Is Brettstapel an Answer to Scotland's Sustainability Aims

CASE STUDY 1

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a n A n s we r to S c o t l a n d ’s S u s t a i n a b i l i t y A i m s?

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Theodore Shack Angus Henderson Edinburgh University MArch Programme October 2020 Brettstapel in Scotland

1

Contents 7. Brettstapel in the U.K. 8. Case Studies

4. Strategic Benefits of Brettstapel

3. Why Brettstapel?

5,6. Environmental Context

Introduction This report looks into the possibility of introducing Brettstapel (dowel-laminated mass timber) into the building culture in Scotland and how this could help to meet many of the country’s sustainability targets. We do this by looking into the material’s properties, it’s strategic benefits in the context of existing policy, and how it fits in with Scotland’s future forest management. The report goes on to explore its future use here by examining three case studies and drawing lessons from these.

We conclude with some of the challenges and opportunities that Brettstapel manufacturing in Scotland could encounter.

9,10. Solares Direktgewinnhaus

Mobile Factory

11. Ulva Ferry Housing

Conclusions Front cover photo by Angus Henderson: clear felling near Forres.

Brettstapel in Scotland

2

Construction process

scientific research into this natural pheno- wooden structures� menon at the Thoma Research Centre and developed the Holz100 dowelled solid wood

Why Brettstapel

Due to the storage mass of Holz100, many Thoma houses require 30-50 % less energy in operation than the simplified heat demand calculations according to the current standards� Solid wooden walls are the building's key element, enabling us to dispense with complex building technology such as ventilation or air conditioning systems�

Material Properties Brettstapel is a dowel-laminated mass timber panel system, that is 100% timber, entirely glue-free. Softwood lamella are held together by hardwood dowels. It has specific advantages over otherWallconstruction forms, and is a suitable types resource for Scottish timber, as it is able to increase the strength class significantly through lamination.2 Material advantages include:

Cooling (h) Cooling Timetime (hours)

777

• • • •

•

•

Lightweight construcTimbertion, frame,

Brick 38 cm,

10 cm Styrofoam Brick, 10cm 2

H100-W36, 10 Brettstapel cm flax insulation

All components are safely lifted with special mounting hangers� Already in the planning stage, the assembly sequence of the individual elements is taken into consideration in a loading plan prepared by us and the elements can be lifted off the platform one after the other�

mineral wool U-value = 0�16 W/m K U-value = 0�19 W/m K Our 25 cm wall is theby firstmaintaining to be designed in Creating a healthy indoor environment U-value W/m K mineral= 0�16 wool styrofoam 10cm Flax "Holz100-Thermo" and thus offers higher instable internal temperaturesulation and humidity, U-Value= U-Value= 0.19 U-Value=0.16 properties than neutralising normal solid wood� Comparison of the 0.16 cooling time of 3-series constructions with a similar U-value (TU Graz, Thermische Simulation zum Holz100 Bausystem, 2001) The 80 mm thick core also increases the any toxins in the air, and a pleasant acoustic vertical load-bearing capacity of the wall� The thermal storage capacity of brettstapel in a building creates a buffer Brettstapel build-up process environment with good sound absorption.3 For Holz100 there are only two further values cooling time of three constructions (lightBeech wood dowels swell Product name: H100 - W25 11 for a more stable internal temp, reducing energy demand by 30-50%. used by Thomain1 the wood and mechanicalIncreases the strength classFunction: of Scottish timber from apart from the thermal conductivity, which weight construction, brick, wood100) when Thermal outer wall, load-bearing ly create an insoluble bond, Element thickness: 25�0 cm form the basis for a complete, transient, the heating is switched off in winter� The View into the workshop: A wall element is laid by C16 to C30.4 which replaces any kind of Core layer: 80 mm structural-physical consideration� With the itfollowing graphinshows the time hand before is dowelled the next step�until the surglue� 5 or vertical Top layer: horizontal gross density (kg/m³) and specific heat sto- faces on the inside reached 0°C� A month for Fire resistance due to charring surface.

