Paola Sassi: Home is where the hearth isn't

view gallery VIEW GALLERY

Architect Paola Sassi was so fed up with the amount of waste created by builders, she decided to construct her own energy-saving house. Tim Pullen takes a tour

A A A

You don't expect to find a contemporary, not to say minimalist, eco-house tucked into a quiet cul-de-sac of Victorian terraces in the Roath district of Cardiff. But that's only half the story because Paola Sassi has built her house, comprising two one-bedroom flats, to the German Passivhaus standard, which requires no central heating. In fact, no heating at all. On the mid-January day when I visited, the outside air temperature was just 7C, so it would not have been unreasonable to expect a chilly welcome. But the internal temperature was a comfortable 19C. And there was no heating – no central heating, no fireplace, no wood burning stove, no electric fan heaters, nothing.

The Passivhaus standard was established by the Passivhaus Institute in Darmstadt, Germany in 1996. Since then about 6,000 houses have been built and certified to the standard across Europe and the US. What Passivhaus means, in broad terms, is that the building is insulated to a level that allows the sun and other passive heat gains to produce enough energy to heat the home. Passive gain is the heat from daily activity, given off by people cooking, using the shower, making toast and boiling the kettle. Pretty much everything we do produces heat that can be captured and circulated from warmer rooms (bathroom and kitchen) to cooler rooms (lounge and bedroom) by a heat recovery and ventilation system.

Sassi has gone to some trouble to ensure that the sun warms the house with big triple glazed windows to the south elevation and solar panels on the roof. These produce most of the hot water she needs for washing, showers, laundry etc. and about half the electricity she needs. There are dual-flush toilets, flow-regulated showers and taps and a rainwater harvesting system which meets about half the water needs of the house. "I needed somewhere to live and could have bought a house cheaper," Sassi says. "But I wanted to prove that it is possible to build a house in a city centre that is sustainable, comfortable and cheap to run."

Sassi, a professional architect, was born in Turin and educated in Munich. She worked for 15 years in London at two architectural practices before taking up a post at Cardiff University's School of Architecture. It was working in London that informed her decision to focus on sustainable buildings. While working on large commercial projects, she became disenchanted with the levels of waste in the construction and use of the buildings. "It was our arrogant attitude that we can do whatever we want that struck me," says Sassi.

She decided that her house in Cardiff would be built entirely from sustainable materials and that every part of it, from the floor covering to the zinc roof, would be reusable or recyclable. She used hemp insulation throughout. Hemp has very similar thermal properties to its non-sustainable mineral wool alternatives, but has three significant advantages: it uses less energy in manufacture; it "locks in" the CO2 that the plant absorbed as it was growing; and it is entirely recyclable. It has been installed in such a way that when the house is finally demolished, it can just be taken out and used again in another house.

The internal walls are lined principally in plywood sheets from sustainable timber, coated with a natural wax. This has the twin affect of allowing the ply to be completely recyclable and giving a warmer feel to the house. Brick, plaster or stone walls feel cold to the touch, whatever the air temperature, which makes a room feel cooler. The highly insulated plywood walls are what make a 19C internal temperature comfortable when 21C or even 24C would be more usual.

A house that needs no heating needs a lot of insulation. Sassi has installed 380mm in the walls, 200mm under the floor and 430mm in the roof. This compares to the normal UK standard of 90mm in the walls, 75mm under the floor and 270mm in the roof. In also needs a very high level of air-tightness to prevent heat losses from air movement, and that is where Sassi's contractors encountered most of their problems.

Building air-tight houses needs precision and the typical British builder is not used to building houses in this way and to this standard. Sassi's contractors were forced to learn on the job and this led to a longer build time than expected. It also led to mistakes, and the extra cost involved in rectifying them.

"It was very difficult to persuade people to build as I wanted them to," Sassi says. "They wanted to do things their way." This meant that she had to work hard to achieve her goals, and did not always succeed. The ground-works contractor was instructed to keep any concrete from demolition work on site to be re-used on the new front drive. But, much to Sassi's annoyance, he had it taken away to landfill.

Sassi's is a timber-frame house, with all the timber sourced from sustainable forests. A typical UK timber-frame will use 100mm or maybe 140mm timbers. Sassi wanted 200mm and the manufacturer who was initially given the contract pulled out. A second supplier then had to be found, and a way of manufacturing, delivering and erecting the frames decided on. All of this added delays and cost to the project, so much so that Sassi and her partner finally decided to take up tools and do the internal finishing work themselves.

Was it worth it? Sassi is, quite rightly, proud of her achievement. "I knew going in that it would be tough, and really I took on too much", she says. "But the house I have built was worth it."

The project should have taken nine months but actually took 14. It should have come in at £1,200 per sq m but came in at £1,400. Expensive perhaps, but not as expensive as might be expected. The finished house is comfortable, inviting and worth at least what it cost to build. With a fair wind it could even realise a small profit.

Her advice to anyone contemplating a similar project is to stay hands-off. "I did too much. I was architect, I sourced all the materials, selected and engaged the contractors, did the project management and even went on the tools. It is too much." Kevin McCloud said that building your own house is the last great adventure. Sassi says: "Building a house like this is rewarding. It is sunny, warm, a comfortable living and working space. It costs very little to run, and I built it."

The Passivhaus standard has been around for about 12 years and it is likely to be the way we will build all houses in the future. The Government has called for all new houses in England to be "zero carbon" from 2016 (2011 in Wales) and has introduced the Code for Sustainable Homes.

