This guidance has been written for those wanting to both increase their knowledge of Embodied Carbon in the housing sector and to understand how to reduce it. The target audience encompasses key stakeholders within Welsh social housing organisations including development and asset managers, their design teams, contractors and suppliers.
Clear and authoritative guidance is provided on how to procure and undertake an Embodied Carbon assessment, what benchmarks can be set, tools that can be used and how Embodied Carbon can be reduced. Examples are provided to show how others have tackled Embodied Carbon within their organisations and projects, with a focus on housing. Where relevant, other guidance and useful information is signposted.
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Authors: This guidance has been produced for Woodknowledge Wales on behalf of the Home-Grown Homes project. The document was authored by Jane Anderson of ConstructionLCA Ltd together with Katherine Adams, The Alliance for Sustainable Building Products.
Publication date: December 2020
Manufacturing
WoodBUILD 2020 Autumn Series – Podcasts
A series of four 60-minute conversations on some of the themes of the Home-Grown Homes Project – Forestry, Manufacturing, Housing and the Foundational Economy. Each podcast features two individuals with a passion for the subject matter and a willingness to share their thinking. David Hedges, Home-Grown Homes Project Manager introduces each podcast and asks the questions.
Our Future Forests
Two chartered foresters in conversation: Jo O’Hara, Managing Director at FutureArk Ltd in Edinburgh and John Healey, Professor of Forest Sciences in Bangor University’s School of Natural Sciences. They discuss our forests, what they look like now, how and why they have changed over time and what the future holds. Plus, forest use, growth and management, culture and history, land use policy, governance and forestry as a career.
| Jo O’Hara | John Healey |
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Jo is a member of the Institute of Chartered Forester’s Council – see details here / And you can follow Jo on Twitter @mrsjo |
John Healey refers to his work in Bangor. You can find out more about the University’s work in forestry here. |
Future Homes and how we build (or make) them
Two timber housing manufacturers in conversation: Jasper Meade, Director of PYC Group in Welshpool and Neil Sutherland, Director of MAKAR in Inverness in the Scottish Highlands. They talk about natural materials, high performing homes, change and the barriers to it, specifications, legislation and regulations, energy and carbon, Passivhaus, collaboration, culture, behaviours and more.
| Jasper Meade | Neil Sutherland |
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| Jasper is a board member of Woodknowledge Wales and for more information about Jasper’s company, PYC Group, see here. | Neil’s company is MAKAR and their website is here. You can follow Neil on Twitter @makarneil |
Better Performing Homes
Two architects in conversation: Fionn Stevenson is Professor of Sustainable Design in Sheffield University’s School of Architecture and Rob Wheaton is Senior Associate Architect at Stride Treglown. They talk about how different the homes of the future will be from the homes we live in now, sustainability, standards, building performance, architecture education and more.
| Fionn Stevenson | Rob Wheaton |
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| Fionn is the author of Housing Fit For Purpose: Performance, Feedback and Learning, published by RIBA Publishing in September 2019. You can read more about Fionn and her work here. You can follow Fionn on Twitter at @fionnstevenson |
Rob is based in the Cardiff office of Stride Treglown which is a multi-disciplinary employee-owned practice working across the UK. He has recently been working with housing associations on schemes under the Welsh Government’s Innovative Housing Programme. See here. You can follow Rob on Twitter at @robwheaton |
The Foundational Economy
Two Housing Association people in conversation: Debbie Green, Chief Executive with Coastal Housing and Steve Cranston, Foundational Economy Lead at United Welsh. They talk about what the foundational economy is, the pandemic, risk aversion, communities of practice, decarbonisation, listening to people, paradigm shifts and a green recovery.
| Debbie Green | Steve Cranston |
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| Amongst other things Debbie, who is based in Swansea, has been chairing the Ministerial Foundational Economy Steering Group. You can find out more about her and her career here and follow Debbie on Twitter at @debbiegcoastal | Steve, who is based in Pontypridd, has been with United Welsh since 2009 heading up their community investment and in the last year, leading their FE work. He’s also had a period of secondment in the Office of the Future Generations Commissioner. You can find out more about Steve here. and follow him on Twitter @stevecr |
Mandatory quality standards for new homes – WKW response
Woodknowledge Wales have responded to a Welsh Government consultation on “Mandatory quality standards for new homes” which closed on 31 October 2020.