Structure: 7 layers rage capacity (kJ/kgK), all other necessary a thick wooden wall! It should be noted that Quick, dry-fit assembly on site short v – h– dsuitable – k – d – h – for v key figures and calculations can be deter- all designs have a comparable U-value� mined for a realistic consideration and for weather windows of construction.6 the design of sustainable house engineering 3 Sequesters Carbon, around 0.7t CO2 per m soand capable is placed concepts� on the mounting Together with the Graz joist University of Technology, we have carried out dynamic of producing carbon negative buildings.7 building simulations and obtained remarkaThe larch joists determine of the timber High thermal mass bleouter results� One question the was theposition different 20cm wall structure on the floor slab and are installed and levelcapable of reducing The 20 cm wall offers a high level of led with millimetre precision� fire protection and all advantages The walls are fitted with a heating demand.8 of a solid wood wall thanks to the groove on the underside to fit precisely onto the moun46 Insulative and thick wall structure� ting joists and can be assembled in no time at all thanks air tight building Product Name: H100 - W20 to the enormously high and precise degree of prefabriFunction: External wall, load-beastructure, simplifying ring cation� construction.9 Element thickness: 20�0 cm Core layer: 60 mm Total end-of-life Top layer: horizontal or vertical Structure: 6 layers re-usability.10 12 13 2

Brettstapel cross-laminating construction process.

v–h–d–k–d–v

2

Each element is unique and creates a feeling of joy�

•

A wall floats over the construction site

256

41

25cm outer wall

•

Moonwood is more durable than conventional wood – it replaces wood preservatives in a natural way�

5

Solid panels are quick to assemble on site.

17

Brettstapel in Scotland

8

The ceiling elements are mounted

3

Strategic Benef its of Brettstapel Social and Environmental Sustainability Policy By using up mono-species softwood timber (larch, spruce), brettstapel can lock this carbon and give space for the replanting of these areas as biodiverse woodland. It also creates a market for hardwood timber (beech) as dowels.

Brettstapel production would contribute to providing skilled jobs in the rural economy in fabrication and forestry management.

Rural employment and training 18 19

Restoring biodiversity 14

Zero Carbon Emissions by 2045 22

End-of-life material reuse 20

Each m3 of brettstapel sequesters around 0.7t CO2. In an average home, the carbon stored can be around 21t, this is equivalent to taking 100 cars of the road for a year.15

50,000 new affordable homes by 2021 23 Long life construction 21 Brettstapel’s simple material build up and 100% timber content makes it easier to disassemble and separate at end of life. By being almost completely reusable, it can be reused as a low energy material long into the future.17

Mass timber buildings have a much longer lifespan than timber frame which currently meets housing needs.16 By building once and well, Scotland could build affordable housing that is lower maintenance and longer lasting. Thus better value in the long term.

Home-grown brettstapel will reduce current reliance on imported construction materials and consequent energy use of transport.

Brettstapel in Scotland

4

varies in each country.

Forestry in Scotland

Great Britain

48%

Great Britain

48%

Native Near native & fragments Non-native Not determinable

Undetermined Native

Historically, Scotland does not have a particularly positive track record in relation to forestry. Since the enormous expanses of the Caledonian forest after the last ice age, Scotland has seen continuous deforestation, sometimes gradual, sometimes abrupt. Although mankind was the predominant cause of deforestation, and has often opted for solution to forestry which tended towards short-term gain, there were also macro climatic shifts that concurrently affected deforestation.24 After the introduction of the Forestry Act in 1919, there were efforts to reforest much of Scotland however, much of this was non-native Sitka Spruce, and the £8.3 billion £1.7 billion resulting mono-speciel environments have produced relatively imported to UK exported from UK low quality timber, 94% of which was softwood in 2017.25 The UK is the second biggest importer of wood in the world.

Imports and exports

Near-native & fragments Woodland Ownership Non-native 65%

20

0

Other Forestry Commission

32%

35%

Woodland Type28 65%

35%

Woodland Ownership29 65%

The total area of native woodland in Great Britain is estimated to be around

1.5 million hectares

Woodlan Type 65%

The total area of native woodla Great Britain is estimated to be ar

1.5 million hectare

Source: National Forest

Source: National Forest Inventory.

