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Matriculation Number: s1343000
A SUSTAINABLE APPROACH TO MATERIALS AND CONSTRUCTION SYSTEMS In Scotland
Plummerswood, River Tweed Gaia Architects
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INTRODUCTION A sustainable approach in construction and material choice has been already predicted to be a leading force in design in Europe and now it is also reinforced by the Scottish Government’s adoption of the Climate Change (Scotland) Act 2009 and its delivery plan. “Think Global, Act Local” by Edinburgh thinker Patrick Geddes in 1915 should be a common approach after more than a century of development. Unfortunately even from my own practice in a a Design Consultancy company I can see that the choice of materials as well as sustainable approach to the existing buildings in Scotland is often omitted. This might be caused by still too little knowledge on how good and effective not only for the environment, but also in longer terms for the client’s profit, sustainable design is. Finally maybe because my profession involves renovating existing buildings, but there is much more changing in terms of new technologies in new build sector and that together with social (quality of life), economic (business environment) and environmental (‘green’ factors) sends capital of Edinburgh on the list of the most sustainable cities (website: Arcadis). Certainly there also has to be an appreciation for the traditional architecture - its history and tested through the centuries long lasting structure solutions, as it also is in a way a sustainable approach - building to last or building to be flexible and adaptable. Due to the the change in the way of living as well as technologies allow us to transform some of the sectors in the art of building much further now. This is a review of currently available materials and construction assemblies that could be the alternative choices to the traditional style of building. Particularly if that would be in better balance with nature and in the future it would require much less alterations to be comfortable to live in. Evaluating sustainability of construction and materials in global way would be only possible after dividing it to bioclimatic zones which will allow to choose the best technique for the region. Only then a comparison would be possible. Each part of the world is to some extent ‘struggling’ with different weather conditions in which buildings’ fabric has to correspond to. Those require different strategies for cooling, heating, controlling humidity as well as choosing suitable for the local area materials. The approach has to change significantly from the recent periods when architects and designers could rely in their designs on fossil fuels to endlessly support the comfort in the house. Nowadays we somehow have to go /1
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back to times when we could only confide in nature in aspects like for example, the orientation of a building, renewable resources which it could self-sufficiently generate et cetera. Unfortunately this approach is not caused by its clear logic, but when we start seeing the failure of previous views and lifestyle, which we simply cannot maintain much more longer.
Methodology Using literature review will serve as a main tool to show the existing as well as proposed state of construction materials in Scotland. The sustainable approach in this work will be directly linked with the recent (2017) Climate Risk Assessment predictions, which should provide guidance in terms of temperature change - which will affect internal comfort inside the building. This report will also try to merge new technology with the existing construction style and materials, which will help in urbanistic coherency in social aspect of sustainability. Brief description of Scottish construction will be provided and on top of which main issues with manufacturing in Scotland will be presented due to which only some of the traditional materials are currently still obtainable. The list of successfully built ecologically friendly houses in Scotland has grown in past few years which incite growing interest in sustainability. Those developments often had to rely on imported materials and this will be addressed in this report. Recent academic project created by the author will also be shown which shows some examples of variety of roof, walls, floor material's conductivity, resistance and U-values that could be successfully used in Scotland.
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CONTENTS: 1. Construction culture and climate in Scotland a. Bioclimate and comfort zone b. Introduction to climate change forecast for Scotland c. Traditional construction types 2. Emerging sustainable trends in Scotland a. Timber construction b. Insulation types c. Roof structure 3. Construction and materials for the coming future (climate change)
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MAIN BODY
Construction culture and climate in Scotland Scotland is a very interesting land, which consists of different bioclimatic zones. From severe in rain on the West to moderate and sheltered in the East with temperate maritime climate. Temperatures are relatively mild despite its northerly latitude which is caused by the Gulf Stream (Figure 1). Currently Scotland does not represent a climate with hot summers - that would require extensive cooling and the heat still accounts for more than a half of energy demand. There is a growing concern about the future type of energy demand, caused by the climate change predictions (Figure 3). As we can see on the Figure 2, it might rise up to 40C which already will bring up a problem to unprepared to these temperatures buildings. As it will be described in more detail in this work, the conventional construction and materials in Scotland might not deal well with the predicted temperatures, in keeping the internal temperatures at the Comfort Zone scope, as provided by Scottish Government in Technical handbook for the Environment at minimum 210C (with variations according to the seasons) (Table 1). Nevertheless the expected changes are not easily perceptible at the present, with only a slight change in temperatures across the temperature reconstruction graphs (Table 2). Those are derived from temperature-sensitive Scots pine trees, so should be viewed with caution, but still summertime warming can be noticed. Good example of those changes can be noticed in example of England where the temperature reconstructions are greater than in any time in 1000 years and even some of older generations of Londoners can notice unusual in the past, very uncomfortable summers (also caused by heat island effect) and Scotland by addressing those issues today has good chances to go through those changes differently to its neighbours.
