Tour of the Second PassivHaus in UK


Photo: B. Alter

This lovely looking Victorian house in west London seems deceptively straightforward except for a tiny plaque on the front door. It notes that this is the second house in the UK to reach PassivHaus standards. And that is no mean feat.

Last year Lloyd outlined the challenges of bringing high environmental standards such as PassivHaus to this heritage house. Now we went back to see the finished product: it's the Livia Firth of houses.


Photo: B. Alter: Kitchen/Dining Room

Tom Pakenham, creator and owner of Green Tomato Cars ( a green mini-cab firm) has renovated this house to PassivHaus standards. He wanted to prove that "low-energy houses are not only much more comfortable living spaces than the old clunkers we live in now, but also don't have to look like a nuclear bunker."

The year long conversion is finished now, and as can be seen, it is a beautiful, light and airy house and a showcase for people and architects wanting to have a green home. It's not about interior decoration although they used eco paints, a wonderful kitchen counter made of recycled glass bottles and great old furniture. It's more about minimizing energy consumption--the emphasis is on the physical plant of the building.

The essence of PassivHaus-ing is insulation. The PassivHaus standard is tough to meet; it requires a lot of insulation, really low air infiltration and a compact form. Old houses often meet the latter requirement but leak air like sieves.

"PassivHaus dwellings:
* are the worlds leading standard in energy efficient construction
* are designed and built using a step-by-step approach
* use efficient components and a whole house ventilation system to achieve exceptionally low running costs
* are comfortable, healthy and sustainable"

Edward Borgstein, an engineer at Green Tomato led a group of architects (and one non-technological person--this TreeHugger) around the house and outlined the steps of the renovation in great detail. The really technical details are beyond me but described on his blog.

He noted that planning opposition to the project was quite a problem in the beginning but now the planners are starting to come round and their suspicions about this kind of renovation are weakening.

The house is south facing so in the summer some temporary shading is needed. An east-west house is easier to shade.

The heat sources in the whole place are passive heat: the sun, body heat, appliances and thankfully, the heat recovery ventilation system. So the insulation has to be very high and very air tight to keep it warm. The PassivHaus upper level is 15kwh/m2/per year and this one is 13. In fact there was no mobile phone signal because it was so well done.

And what a job. The roof was taken off and stripped back to the plaster. Because outside insulation is not allowed the whole build up had to be from within. They have to create an airtight skin around the inside of the house. Every single detail has to be examined. Air tightness is essential so they had to check endlessly and thoroughly to capture it. This meant rehanging the floors which now sit on steel beams.


Photo: B.Alter: Heat Extractor

The basement heat exchanger system is the engine to provide constant fresh air.
It is hard to understand for a layman but there is no boiler or central heating system. That is why the high level of insulation is key. Apart from the passive heat gains, the only heat is through the ventilation system supported by the heat exchanger.

Amazingly, seventy per cent of the hot water is derived from solar panels on roof with the remainder being provided by the air source heat pump in the ventilation system.


Photo: B.Alter: Outside back View

The pipe on the right, with the bird cage atop is the intake for fresh air and the left one is an expulsion pipe.

At the same time humidity had to be able to get out otherwise the place would be too moist inside. There has to be continuous extraction of moist air from "wet" rooms such as the kitchen and bathroom, into rooms needing it. An extractor in the basement is key to the whole operation. There are inobtrusive extractor points in the ceilings of the bathroom and kitchen which take damp and smelly air to the outside. On our visit, on a coolish spring day, we were crying for the windows to be opened; there was a stuffiness and slightly moist feel to the air inside.


Photo: B. Alter: Green Roof

This is the top of the kitchen extension and will be a flourishing green roof in the future. This photo shows the first weeks and by summer it will be (hopefully) a wildflower meadow. Even at this stage it is attracting plenty of interest from the local birdlife.


Photo: B. Alter: Windows Over Kitchen

The PassivHaus certificate holds place of honour. Solar thermal panels were installed on the roof, they had to be flat and integrated into it so that they couldn't be seen by the neighbours. There are 3 in total, 2 integrated into the slates on the front roof slope and one mounted on an A-frame on the flat roof. Planning permission was only granted on the basis that the panels are unobtrusive.


Photo: B. Alter: First Floor Bay Window

The windows are all triple glazed. Although some were wary initially, in fact they look perfectly fine. It was so hard to find windows with 3 layers that these windows were designed and built entirely from scratch. They open in two different ways; outwards and upwards. Bay windows capture heat so they are good in winter but can be a problem in summer if south facing.

The work is almost finished now and the plaudits are rolling in. Graciously, the family has allowed tours so that others can gain the enthusiasm to undertake this work. It wasn't cheap but 20% of the money spent on this massive renovation was for all the efficiency and renewable elements. This will result in direct energy saving and add to the value of the house.

More on PassivHaus
A PassivHaus Renovation: Heritage Meets Energy Efficiency
Passive Design and Passive House Mean Two Different Things
Passivhaus in the New York Times

Tags: Air Filtration | Architects | Heating | Housing Industry | Life Cycle Analysis