Sunday, 26 May 2013

There's nothing slippery about the Slip house

slip house
I don't usually go to Brixton (South London) much, in fact I've only been once, on a dull grey Friday afternoon. It's a good thing I was going to see something quite interesting! Another event as part of Green Sky Thinking week was a tour of and a talk on Slip House by Carl Turner of Carl Turner Architects. Completed at the end of 2012 to almost Passivhaus standards, I was interested in learning about the lessons from the first 6 months of occupancy of this super sustainable building.

Turner was the architect for this home and studio for himself and his partner. The couple chose one of 4 empty plots in a gap of Victorian terraces for the building. As a brownfield site the project was already heading in a positive direction in terms of its 'eco' ethos and the main concept is to provide an affordable flexible sustainable home within an urban environment. This was to come not only from the materials and the method of construction but also the maintenance through technology installed within the building.

The design of the house is a series of staggered stacked boxes that jut out as required to achieve the functional requirements for the spaces within - primarily views and sunlight. This 'upside down' house has the living and eating area on the second floor (where there is easy access to the rooftop terrace), the sleeping areas on the first and a flexible space at ground level. Currently this is being used as the practice's studio but in the future it offers the flexibility either to become an extension of the home or a stand alone apartment.

Walking around the house it's clear that a lot of thought has been put into the design with clever detailing to conceal edges and connections. The perimeter walls are load bearing thus freeing up the space within to allow flexibility. Lightweight partitions divide up the spaces as required or can be knocked down in the future to change the configuration. There are also lots of sliding panels and built in storage spaces that not only hide away the clutter of everyday living but also allow division of space in some areas. On the ground floor, for example, there is a whole 'pod on wheels' with a workstation and storage that can be wheeled around as required. In addition to this almost all doors are sliding which makes a big difference in space saving. Although not generous in space standards, the use of these mechanisms allows the house to be perceived as spacious.  

The structure of the building is steel to allow for future flexibility. When the project was first on the drawing board (5 years ago) there were discussions around using cross laminated timber (CLT) for the load-bearing structure. However, at the time there was not as much knowledge on the material and it was more expensive than steel. It's a shame that it's not built of timber since perhaps that is one of the things that lets down it's eco credentials, well that and the concrete floors (but we'll come onto those shortly). However, despite the above, the house makes up for it in many other ways. The building is super insulated with thick walls and is airtight (almost up to Passivhaus standards). It's important to note here that simply super insulating the building will not improve the energy performance. If the building is not airtight then the heat will escape thus rendering the extra insulation completely useless. The floors are composite concrete with a pre-cast slab on the underside and in-situ on top. Although very unsustainable in its embodied energy, concrete has advantages in terms of its thermal mass and it's also a great sound insulator thus preventing the need for any additional insulation to be laid on top. It is able to retain heat to reduce mechanical cooling demand. The walls of the building are pre-fabricated timber sandwich panels - OSB boards with insulation within. These use waste material and can easily be re-used. The windows are triple glazed to Passivhaus standard thus keeping the weather out and the heat in! 

Apart from the material nature of the building, there is technology in place that plays a part in the use of the building. The rooftop terrace serves as much needed private outdoor space but is also where the PVT (photovoltaic thermal) panels live. These panels combine the abilities of solar panels with solar water heaters to provide both electricity and hot water using one product. This saves space and is also more efficient. The terrace also helps in collecting rainwater for the rainwater harvesting and the use of water is controlled within the building. All the technology is integrated well into the building with the mechanical equipment sitting hidden away behind one of the bedroom's built in wardrobes. These are not 'add-ons' but actual design decisions for the house.

PVT panels on the roof terrace
This house is beautiful with crisp detailing throughout where extra effort has been put into concealing connections. The house was designed to achieve Code for Sustainable Homes (CSH) level 5 but in reality it is becoming difficult for it to achieve this. This comes down to a problem with the assessment method. CSH measures according to set parameters and even if you provide something over and beyond these parameters, if they are not on the list and the box can't be ticked, then it cannot be achieved. In this way there are various things designed and installed in this building that are not on that CSH list and therefore the building is falling short of achieving this target. It's a real shame that methods of measurement such as these that are meant to be there for achieving high quality sustainable architecture are actually failing in recognising the really exemplary buildings.

I like the house, its cleverly designed and is contemporary and functional. The deep plan could have been problematic in terms of getting light into the spaces but this only seems to be a problem at ground level. On the upper floors large windows and rooflights let in plenty of light making the space feel bigger than it is. However, despite my admiration for the design and sustainability of this house, I'm a little disappointed by its integration into the neighbourhood. Although the house sits within the footprint of a terraced house, it seems very dominant and a little out of place. In addition, this building has it's own private gate which has monitored access and seems a little fortress-like for the neighbourhood. Maybe this is because it is also an office - I don't honestly know. But the form and appearance is a contrast to it's neighbourhood and it would have been nice to see it working better with it's context. I don't have a problem with the aesthetic of the building but I do feel perhaps it's not appropriate for this location, but that's just my opinion.


  1. A great invention should I say!!! This is just awesome as this structure is sustainable, eco-friendly and one that would stand for a longer period of time..

    Jason Wren, Shape Architecture

  2. Thanks for your comment Jason, indeed it's a beautiful space too!