Sustainable Retrofitting – the Passivhaus way (Part 1)

Dr Jennifer Hazelton, a Research Co-ordinator in Newcastle Institute for Research on Sustainability (NIReS) at Newcastle University, recently stayed in a Passivhaus bed and breakfast. In the first post of a two part series, she speaks to the owners, Adam Dadeby and Erica Aslett, about their experience of the renovation process.


I was recently afforded the opportunity to stay in Totnes ‘Passivhaus’ bed and breakfast during a trip to visit family in Devon. Further investigation revealed that owners Adam Dadeby and Erica Aslett were awarded this status in September 2011 for their 1970s detached house, which they painstakingly retrofitted over two years. A Passivhaus building is designed to “use vastly less energy than conventional buildings, irrespective of the climate. This is achieved by careful design informed by building physics, and, crucially, by thoughtful and careful construction by a properly skilled and motivated team”.[1] The standard originates in Germany, where certification is much more widespread (though, even there, still only one in five Passivhaus building owners ever obtain the full certification).

Adam and Erica’s home is not the only certified Passivhaus in the UK, far from it, but it is the only one to be run as a bed and breakfast, and only the third to have achieved the coveted status on a renovated building. This added in a whole new level of complexity and difficulty, as Adam explained, but considering planning and other restrictions in this (and many other) areas of the country, not to mention the lower carbon impact of retrofit over new build, ultimately the building is all the more sustainable for it.

So, how do Passivhaus buildings achieve their ultra-low energy requirement whilst being very healthy and remaining a comfortable 20°C? They rely on high levels of uninterrupted, all-round insulation, airtight design and on heat gained from the sun through the windows. Solar gain is not in itself sufficient to heat a Passivhaus in most climates, however, so a trickle of heat is required to maintain the temperature (though not nearly enough to justify a central heating system). There are no draughts or cold spots in a Passivhaus, making it more comfortable, and it is healthier as the air is fresher than in a conventional building.1

What is a Passivhaus building actually like? Does it really feel healthier and more comfortable? Well, when my husband and I arrived, we were informed that they were terribly sorry but that the heating system had been off for four days and they had only just realised and turned it back on, so it would take a little while to get back up to temperature. Given it was the coldest March for over 65 years and frosty outside, we were understandably concerned (had our own central heating been off for four days, we would have been camped inside our wood burning stove and making hot water bottles continuously). However, the house was remarkably warm and I could fully understand why they had only just noticed. This illustrated for me perfectly the thermal properties of the building, and we were not at all uncomfortably cold, or warm, for the remainder of our two night stay. As for being healthy, we are lucky not to suffer from any allergies or asthma so it wouldn’t be as noticeable, but the atmosphere inside the house was certainly very fresh and not dingy or dusty in the slightest. That may have been down to Erica’s efforts to keep the place spotless, but allergy sufferers and asthmatics have confirmed that they find Passivhaus buildings to be extremely comfortable and allergen-free, a fact that is primarily down to the filters. The air is circulated around the house, and a constant zero pressure gradient between the outside and the interior is achieved by a specially-designed system which maintains the pressure balance in order to prevent air from being drawn in or leached out, which would create a draught. As the air is drawn through the system, filters remove airborne particles to ensure the fresh and healthy feeling.

[1] Cotterell, J. and Dadeby, A. 2012. The Passivhaus Handbook: A practical guide to constructing and retrofitting buildings for ultra-low-energy performance. Green Books, ISBN 978 0 85784 019 6

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