Sassi's was a personal project. However, Kingspan, the leading UK insulation manufacturer, have developed something similar with their Lighthouse, a zero carbon, 2-bedroom home, the first to meet the level six requirements of the Code for Sustainable Homes. So now it seems that there is no reason why what Sassi has done could not be taken up by the big house-building companies and made profitable – for themselves and the planet.

PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
News
video
Life and Style
tech
Arts and Entertainment
Southern charm: Nicolas Cage and Tye Sheridan in ‘Joe’
filmReview: Actor delivers astonishing performance in low budget drama
Arts and Entertainment
While many films were released, few managed to match the success of James Bond blockbuster 'Skyfall'
film
Arts and Entertainment
Up my street: The residents of the elegant Moray Place in Edinburgh's Georgian New Town
tvBBC's The Secret History of Our Streets reveals a fascinating window into Britain's past
Extras
indybest
News
Albus Dumbledore, the headmaster of Hogwarts School of Witchcraft and Wizardry has been the teaching profession's favourite teacher
education
Sport
Luis Suarez looks towards the crowd during the 2-1 victory over England
sport
Life and Style
Cheesecake frozen yoghurt by Constance and Mathilde Lorenzi
food + drinkThink outside the cool box for this summer’s frozen treats
News
John Barrowman kisses his male “bride” at a mock Gretna Green during the Commonwealth Games opening ceremony
peopleBarrowman's opening ceremony message to Commonwealth countries where he would be sent to prison for being gay
Sport
Sir Bradley Wiggins removes his silver medal after the podium ceremony for the men’s 4,000m team pursuit in Glasgow yesterday
Commonwealth games Disappointment for Sir Bradley in team pursuit final as England are forced to settle for silver
Sport
Alistair Brownlee (right) celebrates with his gold medal after winning the men’s triathlon alongside brother Jonny (left), who got silver
England's Jodie Stimpson won the women’s triathlon in the morning
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

SQL Report Analyst (SSRS, CA, SQL 2012)

£30000 - £38500 Per Annum + 25 days holiday, pension, subsidised restaurant: C...

Application Support Analyst (SQL, Incident Management, SLAs)

£34000 - £37000 Per Annum + excellent benefits: Clearwater People Solutions Lt...

Embedded Software / Firmware Engineer

£40000 - £45000 per annum + Pension, Holiday, Flexi-time: Progressive Recruitm...

Developer - WinForms, C#

£280 - £320 per day: Progressive Recruitment: C#, WinForms, Desktop Developmen...

Day In a Page

Backhanders, bribery and abuses of power have soared in China as economy surges

Bribery and abuses of power soar in China

The bribery is fuelled by the surge in China's economy but the rules of corruption are subtle and unspoken, finds Evan Osnos, as he learns the dark arts from a master
Commonwealth Games 2014: Highland terriers stole the show at the opening ceremony

Highland terriers steal the show at opening ceremony

Gillian Orr explores why a dog loved by film stars and presidents is finally having its day
German art world rocked as artists use renowned fat sculpture to distil schnapps

Brewing the fat from artwork angers widow of sculptor

Part of Joseph Beuys' 1982 sculpture 'Fettecke' used to distil schnapps
BBC's The Secret History of Our Streets reveals a fascinating window into Britain's past

BBC takes viewers back down memory lane

The Secret History of Our Streets, which returns with three films looking at Scottish streets, is the inverse of Benefits Street - delivering warmth instead of cynicism
Joe, film review: Nicolas Cage delivers an astonishing performance in low budget drama

Nicolas Cage shines in low-budget drama Joe

Cage plays an ex-con in David Gordon Green's independent drama, which has been adapted from a novel by Larry Brown
How to make your own gourmet ice lollies, granitas, slushy cocktails and frozen yoghurt

Make your own ice lollies and frozen yoghurt

Think outside the cool box for this summer's tempting frozen treats
Ford Fiesta is UK's most popular car of all-time, with sales topping 4.1 million since 1976

Fiesta is UK's most popular car of all-time

Sales have topped 4.1 million since 1976. To celebrate this milestone, four Independent writers recall their Fiestas with pride
10 best reed diffusers

Heaven scent: 10 best reed diffusers

Keep your rooms smelling summery and fresh with one of these subtle but distinctive home fragrances that’ll last you months
Commonwealth Games 2014: Female boxers set to compete for first time

Female boxers set to compete at Commonwealth Games for first time

There’s no favourites and with no headguards anything could happen
Five things we’ve learned so far about Manchester United under Louis van Gaal

Five things we’ve learned so far about United under Van Gaal

It’s impossible to avoid the impression that the Dutch manager is playing to the gallery a little
Screwing your way to the top? Good for Lana Del Rey for helping kill that myth

Screwing your way to the top?

Good for Lana Del Rey for helping kill that myth, says Grace Dent
Will the young Britons fighting in Syria be allowed to return home and resume their lives?

Will Britons fighting in Syria be able to resume their lives?

Tony Blair's Terrorism Act 2006 has made it an offence to take part in military action abroad with a "political, ideological, religious or racial motive"
Beyoncé poses as Rosie the Riveter, the wartime poster girl who became a feminist pin-up

Beyoncé poses as Rosie the Riveter

The wartime poster girl became the ultimate American symbol of female empowerment
The quest to find the perfect pair of earphones: Are custom, 3D printed earbuds the solution?

The quest to find the perfect pair of earphones

Earphones don't fit properly, offer mediocre audio quality and can even be painful. So the quest to design the perfect pair is music to Seth Stevenson's ears
US Army's shooting star: Lt-Col Steven Cole is the man Hollywood calls when it wants to borrow a tank or check a military uniform

Meet the US Army's shooting star

Lt-Col Steven Cole is the man Hollywood calls when it wants to borrow a tank or check a military uniform