Passivhaus & Embodied Carbon
The Passivhaus standard champions an efficiency first approach renowned for squashing energy consumption and eliminating the performance gap in buildings without compromising on health or comfort. Do thicker insulated walls, triple glazed windows, & MVHR units tip the scales unfavourably for Passivhaus when it comes to embodied carbon?
As buildings become more energy-efficient, and with a rapidly decarbonising National Grid, the balance between the carbon emitted when running a building (operational carbon) and the carbon emitted to build it (embodied carbon) is changing.
Two of the most common materials in construction, steel and concrete, are responsible for 15% of global carbon emissions. To address the climate emergency, we must tackle the whole life carbon of buildings addressing both operational and embodied carbon of buildings simultaneously.
The “cradle to grave” whole life carbon footprint provides a good indication of a building's carbon impact through its lifetime. From product material extraction to ultimate building demolition (or better still deconstruction).
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Passivhaus buildings are optimised for net-zero, providing the best route to minimise whole-life carbon. Outstanding levels of building performance minimise operational carbon, while the Passivhaus design methodology encourages optimisation of embodied carbon through efficient use of materials and radically reducing the heat and cooling plant.
PHT Embodied Carbon Paper
Passivhaus can apply to any construction method. This design flexibility allows its application across various vernaculars. It is material agnostic and can apply to any form of construction, from concrete, steel, timber, or straw.
The Passivhaus community is increasingly acknowledging and focusing on the issue of material choices, resource efficiency and the circular economy, demonstrated by the development of several carbon counting tools, including the PHribbon plug-in for PHPP.
The UK Passivhaus Trust wholeheartedly acknowledges the appropriateness of bio-based materials for Passivhaus buildings. While the Passivhaus standard remains material agnostic, it places great emphasis on the need for comprehensive decision-making in light of the climate emergency. As building clients, designers and contractors, we have a unique opportunity to make choices that go beyond operational carbon and encompass the critical aspect of embodied carbon. Bio-based materials, with their positive impact on the environment and potential to enhance indoor air quality through reduced VOC emissions, play a pivotal role in this holistic approach. Bio-based materials can contribute to enhanced insulation performance, through easier installation with fewer gaps and reduced risk of thermal bypass. By integrating bio-based materials into Passivhaus construction, we can create sustainable, energy-efficient buildings that not only address the climate crisis but also contribute to a healthier and greener future.
PHT Activities
It has sometimes been argued that designing to decrease operational carbon emissions increases embodied carbon emissions. Do thicker insulated walls, triple glazed windows, & MVHR units tip the scales unfavourably for Passivhaus when it comes to embodied carbon? What is the embodied carbon impact of renewable technologies? Are low carbon materials better for our health? The resources & research below explore these concerns, and outline the Trust’s current activities on the subject:
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2022: Net Zero Verification Working group - in partnership with LETI, CIBSE, UKGBC, & others
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2022: Research project investigating operational carbon in whole-life carbon assessments in partnership with LETI.
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Training & Activities
Get ahead by up-skilling with the Trust's following on-demand training resources:
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Passivhaus & Embodied Carbon webinar
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Getting to Net Zero tutorial: on-demand
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Retrofit Masterclass lecture series: on-demand
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Keep an eye on our certified training listing for upcoming tutorials on PHribbon and associated webinars. Below you will find further useful resources. Watch several free webinars that we have compiled into a handy playlist.
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Case studies
The handful of schemes below all champion low embodied carbon, whilst meeting (or aiming for) Passivhaus certification. They provide a variety of building typologies, but for more examples in the UK please visit our Passivhaus projects gallery and map, or search for inspiration further afield in the International Passivhaus Buildings Database.
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(1).jpg "Larch Corner Passivhaus © Mark Siddall") |
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Retrofitting existing buildings is almost always the best option with embodied carbon in mind. Even compared to a timber-framed new build – retrofit can often account for a fraction of the embodied carbon of a similar-sized new build project.
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/Entopia_Soren Kristensen_exterior 1.jpg "Entopia Building © Soren Kristensen") |
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What about in retrospect? Read some interesting exploration surrounding embodied carbon in the UK’s first cavity wall Passivhaus at Denby Dale. We also highly recommend visiting a Passivhaus – take advantage of the biannual International Passivhaus Open Days.
Carbon Counting Tools
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PHribbon: An embodied carbon calculator that works as a plug-in for PHPP. Discover more in our Getting to Net Zero tutorials.
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ECCOLAB: A carbon counting tool, developed by PHT Patron Architype, helps designers explore and model the lifecycle energy, carbon and cost impacts of different design options. The tool has BIM/ REVIT integration capabilities and can be used in parallel with PHPP Passivhaus software. ECCOLAB undertakes whole life carbon modelling of all stages of a project and is especially useful in early project decision-making.
The relationship between embodied and operational carbon is rapidly changing, as energy supplies decarbonise worldwide. Continuing to reduce energy demand remains critical as it reduces peak loads and shrinking our collective winter energy demand will reduce the level of future zero carbon energy infrastructure and storage needed. Designing to Passivhaus standard does not need to result in increased embodied carbon and that choice of materials, rationalisation of build form and reduction of building services play a significant part in reducing whole carbon.
Further Information
Passivhaus & Embodied Carbon webinar
Passivhaus Primers: Net Zero, Retrofit, Embodied Carbon
Getting to Net Zero: on-demand tutorials
iPHA webinar: Embodied energy and carbon in Passivhaus construction
RICS: Whole Life Carbon Assessment for the built environment
