expertise, thanked for ‘going the extra mile’, praised for good works, etc.

Here are a few pointers that I believe will engender the right environment for a build process to be successful;

•    Absolute client commitment and understanding of the core issues.
•    Architect to be aware of their Master Builder ancestry and to realize the shortcomings of the ‘gentleman architect’ mentality.
•    Buildability of design, function before form.
•    Relatively long lead times before commencement on site, giving space for well thought through detailed design and subsequent comfort time for good estimating and programming of the build process on site.
•    Partnership contracts allowing early involvement of contractor/builder/craftsmen, to facilitate input into the design process and to gain ‘ownership’ of the task.
•    Value engineering to be reclaimed from cost cutting, where value is seen in reference to performance (in its widest sense) not just in profit margins.
•    Moving away from sub contracting to in-house trades, offering more control and continuity.
•    Realistic contract times and realistic extensions of time.
•    Fair payment terms and on time for contractors, suppliers and sub contractors.
•    Steer clear of lowest tender mentality which inevitably leads to disputes and bad workmanship.
•    A code of conduct for buyers which gives transparency of procurement procedures allowing security to suppliers and sub contractors to plan ahead to calmly provide the most appropriate materials and labour.
•    Maybe, above all, strong leadership.

I could carry on with this list, but I am just trying to point out that, as with all work related activities, good management procedures lead (hopefully!) to a good final product. Site managers and workers will respond well to good design and good contract procedures, allowing them to concentrate on delivery. It is my experience that when the momentum of the build is tripped up by designing detail ‘on the hoof’, particularly where the operative is working to a price, morale tumbles and quality will suffer.

Site managers and site workers are, by nature, practical people who are more receptive to the learning process when faced with an actual project. We are waiting to see a Certified Passivhaus Tradesman Certification course from Germany which was promised late last year. It may well be that for a Builder to be successful in gaining a ‘Passivhaus’ contract he would have to put a certain percentage of his workforce through the course. Could we use such a method for all ‘good’ construction where clients would insist on potential builders having passed an exam?

Passivhaus methodology can, I believe, be used as a framework for training of good onsite practice. Passivhaus is fairly prescriptive but liberating at the same time. Performance criteria have to be met to reach certification, everyone from client to site labourer has to work towards the same goal or it is a failure. Dilution of build quality is far less possible than the with the UK standard.  Maybe Passivhaus will be deemed a step too far, whereas the phrase Fabric First might be seen as more acceptable.

Communication is paramount. If someone has not understood an instruction, it does not necessarily mean that they are stupid. In fact the communicator might be deemed as stupid for not communicating in an understandable format. A tradesman’s existing experience and skill should always be respected and any new knowledge is extra to their skill base, stressing that the industry is changing fast and that they are part of that improvement change. They will be more in demand for their new expertise.

Passivhaus might be deemed as too narrow with its emphasis on thermal performance, but when we run Passivhaus training sessions to any interest group, housing officers, architects, builders, site staff, for example, we base it around four basic topics which when expanded can help to close the so called performance gap.

•    Insulation
•    Minimizing thermal bridging
•    Air tightness
•    Minimizing thermal bypass

We find that these subject areas or principles appear to be easily understood at all levels. For example ‘Insulation’ would include material properties, lambda values, understanding U values, appropriateness, application, and so on. ‘Air tightness’ would include ventilation principles, vapour control, interstitial condensation, etc. We also find that there is a more positive response to a course where actual builds are featured with plenty of photographs; too much theory tends to turns practical people off!


Bill Butcher, Director, Green Building Store

13th February 2012

4 responses to “Narrowing the performance gap”

  1. blank Dan Bates says:

    I’m doing a passivhaus refurb dissertation specifically looking at buildability for these reasons. Although I have not much experience of being either an architect or builder it’s something I’ve sensed the importance of, i.e. designing/building being unified in some way, as a team or in an individual’s outlook.

  2. blank Nick Grant says:

    Very good, I get really fed up with the blame the trades person mentality. I don’t know about formal partnering contracts but a partnering mentality is crucial.


  3. blank Sofie Pelsmakers says:

    ‘Even’ as an architect, I wholeheartedly agree! A few thoughts I’d like to share: The notion of PH or similar standard leading to the same goal and therefore possibly greater solidarity and mutual respect within the multi-disciplinary team is an interesting one and I’d love to hear if anyone has any precedents of this from other EU countries? Over 14 years ago, when I did my RIBA architecture Part I apprenticeship I was based on-site and worked closely with the contractor, seeing everything build. Not only is this an eyeopener to any designer; it creates a mutual respect for each others’ skills. Nowadays with Design & Build contracts, most designers don’t even get to visit a site let alone see any regular build process; missing out on this crucial ‘design-detail-building’ feedback loop. I do think this contributes to the lack of understanding and respect between professions,….

  4. blank Elrond Burrell says:

    All very good points well made I think. Particularly agree with –
    • Value engineering to be reclaimed from cost cutting, where value is seen in reference to performance (in its widest sense) not just in profit margins.
    • Moving away from sub contracting to in-house trades, offering more control and continuity

    From an architect’s perspective, it is very frustrating dealing with main contractors who are just contract managers and can’t talk about detailing and construction and who see value engineering as a way to increar the contrator’s profit margin. There also many areas where subcontracting out “packages” can create gaps in responsibility / accountability (continuity as you note)

    As Nick commented though, partnering mentality counts more than formal partnering contracts (which I broadly support) in my experience.

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