27

Largest net importers and exporters of forests products in 2018 40

varies in each country.

Native Near native & fragments Non-native Not determinable

Brief Overview

60 billion $

49%

20

Imports Exports

China

UK Japan Italy India Mexico Indonesia Russia Brazil Sweden

Imports and Exports of Forest Products 2018.27

Finland Canada

Forested area in Scotland 26

Brettstapel in Scotland

The UK is the second largest net

5

Environmental Context

74%

Differences with Mainland Europe

Opportunity for Brettstapel

Prevailing forestry practice in Scotland differs greatly from that of many nations on mainland Europe. While Scotland has predominately had large expanses of managed woodland, planted and then felled at the same time. In many countries in mainland Europe, large portions of forest are unmanaged, with trees self-sowing to create a rich, healthy and diverse habitats of value. Scotland’s Forestry Strategy seeks to grow from earlier strategies to engage in more holistic praxis in line with European and international imperatives.30

Brettstapel’s ability to create high quality timber products from low or medium grade timber means that it could be ideally suited for Scotland’s present needs. As one of the primary aspirations of Scotland’s Forestry Strategy is to add value to forestry and create markets, Brettstapel is ideally suited to at once create high quality timber and address the current glut of fast growing Sitka spruce.

By felling these areas of Sitka Spruce, more room can be created for native and mixed forestry whilst adding value to timber whose current destiny is pallets, fence posts and paper.

69%

Finland

40%

Norway

Sweden

15% Denmark 11%

Ireland

13% UK

Netherlands

31%

11%

23%

33%

Poland

Belgium Germany

Traditional forestry practice in Scotland

32%

France

36% 37%

33%

Italy

Portugal Spain

Aspirational forestry in Scotland

Forestry cover in Europe 31

Brettstapel in Scotland

6

Brettstapel in the U.K. Existing Examples Although Brettstapel is a new material in the U.K., there are a select few projects that make use of Brettstapel, mainly in rural areas. Projects by both Architype and Gaia Architects are focused on high performance, low carbon solutions, however, due to the lack manufacturing in the UK, brettstapel must be either shipped from mainland Europe or fabricated on-site.

This either negatively impacts on their embodied carbon and increases expense, or relies on a lower quality product that cannot take advantage of pre-fabrication. By comparison the density of brettstapel manufactures in Germany, Austria and Switzerland make the material much more viable.

Archaracle Primary School34 Gaia Architects Brettstapel imported from Sohm, Austria

Plummerswood33 Gaia Architects Brettstapel imported from Sohm, Austria

Coed-y-Brenin Visitor Centre32 Architype Brettstapel contructed on-site

3 hou.5 rs

Thoma

Solares Direktgewinnhaus

Burry Port Community Primary35 Architype Brettstapel contructed on-site

Brettstapel Manufacturers36

Brettstapel in Scotland

7

Case Studies we will se studies a c e re th f and analysis o el in Scotl Through Brettstap f o y it il b e suita look at th

First we will look at the existing examples of the G erman context

1.

Solares Direktgewinnhaus

mber at mass ti k o lo l il w Then we l Scotland se in rura u d n a y it capabil

Ulva Ferry Housing

2.

We wil l prese nt a ne w prop a mobil osal for e Brett stapel fa ctory

3.

Build Back Rural me raw so d l il w we enges e chall Finally h t m ro e case sions f of thes s conclu ie it n ottish por tu el in Sc p a and op t s t t for Bre . studies uction constr

Brettstapel in Scotland

8

Solar Energy

Solares Direktgewinnhaus

Oxygen

CO2

Thoma & Holz100

Ti m

The current centre for the production of Brettstapel is in and around the Black Forest in Germany, Austria and Switzerland (see page 7). Many of these manufacturers started as carpentry companies such as Rombach, Zwick and Tschopp37. Generally these companies grew steadily from joinery and carpentry to solid wood construction. One such company is Thoma which began as a sawmill in 1907, whose associated brettstapel product is called Holz100. This product is incorporated into a holistic practice which starts from felling timber in line with the lunar calender, through to prefabricating brettstapel panels and then assembling them on-site. Thoma also encourages the recycling of it’s products, stating that ‘Products should function in material cycles, so that there is no useless waste, but only useful raw materials.’38 Holz100 was the Brettstapel product used by n11 Architekten for Solares Direktgewinnhaus.

