FCBStudios’ Nick Hodges and Max Fordham’s Sophia Barker look at the opportunities and challenges of Passivhaus in practice.
In the context of Architects Declare, Engineers Declare, the climate emergency and the intense need to reduce carbon emissions to net zero by 2030, Passivhaus is a crucial player. Passivhaus buildings allow a future that can be wholly reliant on renewable energy. If we want to meet expected available renewable energy by 2050, there is currently no other established route.
For many, the climate emergency feels beyond their control. Commissioning, building or designing with Passivhaus standards could be considered empowering at a personal, community or institutional level. Our experience is that those engaged in Passivhaus projects are proud to feel they are contributing to action on the climate crisis. As local authorities and housing associations increasingly take the lead in delivering low energy buildings and public awareness is increased, this approach is likely to become more commonplace.
Towards net zero
From an holistic climate viewpoint, Passivhaus can be considered to have a relatively narrow, but deep, focus on energy consumption and comfort. For a more complete view of sustainability, Passivhaus should be used in parallel with other systems. FCBStudios work within a broad One Planet Living framework, which includes net zero carbon, water use, social sustainability, zero waste and ecology. For example, on Croft Gardens, residential accommodation for students and fellows for King's College Cambridge, the Sustainability Matrix developed by Max Fordham is being used, which is a bespoke set of targets produced in line with the project's specific ambitions and aims.
Embodied carbon is an area in which we hold responsibility for reducing carbon emissions and mitigating climate change. For Passivhaus buildings, where in-use energy demand is very low, embodied carbon becomes a large proportion of the overall carbon extent of the building over its life. By reducing both energy in use and embodied carbon, we can get closer to zero carbon architecture.
Forecasting energy use
In the UK, forecasts suggest we don't currently have enough renewable energy to supply all our domestic needs unless we reduce demand across all our building stock to something akin to Passivhaus standards. Improving the fabric performance of buildings is critical to reducing our dependence on fossil fuels.
The Passivhaus Planning Package (PHPP) model seeks to bring the MEP system and fabric together to create an efficient building. It is also effective in predicting in-use energy, which can be necessary for forward planning – for owners, estates departments, local authorities and tenants.
An accurately predicted, low-energy building is also less exposed to variations in energy rates. For many households and estates, this creates a beneficial resilience for both consumers and energy suppliers. Heating and cooling requirements become a fixed and very small outgoing.
A benefit of Passivhaus is that it allows thermal performance to be part of the conversation as a quantified entity. As thermal performance hasn't been part of design conversations in this way before, the challenge of this new constraint for the design team is to find ways of creating good design within it. How we view this new constraint will impact on how well the design works. To achieve optimum thermal performance, it is vital that the whole design team collaborates and shares information.
From our experience, Passivhaus projects should be capable of being as close to budget expectations as non-Passivhaus projects. There is a level of learning required, but as design and construction teams are 'upskilled' we are hopeful that projects should eventually be deliverable to the same programmes and cost envelopes as other, similar, buildings.
Aiming for Passivhaus certification has distinct advantages, through monitoring work on site and at post-completion, maintaining quality throughout. There is often a level of enthusiasm and spirit throughout the site team that is harder to quantify. Many of those involved feel they are making a difference in terms of climate action.
Planning departments can sometimes be a hurdle to achieving an easy/cost-effective route to Passivhaus. Educating planners on the reasons why Passivhaus creates better spaces to inhabit is an action to undertake. For Passivhaus to become mainstream support is needed from government policy. This will bring its own challenges in terms of educating the industry and monitoring to ensure that the buildings are built as designed.
Passivhaus vs creativity
It is possible to achieve Passivhaus for other building typologies beyond housing, and there are examples of completed projects in schools and higher education. If we embrace the aspirations of a Passivhaus approach and fully understand the opportunities and constraints, it is possible to have efficient, interesting and beautiful outcomes.
So, does Passivhaus kill creativity? We don't believe so.
It is another layer of the design of a building; another friction within the creative process, alongside site, budget, brief and the planning context. Without creative architecture, Passivhaus buildings may perform well, but run the risk of lacking inspiration. We need to develop skills in this area so that high performance and beautiful architecture can be achieved in tandem.
Nick Hodges and Sophia Barker
Nick Hodges and Sophia Barker spoke at a Max Fordham event in Bristol: Passivhaus, Does it kill creativity in November 2019, looking ant the challenges and opportunities of Passivhaus design.
Croft Gardens is a Passivhaus project for King's College Cambridge, with a 100-year design life.