The ASBP always puts together a good conference with speakers you don’t hear elsewhere. This year was no exception – an intense day with several quite technical presentations. What was striking this year was an increasing number of completed projects that feature bio-based materials, despite the lack of regulatory requirements in the UK. A highlight for me was the IMPACTT project tracing and mapping timber supply chains for ten completed projects. We need more research like this that promotes transparency in supply chains.
I’ve summarized highlights below, but I urge anyone who wants to delve further to have a look at the presenters’ slides. They are packed with useful information!
Keynote talk from MHCLG
Keynote speaker John Palmer, Deputy Director of New Build Standards and Performance Ministry of Housing, Communities and Local Government (MHCLG), started the day with a positive and proactive view from government. Ex-Passivhaus Trust engineer John, who joined MHCLG in 2021, shared insights about how policy is developed in government – and why it’s so slow!
One excellent slide mapped the intricacies of the ‘housing system’ to make the point that intervention in one area of the system can trigger complex interactions that lead to unintended consequences. Therefore new regulations and policies must be thoroughly ‘road-tested’ to avoid this and this takes time.
A particular challenge is that different government departments have different agendas and priorities and Palmer suggested several short-term workarounds that can influence change: developing guidance (as opposed to regulations) – and not to be underestimated – the soft power of convening.
Palmer also shared various updates on current government initiatives, including a compelling slide listing more than 30 consultations and policies published by MHCLG and DESNZ since January 1:
- Clean Power 2030 Action Plan which has lifted the onshore wind ban and is fast-tracking clean energy infrastructure though planning
- Responding to Grenfell
- Embodied carbon – lots of research and engagement but no Part Z yet! Forthcoming planning guidance will assist local authorities in incorporating embodied carbon considerations in local plans. Also government looks favourably on both MMC and greater use of timber.
- Circular Economy Task Force – established November 2024 with broad focus across government
- EPC reform closed 26 February.
- Future Homes Standard – due to be published in 2025. Will include ban of gas boilers in future homes. Extent of solar to be required still under discussion.
Built by Nature
Anna Lisa McSweeney, UK Networks Lead for Built by Nature (BbN) presented the organisation’s mission – to build in unison with nature by mainstreaming the use of bio-based materials, with a focus on timber. Timber offers three advantages:
- Trees sequester CO2 as they grow
- Building with timber sequesters that CO2 for the lifetime of a building
- Building with timber means substituting high carbon materials such as concrete and steel with a low carbon renewable material
BbN is a grant-funding organisation whose approach is to establish ‘knowledge networks’ of innovators in timber construction in markets that have the largest volume of construction. Networks are underway in the UK, the Netherlands, Spain and Italy, with French and German networks launching this year. The goal is to share knowledge, stimulate demand, and influence policy.
BbN has identified seven main stakeholders types across the built environment: developers, investors, designers, asset owners, insurers, cities and contractors and currently numbers 107 front runners across its networks.
An annual survey of front runners and cross-industry roundtables have identified numerous barriers to adoption of timber. Fire and insurance are top concerns followed by lack of standardized building codes and regulations, and to a lesser extent concerns about biodiversity loss. BbN funds grants to target these barriers.
BbN’s 2025 priorities for the UK include:
- Housing, because the residential sector comprises two-fifths of construction volume and due to the government’s 1.5 million homes target
- Addressing perceptions about fire
- Working with insurers
A recent grant to BEST in Scotland supports the development of a fire-safe mass timber road map for the UK by identifying policy gaps and what further research and testing is required, as well as supporting cross-sector collaboration with insurers.
Recent BbN grants include:
- The New Model Building Code developed by Waugh Thistleton Architects outlines design principles for mid-rise residential using engineered timber.
- IMPACTT (2024) – development of interactive maps which increase transparency in timber supply chains by tracing the route of construction materials from forest to building site.
- Mass Timber Insurance Playbook (2023), detailed guidance which explains the process for obtaining insurance, has had 7500 downloads and now been adapted for the American market.
