Friday18 August 2017

Are architects ready for a retrofit revolution?

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Getting energy-efficient retrofits through planning is tough at the best of times, but the Green Deal is set to bring the issue into sharp focus

Replacement windows and external cladding have often been stumbling blocks for period properties but, with the Green Deal launching later this year, the thorny question of how to get an energy-efficient retrofit through planning is coming to the fore.

“I don’t think people are talking about it enough,” says Mark Elton, head of sustainability at ECD and a member of the RIBA Sustainable Futures Group, who has been researching the issue. “The risk is that it’s a barrier to widespread uptake.”

Mark Elton, head of sustainability at ECD

Mark Elton, head of sustainability at ECD

A key issue, adds Elton, is an inconsistent attitude among planners to external wall insulation — one of the most effective retrofit measures — which can result variously in sub-standard solutions, intransigence and sometimes off-puttingly costly and time-consuming planning procedures.

“We find completely varying responses from local authorities in different areas. A lot of areas let you go ahead without a planning application; others require you to make an application even to ask the question,” says Elton, adding that this puts even more pressure on the already overloaded planning system.

“The planning industry seems ill-prepared for an influx of Green Deal-driven applications for external wall insulation. What provisions are being made to address this barrier, perhaps through standardised fast-track applications for external wall insulation?”

‘In terms of achieving carbon reduction we need to do more than tinkering’

Meanwhile, architects involved in sustainable retrofit have been adopting a variety of tactics to upgrade the environmental performance of walls and windows. Bere Architects recently went to appeal — successfully — to win permission for a retrofit in a conservation area in the London Borough of Brent after the practice’s first application, which involved external cladding at the rear and flank of a Victorian brick property, was rejected on aesthetic grounds. The appeal process took a year, but Justin Bere hopes the case might create a precedent.

Bere Architects' north London house retrofit

Bere Architects successfully went to appeal to get approval for work on this north London house, which involved retrofitting thermal cladding at the rear.

“We explained to planners the technical difficulties and risks associated with internal insulation and the poorer savings that would be achieved as well, and explained the relative difficulties and merits of the two approaches,” says Bere. “We also explained that the building would look much better than it did before.”

“It’s [external insulation] the thing that will achieve the greatest benefit at the lowest cost.

In terms of achieving carbon reduction we need to do more than tinkering. External insulation can achieve significant and reliable energy savings,” says Bere, adding that it is also reversible if another solution is found in the future.

Conservation areas are notoriously frustrating contexts for sustainability retrofits, even when the changes are at the rear, says Robert Prewett of Prewett Bizley, who has found that such projects usually run into planning difficulties.

“As soon as you propose using external wall insulation hackles are immediately raised. It’s seen as an alien material,” says Prewett, who expects the Green Deal to provoke much more friction and debate in this area.

The practice has, however, had success with replacement windows and Prewett says architects need to be more assertive and set out the sustainability benefits clearly.

“There’s a huge amount of confusion among architects. Often they can get away with more if they are bold enough… If an Article 4 notice hasn’t been added often you can upgrade glazing as long as you stick with the broad fenestration pattern.

“Court them [planners] and charm them with your meticulous designs… If all else fails, grinding them down in a battle of attrition until someone believes you aren’t just doing greenwash will often get you there.”

Failing that, another tactic, especially for listed buildings, can be well-designed secondary glazing — Prewett Bizley has recently developed its own Sec Vac system that gives a u-value of around 1.0W/m2K.

Bere Architects' north London house retrofit

The retrofitted thermal cladding at the rear of a north London house by Bere Architects

ECD Architects has used a brick-effect render to address the issue of external cladding changing the visual appearance of the property. But in some cases, the changed appearance that results from external insulation can prove to be a planning asset.

“It cuts both ways. Planners are only too happy to overclad buildings they don’t like the look of, whether it’s in a conservation area or not,” says Dan Jones of Civic Architects, adding that the green agenda can generally be a powerful tool in a planning argument. “Planners feel less able to resist,” he adds.

With initiatives such as the Green Deal to boost retrofit, the ability to balance sustainability and aesthetics is becoming more important than ever.
“I’d like to see a consistency in approach. Planning authorities should have a responsibility to make it clear what their expectation is,” says Stephen Gleave, chair of the Royal Town Planning Institute’s Urban Design Network Advisory Group and managing director of architect and planner Taylor Young.

“There is definitely a conflict between achieving quick solutions to quantifiable environmental issues and the wider aesthetically responsible agenda about the legacy of the physical place we leave behind,” he says, adding that this tension inevitably increases where budgets are limited.

But it’s also the responsibility of the architect — and the householder — to find a way through, he says.

“Good quality design professionals need to explain and justify why their proposals are appropriate to the context.”


Readers' comments (4)

  • Robert Park

    External cladding at the rear with UPVC windows is fine. But I'm not quite ready to see our vernacular historic housing stock change its front-face just yet. Internal insulation and secondary glazing should do.

    It's all very well saying that “good quality design professionals need to explain and justify why their proposals are appropriate to the context", but most conversions will not be guided by any kind of design professional, let alone good ones.

    There is a danger that we might be opening the door to something we will painfully regret in the longterm.

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  • bere:architects

    If Robert is referring to the featured project, just to clarify there are no UPVC windows! All windows are high quality timber windows.
    With regard to the second and third point, good quality pilot projects are urgently needed across the country, with dissemination, otherwise in the long term the regret will most likely be that the UK should have acted to reduce carbon emissions more strongly and earlier.

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  • bere:architects

    The windows in the project featured in this article are beautifully crafted timber conservation sash windows made by a well established English company called Mumford & Wood. These windows match the originals so well that it is almost impossible to identify them against the original leaky single glazed windows which are still in place in the house next door. The only significant difference is a 100% improvement in energy performance and a huge comfort improvement for the occupants who are now enjoying their draught free windows. We have also taken the opportunity to install even higher performance windows in the two larger openings on the rear façade, these windows are triple glazed timber windows made bespoke for this project by a Passivhaus window company.

    The project also demonstrates that even with sash windows, when in collaboration with a high quality and highly skilled contractor, it is possible to achieve excellent air tightness results, this project achieved a result of 1.94 ACH-1 @50pa, approximately 5 times higher than the standard set for new build projects. Which is a great credit to Firmco’s site foreman Jamie Bartley and his whole site team.

    Response from Project Architect, Sarah Lewis

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  • Robert Park

    Sarah. I agree - this project looks lovely - a testament to your skill, and that of the contractor. And no UPVC in sight.

    But then, someone who lives in a house two doors down receives a letter through the door from a company who say they specialise in retrofit, and they know the planning system. Before you know it, an overworked planning officer gives consent for a development that on paper looks similar to yours, but in effect, is a world apart.

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