Fabric First Round Table Debate
Bruce Meechan, the Technical Editor for MMC Magazine, was invited to chair a round-table discussion between leading industry figures, looking at the ‘Fabric First’ approach to construction. Those present were Mike Stevenson – Development Director at Sidey Limited and hosts for the discussion, John Freeman - Director of Architectural practice Church Lukas, Simon Orrell’s - Managing Director of Frame Wise & Director of the UKTFA, Pete Blunt - Managing Director of Innovare Systems, and Stewart Dalgarno - Director of Product Development at The Stewart Milne Group.
Discussion panels have become a familiar feature to construction industry conferences, though their timeframe rarely allows the participants the chance to make more than a couple of points before the chairman has to announce the speakers for the next session. I therefore welcomed the opportunity to attend and chair a debate arranged and hosted by leading offsite fenestration specialists Sidey Limited to hear the views of some of the major players in the off-site manufacturing sector, along with those of an architect whose practice has broad experience of the markets served. Whilst accepting that those involved with renewable technologies might hold quite different opinions, given that this is a Fabric First orientated debate I hope that readers of MMC Magazine will find this overview of the discussions informative and stimulating.
Asked initially to offer their own definitions of “Fabric First” as a concept, Stewart Dalgarno from the Stewart Milne Group said: “For me, it’s about speed of construction, quality of construction, and getting your superstructure up with all the windows, doors and insulation integrated – wind and watertight – so that you can carry on building inside, efficiently”.
“Then not only have you got a good external envelope in terms of energy performance, but also a weather-tight and secure shell. The traditional approach – getting the blockwork up but leaving the openings for windows and doors, and putting a roof on some time later – is a lot more disjointed and piecemeal.”
I questioned Stewart as to whether he therefore believed that factory prefabrication also offered an advantage in delivering ‘as-built performance.’ He responded: “There is a far higher likelihood you will achieve the as-built performance figures, than if you are relying on all the workmanship, skills and supervision being carried out on site.”
This was a point echoed by Mike Stevenson of Sidey whose KitFix ® system is now playing such a pivotal role in enabling fenestration to be included in the offsite process as a part of the main structure; “only by building with a ‘fabric first’ approach can you truly justify the claimed energy performance figures of the entirety of the integrated structure, rather than rely on the often over-stated achievements of products installed later”.
Simon Orrell’s, MD of Frame Wise, added: “I think these days it is all about solutions, rather than individual products because, at the end of the day, do you want a house built by individual people, under site conditions – where it’s sunny one day and snowy the next – or a factory-fitted, structurally airtight, thermally efficient solution.
“It is a case of Fabric First - fit it and forget it – because you are actually in control of the performance of that building. You haven’t got on-going maintenance costs, on-going running costs, and you are not fitting products to the structure to help them perform today which in reality could fail in five or ten years’ time.”
As an architect who has worked on many housing as well as student accommodation and other projects, Church Lukes’ John Freeman offered a slightly different perspective. He said he viewed Fabric First as a “strategy,” and as “the only approach which genuinely considers the trade-off of energy consumption in the round.”
He continued: “ For us, as a practice, this is probably the key difference from low to zero carbon technologies, which seek primarily to meet current energy demands in the home by promoting solar and wind generated energy at a massively subsidised rate and with a limit to their efficiency”.
“Fabric First on the other hand, seeks to limit actual energy consumption by utilising the heat energy which is a by-product of modern lifestyles. So, effectively, within a housing design, we see it as a means of using (just) one input of power to the building, rather than paying for two energy sources: one for all our electrical devices, and then another required to heat the building. It can be argued then there is a socio-economic dimension to Fabric First that is currently not promoted.”
If you offered the public a car that you would only have to put fuel in occasionally, they would buy it. The same principle is true of a ‘fabric first’ constructed house.
What was coming to the fore was that there is a general need for education and support, both industry and government, and society wide when it comes to Fabric First. The off-site sector frequently compares its efficiency to that of automotive manufacturers, and a telling comment came when it was remarked that if you offered the public a car that you would only have to put fuel in occasionally, they would buy it. The critical point being that we need to educate house purchasers that Fabric First means you would only need to turn on the heating in extreme weather conditions, whether it was a renewable heat source or a gas boiler.
It was also the view that there was a need for much more support from government. Other products and other sectors are significantly subsidised, when in-fact Fabric First appears to be stymied by outdated legislation, although the first green shoots of legislative support are starting to appear.
When John Freeman noted that Building Regulations did not offer a level playing field for Fabric First to compete, Stewart Dalgarno reported that although Scotland’s Climate Change Act stipulates the use of 15% micro-renewables, lobbying has brought about the prospect of amendment which – from 2014 – could include “all forms of carbon reduction technologies,” including Fabric First and offset strategies. Apparently the planning authorities in Aberdeen have already accepted that a new development of 800 homes will achieve the 15% through enhanced building envelopes. What the panel all agreed was the “common sense approach” to energy saving has won recognition.
In particular, it was noted that the Scottish Government has recognised the country’s expertise in timber frame as a core strength north of the border, and a more logical way of tackling carbon reduction that importing PV panels from the world’s highest carbon economy.
Our panel also dismissed the fallacy that a Fabric First approach reduces the number of dwellings which can be built on a site, due to greater wall dimensions. Simon Orrell’s observing that housebuilders were now following commercial developers by adding extra insulation, but switching to lightweight, thinner cladding solutions.
Peter Blunt, MD of Innovare Systems expanded on this saying: “The other side is the understanding of how they (clients) approach it, so if you examine the specification for a building, they’ll quote U-values and almost forget about airtightness and thermal bridging. The point being that you can have a U-value of 0.1, but if you go to backstop Y-value on that, and backstop airtightness, you will get the same energy usage as you would with a U-value of 0.2: you just have to be cleverer with the detailing.”
This insight prompted John Freeman to cite contractors’ reluctance to attempt airtightness figures of below 6; and their assumption that achieving it by using SIPs systems would involve the same on-costs as they would incur in terms of site supervision if they were to build in a traditional manner.
It was in fact generally felt that contractors had lost the in-depth understanding of how to build, having replaced it with adeptness at bringing sub-contract packages to site. Our panellists felt that, across the board, large contractors failed to grasp the importance of interface detailing; having largely got rid of design managers from their teams. Furthermore, their reluctance to put too much reliance or risk with one supplier, stifles the adoption of holistic solutions. It is clear and was widely agreed that this mentality has to change, and that sub-contractors have to be invited into the design process from the outset, and be a part of the overall construction brief.
Stewart Dalgarno benefits from the developer perspective offered by sister company Stewart Milne Homes, but justifiably lamented that the ‘valuation community’ does not recognise the long term running cost savings offered by low energy homes; instead giving a Code 4 or 5 dwelling the same market valuation as second hand properties when it comes to the end user borrowing money. Peter Blunt remarked: “Fabric First is not going to gain traction just on the back of legislation, it has got to be driven by market forces and education”.
Could Government implemented mechanisms redress the balance? Both council tax and stamp duty tax relief were considered possible solutions.
Mike Stevenson of Sidey concluded the discussions by calling for more companies to join the debate on the value of building ‘Fabric First’ and to help to create a wider market awareness of the philosophy. Like all the other attendees he would like to see pressure applied to ensure a level playing field when it comes to government and legislative support, and an open discussion on the truest way of constructing to ensure the maximum performance when it comes to energy efficiency in construction in the UK.