Woodknowledge Wales

Woodknowledge Wales

Inspiring innovation through collaboration

Case Study

Carbon Storage Contract

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The future building stock is the most effective and most immediate opportunity for carbon reduction and long-term carbon storage. By creating a new economic model for monetising the carbon reduction and storage capacity of the future building stock, the use and specification of low-carbon and carbon-storing materials could be incentivised.
Woodknowledge Wales have been working with providers of a voluntary carbon marketplace that pairs business buyers with building projects that demonstrate meaningful carbon reduction and carbon storage (30+ years). To demonstrate the viability and potential economic incentive, we have developed this exemplar carbon storage contract based on a recent social housing development in Llanbedr, Wales.
The goals are:

  • To change the financial equitation for developers, architects, engineers, and builders to use more low-carbon and carbon storing building materials.
  • To enable businesses to achieve their carbon reduction goals by purchasing reliable, verifiable, and asset-backed carbon reduction and storage contracts (CRSCs).

The building industry has adopted EN 15978 as the platinum standard for quantifying CO2 avoidance and CO2 storage which allows this mechanism to work internationally.

For further information, please get in touch: info@woodknowledge.wales.

Google Map highlights exemplar timber housing projects in Wales

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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 →

Demonstration of Practical Building Performance Measurements

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Woodknowledge Wales (WKW) believes that we can only improve the performance of housing and really deliver zero carbon through the measurement of whole life carbon and testing of building performance. Otherwise we live in the dark.

How do we make building performance measurement practical and affordable?

Woodknowledge Wales and Cardiff Metropolitan University recently carried out detailed performance measurements on two newly built timber frame low rise blocks of flats as part of our Home-Grown Homes Project. The purpose of the work was to test out novel methods of building performance evaluation being pioneered by Build Test Solutions (BTS), who specialise in making practical building performance measurement technologies.
The two building projects participating in the testing were:

  • Pentland Close, Cardiff, a development for Wales and West Housing Association. Built by Hale Construction who procured Sevenoaks Modular as a specialist timber structures supplier using their Trisowarm system.
  • Croft Court, Welshpool, a development for Mid-Wales Housing Association. Built by Mid Wales Properties Ltd, who contracted AC Roof Trusses to provide the timber frame.

Both projects were designed with high thermal performance aspirations, and the measurements have shown that this high performance was delivered in practice. WKW hope that these measurements could provide the template for as-built performance measurement testing in the future.

Testing equipment in place at Croft Court.

The performance testing enables the contractors to demonstrate the quality of their work and providing quality assurance to their clients.

The Clients Perspective

Grant Prosser from Wales and West Housing Association commented that

“these measurements for the first time allow us to quantitively assess the energy performance of the built product at completion, as the performance gap is a significant concern for us as it negatively impacts on our residents this is fantastic quality assurance on this project and could be a great way for us to inform our product selection and work with contractors to provide high quality, low carbon new homes.”

The Manufacturers Perspective

Matt Hall from Hale Construction said that

“it’s been great to be involved in the project and get assurance of the quality of our work. We pay close attention to detailing to achieve the design airtightness and limit thermal bridging and it’s great to see the proof that this pays off”.

Thermal Performance and Buildings

Thermal performance refers to building’s ability to retain heat, so that when the performance is higher the dwelling can be heated inexpensively and with lower consequent emissions. It is measured by the Heat Loss Parameter (HLP), which is a measure of the rate of heat loss per degree of temperature difference between inside and out per m2 of floor area.
The performance gap is a much-researched phenomena in buildings, where the actual thermal performance is typically worse, and sometimes much worse, than the design expectation. For example, the Building Performance Network’s recent State of the Nation report which was part funded by Woodknowledge Wales found that in their sample of 29 buildings measured, 20 performed worse than expected by an average of 18% with an extreme case 100% worse than predicted.
Heating buildings accounts for around a third of all emissions in the UK, and addressing these emissions is therefore a key part of any national decarbonisation plan. At present all policy in this area is based on predicted, rather than measured performance, this is largely driven by a lack of practical methods to measure building performance.

The Pulse air permeability testing equipment.

How to Test Thermal Performance in Buildings

Currently the most widely used method to measure building thermal performance is called the co-heating test, it has been a crucial tool in revealing the performance gap but at a cost of thousands of pounds per test and requiring a building to be empty for two weeks it is not practical on a wide scale.
Build Test Solutions make building performance measurement equipment and methods to address this gap, which they applied alongside traditional methods on these two demonstration projects. The measurements included airtightness using BTS’ Pulse equipment and a blower door test, whole building thermal performance using BTS’ SmartHTC and a co-heating test and the thermal performance of the external walls using BTS’ heat flux plate kit. Richard Jack, a product manager at BTS, said that

“this project is an excellent demonstration of a full range of thermal performance measurements, and an excellent opportunity to engage with clients, manufacturers and contractors to understand how the measurements can help inform their processes”.

Croft Court, Welshpool

In Croft Court, the performance measurements were carried out in a top floor flat, for each measurement the measured performance was very similar to the design value.

This suite of measurements allows not just a judgement of the overall thermal performance, but also allows sources of heat loss to be further broken down through different heat loss paths.

Pentland Close, Cardiff

In Pentland Close, measurements were carried out in a top and bottom floor flat and for each showed close agreement with the design values. Data collection for the SmartHTC measurements in these flats was interrupted by the movement restrictions imposed by COVID-19 which means these results can’t yet be calculated.