- Commercial Timber Guidebook – collaboration between major UK developers to develop design guidance for £25M+ timber office buildings (underway).
- Ottoppen – developing a strategic approach to adding timber floors to existing buildings (underway)
- Timber in Real Estate – Investor perceptions (underway by Systemiq)
- Measuring Mass Timber (2025) Evaluation of five completed UK timber buildings (led by dRMM)
Other BbN work includes amplifying the success of exemplars. These include General Projects’ Technique building in London, the proposed Phoenix project in Lewes, Timber Square, Black & White Building, Gabriel Garcia Marquez Library in Barcelona, Magasin X in Uppsala, Sweden.
Finally, with an eye to COP30 in Brazil in November 2025, BbN is working with The Forest & Climate Leaders’ Partnership (FCLP) to gain endorsements for a set of Principles for Responsible Timber Construction (currently in draft). Do have a look!
IMPACTT research: Innovative Mapping and Processes to Advance Construction Timber Transparency
IMPACTT is a fascinating BbN-funded mapping project led by the ASBP that aims to promote greater transparency in timber supply chains and addresses the ubiquitous question of whether the planet can supply enough timber to support widespread adoption of timber buildings. The industry is desperate for more information on timber sourcing and sustainable forest management, and this report is a really useful contribution.
The IMPACTT project targets this knowledge gap and addresses prevailing misconceptions by researching and mapping the supply chains for the timber in ten recent buildings (seven in the UK, two in Belgium and one in the Netherlands) back to the forest of origin. This is enormously complex because it requires identifying all the different entities involved in supplying timber to a building site:
- Sourcing
- Harvesting
- Manufacturing
- Trading
- Transporting
Information from both interviews with the many different companies of the supply chain and the links between them and information gathered on the biodiversity and forest management practices of the forest of origin were gathered by ASBP researcher Asselia Katenbayeva and mapped here on a platform supplied by Double Helix.
Mila Duncheva of StoraEnso (an IMPACTT partner and timber supplier for one of the ten projects) explained the various steps in the supply chain for an educational campus in Cambridgeshire. The timber was sourced from an Austrian forest that uses ‘regenerative felling,’ transported by train and road to the factory where the CLT was manufactured and sprayed with a hydrophobic coating using robotic arms and then transported to the UK by ship via Rotterdam.
John Kirkby of PEFC (another IMPACTT partner) explained PEFC’s two-stage certification process that covers both forest management and chain of custody until delivery to site and explained how the IMPACTT project could feed into greater transparency in the certification process which is currently quite compartmentalized. Currently the end user generally sees the next link up the supply chain rather than the full supply chain to forest of origin.
John also described the numerous challenges in measuring biodiversity and agreeing biodiversity criteria for certification and the importance of developing clear narratives explaining biodiversity for different audiences.
Greater transparency resulting from projects such as IMPACTT can help counter a prevailing industry perception that commercial forests are ecological deserts.
Adedayo Shittu-Balogun, director of projects at EURBAN, described the company’s track record of delivering ‘end-to-end’ (factory to site) digital solutions for over 400 timber buildings over the last two decades in the UK, Switzerland and Germany. She then presented the Cascade project in Cardiff, a 48-unit midrise block for housing association Linc Cymru designed by Powell Dobson Architects.
The original proposal for a 10-storey building was impacted by height restrictions for timber buildings following the Grenfell tragedy, and the final scheme was reduced to 7 storeys. The building makes extensive use of CLT that is designed to char and withstand fire for 60 minutes in accordance with Euro Code 5. The building is fully sprinklered and is also raised off the ground to mitigate ground source moisture. A mid-rise residential building with this extent of CLT is a first for Wales and the project is due to complete in autumn 2025.
Transforming Homes
Prior to introducing the next speaker, Simon Corbey described the ongoing Transforming Homes project, led by a team at the University of Bath (including retiring Professor Pete Walker) which is exploring the use of bio-based materials in domestic retrofit through co-design with residents.