be

r

h

ar

ve

ste

da n cycleof moon t sp e n ts i c i fi c p oi

ener gy

ER

T

OO

NW

e

OO

D’

y rg ne

P OW

N PLA

‘M

energy

rec ylin g

USE HO

LZ

FA 100

CT

OR

Y

alit qu

y

te

m diu me

O

ILL

w as

HO

TH

high quality

WM SA MA

bio

da ti o n

stru

c tio n

wa

g re

con

st e

de

On-site assembly of Holz10039

Diagram by the authors based on info from Thoma40 Brettstapel in Scotland

9

Solares Direktgewinnhaus

Roof Build Up 1. Photovoltaic module 6mm 2. Photovoltaic module point fixing 3. Counter batten 80/60mm 4. Polyethylene roofing felt 5. Soft fibreboard 22mm 6. Flax insulation 200mm 7. Holz100 roof element 176mm

The Building Solares Direktgewinnhaus is a mixed use building built by an architect an engineer for themselves, comprising of rent-able office space on the first two floors, including the architect and engineers’ office and a private residence for the family above. The use of Brettstapel, along with some other intelligent moves including rammed earth floors, a small footprint and orientation, means that this building does not have or require a heating or ventilation system, sufficient energy is drawn from the sun, people and electrical appliances41. The internal environment stays very stable due to the thermal and hygroscopic properties of solid timber.

Along with solar tiles on the roof, this building is net positive for energy production.

1.

2.

3.

4.

5.

6.

7.

Solares Direktgewinnhaus, n11 Architeken43

The example of the Thoma factory and Solares Direktgewinnhaus show how a brettstapel factory could serve local need and produce extremely high quality buildings. This mode of operation could be extremely effective Scotland, all that is required is strategic investment.

3.

Wall Build Up 4.

1.

5.

2.

1. Vertical rough pine board 32-80mm 2. Grid support beam 60/60mm 3. Flax insulation 100mm 4. Fibreboard 22mm 5. Holz100 wall element 306mm

0

Comparison of outside temperatures and inside temperature without heating during coldest months 42

Solares Direktgewinnhaus, n11 Architeken44

5

10

20

Eave Connection45

Brettstapel in Scotland

10

Ulva Ferry Housing Rural Community Initiative

nn

y

en

ny

spen

n y s p e n ny s p e n

ny

pe

sp

Area (per unit): 89m2 Budget: £417,000 Monthly heating costs: £20 Build time: 9 months Source47

s

sp e

ys nn

pe n

p en ny ny s

Thornes Wyness designed these two affordable semidetached houses in Ulva Ferry on Mull after the local community approached them, seeking to increase children to support the local primary school. The design uses CLT imported from Spain to create a very energy efficient, comfortable and attractive homes.46 The project shows that there is an appetite for using mass timber in rural housing in Scotland. And that the system of community land trusts is one that has the confidence to invest in the long life qualities that brettstapel offers.

Right: CLT came to Ulva Ferry from Bilbao.

Far right: photos of Ulva Ferry Housing.48

Brettstapel in Scotland

11

Mobile Factory Build Back Rural

“We asked ourselves, how do we innovate to suit a market demand that is not being met by existing systems.” - Peter Wilson

Build Back Rural is an project led by Timber Design Initiatives that seeks to establish a mobile brettstapel factory that will travel to rural sites, building affordable housing in location with local labour and materials.

The project takes advantage of the existing condition of rural communities that will often already have easy access to land and forestry, and yet a need for affordable housing that is not being met by mainstream house-builders. There is often a strong need in these areas to build new warm, comfortable homes that can support new families and elderly people down-sizing. Whilst they may only be a handful in each community, the cumulative number could be several hundred, and will have a strong impact.51

forest

sawmill felling

planer

At the moment, the key aims are:

solar-powered kiln

1. Increasing awareness of brettstapel.

dowel-laminating press

2. Attracting funding for the project 3. Developing a portable dowel-laminating press, the only element of the mobile factory system that does not yet exist.