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Figure 1. Diagram by Sara Kliczka based on MeteoBlue.com average weather in Edinburgh
Figure 2. ‘Reconstructing 800 years of summer temperatures in Scotland from tree rings’
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Figure 3. Climate change predictions The traditional style of building differed depending on the character of the part of the country, wealth and period. Nevertheless the primary building material was definitely a building stone, which has the lowest embodied energy (HES, 2016). Unfortunately out of 2,500 stone quarries in its peak of 19th century, only 7 have remained to this day as active stone block producers. Now when architects either want to refer to the unique for the region tradition of using stone have to be imported, with around 50% of stone needed today in Scotland imported from England. As warned by Historic Environment Scotland (2016), it not only means additional costs on transport but also conservation
Figure 4. Historic Environment Scotland: ‘Scotland’s traditional building materials’ most of which could still be used as sustainable material choices. /6
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issues in matching right stone particles with the existing. Not only building stone undergoes changes in the industry but also granite which especially in Aberdeen was a popular building material retrieved from North-East Scotland, now is sourced from Portugal or even from China. Very popular in the past: scottish slate had the last quarry closed in 1950s’ and now limited amount of recycled scottish slate has been left (HES, 2016). Currently the most similar to traditional various in shape type of slate, resembling the scottish one is imported mainly from Wales and England. Another construction type which was withdrawn, but from totally different reasons, in order to prevent city fires, was timber construction mostly succeeded by stone and then after Industrial Revolution also steel with a famous Scotsman designed by Dunn and Findlay architects in 1899 and completed in 1902 which was a starting point in using steel frame (Jackson, 1998). For the roof before getting more softwood plantations, hardwood has usually been used together with Scottish slate for cladding; steep to shed rain and snow quickly to avoid water penetrating the building. Another material which started to be used in 20th century and which covered many of newer buildings fabric were clay tiles made of local clay sources by hand and therefore varying in colour and size. Finally cement, concrete, and mass-produced brick with often little regard to energy or environmental issues.
Figure 4. Largest net exporters of forest products, 2012. Source: FAO
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United Kingdom in comparison with other European countries unfortunately does not have very good forest cover (Figure 5.). This history of deforestation is long and includes more and less direct human’s influence (Puplett: n.d.). Starting from natural climate changes 4,500 years ago to farming which involved burning forests for grazing by animals and finally to over-exploitation caused by Industrial Revolution and the Wars. As we can see in the Figure 4 of the main exporters, Scotland has a market share of 75%, 22% more than national average which already gives a good starting point in taking this as one of the resources for sustainable construction. Nevertheless its is mostly a low grade timber made mainly from Sitka spruce which is not very suitable for heavy loads and ultimately most of it is used for chipboard production and packaging. Imported timber still has to be a main source for construction and is calculated to be around 60%. Scottish Government has targeted massive changes which started in 2012, which in its ambitious proposals take 100,000 hectares of planting in 2014, with this year 2017 to be 15,000ha larger (Ewing, 2017). In each of the years 2020-21 there will be 12,000 hectares planted which means around 26.5 million trees and the predicted number will grow with 14,000 in 2022-23 and 15,000 hectares of new woodland from 2024-25 (Davidson, 2017). Scotland in comparison with the rest of UK also actually does delivers 83% of the new planting, which proves that the plans of increasing the forestry might actually dramatically change the construction industry. These are very optimistic forecasts for timber industry which soon could become more and more affordable, due to the larger resources and as a result much more often used then at present.