Pentland Close. Ground Floor Flat Pentland Close. Top Floor Flat

The difference in performance between the two flats is caused primarily by the adjacency of the ground floor flat to an unheated buggy store. By comparison, the top floor flat (which is of the same dimensions) is next door to another heated flat and hence assumed to have no heat loss through the equivalent wall. This results in an extra source of heat loss through the internal wall between the two and also a higher calculated thermal bridging due to larger exposed area. The breakdown in heat loss for the two flats shows this additional heat loss to the buggy store.

Comparing different Build Projects

Beyond the comparison with the design figures for each flat, it’s also possible to consider what level of performance the flats reach in comparison with others.
At present, fabric performance metrics are not common measures of the energy performance of dwellings, with the Energy Efficiency Rating from the Energy Performance Certificate the most commonly used metric. The Energy Efficiency Rating is based upon the expected cost of fuel consumption to heat a dwelling, calculated using the Standard Assessment Procedure (SAP). This calculation is based upon the thermal performance of the dwelling, but also an assumed occupancy pattern, the efficiency of the heating system and the assumed cost of energy (gas and/or electricity). The Croft Court flat has solar PV panels which significantly offset the cost of electricity, and hence result in a higher (better) EPC rating.

Flat EPC Rating
Croft Court 92 (A)
Pentland Close ground floor 81 (B)
Pentland Close top floor 82 (B)

Measuring fabric performance

A building’s thermal performance is key to its energy performance and thermal comfort, it is fundamentally important because the building will likely last longer than its systems or occupants. As such it makes sense to consider a specific fabric performance metric such as the Heat Loss Parameter, alongside the EPC rating, promoting a fabric-first approach. The HLP has previously been used as a key performance indicator in the Code for Sustainable Homes.
All three flats measured display high levels of thermal performance, with insulation levels similar to those recommended in schemes such as Passivhaus (though with higher air permeability). This is clear when comparing the measured HLPs in these flats, which ranged from 0.65-1.00, with the HLP scale produced by BTS.

The performance measurement demonstrations provide quality assurance on these three flats, and a demonstration of what’s feasible using performance measurement. Diana Waldron from Cardiff Metropolitan University, project partners on the Home-Grown Homes project, summed up the project as;

“a unique opportunity to gain further understanding in the area of building performance evaluation methods, aiming to find ways to make them more approachable to all relevant actors in the building industry. All the learning captured during this investigative work will be further disseminated, put into practice and re-tested, in tandem with our main aim: to achieve better quality homes in Wales”.

 

Coast Redwood Groves in Wales – a planting solution in a changing climate?

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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.”
Shot from ground up of coast redwood tree at Leighton GroveIn 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

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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 on planer showing straightness of the grain

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

2 windows displayed on a table at a conference trade show

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.

Grŵp Cynefin video about benefits of building with timber

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Video from Grŵp Cynefin explaining the benefits of choosing to build with timber. In this video see the project under way at the former Buckley Medical Centre, in the town centre. The £2.2m two-storey timber-framed building will comprise 14 two- and ten one-bedroom apartments and is being developed in partnership with Flintshire County Council.

Home-grown Timber Construction

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Cwrt Rhos Fynach, Rhos on Sea

Quality homes designed, constructed and built from Wales’ woodland resource by local companies, to meet our housing needs – surely a win, win, win for our economy, environment and society?
Cwrt Rhos Fynach, Rhos on Sea was designed by Cru Architects, for Wales and West Housing Association to meet the needs of Conwy Borough Council in North Wales. Housing up to 26 residents in 11 flats, it was constructed and built by Williams Homes (Bala) Ltd using home-grown timber.

Benefits Of Using Home-Grown Timber
The Rhos on Sea project demonstrates that in Wales we have the raw materials and technical capacity to create a modern high performance and sustainable built environment. The project presents a model that if repeated all over Wales using a multitude of offsite techniques[1] available to clients would transform the quality and sustainability of the built environment and create additional economic and social value. This projects gives more confidence to an emerging Welsh industry that aspires to supply both the Welsh and English markets.
Wales has 13.8% forest cover. The European average forest cover is 37%.  Increasing the forest cover of Wales would be good for bio-diversity, water, air, amenity, flood prevention and soil health. It could also supply a sustainable construction resource for our future generations.
85% of timber used in construction is imported.  This means that there is a substantial market demand to enable expansion of the UK timber industry.  Increased production of home-grown timber is good because:

  • It improves the balance-of-trade,
  • It creates employment – particularly in rural areas
  • It encourages forest planting, which is good for the environment.

Increasing forestry and increased construction timber form part of climate change mitigation strategies.  Forests provide a permanent carbon store. When timber is used in long life applications such as a construction beam, a carbon store is then created in buildings. Both forests and construction timber can be accounted for in a way that helps Wales meet its climate change commitments.
The Rhos on sea projects contributes to climate change mitigation in 3 key ways. (1) The high performance housing reduces operational energy consumption. (2) The use of homegrown timber creates carbon store that can be quantified and accounted for to help Wales meet its climate change commitments. (3) The indirect stimulation to forest planting is a further benefit, although difficult to quantify.
The Rhos on Sea apartments demonstrate that home-grown timber is suitable for use in modern timber frame construction. The project demonstrates that with a motivated client, it is entirely possible to construct modern affordable high performance Welsh houses in a way that stimulates the development of Welsh businesses and the local timber industry and creates confidence about future demand.
[1] Open panel, closed panel, pre-insulted panel, volumetric etc.

Homegrown Timber in UK Construction – Case Studies, Volume. 1

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The projects showcased here represent a snap-shot of what’s happening throughout the whole of the UK, but with an emphasis on projects in Wales – from housing to retail, simple homes and social housing to high end self-build, as well as offices and schools.
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