“Bringing off-site construction on-site” - Peter Wilson

assembly

CNC cutter

Research and prototyping of Scottish brettstapel led by Timber Design Initiatives working with Makar and Napier University.49

Build Back Rural mobile factory 50

Brettstapel in Scotland

12

CO2

Oxygen

Mobile Factory A Circular System Benefits • • • • • •

Challenges • • •

Difficulty accessing start-up investment Culture change / awareness of advantages over timber frame.

Slightly more up-front investment for increased long-term value.

Circular system diagram by the authors using information from interview with Timber Design Initiatives.52

MOBILE FACTORY

RURAL COMMUNITY WITH LAND & FOREST

SKILLS TRAINING

GR U OWTH IN R

• •

Adding value to Scottish Forestry Local employment and up-skilling.

Financial independence for rural areas Resilient, low maintenance, low running costs, long-life affordable housing Supports the long term viability of rural areas, services, schools etc.

Local production and use mean very low costs and carbon impact + reduced reliance on imports, a resilience welcome in light of Covid and Brexit.

Innovation and export potential.

Carbon sequestration to help meet national net zero emissions targets.

RA LS ER VIC ES &

ECO NO MY

AFF O H O R DA B USI LE NG

SEQUESTERED CARBON

NEW COMMUNITY MEMBERS

Brettstapel in Scotland

13

Conclusions A promising and undervalued material Analysis of brettstapel and Scottish policy shows that it could be an excellent tool in helping Scotland to achieve it’s sustainability agenda, both social and environmental.

However, there are a number of key issues that have been preventing it’s uptake so far. Any proposals for brettstapel fabrication in Scotland will have to tackle: 1.

Lack of awareness of the material and it’s benefits.

2.

Upfront investment in manufacturing facilities.

3.

Conservative nature of construction industry.

4.

Client interest & potential contracts.

5.

Short-term vision that doesn’t value long-term cost benefits.

These issues are highly interlinked. The lack of knowledge and awareness of brettstapel in the UK is what causes the difficulty in attracting investment and potential client interest. This is combined with a shortage of built examples of it. Essentially it is a chicken and egg situation.

Building with brettstapel represents a higher outlay in upfront costs, however, its longevity, maintenance savings and end-of-life value more than make up for these over the building lifespan.

The current market of profit-driven volume house builders seems unlikely to carry out this kind of up-front investment.

Instead, in Scotland, the initiative is more likely to be taken by community land trusts and public sector or institutional clients who retain ownership of their buildings well into the future and so will be more motivated by the long term advantages of the material. As all new public buildings in Scotland now have to be designed to a net zero carbon standard, mass timber, as the most carbon sequestering material around, will inevitably have a big part to play. 53 Brettstapel, with its suitability for Scottish timber,54 offers an excellent means for meeting this swiftly growing demand.

Below: Qualitative comparison of design life of a brettstapel house vs typical timber frame house. The stated life of a brettstapel building is ‘several hundred years’ within that same period, several disposable timber frame houses would have to be built to meet the same needs.56

one hundred and fifty years plus

30-50 years

Factor

Timber frame

Brettstapel

m3 of timber: Complexity of wall build-up: Maintenance costs:

Carbon Sequestration: End of life material re-use (by volume):

40%

97%

Above: Qualitative comparison based on information from Timber Design Initiatives and analysis of typical construction details.55

maintenance

30-50 years

30-50 years

Brettstapel in Scotland

14

Endnotes 1

Thoma. ‘Holz100 Building System Planning Guide’. Version 01/2019. pdf. Available at https:// www.thoma.at/cms/wp-content/uploads/2019/02/planungshandbuch_v1_2019_web_rgb_ en.pdf.

