Playing all the angles

Building: 110 m2 detached home and office
Build method: Brick & clay block cavity wall with timber frame elements
Site & location: Urban infill site, Tottenham, London
Standard: Fabric-first low energy dwelling (no specific standard)
Budget: £325,000 (build costs)
ENERGY BILLS £35 PER MONTH FOR ALL HEATING & ELECTRICITY (includes feed-in-tari", see ‘In detail’ for more)

The award-winning Angle House is a low energy dwelling sandwiched between Victorian terraces on a previously neglected site in Tottenham. The two-bedroom home and office was co-designed by Italian architect Andrea Carbogno and his partner, French architect Sophia Ceneda.

Although the couple now live there contentedly, transforming the original run-down plot into a comfortable home took longer than expected and provoked much stress. Not only did the narrow site present design constraints, but there were long delays, and the build stretched the project out.

“There were times when it was one of the most stressful experiences I’ve ever had. We were so invested in it as our personal project. But now it is all over living in the house is great,” says Andrea.

“The interiors are modern and it’s very functional. Everything is open space, and all the transition spaces are made use of, and are user-friendly. It’s big enough for large gatherings of family and friends, but not too big for two of us. We’ve designed it with lots of natural light and it’s tightly enclosed. But there are views out to back gardens on one side and at the front there’s a little courtyard with greenery.”

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Both Sophia and Andrea had always wanted to build their own home. In part this was to take advantage of their skills, but it was also for cultural reasons. “I’m French, but my family is all from Italy, where it’s a longstanding tradition to build your own house,” says Sophia. “My grandfather built an incredible house in France and I always thought I’d build my own home. I just never thought it would be in Tottenham!”

Neither Andrea nor Sophia began their working lives as architects. Andrea studied accountancy in Italy, before leaving the picturesque Dolomites for London in 2000. For a couple of years, he worked in bars and restaurants.

Then, in 2003, he enrolled at the School of Architecture at London Met, where Sophia was taking the same course. She had arrived in London with a background in geopolitical studies and worked for human rights groups. But like Andrea, she found herself drawn to architecture, especially sustainable design.

The house was the winner of the dwelling prize at the 2020 New London Awards.

Before striking out on his own, Andrea worked for a decade for a London firm designing high-end residential homes. Then in 2014, the couple founded Carbogno Ceneda Architects, in Tottenham. Sophia still works full time as architect and sustainability lead at Glenn Howells Architects, but helps Andrea with business development and some design.

Angle House was the first time they designed a house together.

The couple began to look for a site to develop eight years ago while they were living in Sophia’s Tottenham flat. Her rule of thumb was that the combined cost of the land and the build should be “no higher than it would cost to purchase and refurbish a house in the same area”. Based on these parameters, they needed to find a bargain, but Tottenham was gentrifying fast and prices were escalating. The best site they could find for £100,000 was a section of the garden at the end of a row of terraces. It required a lot of imagination to see beyond the debris. “It had been sold 14 years earlier to a man from Birmingham doing shop-front glass glazing. There was a massive prefab concrete structure wrapping around a caravan, where he slept when he came down to work. There were lumps of concrete strewn on the floor,” says Andrea.

The site had a poor history in planning terms, and it became clear that it would be a challenge to get planning permission even for a modest two-storey structure. In 2013, the couple submitted a simple design that focused on massing, layout and orientation for outline planning permission. There was an agonising wait for planning, and once it was granted, the sale was rushed through.

Andrea and Sophia spent the next six months refining the original design in their spare time. In general, there was a lot of harmony between their ideas, and few disagreements. However, Sophia insisted on a staircase in the middle of the dwelling and Andrea refused to have any corridors. Sophia took charge of the sustainable elements. Having taken courses at the Centre for Alternative Technology (CAT) in Wales, she was cognisant of passive house principles.

Sophia opted for a zinc roof, although it was more expensive, and a smaller 20 square metre green roof at the back which is made of fibreglass and will eventually be covered in wildflowers. The couple opted for a hybrid construction, with a brick-and-clay block full-fill cavity wall on the ground floor, and on the first floor, a mix of this build-up plus timber frame wherever the footprint is set back from the ground floor wall. The house also achieved airtightness of 1.87 m3/m2/yr, though this was prior to completion, and it has not yet been retested.

All of these measures raised the energy performance to near the passive house standard.

It’s possible to deliver low-energy buildings without relying overmuch on technology.

“We aimed for passive house space heating at 15 kWh/m2/yr, and we ended up slightly above it at 27, which is 85 per cent less than a standard UK house,” Sophia says.

The tightness of the site demanded some ingenuity.

