Wednesday, 24 May 2017

Testing technology

The government spent £17 million testing cutting-edge green technology in preparation for widespread retrofitting of the UK’s homes under the green deal. So what did it learn? Mark Wilding reports

You could retrofit a lot of houses with £17 million of taxpayers’ cash. But that was never the intention of the government’s retrofit for the future programme - it was all about innovation. Hence the majority of this substantial sum was split between just 86 projects led by social landlords. Each was allocated £150,000 and a monitoring programme, not only to test cutting-edge green technology in a variety of property types, but also to identify the obstacles standing in the way of its widespread adoption.

But, nearly 18 months after the experiment was announced, and a year away from the start of the government’s flagship retrofit programme, the green deal, the housing sector has yet to learn some of the valuable lessons the programme has to contribute towards the UK’s ambition to cut carbon emissions by 80 per cent by 2050.

Sustainable Housing receives frequent press releases publicising the latest ‘innovative, exemplar retrofit scheme set to achieve 80 per cent carbon cuts using cutting-edge technology’. Great. But given a £150,000 spend and, in some cases, more than a year’s work, this is surely expected? And social landlords leading the retrofit revolution don’t need this gloss - they need to know where projects went awry and what best practice can be shared from these experiences so they are better placed to retrofit at scale.

This will happen eventually, but many retrofit for the future schemes have only just been completed and monitoring by the Energy Savings Trust has either not yet begun or it is too soon to see any meaningful results. In fact, this is set to continue into 2013 with the first results emerging next year, ahead of the launch of the government’s green deal, which funds energy efficiency measures through the reduction of future fuel bills.

We decided to speak to the architects behind the retrofits to bring some early onsite lessons to the fore. So, what are the major challenges and how can they be overcome? Here, we identify five key areas.


The poor airtightness of much of the UK’s existing housing stock creates a significant challenge. Much of the technology used in the retrofits had been extensively tested beforehand, meaning it was expected to perform if fitted correctly. But airtightness required a very precise process, with margins for error much lower than for other construction projects.

Bere Architects worked on projects in the London borough of Tower Hamlets for 25,000-home Southern Housing Group and in west London for arm’s-length management organisation Hounslow Homes. The practice found that the properties performed in unexpected ways. Partner Dan Gibbons says: ‘We found one of the main areas where properties weren’t as airtight as expected was the floors. It looked like there was an air path through the timber floors into the party walls [the partition walls between houses] where they were penetrated by joists.’

In Tower Hamlets the original permeability target was one air change per hour - one being a high level of airtightness. Additional insulation meant a measurement of 1.7 changes was eventually achieved.

Party walls created the same problem for Anne Thorne Architects at its projects in Haringey, north London, for Metropolitan Housing Trust and in Stoke-on-Trent for Sanctuary Group. ‘We hadn’t anticipated air escaping through the joists and through party walls,’ says architect Jennie Swain. ‘It was a real shock.’

The practice had also hoped to achieve one air change per hour but was forced to settle for just under two at Hawthorn Road, in Haringey, and between three and four in Stoke-on-Trent. The difficulty in meeting the original targets suggests the extent to which airtightness can help achieve carbon reduction targets may have been overestimated.

Space constraints

Lots of impressive energy saving solutions are possible in new build houses, but problems can crop up when trying to replicate the same approach in existing homes. Technology such as whole house ventilation and heat recovery systems can demand a lot of space, which might be in short supply.

Ms Swain, explains the need to assess the space available early on. ‘We were using a whole house ventilation system [in both projects],’ she says. ‘One thing you really have to grapple with is finding a space in an existing house and duct routes that are unobtrusive. It took up more space than we thought. There is not only the box but also quite large ducts that you have to insulate and we needed more room than we originally planned. Next time, we would plan in more detail before going in onsite.’

The amount of space required will inevitably mean some properties are unsuitable for this type of technology. Prewett Bizley Architects designed a retrofit in Balham, south London, for Family Mosaic. Architect Robert Prewett says: ‘It’s all very well to say you will install a box and duct work - in a new house you have a reasonable chance of that happening. But in a retrofit situation you have walls that are immovable and an existing network of joists. Trying to stick a ventilation system into that is quite a challenge.’

Supply chain

The availability of products proved to be a major issue for some of the projects. In some cases, innovative technology that was supposed to be available wasn’t, and less suitable solutions had to be used. For example, one insulation product was meant to be used in several projects but manufacturer Aspen Aerogels was unable to keep up with demand. ‘There wasn’t enough product to go round all the projects and the cost went up by around 10 per cent during the programme,’ says Andrew Mellor, head of environmental at PRP Architects. Aspen Aerogels is aware of the problem and says it intends to gear up production.