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Figure 5 . Global Forest Resources Assessment 2010
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Emerging sustainable trends in Scotland Recently construction in Scotland undergoes changes both caused by emerging new trends and rise of supporting it new associations, notably SEDA in Edinburgh which published recently (2017) compilation of 100 most sustainable buildings in Scotland, with variety of actions promoting sustainable approach in construction and materials. Another factor is awareness raised by the government and the regulations and additional funds supporting renewable heating systems, FITs (Feed-In-Tariff) or community sustainable actions grants. Unfortunately the sustainable approach towards small scale, domestic dwellings usually means additional costs which makes them still very exclusive, but the larger building’s input is much more cost effective. This is connected with prefabrication costs and some of the considered as sustainable materials still being imported from the abroad. Another issue for sustainable aiming architectural studios and contractors is the need to add costs of quality control certifications, such as BREEAM, LEED, Passivhaus Premium which are usually required by clients as a prove of the future performance of a building. Nevertheless the market for sustainable materials such as: CLT, well insulated wooden I-joists construction, Brettstapel, natural insulation or blockwork is growing. Therefore the main section of this report will focus on the timber construction, insulation possibilities that would work well with timber and two excellent options for the roof structure in Scotland.
Timber Construction Timber-frame construction if sourced from sustainably managed forests and plantations can be a very good solution. Organisations such as Forestry Stewardship Council, Programme for the Endorsement of Forest Certification are providing trademark signs to ensure these could be approved beforehand. Alternatively organisations like LOOP hub provides online space to bid for materials from demolitions and wood can often be reused in construction. It is already very popular choice in Scotland and accounts for 75% of all new homes in Scotland (Guide The Highland Council: 2013) another popular construction type which can be recycled are steel construction and renewed blockwork, but often have much bigger environmental impact and unless from recycled source can’t be seen as the best sustainable solution. These materials are also having a high embodied energy and /10
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different lifespan to timber but it’s important to mention that if designed to last longer and used with other materials with similar longevity it could be successfully used in a sustainable construction - building to last.
Figure 6. ‘Global Forest Resources Assessment 2010’ Michael H.Ramage et
Timber-frame construction made with wooden I-joists improves the sustainability of buildings not only because timber itself is much more ecological friendly material (A typical timber house saves 4 tonnes of CO2 *) , but it is also very flexible material which could be used in variety of different shapes. There are common timber studs but also I-joists which allow for the insulation to be much greater and ultimately lower heating demand. An example of successfully used timber I-joists is Suburban Passive House by Brennan & Wilson Architects which demands 16kW/m2/year of energy. Timber frame shaped this way not only enabled the walls to reach around 300mm thickness, but also prevented from heat loss in thermal bridging.
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Figure 7. Photos taken by the author. BWA Passivhaus This building is also interesting for its use of reclaimed timber for the flooring which as been sourced from hospital’s refurbishment, concrete slab mixed with reclaimed potash and the slate worktop in the bathroom from snooker table. Wood surprisingly for some proves to become one of the most advanced materials as discussed by Risen in his Article (2016, Risen). Compared with other robust materials like steel or concrete, mass timber will equally well perform in new urban developments. It is much cheaper, renewable, easier to assemble, more fire resistant (steel melts, concrete often does ‘explosive spalling’, while wood chars slowly and on the surface first).
Figure 8. A WOODEN SKYLINE Dan Bracaglia
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Mass timber constructions like n-SIP panels, CLT and Brettstapel all have to be prefabricated. These methods of construction is very effective as it does not require slow growing hardwoods but can easily be made of softwoods. Manufacture then takes place indoors, therefore the season is not as issue in production and building can be erected very quickly on site afterwards. On the other hand fabrication sites are often very far and in an example of Brettstapel till 2013 had to be imported mainly from Germany. Brettstapel is a solid timber construction system fabricated from softwood timber posts connected with hardwood timber dowels. The concept for this structure type comes from a German engineer Julius Natterer who in 1970’s propagated innovative but also very simple in its concept way of producing structural walls without need to support it with other materials (which will probably have much different lifespan and environmental impact). In Scotland the first house to be built in this emerging technique was Plummerswood project by Gaia Architects in 2011 and has been chosen by the architects for its toxic free and glue-less timber joining. Gaia Architects prove to be designing not only to meet excellent standards of Passivhaus (Passivhaus Trust, 2013) but also control the air quality by using pure materials. Although this technique is still relatively new in Scotland, with supplementary manufacture sites so far opened in England, the interest might grow.