Key targets Woodknowledge Wales propose are need are:
- A target for upfront carbon from April 2023. We propose 300kgCO2e/m2.
- A target for embodied carbon from April 2023. We propose 400kgCO2e/m2.
- A space heating demand target by April 2023. We propose 15 kWh/m2/yr.
- A total energy use intensity target by April 2023. We propose 35 kWh/m2/yr.
Read our full response here.
Google Map highlights exemplar timber housing projects in Wales
Explore information on construction, innovative products, use of home-grown timber and Welsh manufacturing, carbon impact and building performance in innovative timber housing projects across Wales.
This map showcases the exemplar timber housing projects Woodknowledge Wales has worked on in some way over the past few years. The Exemplar Housing Project layer contains basic project information. The Whole Life Carbon layer contains data on the carbon impact of those projects for which we have undertaken analyses. The Building Performance layer contains projects where we have undertaken some experimentation into different building performance methods. The Forest Nation Attribute layer attempts to capture the timber story such as the use of innovative products, the use of home-grown timber and the use of Welsh manufacturing.
This map represents our progress to date. We will continue to record the progress of our timber development agenda as well as the progress of Welsh housing in meeting the challenge of Net Zero whole Life carbon over the coming years.
VIEW MAP ON GOOGLE →
Wood Fibre Insulation in the UK
A relatively old report written in 2013 on wood fibre insulation in the UK authored by our now Chief Executive, Gary Newman, when acting as an independent consultant for Forestry Commission Scotland and Woodknowledge Wales. The report was never published but we consider it highly relevant to today’s discussions about how Wales can become a high value forest nation and delivery zero carbon housing (both new and existing) by 2050. Access to the full report here.
Net-Zero targets for Wales
Building on the work of the UKGBC and LETI, the Home-Grown Homes Project have developed a graphical net-zero guide with a set of targets & principles that we believe are achievable within a Welsh context. The guide is aimed at helping developers, designers and manufacturers achieve net-zero whole life carbon. This means tackling upfront carbon, energy demand, use of renewables and embodied carbon in order to reduce the overall emissions associated with any proposed development.
Download in pdf
Later this year we will publish a set of additional supporting guides that run alongside this graphic, describing, for example how to measure and reduce embodied carbon, a zero-carbon design guide using typical Welsh timber frame systems, and a guide to support building performance evaluation to address the energy performance gap.
Coast Redwood Groves in Wales – a planting solution in a changing climate?
Sequoia sempervirens, also known as coast redwood, coastal redwood, Californian redwood, is a species which is increasingly mentioned when considering alternative tree species to cope with a changing climate in Wales. This may come as a surprise to some given that the deep leaf litter it produces decays slowly and deters ground flora causing a lack of biodiversity. In recent years, this has often been used as evidence against its wider planting benefits. At the same time coast redwood is delivering landscape and societal benefits by storing carbon in the leaf litter substrate and standing timber. As Forest Research say “This is a species that could be grown more widely in Britain with climate warming, not least because it produces a high quality timber.”
In early February 2020, Woodknowledge Wales staff Dainis Dauksta and Ceri Loxton visited the Royal Forestry Society’s Redwood Grove at Leighton, near Welshpool, with Dominic Driver of Natural Resources Wales and Anna Dauksta of Tir Coed to see the coast redwood grove and discuss the potential for Sequoia sempervirens and other softwood species in Wales.
In its natural range, Sequoia sempervirens is confined to a narrow coastal belt, mainly in central and northern California. In the UK, coast redwood was introduced in the 1850s and has been planted on a small scale, often for silvicultural demonstration, landscape and amenity purposes by the Forestry Commission and private estates. The redwood grove at Leighton is impressive – tall straight stems, large diameter trunks covered in thick fibrous bark, towering canopies and dappled light throwing patterns on the deep leaf litter.
New Zealand is one of the countries starting to look at the species more closely and to encourage its planting and establishment. Should Wales follow this example?
Mitigating climate risks
Sequoia sempervirens has some natural advantages to reduce risks associated with climate change in our regions:
● Wind: Its root system can reduce the effects of severe wind. Trees join roots with neighbouring trees and form a strong underground link. The bonding with nearby trees enables them to withstand major weather events.
● Fire: It has the unique ability amongst conifers to re-sprout branches after a fire. Tough fibrous bark insulates the trunk from much of the heat of a fire. While existing branches may be burned the trunk remains alive and sprouts new branches. If a forest has been planted for carbon offsetting, this means that the forest will continue to grow and reduce the potential for future liabilities.