Health co-benefits of climate action for housing
Next up was a session with Bartlett professor Mike Davies (UK Climate Change Committee member 2018 – 2024) who described the urgency of more research on the health co-benefits of climate action for housing, given the crucial role of domestic retrofit in meeting next zero targets since housing is responsible for about 20% of UK emissions. Key measures include decarbonisation of the grid, transition to low carbon heating, more efficient lighting and appliances and behavior change.
Early research published in 2009 explored the relationship between indoor and external air quality and different modes of ventilation. Increased airtightness may improve winter temperatures but have unintended consequences such as increasing summer temperatures, increased humidity and mould growth, and radon concentration.
More recent research undertaken by the Health Protection Research Unit (HPRU) has undertaken monitoring and modeling to better understand these issues in different housing architypes and then estimate and monetize health impacts to inform guidance and policy. For example, is opening windows on a hot day good or bad for health? It might simultaneously reduce temperature and increase indoor pollution.
Aggregated modeling for existing stock tested a range of different measures and found application of shutters to be the most effective measure with a 40% reduction in heat mortality. Environmental modeling was overlaid with socio demographic data and post codes to identify the most critical areas for intervention. Work with the GLA is currently underway to test the national findings at a local level.
Mike concluded that substantial health co benefits can be achieved from domestic retrofit, but it is crucial to be vigilant about unintended consequences. Action is needed across five key areas:
- Enforcing standards and closing the ‘performance gap’
- Delivering a step change in construction skills
- Retrofitting existing homes
- Ensuring new homes are low carbon, energy efficient and resilient
- Addressing urgent funding crisis
- Cross-sectoral and transdisciplinary work is essential to identify the most effect interventions in a complex system.
Indoor air quality in UK Passivhaus primary schools
Chryssa Thoua presented part of her PhD research on the in-use performance of four UK Passivhaus primary schools by Architype. While Passivhaus is widely recognised for delivering net zero carbon in schools, there is an evidence gap on thermal conditions, overheating risk and indoor air quality. The purpose of the research was to develop evidence-based recommendations to inform the design and operation of UK Passivhaus primary schools, in terms of thermal conditions, indoor air quality and ventilation rates in both heating and non-heating seasons.
Four schools, completed from one to seven years ago, were studied. Extensive monitoring and data was collected, including temperature, RH and CO2, VOCs and other particulates, occupancy patterns, operation (esp ventilation strategies), as well as energy bills and user questionnaires.
Key findings:
- PH schools achieve both net zero carbon and healthier environments than baseline UK primary schools (based on DEC data)
- PH recommended for new schools in high pollution area so that PM2 and NO2 can be filtered
- High fixed rate ventilation improves air quality
- IAQ present challenges in warmer months (increased formation of formaldehyde)
- Material specific focus is need to reduce VOCs
- Night time cooling has proven effective in controlling overheating in Architype’s more recent schools. Greater use of mechanical ventilation means less reliance on opening windows.
A particularly interesting aspect of the study was the comparison of different surface finishes in classrooms (acrylic paint vs mineral paint and vinyl vs rubber flooring) to assess levels of VOCs and other particulates. Formaldehyde, limonene and pinene were detected in all four schools. VOCs are lower in the heating season and reduce significantly with building age. Much more research is needed in this area.
Measuring Mass Timber
Measuring Mass Timber is a BuiltbyNature-funded project led by architects dRMM with the support of the Quality of Life Foundation and Edinburgh Napier University that measures the performance of five mass timber buildings across a broad range of metrics – beyond carbon – to lay the groundwork for an evidence base that demonstrates the impacts of timber construction on well being. This is often cited, but little evidenced. The report is packed with useful information for those who want to understand more about mass timber. For example, it includes a very useful diagram (p16) that illustrates the range of mass timber products and how they are used in buildings.