2

Robert Hairstans et al. ‘Understanding the Compatibility of UK Resource for Dowel Laminated Timber Construction’. Edinburgh Napier University. 2015. pdf. Available at https://www. napier.ac.uk/~/media/worktribe/output-1127691/understanding-the-compatibility-of-uk-resource-for-dowel-laminated-timber-construction.pdf

15

Cooper. Op. Cit. Based on assumption of 30m3 timber in a house recieved from Peter Wilson.

Op. Cit. Calculations of car equivalence made using United States Environment Protection Agency. ‘Greenhouse Gas Equivalencies Calculator’. March 2020. Online. Available at epa.gov/ energy/greenhouse-gas-equivalencies-calculator

16

Foster et al. Op. Cit.

17

Thoma. Op. Cit.

18

Scottish Enterprise. ‘Building Scotland’s Future Today’. Scottish Enterprise. 2019. pdf. https:// www.scottish-enterprise.com/media/3109/scottish-enterprise-building-scotlands-future-today. pdf

3

Foster et al. ‘What are the benefits?’. Brettstapel.org. Online. http://www.brettstapel.org/ Brettstapel/Why.htm

4

Peter Wilson, Director of Timber Design Initiatives, in conversation with the authors. Timber Design Initiatives, Leith. 7 October 2020.

19

5

Woodknowledge Wales. ‘Brettstapel production in other parts of the world; adapting techniques for utilisation of homegrown timbers in Britain.’. Woodknowledge Wales & Wales Forest Business Partnership. September 2014. pdf. Available at http://woodknowledge.wales/ wp-content/uploads/2017/02/Brettstapel-Sept-2014.pdf

Scottish Government. ‘Skills Action Plan for Rural Scotland: 2019–2021’. Skills Development Scotland. June 2019. Online. pdf. Available at https://www.skillsdevelopmentscotland.co.uk/media/45683/skills-action-plan-for-rural-scotland-summary-report.pdf

20

Zero Waste Scotland. ‘Construction Resources For a Circular Economy’. Zero Waste Scotland. September 2020. pdf. Available at zerowastescotland.org.uk/sites/default/files/Construction%20Circular%20Economy%20Resources%200920.pdf

6

Peter Wilson. Op. Cit.

21

Ibid.

7

Based on estimates for CLT, Brettstapel, containing no glue would sequester even more.

Greg Cooper. ‘Carbon sequestration – locking up carbon and unlocking the full potential of timber’. Building Construction Design. 2015. Online. Available at https://www.buildingconstructiondesign.co.uk/news/carbon-sequestration-locking-up-carbon-and-unlocking-the-full-potential-of-timber/.

22

Scottish Government. ‘Scotland to become a net-zero society’. News. Scottish Government.

25 Sep 2019. Online. Available at https://www.gov.scot/news/scotland-to-become-a-net-zero-society/

23

Audit Scotland. ‘Affordable housing The Scottish Government’s affordable housing supply target’. Audit Scotland. 2020. pdf. Available at https://www.audit-scotland.gov.uk/uploads/docs/ report/2020/nr_200409_affordable_housing.pdf

24

T. C. Smout, Alan R. MacDonald, and Fiona Watson. A History of the Native Woodlands of Scotland, 1500-1920. Edinburgh: Edinburgh University Press, 2004, 389.

8

Thoma. Op. Cit

9

Ibid.

10

Ibid.

11

TU Graz, ‘Thermische Simulation zum Holz100 Bausystem’, 2001. Ref. in Thoma. Op. Cit.

25

Scottish Government. ‘Scotland’s Forestry Strategy’. 9.

12

Thoma. Op. Cit.

26

13

Ibid.

Scottish Government. ‘Scotland’s Forestry Strategy’. Scottish Government. 2019. pdf. Availabe at https://www.gov.scot/publications/scotlands-forestry-strategy-20192029/ 8.