● Insects: In its native range in California there are lots of insects. No insect is known to cause economic damage and none is capable of killing a mature tree.
● Vegetative reproduction: It will sprout from old cut stumps and fallen logs. Because the stumps and roots remain alive and because the heartwood is naturally durable coastal redwood carries more carbon forward into the next rotation.
Adaptability and Carbon Storage Potential
The most interesting characteristics of coast redwood reside in its genetic makeup. Its genetic diversity is very high and the highest of all North American conifer species. Sequoia sempervirens is the only hexaploid conifer with a genome size three times that of its near relative, the giant sequoia. This polyploidy (having more than two paired sets of chromosomes) may explain its extreme survival capability and longevity. The species can clone itself from roots, burls and cuttings. The phenotypic plasticity (how of its leaves allow them to adapt to a wide range of light conditions.
New Zealand foresters are confident that they will be able to breed coast redwoods with more desirable traits than their Californian peers, so that the species can be optimised as industrial roundwood. Attractive compact groves could realise an extremely high carbon storage potential which would justify their new role within Welsh mosaic landscapes.
Suitability for Welsh geography
Forest Research (2016) advise that coast redwood is most suitable for mild, moist climates with more than 1250mm of rainfall, such as those found in Argyll, Wales and southwest England. Favourable locations in terms of climate and site quality will be lower slope and valley bottom sites.
Coast redwood is likely to be a high yielding species. Data from the limited trial sites in the UK indicate high productivity with general yield classes of between 24 and 30 being achieved in England and Wales.
Coast redwood is a species to consider where larch crops are being diversified due to Phytophthora ramorum infection and where site conditions are suitable.
Timber quality – suitable for construction and joinery?
A chalet built in 1966, and redeveloped in 2000 using local wood, including redwood thinnings from the site. The Charles Ackers Redwood Grove at Leighton, Nr Welshpool.
At the site in Leighton a small cabin has been built using local timbers including coast redwood cut from the site. In its native range coast redwood is reported to be used as “veneer, construction lumber, beams, posts, decking external furniture and trim (https://www.wood-database.com/redwood/). However, there is a lack of information about wood properties grown under British conditions.
“My own experience as a sawmiller is that coast redwood cuts and dries really nicely. The heartwood is reasonably durable although there’s a lower proportion compared with western red cedar or larch. The thick fibrous bark may offer potential as an insulating material.” Dainis Dauksta.
Future uses: explore and experiment!
There is more to learn about this species, and while there is a lack of information about wood properties, we also do not know precisely what our wood requirements will be in the future and what processing advancements will have been made. Given the diverse and evolving nature of the timber processing sector it is likely that there will be many future uses.
Because of its high productivity and unusual growth characteristics this species will be of increasing interest in British forestry under predicted climate change. If the carbon sequestration potential of different species is to be considered alongside other properties and multiple landscape requirements, then surely it won’t be long before we start to see increasing groves of coast redwood planted here in Wales?
From garden sleeper to beautiful window. Challenging perceptions about Welsh timber
Custom Precision Joinery rose to the challenge laid down by Dainis Dauksta at a Woodknowledge Wales knowledge event on Developing the Welsh Joinery Sector – Barriers and Opportunities for Windows by offering to make a demonstration window from (1) local Welsh timber (2) to a specification acceptable to housing associations and (3) have it ready for WoodBUILD 2019. We were not disappointed!
This second knowledge event in our “Campaign for Wood Windows” looked at how the Welsh Joinery sector can respond to the real and growing demand from the social housing sector to supply wood windows and ultimately how the joinery sector can access home-grown timber to be used in making those windows.
Larch for the windows on planner. This photo shows the straightness of the grain after the first 20-30cm which can be removed.
During the event Dainis Dauksta (sawmiller, designer and consultant) had challenged perceptions that Welsh (and UK) forest plantations provide low grade softwood which is only fit for fence posts and biofuel. He urged us all to learn more and not to make the mistaken judgement that fast grown is always inferior to slow grown or that large ring width means low density. His talk illustrated how large Welsh logs which are currently being used in low value markets such as fencing and bio-fuel can provide high grade joinery timber.
