Retrofit radicals: housing can be energy efficient and beautiful

At first glance, John Christophers’ house in Balsall Heath, Birmingham, resembles the kind of statement home that many architects design for themselves. A bedroom extension in bold, contemporary style extends out over the street, while the roof of a top-floor extension is angled to ensure an array of solar panels catches the sun.

But, looked at from closer up, it becomes clear why this house — which Christophers calls the UK’s first zero-carbon house — has become a flagship example of how an approach known as “deep retrofit” can transform the energy efficiency and aesthetics of the UK’s built environment.

Parts of the building’s front continue the red brick walls of neighbouring properties. The neoclassical window frame reflects the terraced houses’ early Victorian construction. Meanwhile, the walls’ thick layer of cellulose insulation, known as Warmcel 500, illustrates how the house’s energy-efficiency has been upgraded to exacting contemporary standards.

The bold and sharply contrasting styles have helped to make the Balsall Heath house a landmark. Although work was completed in 2009, it remains an inspiration for many architects and campaigners seeking to reduce the tendency of UK homes — some of Europe’s oldest and least energy-efficient — to leak heat and carbon dioxide.

Imandeep Kaur, founder of Civic Square, which calls itself a “neighbourhood economics lab” for Balsall Heath, says the house has shown the potential for retrofit to renew the whole feel of an area. “Examples like John’s start to tell a story that retrofit can be beautiful, can be brilliant,” Kaur says.

As well as the climate crisis that originally inspired Christophers, the need to retrofit has been given impetus by this year’s jump in UK energy prices. In August, Ofgem, the industry regulator, announced it would allow typical household bills to rise a further 80 per cent in October from levels already well above the recent average. This week, the new prime minister Liz Truss announced that the energy price cap would freeze about 27 per cent higher than its current level.

According to Justin Bere, a London-based architect specialising in energy-efficient retrofitting, the recent price rises have pushed up the number of calls he has been receiving — which had already been at a high level for some time. “We’re inundated with inquiries,” he says.

In March, the UK’s independent Climate Change Committee, which issues advice on environmental measures, said that improving the energy efficiency of homes was “one of the easiest and most cost-effective steps to reduce the impact of high bills in the near term[ . . .] Recent events have shifted the calculus on this even further in favour of taking decisive action now,” it added.

Kaur says that in Balsall Heath some householders face serious financial problems thanks to their homes’ current poor insulation. “A real retrofit is one of the biggest challenges of our time,” she says.

Yet Christophers’ house remains a relatively rare example of a radically refitted, energy-efficient older house because recent UK governments have shown only limited enthusiasm for stemming buildings’ leaks. Christophers designed his retrofit to meet the highest, “true zero carbon” level of the Code for Sustainable Homes, introduced under the last Labour government as a voluntary standard in 2007. The standard was withdrawn in 2015 and has never had an official, government-set replacement.

He insists, nevertheless, that his project makes a philosophical and aesthetic point as well as a practical one.

“I’m trying to show a manifesto architecturally — that we can still have a great quality of life with a microscopic carbon footprint,” Christophers says. “The same is true of energy use — we’ve throttled down energy use by 95 per cent in the whole big house in comparison with the old, smaller house.”

Christophers says efficiency and beauty are linked. “If we’re looking through the lens of the carbon footprint of these things, can it really be beautiful if it’s unsustainable?” Christophers asks. “I think a high-carbon product has to become abhorrent to us.”

But although there is no suggestion that they will produce the huge energy-efficiency improvements of projects such as the zero-carbon house, there are some more incremental steps that householders can take to improve their homes’ fuel efficiency.

Martina Pardo, founder and director of Designer at Heart, an interior design consultancy based in Finsbury Park, north London, suggests people should rethink how they manage their houses. She points as a model to the approach to energy conservation of her relatives in her native Sicily. To reduce reliance on air conditioning in the hot climate, they keep rooms shaded from the sun as it moves during the day, while opening windows on the side that has cooler air.

In the UK, Pardo suggests, it might be appropriate to use thick, warm rugs in dark colours on floors in winter, then switch to lightweight alternatives in summer. “You think of the house almost like needing clothing,” she says. “You need to dress it for the season.”

The work to extend Christophers’ house drew on similar thinking. The new extension to the original 1850s terraced house, into what was once the house’s garden and a vacant space, features a kitchen and dining area with a floor-to-ceiling glass wall. The glass was positioned, according to Christophers, at a 15-degree angle to the old structure’s walls to catch the rising sun an hour and a half earlier each morning than if they had been aligned.

The change has contributed to the sharp decline in the new, larger house’s use of energy for heating to just 7.3 Kilowatt Hours (kWh) per sq m annually, compared with 160 kWh per sq m per year in the old, smaller property.

“This glass is providing about a third of the heat we need [for the house],” Christophers says.

The need to transform UK buildings’ energy efficiency has been clear since long before this year’s European heatwave and vertiginous energy price rises. The Committee on Climate Change estimated in 2006 that 13 per cent of the UK’s greenhouse gas emissions come from energy use in homes — a figure that, in 2020, hit 16 per cent because more people stayed at home.

It has said that their energy use needs to drop 24 per cent by 2030 as part of a gradual process of meeting targets to reduce the UK’s net carbon emissions to zero — a state where carbon emissions are balanced out by carbon absorption. Neither the 2030 target nor the 2050 target currently looks likely to be met.

The challenge is particularly urgent, according to James Rixon, a London-based architect and co-ordinator of the Architects’ Climate Action Network, a campaign group, because around 80 per cent of current buildings will still be standing in 2050. “[That] means that our existing building stock needs to be upgraded to net zero [standards] by that point,” Rixon says. “The likelihood is that the house you’re living in now will need to have something done to it to improve its energy efficiency.”