14

Scottish Government. ‘2020 Challenge for Scotland’s Biodiversity’. Scottish Government. 2013. pdf. Available at https://www.gov.scot/binaries/content/documents/govscot/publications/strategy-plan/2013/06/2020-challenge-scotlands-biodiversity-strategy-conservation-enhancement-biodiversity-scotland/documents/00425276-pdf/00425276-pdf/govscot%3Adocument/00425276. pdf?forceDownload=true

27

Forest Research. ‘Forest Facts & Figures 2020’. Forest Research. 2020. pdf. Available at https:// www.forestresearch.gov.uk/research/forestry-facts-and-figures-2020/, 14.

28

Forest Research. Op. Cit. 27.

Brettstapel in Scotland

15

29

Forestry Commission. ‘NFI 2011 woodland map Scotland’. Forestry Commission. 2011. pdf. Available at https://www.forestresearch.gov.uk/documents/2730/NFI_SCOTLAND-REPORT_010813.pdf 13.

es%20have%20been%20designed,and%20was%20completed%20on%20budget.

47

Ekaterina Tikhoniouk. ‘Scottish isle eco cottages need no central heating’. Passive House Plus Magazine. 27 April 2018. Online. Available at https://passivehouseplus.ie/magazine/new-build/ scottish-isle-eco-cottages-need-no-central-heating.

48

Thornes Wyness. ‘USCA Community Housing ‘. Thornes Wyness Architects. Onine. Available at https://www.thornewyness.co.uk/architecture/isle-of-mull/2017/05/26/USCA-community-housing.html.

30

Scottish Government. ‘Scotland’s Forestry Strategy’.

31

Forest Research. Op. Cit. 23.

32

‘Coed-y-Brenin Visitor Centre’Architype, accessed October 10, 2020, https://www.architype. co.uk/project/burry-port-community-primary-school/

33

‘Plummerswood - Active House,’Gaia Group, accessed October 10, 2020, http://www.gaiagroup.org/projects/project/26

49

Timber Design Initiatives. ‘Build Back Rural’. Website. Available at https://www.build-back-rural.com/

34

‘Primary School, Acharacle, Ardnamurchan,’ Gaia Group, accessed October 10, 2020, http:// www.gaiagroup.org/projects/project/65

50

Ibid.

51

Peter Wilson. Op. Cit.

35

‘Burry Port Community Primary School,’ Architype, accessed October 10, 2020, https:// www.architype.co.uk/project/coed-y-brenin-visitor-centre/

52

Ibid.

53

36

‘Brettstapel Manufacturers,’ Brettstapel, accessed October 8, 2020, http://www.brettstapel. org/Brettstapel/Manufacturers.html

37

Information from manufacturers websites. Respectively; https://www.nur-holz.com/, http:// zwick-holzbau.de/, and https://www.tschopp-holzbau.ch/.

Ella Jessel. ‘Sturgeon: all new public buildings in Scotland to be zero carbon’. Architect’s Journal. 5 September 2019. Online. Available at https://www.architectsjournal.co.uk/news/ sturgeon-all-new-public-buildings-in-scotland-to-be-zero-carbon#:~:text=Sturgeon%20 said%3A%20’Earlier%20this%20year,than%20any%20other%20UK%20nation.

54

Hairstans et al. Op. Cit.

38

Thoma. Op. Cit.

55

Peter Wilson, Op. Cit..

39

Ibid.

56

Thoma. Op. Cit.

40

Ibid.

41

‘Like a Diamond in the Rough,’ Holzbau Schweiz, accessed October https://www. holzbau-schweiz.ch/de/first/magazine-online/detail/?tx_hbchmagazin_article%5Barticle%5D=595&tx_hbchmagazin_article%5BbackPid%5D=58&tx_hbchmagazin_article%5BforceSession%5D=1&cHash=308e767f060abefe35950017068d3c53

42

Thoma. Op. Cit.

43

‘The Solar Chalet,’ Solararchitecture, accessed October 12, 2020, https://www.buk.arch.ethz. ch/Solardatenbank/BilderZweisimmen

44

‘The Solar Chalet,’

45

Ibid.

46

Mull and Iona Community Trust. ‘Ulva Ferry Housing Phase 1’. MICT. Online. Available at https://www.mict.co.uk/projects-services/ulva-ferry-housing-project/#:~:text=The%20hous-

Brettstapel in Scotland

16