The Timber
Two reject larch garden sleepers (2.4m*250mm*125mm) obtained from BSW were resawn (by Dainis Dauksta) into joinery sizes as specified by Custom Precision Joinery. The sleepers, which had been air dried were cut so that the juvenile corewood [1] was specifically sawn out and excluded from the final joinery grade product, this is because the core wood can have properties which are significantly different, and variable compared to the mature wood.
“Home grown larch is currently such an under-utilised joinery timber” said Dainis Dauksta who supplied the material used by Custom Precision Joinery. “High quality joinery grade timber is currently going into low value end markets which is such a waste of our resources. This project showed just how easy it was to select and cut joinery grade timber from larch that was being sold as reject garden sleepers.”
Custom Precision Joinery checked the joinery grade larch on delivery and confirmed that it was fit for purpose. The scantlings where then conditioned in their workshop for two weeks before machining into the required profiles.
| British grown larch is a moderately durable softwood with a colour that ranges from a light to dark brown heartwood to a white sapwood. It has a density of around 550kg/m3 at a moisture content of 12%. When wet it has a tendency to distort but once dry it is generally stable. Potentially large volumes of larch could become available in Wales because of the Phytophthora ramorum epidemic. Larch is a very useful construction timber and larch grown in Wales can already be visually strength graded to C24. It can be used for cladding, structural and joinery applications. High-quality stainless-steel fixings should be used to avoid corrosion of fixings. |
The Windows
Two windows made by Custom Precision Joinery from Welsh larch and on display at WoodBUILD 2019.
Two windows were made at Custom Precision Joinery in Buckley, north Wales, they were the same design but had different paint finishes. The windows were made to a design supplied by Coastal Specialist Ironmongery Ltd (also participants in our windows workshop). The design used was one which has already been approved as suitable for social housing.
“We are very pleased with how these windows turned out” said Colin Morris from Custom Precision Joinery. ”A large percentage of home grown timbers are generally of a higher standard than that of imported timbers. However, the Welsh supply chain is an issue for manufacturers in the joinery sector like us. But with the right investment and perseverance Wales has a unique opportunity to enhance this sector.”
What next?
Profile detail of window made by Custom Precision Joinery, fixtures by Coastal Specialist Ironmongery and paint finish by Remmers (UK) Lrd.
This project has shown that high quality joinery items can be made from Welsh timber that is currently being sawn and sold for low value garden sleepers. Just by grading and sawing that same material in a different way it has been transformed into a high value joinery grade timber.
Simple interventions like this could help develop the supply chain for Welsh timber and offer smaller sawmills opportunities to diversify and provide higher value products into the joinery sector. However, the demand for joinery products made from Welsh timbers need to developed. One way to do this is by working with housing associations and local authorities. This is being done through the Home-Grown Homes Project, led by Powys County Council which is exploring supply chain interventions to encourage growth of the timber sector in Wales.
At the end of the Home-Grown Homes Project a set of recommendations will be presented to Welsh Government with case studies to demonstrate how interventions could help improve the supply of Welsh timber to Welsh house building manufactures to build more and better homes.
| Woodknowledge Wales would like to thank Custom Precision Joinery for offering to make these windows from Welsh timber and putting them on show at WoodBUILD 2019. We would also like to thank Coastal Specialist Ironmongery for their part in providing the specification for the window design and Craig Lovatt, formally of Custom Precision Joinery and now of Remmers (UK) Ltd for initiating the project. |
[1] Corewood or ‘juvenile wood’ is found within the first 10–20 annual rings adjacent to the pith.
Cartrefi Di-Garbon
Comisiynwyd Woodknowledge Wales gan Lywodraeth Cymru I baratoi strategaeth ar gyfer integreiddio cadwyn gyflenwi diwydiannau coedwig Cymru ag adeiladu â phren oddi ar y safle. Mae’r ddogfen hon yn darparu cynllun gweithredu strategol ar gyfer trawsnewid y defnydd o bren adeiladu a dyfir gartref ar gyfer adeiladu tai a helpu i gyflawni dyheadau Deddf Llesiant Cenedlaethau’r Dyfodol.
Darllenwch yr adroddiad llawn yma.
Zero Carbon Homes
Welsh Government commissioned Woodknowledge Wales to prepare a strategy for the integration of the Welsh forest industries supply chain with offsite timber construction. This document provides an action plan to transform the use of home-grown timber in house building and help deliver the aspirations of the Well-being of Future Generations Act.
Read the report here.