Figure 9. Building Envelope of Plummerswood from ‘Passivhaus Awards 2013 Air permeability: 0.6m3/hr/m2 @ 50Pa Air changes 0.42h-1 @ 50Pa U-values: Wall: 0.14; Floor: 0.12; Roof: 0.12; Windows: 0.8
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CLT - Cross Laminated Panels are made of pieces of eg. Spruce, Pine in overlocking system of panel sandwich which makes them very strong and 95mm thick. CLT sometimes is referred by engineers as “plywood on steroids” and this type of construction has been successfully proven to be performing well instead of steel. Well known example of 7-storey apartment tower in Stadthaus, when opened in 2009 was the world tallest modern building to be made of timber. Those methods are about 30% faster than steel/concrete construction, where parts just like flat pack furniture is screwed together on-site, which is possible because of precision of computer aided machinery. One of the winning entries for Scotland’s Housing Expo 2010 (SEDA, 2017) is Timber House by John Gilbert Architects which in unusual way shifts metal and timber. Corrugated aluminium in this project is used as cladding and the construction entirely relies on CLT imported from Sweden, aiming to foster a market in Scotland.
For cladding and especially indoors, but possibly in construction too thermally modified wood is another wooden building material in which production thermal modification process of timber takes place, turning poor quality to timber with significantly more stable properties (expand and contract less in contact with change in temperature and humidity). According to European Standard EH 350-2 published in 1994 durability class can be improved from class 5 softwoods up to 1-3 class due to this process. It is worth mentioning possible use of this timber in comparison to CCA-impregnated wood which is used in construction (Sandberg, 2015). It is still unknown how this product will behave in cradle to grave analysis as it has not been used as a building material before.
Insulation Insulation is a very important part of sustainable design, especially in Scottish climate and can dramatically reduce energy demand for heating in a building. Unlike the last couple of decades when the perception was that it is important to fill the cavity wall or add insulation on the blockwork regardless to the ecological footprint of a product ( as the building itself will then become more energy efficient) its has been proved and is much more sustainable to install more breathable and naturally derived, non toxic insulation (eg. in case of fire).
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Embodied energy (by GreenSpec): Cellulose – 46 MJ Sheeps wool – 100 MJ Polyurethane – 424 MJ Wet-formed wood fibre-board – 546 MJ Cellulose is one of the oldest insulation materials, dating 1950s’. Is produced from old newspapers and other paper waste. That makes it still a good sustainable choice, with recyclability its content around 85%. The flame retardant used in protecting the insulation is made of borates which has not been proved to be toxic (Morgan, 2006). As pictured in the experiment in the figure 10, cellulose insulated construction thanks to the amount of fire retardants collapsed after 42:30 minutes, which might be a good result in comparison with fibreglass and not insulated structure which collapsed first. It might be worth checking before specifying this product if the flame retardant product has health certificates as it might break down or dissipates after use.
Figure 10. Steven Winter Associates, ‘The Big Burn’. Source: youtube, RIGHT: Photo credited: GreenSpec Sheep’s wool Is a good choice especially in loft and in-between floors areas, as a bioproduct deriving from commonly bred animal in Scotland this makes this product easily accessible and this reduces transport impact in comparison to other insulation types. Variety of manufacturers in Scotland offer insulation in different thicknesses and suitable
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for different elements of a building.
Photo credited: GreenSpec Wood fibre insulation is especially a good choice in combination with mentioned above timber construction which produces spaces with excellent air quality and quiet living soundproofing (Fallwell, 2017) and with quite constant temperature within the building regardless to the external temperatures. Although Fallwell (2017) in his article argues that the market share for wood fibre insulation is still very small, it is growing and now also finds new applications (roof, walls, floors). An example of successfully used wood fibre insulation is mentioned above Plummerswood by Gaia Architects (figure ) with their strict non-toxic standards used low grade wood fibres bonded by tree resin. Furthermore the heat capacity of natural wood fibre is more than twice that of mineral wool. As its fibre has the capacity to both absorb and release moisture making it a breathable structure, which again considering the climate change would be very useful in hot summer days.
Photo credited: GreenSpec
Roof Slate and clay tiles are traditionally used and well tested natural material in Scotland.