When demand outstrips supply on a programme of 86 projects, concerns are inevitably raised about whether the industry is ready for a nationwide retrofitting drive. And even when products were available, unexpected procurement delays caused problems on some projects. ECD Architects worked on several projects using windows from the Green Building Store. ‘It was a steep learning curve,’ said Ruairi Kay, senior architectural technologist. ‘These high-performance windows were quite new to the market. We’re talking about a 12-week lead-in time. But the windows need to be there at the start of the project. That caused some significant delays.’

Mr Mellor also says that there were concerns about repairing Pilkington vacuum glass, which a lot of people wanted to use but is only manufactured in Japan. ‘The glass is relatively cheap but it takes a long time to replace. There were concerns from housing associations that if it got smashed they would have to board the window up for weeks.’

Paul Ruyssevelt, a consultant for the government’s Technology Strategy Board, which funded retrofit for the future under the small business research initiative, concludes: ‘The supply chain is going to be a critical issue for the green deal programme and that’s why it’s going to be very important to identify the measures that can be used early so that the various manufacturers can gear up to expected demand.’

Communication and training

Several retrofit for the future projects reported issues surrounding communication, or lack of it, onsite. Lack of understanding among sub-contractors about the aims of the project was cited on more than one occasion. At best this was frustrating. But in the worst cases, it had severe programme implications.

Penoyre & Prasad designed the Warwall Road project in Newham, east London, for East Thames Housing Association. Architect David Cole says: ‘When reviewing the project, we were all asked if we were to do it again, how would we do it better? A lot of that was to do with better communication with contractors. Better training of contractors is needed and making sure that everyone onsite has the right information, rather than just making it up themselves.’

It was only because of weekly site inspections that Mr Cole noticed sub-contractors weren’t following instructions with regards to materials - a crucial aspect of any retrofit project. As a result, a 12-week build programme was continually delayed and finally completed in week 33.

‘Throughout the project, people were ordering the wrong materials and even fitting the wrong materials,’ says Mr Cole. ‘Quite fundamental parts of the project, such as the wrong insulation, were fitted. We didn’t realise that it’s sub-contractors who order the materials, not the main contractor. That came as a surprise.’

The TSB’s Mr Ruyssevelt concludes that communication has been one of the greatest stumbling blocks for the projects so far. ‘It’s critical on any construction project to have good communication, but when you’re working in an existing building, if communication isn’t very good, it’s easy for things to fall between the gaps,’ he says. ‘You don’t always have the same level of site supervision as you would on a new build site.’

Paul Davies, sustainable technology manager at contractor Wates Group, which worked on nine retrofit for the future projects, concludes there needs to be training ‘across the whole supply chain, from consultants to contractors’. ‘There aren’t enough people out there who understand the issues involved in retrofitting. A lot of people doing the work need training to understand why they are doing it. Communication is vital, but it needs to have everybody involved,’ he added.


In the case of many of these schemes, challenges were eventually overcome, and they are producing some impressive results. There is, however, one especially big problem the programme highlighted: cost. Despite the vast sums spent, many schemes struggled to complete on time and within budget. What does this mean for the green deal - and can techniques tested on projects costing up to £200,000 be rolled out across the UK for around £10,000 a home?

Mr Ruyssevelt answers this question bluntly. ‘The green deal is not going to cut it because it’s very unlikely to finance some of the more expensive measures,’ he says.

But he adds a note of optimism: ‘That’s not to say they won’t happen because social landlords, in particular, will be looking at composite packages of funding with energy company obligation [subsidy from fuel bills] and putting some of their own money in.’

But even with additional sources of funding, bringing costs down will be essential. The green deal will provide economies of scale and opportunities for more efficient uses of technology across whole terraces rather than individual houses. But some of the technology used in this pilot scheme, such as whole house ventilation and heat recovery systems which are bulky and hard to install looks unsuitable for widespread use due to problems finding space.

Other, more radical solutions involved significant changes to the layout of the property or other major work, often taking advantage of a vacant property. Some of those that took part have expressed scepticism that this approach could be repeated widely due to the need to decant tenants at great cost. Justin Bere, director of Bere Architects, is one such sceptic: ‘To achieve the results we need to, we’ll be retrofitting 13,000 homes a week,’ he says. ‘I can’t imagine we’ll be putting all those people into hotels.’

Maybe not hotels - but perhaps, as our Eco Doctor suggests on page 32, holiday camps?

Ultimately, these challenges are exactly what the retrofit for the future programme was intended to uncover. By identifying the practical hurdles now, landlords can start to try to innovate practical solutions to these problems before the £7 billion a year green deal kicks off next year. In that context, the £17 million spend doesn’t sound like very much at all.

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