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Chris Stewart

Collective Architecture's Chris Stewart discusses his overlapping roles as architect and member of the Scottish Ecological Design Association in promoting green design to a wider audience.

EAA: Ostro Passivhaus Virtual Building Tour

May 3rd, 2022

Passivhaus can look like anything, be built from anything, the materials and structure you choose are your own. Not my words, but those of Paper Igloo Architecture, as part of the Edinburgh Architectural Association’s virtual building visit to their recently completed home. The house is very beautiful, but more alluring is to listen to Paper Igloo describe their approach to architecture and discard the myth that passivhaus requires you to live in a plastic bag with no openable windows. A passivhaus which is not passive (none completely are), requires the user to interact with their building and leads with the use of healthy natural materials. Passivhaus is but the construction method they used to hang their design decisions.

The tour starts with a wander down the driveway to the front door on a delightful spring evening. Jo and Alex from the Edinburgh Architectural Association (EAA) are greeted by a relaxed Mhairi and Martin who make up Paper Igloo, and begin by guiding the camera around the outside of the building. Immediately you are struck by the simplicity of the building’s form and use of material, a near perfect cube clad in diagonal Siberian Larch. Facades are punctuated by randomly positioned windows perhaps too generous for a building promoting energy efficiency. It all nestles gently into a sloping garden, the gradient of which allows the entrance deck to wrap around to the south facing side of the house. Orientation is always an important part of passivhaus and once your bearings have been made you become aware that the larger windows are positioned towards the sun. The garden is fed by the rainwater from the sedum roof through a soak-away made up of recycled stone dug up from the excavation of the foundations; the water eventually finding its way to the burn at the foot of the garden. The entire setting is a pleasure and together with the evening sunshine you get the feeling that our tour might end here, as we are all tempted to settle into the garden furniture and go no further.

Wrenching themselves from the outside we are led through the front door and are immediately struck by a second complimentary cubic form, a stained timber central core around which the home is organized. We follow Mhairi and Martin around the central core through a series of clever interlocking volumes while they describe how the house was built. It comes as a surprise to discover that the building is almost entirely self-build an experience which has helped to develop an appreciation of natural materials, not only to make sure the home is healthy to live in but also healthy to construct. The building took several years to build partly due to the focus on long term value; a fabric first approach ensuring those building elements hard to revisit, such as insulation levels built into walls and roofs were maximized while those which can be dwelled upon such as the kitchen, come later.

Technicalities are explained in simple terms as we are guided around the home, much of the language used by passivhaus designers can be unnecessarily inaccessible. The good ‘form factor’ of the cube is simply the common-sense use of a shape to enclose a large volume using a minimal amount of external surface area where energy can be lost. The window shapes and double height volumes balance much loved memories from Victorian architecture and the need to ensure energy efficiency. This is achieved through a ‘Passive House Planning Package or PhPP’; which is an excel spread sheet which brings together the various elements of the building and allow the designer and end user to choose where to place the priorities of their project. The outcome is a home which is warm, comfortable and keeps running costs to a minimum.

Passivhaus is very much about sensible construction and ensuring things are done correctly. A culture the construction industry is starting to embrace and one which honest builders have always understood. The commitment shown by Paper Igloo to this approach is refreshing, learning through their journey to the point they will only use passivhaus for their new build projects. They struggle to think anymore in terms of the Building Regulations and the low bar we have set ourselves, a bar which many in our industry see as a target to scrape below.

I am a passivhaus designer and familiar with many of these discussions and much of the jargon but understand more effort is needed to make Passivhaus principles more accessible. It is simply about considering context, being careful with orientation, using efficient form, respecting thermal performance, ensuring a level of airtightness, and making sure the building is constructed well. My own focus is on large scale passivhaus housing and I was both fascinated and inspired by conversation at the end of the tour, much of which will filter into my own field of architecture.

I must however conclude with a confession, my internet let me down badly that sunny spring evening and I was only able to enjoy the tour through a recording on a grey weekend morning, it was though a whole lot brighter at the end.


Thanks to Paper Igloo for allowing us all into your wonderful home and thanks to the Edinburgh Architectural Association (EAA) for organizing a great event. The recording of the virtual tour will be released soon by the EAA, watch this space.


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