One starting point, according to Pardo, can be to repaint surfaces a colour that will improve their ability to absorb heat, reducing the need for heating in winter.

“Darker colours trap more heat,” Pardo says. “You can look at the surfaces that are directly affected by the sun in that room and paint them darker colours, trap more heat and retain more heat. Sometimes just painting the ceiling in a darker colour can help.”

A house part way down Lena Gardens, a quiet side street in Brook Green, west London, demonstrates how energy-efficiency and aesthetic upgrades can be accomplished even when there is less appetite or scope for the kind of wholesale facelift that Christophers has undertaken.

You think of the house almost like needing clothing. You need to dress it for the season

Bere, whose firm planned and oversaw a comprehensive refit of the house, which was completed in February 2020, points out some subtle aesthetic improvements that set it apart from superficially similar neighbours in its three-storey Victorian terrace. Modern mortar was removed from between the bricks and replaced with an alternative more similar to that used originally, according to Bere. The bricks’ surface was rubbed, to give what Bere calls a “digestive biscuit” texture.

“I think that’s a beautiful-looking house externally,” he says.

For insulation, the Lena Gardens building’s external walls were fitted on the inside with 20cm of wood-fibre insulation, to retain heat in winter and keep cool in summer. Loss of internal space is a disadvantage of such insulation. But Bere says he and the client agreed the reduction was barely noticeable.

The new surface inside the house was also a marked improvement, according to Bere. The client, who wanted to minimise the use of materials that would exacerbate his children’s asthma, asked for traditional, clay-based plaster rather than a more modern, chemically based alternative. The plaster was applied on top of the insulation.

“It has a wonderful, natural aura and smell,” Bere says of the plaster. “There’s a slight softness to the surface visually.”

The client has fitted external, electrically operated blinds above the front windows — which are triple-glazed but in wooden frames indistinguishable from the original sash windows. The blinds — barely visible when rolled up — can be lowered in warm weather to prevent solar warming of the building’s interior.

Bere proudly shows a graph that his client produced showing the house’s internal temperature remained around 22C on July 19 this year, the UK’s hottest-ever day, when the heat outside reached 38C. The house remained cool without use of any air conditioning.

According to figures compiled by the client, who asks to be identified only as Roberto, energy use in the house for heating and hot water has fallen to around 32 kWh per sq m per year. The figure compares with typical usage of 150 kWh to 250 kWh annually per sq m for a similar, unimproved house.

Calculations by Roberto show that rising energy costs pushed the house’s energy bills to £1,896 for the year to August, up £693 on the year before. He calculates that for a similar-sized house heated to a similar temperature with more normal insulation, the annual bill would have risen by £3,250, to £8,890.

Bere says it is “really pleasing” to hear of such improvements.

Rixon says retrofitting projects in the UK capital often have to take the approach that Bere did at Lena Gardens. “On a typical London house, you’re going to keep the facade,” Rixon says. “Everyone loves brick.”

Christophers agrees on the value of retaining some traditional elements during updates, saying the appearance of Victorian-era streets is “intrinsic” to many British cities’ atmospheres. The eye-catching contemporary section of his house was added to the building’s rear and side. Planners are generally far more ready to allow changes to the rears of Victorian buildings, which were typically built to lower standards.

“We can keep our Victorian heritage but also reimagine it,” Christophers says. “I think we can make something which is really exciting as well from it.”

Nevertheless, the House-Within-a-House, an award-winning retrofit project in Brockley, south London, shows the possibilities of working outside such constraints. The project, by London-based Alma-nac architects, involved the fitting of a highly energy-efficient shell round an energy-inefficient 1950s building.

Tristan Wigfall, a partner at Alma-nac who was involved in the project, says that since completion of the project in 2019, the new, larger building annually emits about half the 7.6 tonnes of carbon that the smaller, older building did.

“We effectively put a warm coat round the top of it,” Wigfall says. “That’s what I would call a deep retrofit.”

The transformation of the building’s appearance was permitted because the existing building was built hurriedly to replace one destroyed by second world war bombing and of poor architectural quality. The new shell echoes the lines of the large, neighbouring Victorian villas, while being unapologetically contemporary.

“For that project, because it was such a nondescript box, effectively anything we did was improving it visually,” Wigfall says. The constraints on changing older buildings are a brake on the UK’s ability to improve the energy efficiency of its 29mn homes in time for 2050, according to Bere. External insulation can often be fitted more quickly, easily and cheaply.

“If it’s considered by planners to have heritage value then so far we’ve not been allowed to do external insulation,” Bere says, adding that there is currently no sign of a relaxation of such stances. “There certainly ought to be a trial, an attempt by someone like us, with agreement of the planners, to do, for example, a beautiful, externally insulated 19th-century building.”

Pardo insists that there remain small steps that homeowners not ready for a full refit can take to marry lower energy consumption and superior style. She suggests that cork tiles can be an elegant way to improve a building’s energy efficiency if applied to the inside of an exterior wall. “There are some things that people can do,” she says. “It’s a matter of being a bit clever.”

For more radical retrofitting, meanwhile, Kaur says the task is so huge that it should be seen as an opportunity to reshape the national fabric. “There’s an opportunity to see retrofit as a moment of real renewal in the country,” she says.

Bere says the key is for all architects to make a more concerted attempt to marry environmental and aesthetic aspects. “So often you’re either an environmental designer or you’re an architectural designer.” He acknowledges that it will take harder work for the profession to balance the two disciplines. But he adds: “There should be no reason why you cannot be both.”

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