ARCHITECTURE & DESIGN


industry for energy efficiency upgrades to buildings. Retrofit typically involves adding insulation to walls, roofs, and, where possible, to floors, to eliminate heat losses, alongside window upgrades, and improvements to (or replacement of) heating and ventilation plant. The challenge for building operators is to undertake refurbishment that genuinely improves occupant health and wellbeing, significantly reduces operational running costs, and has a deep and lasting impact on carbon emissions, which may also align with social responsibilities. However, retrofit needs to be designed holistically and implemented to a high standard. The Intergovernmental Panel on Climate Change recently reported that ‘each building retrofitted in a sub-optimal way locks us into a high climate-footprint future’. The message is therefore to ‘do it once and do it well’ or, at the very least, to follow a strategy of retrofit stages that leads to the complete solution.


Standard adapted


The Passivhaus principle relies on the ability to optimise a building’s form and orientation to maximise performance, but obviously this is not possible with retrofit, so the standard is adapted slightly to reflect the challenges of refurbishment, giving a certification standard known as EnerPHit. The ideal retrofit scheme involves a complete overhaul of the building fabric, which might involve wall insulation and cladding, air leakage reduction measures, window and door replacements, and the introduction of heat recovery ventilation. Most of these works can be undertaken externally if the style of the building and planning constraints permit. For older properties of heritage value, these upgrades will have to be carried out internally but, advantageously, this then allows upgrades to be undertaken on a room-by-room or ward- basis, which might be a more manageable solution for hospital estates.


Many specialist products and techniques have been developed in the retrofit field over recent years, including high performance insulations that are pinned to the existing structure and can improve the thermal performance to the same level as new buildings. Typically, roof finishes are removed, insulation added, and new roof


finishes replaced. Floors can be trickier, but in the worst case scenario an insulated ‘apron’ can be installed around the building perimeter to create a heat island underneath the existing structure. Improvements to air leakage levels are also a prerequisite for high performance and comfort, so that even in retrofits, very low rates can be achieved through analysis by an experienced retrofit designer.


Pre-fabricated retrofit


A new approach, involving prefabricated retrofit, is gaining interest, where a new external skin is fabricated in its entirety under factory conditions (including linings, insulation, windows, and cladding), and tailored specifically to correlate to an accurate laser survey of the existing building. The new roof and wall panels are assembled on the outside of the building, with residents still in situ, with the only intervention internally being the removal and re-lining of the old windows. Air leakage and heat recovery ventilation distribution can all be dealt with in the new outer skin.


I used this method recently for a 1967 housing block in east London, and the potential is huge – with predicted energy savings in the order of 75-80%. This technique might just be the ‘silver bullet’: maximum performance and quality for minimum disruption – with the opportunity to transform tired old buildings – and certainly lends itself to overstretched hospitals that aren’t in a position to close entire wards or areas.


Following their lead


A thermographic image showing minimal heat loss in a Passivhaus building.


Greater energy efficiency is undoubtedly the path towards a healthcare estate that is more sustainable in terms of both its financial viability and its environmental impact. Heating and cooling plant and other services have an important part to play – efficient devices, whether in the form of lighting or medical equipment – not only save energy directly, but also simultaneously reduce the cooling demand. However, the replacement or retrofit of building stock to the Passivhaus standard provides the greatest opportunity for truly radical savings in running costs and greenhouse gas emissions. Benefits for a healthier living environment are proven to improve both patient and staff comfort, with significantly reduced absenteeism seen in Passivhaus offices and schools. The conditions for large-scale energy efficiency measures in hospitals are favourable; with the available technology, the energy demand can be reduced significantly in most areas. With our European cousins in companies and hospitals on the Continent poised to take full advantage of the benefits of Passivhaus design, it is time that we followed their lead.


About the author


Mark Elton, director, Cowan Eco Design, has been a practising architect for 22 years, with considerable experience in low energy architecture and retrofit on a wide variety of award-winning projects. His interest in sustainable design stems from a combined architectural and engineering education at the University of Bath, followed by a career in various London practices before joining Cowan Architects in 2016. Here he is working on bringing the synergies of Passivhaus technology to the practice’s healthcare sector client base.


An accredited European Passivhaus Designer, and a UK jury member for the 2014 International Passivhaus Awards, he believes that the deep understanding of building physics and detailing rigour that Passivhaus training brings, coupled with an extensive knowledge of building materials and their environmental impacts, can bring great credibility to the design process. He was a committee member on the RIBA Sustainable Futures group for six years, and continues to engage on RIBA matters relating to the retrofit agenda. He also acts as an architect representative on CIBSE’s ‘Homes for the Future’ group, and is a course tutor on ‘building fabric’ for the Retrofit Academy.


Throughout his career, Mark Elton has been responsible for a number of pioneering schemes, including the Arundel Great Court HQ and conference building in The Strand in London, and the University of Surrey’s School of Management. He has also gained experience in low carbon design through projects such as Cornwall’s Broadclose Farm, which won the Richard Fielden Housing Design Award. He is recognised for his work on social housing retrofit projects, including the Edward Woods estate in Hammersmith, West London, which is highlighted in the LSE study, ‘High Rise Hope’, and Wilmcote House, the UK’s largest EnerPHit refurbishment project, currently on site in Portsmouth.


hej April 2017 Health Estate Journal 51


© Passive House Institute, Germany.


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