Kat Scott and Finbar Charleson explained the challenge of inconsistent industry methods for measuring carbon neutrality when describing projects (a challenge I am well familiar with) and the need for a standard methodology – and ‘a culture shift’; this is even more difficult when trying to quantify ‘quality of life’ impacts. Kat noted the intangible benefits of wide engagement during this research because it jumpstarted conversations that increase industry awareness and instigate change.
The five case study projects are:
- Abbey Wood Station, Fereday Pollard
- Cambridge Central Mosque, Marks Barfield
- 6 Orsman Road, Waugh Thistleton
- Peckham Rye Apartments, Tikari Works
- Sutton Harris Academy, Architype
The report used BS EN40101 (Building Performance Evaluation) and BS EN 15978 along with the Quality of Life Framework to assess the case study buildings.
Key findings include:
- Lean design with engineered timber generally reduces embodied carbon and this offers a route to decarbonisation now
- Many stakeholders and study participants noted quality of life enhancement
Biogenic storage potential is significant - Building Performance Evaluation and Whole Life Carbon assessment need to be more consistently agreed across the industry and more widely used
- This report is an accessible, balanced and informative read packed with information that is very well presented. It unravels and explains the range of issues surrounding mass timber and recommends that further research is needed to shed light on how mass timber can be used more widely without the unintended consequence of over specification of timber and its implication on sustainable forestry management.
Biogenic carbon
ASBP Chair Mark Lynn took a deep dive into the subject of biogenic carbon, prompted by a concern that the subject has become ‘granular and academic’ and overly complicated. This makes it difficult to explain the benefits of biogenic carbon in a consistent and transparent way across the industry.
Recent EU legislation (CRCF – Carbon Removals and Carbon Farming) is starting to address this but in the meantime RICS PS v2 acknowledges biogenic carbon benefit.
Mark is calling for ‘clear, credible, consistent and verifiable messaging’ on this topic, adhering to the government’s Green Claims Code. Claims must ‘not omit or hide important information, only make fair and meaningful comparisons, consider the full life cycle of a product, and be substantiated.’
Regenerative design – Doing better things, not just doing things better
This was a punchy and upbeat final session providing a hopeful end note to a packed programme.
Wood Knowledge Wales’ Louise Townsend provided an overview of Wood Knowledge Wales Regenerative Materials First project.
After almost a decade Morgan Sindall, Louise Townsend is working with Wood Knowledge Wales to create an opensource knowledge hub to build capacity to mainstream regenerative materials into construction supply chains. The ambition is to need to capture knowledge and expertise from boutique exemplar projects so that it can be shared. Louise argued that the environmental argument is not enough, we need to see regenerative design as a business opportunity which supports a different lifestyle and creates meaningful and fair jobs.
Jonathan Fashanu, Dash House Group
‘I was invited to talk about regenerative design, and I get here and we’re talking about module D. I was lost!’ noted Jonathan Fashanu.
He’s an engineer, but he talks to clients about his garden and the importance of growing. Jonathan works with his clients by listening and building a narrative, trying to understand ‘how we can become native in a place’. Jonathan offered as his approach to regenerative design:
‘Imagine a place that makes you feel peaceful,’ Jonathan challenged the audience. ‘We need to be able to call upon the spirit of a place and understand how to contribute to it, not maximise it.’
Anna Lisa McSweeney, Built by Nature
Anna’s approach to regenerative design includes co-evolving with nature, designing with circularity, closed loop energy and water cycles and restoring natural systems that have been depleted. She highlighted the importance of exemplars and the role of prizes in shining a light on the work of front runners, visionaries who are willing to take a risk. Architects Declare’s inaugural Regenerative Architecture Index (RAI), hosted by Architecture Today, included 68 entries last year which capture best practice. RAI 2025 is currently open for entries – deadline May 16.
Find out more about Healthy Buildings 2025 and see the full programme at https://asbp.org.uk/healthybuildings2025.