The road is L-shaped, and the house lies at the short end. It’s the only home on that side fronting the street. Immediately to the left, there is a terraced house, and to the right, there is a row of houses. The planners wanted the couple to set the front of the house back from the road, but they saw this as being against urban design principles, and during a redesign they had to negotiate the extent of this setback. “It’s like extending the street of terraced houses by adding a new unit at the end, however the unit is pushed back due to the triangulated shape of the site, because it’s too narrow at the front. We replicated the gable wall geometry of the end terrace to our street elevation, so there’s continuity to the sequence of angled roofs. Our house is subservient to the terrace which, as a design strategy, helps comply with planning guidelines,” says Andrea.

Most of the neighbours were excited when the two architects presented their plans. One of the neighbours said it was like watching an episode of Grand Designs right on their doorsteps.

One woman whose garden overlooked the new house was a bit concerned about light.

“But when she checked the design on the planning portal, she could see how the green roof would be set back from the rear elevation so it wouldn’t block out the light. Her response was ‘it will be much nicer than overlooking a dump yard’.”

In June 2014, the couple submitted their revised plan and received approval 12 weeks later. However, work did not begin on the development until October 2015. The initial expectation was that the build would take between 12 and 18 months. In the event, it went on for two-and-a-half-years and the couple didn’t move in until June 2018. “It was another stressful period. As architects, you are in control until a certain point, then you hand over the execution and so many points of conflict can erupt,” says Sophia.

We’ve designed it with lots of natural light and it’s tightly enclosed.

The main contractor for the structural works hired a team of builders based in Reading, over fifty miles from Tottenham. This restricted their time on site, and the truncated days meant the build dragged on. Sophia praises the contractor for executing the works well, “despite the builders being out of their comfort zone with a fabric first design like this”. There were also some delays due to a series of misunderstandings, such as when the builders assumed the ground floor slab was ground-bearing, when it was in fact suspended.

As planned another contractor was brought on to carry out the M&E works and internal finishes including the stunning staircase, but there were further delays. Sophia believes contractors in London often stretch themselves thin across multiple jobs, which can lead to delays. “These were the only times Andrea and I had arguments as we didn’t always have the same strategy for dealing with the contractors. However, on the whole the works carried out was well executed.”

The couple finally moved their belongings across to Angle House in the summer of 2018. After a few days sleeping on Sophia’s floor while the electricity supply was connected, they were finally able to sleep in their new 110 square metre home. The more spacious ground level is 75 square metres and would work as a self-contained one-bedroom flat. “An elderly couple could easily live downstairs as there’s a bedroom, bathroom and wheelchair access,” said Andrea. Upstairs there is a further 35 square metres of space, which is enough for a second bedroom with a bathroom and an office space that is separated from the stairs by timber slats. It could also be transformed into a third bedroom. “It’s not a large house, but it uses the space effiiently,” he says.

Sophia’s awareness of passive house principles paid dividends. Even when temperatures fell to zero in January this year, the couple only needed to switch the heating on for a couple of hours a day, and their annual bill for gas and electricity is a modest £400, excluding charges. The couple very rarely use the bathroom radiator upstairs, or the portable electric radiator they bought for the office. Though Sophia took the lead in developing the low energy aspects, Andrea is also passionate about sustainability. He recently took his exams as a passive house designer and intends to take his tutors’ advice to test the house using PHPP software against the Passive House Institute’s low energy building standard (a less onerous alternative to the classic passive house standard). “I’m hoping the course will set me up to expand the services we can offer.

I was drawn to passive house because it’s possible to deliver low energy buildings without relying overmuch on technology. But I’ve got a lot more detailed knowledge now,” he says.

The house was the winner of the dwelling prize at the 2020 New London Awards, and was shortlisted for small project of the year at the Building Awards last year too. The couple also achieved Sophia’s goal of not spending more than they would retrofitting a property.

The overall cost was £425,000, including a £325,000 mortgage in addition to the £100,000 cost of the yard. In 2018 the house was valued at £650,000. “We’ve proved you can still do something really nice in London for under £500,000, and the house is a case study demonstrating our skills as sustainable designers too,” says Sophia.

1 The run-down plot had an existing prefab structure and other debris which had to be disposed of; 2 Coredesk Cellcore Plus insulation1 The run-down plot had an existing prefab structure and other debris which had to be disposed of; 2 Coredesk Cellcore Plus insulationwas installed under the ground floor; 3 wall build-up showing 90 mm bricks externally, 200 mm Knauf Earthwool insulation, and 100 mmPorotherm clay blocks; 4 the use of low thermal conductivity Teplo-L-Wall ties minimises thermal bridging; 5 the first floor timber frame withan opening for a roof window; 6 insulated cavity closer; 7 175 mm Knauf Earthwool rafter roll within roof rafters; 8 & 9 airtightness measuresincluding Intello membrane and taping around windows.

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