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Pitched metal roof with continuous insulation sheeting materials has been used in many projects like: Houl by Simon Winstanley (Standing seam zinc), Model D house by Gokay Deveci, Kincraig Milehouse by David Somerville etc. Surprisingly, as it won't be the first material to come to mind when thinking about 'green materials' using metal after that research has appeared to me as a good choice for its 100% recyclability, durability and high solar reflectivity and emissivity levels which will help in the future when the climate change might become an issue. This material will prevent from absorbing the heat by the building and instead of absorbing solar energy its re-emissive surface will be reflecting the heat. Another positive factor when it comes to standing seam is that it can also be manufactured directly onsite which reduced haulage. Flat green roofs might be a great solution for Scotland, by not only providing greenness to the city which could utilise by habitants in urban areas often striped from local parks and green spaces. This will enhance connection with nature, as variety of different plants could be grown on top of the roofs, from edible herbs and vegetables to simple plants and bushes. The choice varies depending on the needs, but as encouraged in recent pamphlets by Butterfly Conservation (2016) green roofs in busy places like Edinburgh centre, especially around Arthur’s Seat could help in bringing endangered biodiversity to the city like eg. Northern Brown Argus butterfly. Next to as we could say more ‘ethical reasons’ in bringing nature in the place where our building will take natural space are also properties could help in dealing with Urban Heat Island Effect. Green roofs as living building material presents great cooling effect, linked with water evaporation which lowers the temperature. Heat Island as mentioned before is a problem which London has to tackle and through actions like green roofs installation in Scotland this could be reduced. It is being a great solution in areas with concrete tiles or asphalt roofs which tend to absorb the solar radiation into the house during the day and release at night. Water retention is another characteristic of Green Roofs which with precipitation expected due to the Climate Change (ASC,2016) will be a sustainable approach. Another aspect is energy efficiency, as green roofs have proven to reduce energy demand needed for cooling in summer by over 75% (SGRF). In some countries like Iceland for centuries turf has been used as a an outer skin with stone or timber construction (Figure 11). Serving as a great mean of insulation from harsh /17
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climate, today undergoes a real renaissance and which today we see in green roofs, walls not only in rural areas anymore.
Figure 11. Turf houses in Iceland, traditional on the RIGHT, contemporary house in Gata, Hrunamannahreppi on the LEFT.
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Figure 12. Example of U-values of materials compatible with construction type in Scotland. Made by the author
CONCLUSIONS New approach in construction and materials technology is needed to tackle some of the inevitable changes that the world faces now. Those require deep consideration of the bioclimatic zone in which the site is situated and its characteristics as well as properties of materials (embodied energy, lifespan, thermal transmittance, cradle- to- grave analysis, et cetera). Sustainable construction and material choice involves also design connected with the history of a place with long-tested techniques of the craftsmen in that area. That is why local research beforehand is so important, finding out not only current trends but also right inspiration. It not only helps people in identifying themselves with a building as belonging to their culture in the same way traditional techniques can inspire in creating sustainable but also simple in the construction buildings. Those aspects might seem less important but when examined carefully, those building which in their construction were adaptable and prone to changes and those that through their mindful design were loved by its users are those that stayed with us for century. In other words - those that anticipated the future.
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Examined solutions for Scotland in this report show issues that have to be addressed today in sustainable design, such as climate change, small number of good class timber plantations and closed queries (figure 4). It also shows positive shifts in government policies and growing interest in associations (SEDA, Green Tease) and showcasing sustainable methods in Scottish architecture (strongly represented now by architects like Makar, Gaia, Brennan) in projects like Timber House by John Gilbert Architects as one of the entireties for Housing Expo. In each of the researched project, different strategies in achieving sustainable goal have been undertaken. Some designers would decide to sacrifice cost and locality of materials to get 'toxic free' buildings like Gaia Architects, some would be more concerned about affordability and designing 'a pattern' for a sustainable material choices like Gokay Deveci in his “Tigh-na-claddach’ project or David Somerville Architects completed for Highland Small Communities Housing Trust and finally some would be more concerned about tradition and design.
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Traditionally used materials materials as a way of keeping link with the past history and fairly good sustainability scores (pure materials). Tables are excerpts from ‘Scotland’s traditional building materials’
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