ARC6821 Materials for Low Impact Buildings Jing Yiran Student Number: 190183774 Word Count: 2863
Defining Low Impact Materials The first question considered in this article is what a low-impact material is. Low-impact materials require humans to touch the ground lightly. When designing buildings, it should integrate with the local environment. The definition of ‘low-impact development’ was explained by Simon Fairlie, as one that ‘through its low negative environmental impact either enhances or does not significantly diminish environmental quality’ (Fairlie1996, pp.xiii). In sustainable architecture, this definition is reinterpreted, as mentioned in the book of Reinterpreting sustainable architecture: The place of technology. Journal of Architectural Education, it indicates that the more appropriate way to understand this strategic diversity would be to spend more time to find a variety of solutions for problems rather than seeking for complex definitions. (Guy, Farmer2001, pp.140). According to Fairlie, at his book of Low impact development: Planning and people in the sustainable countryside, in chapter 5, the nine criteria for low impact was included, there are: The temporary-the cycle of temporary accommodation is short, so the damage to the environment is minimal compared to the general permanent buildings (Fairlie, 1996, pp.70). Small scale-It is more evident that small scale building would have less harm compared to the larger building because of energy consumption reduction (Fairlie, 1996, pp.72-73). Unobtrusive-The visual impact of buildings is sometimes unacceptable to residents and the installation of solar panels on a ground-impact building is very much in contrast to the surrounding environment (Fairlie, 1996, pp.73). Local materials-There are three reasons for using local materials. First, easily accessible, which are easier to find and adapted to local conditions. Second, it is more natural to accountable. Finally, the local material is easily assimilable (Fairlie, 1996, pp.73). The wild and biodiversity-The undomesticated wild environment is easily destroyed. When people participate in nature and bring in a pollutant, it is easy to cause deep-rooted harm to the surrounding flora and fauna (Fairlie, 1996, pp.73). Resource consumption and Transport-As mentioned above, local materials consume less transportation energy and therefore reduce the use of non-renewable energy sources. Sustainable use and positive environmental impact- Sustainable development can also link the overall improvement of the project environment. Why do we need Low Impact Development? In Fairlie's foreword to Jenny Pickerill and Larch Maxey's book "Low Impact Development-The future is in our hand,' he stresses that The ecological crisis is already a fact of the moment rather than a future probability, 90% of the fish in the ocean has gone, and people's activity intervention on Earth is almost 100 times faster than we predicted (Pickerill and Maxey: 2009, pp10）. Carbon dioxide produced by industry and machine manufacturing leads to global climate and sea-level rise. According to the NASA, and the National Oceanic and Atmospheric Administration (NOAA) Date shows that the warmest year on record globally (fig.1). In terms of the highest annual temperature increase on the Earth's surface, global temperatures have risen by 1.78 degrees Fahrenheit (0.99 degrees Celsius) in the last 150 years, and this trend has not changed significantly. The greenhouse gas emissions will accelerate the melting speed of the Antarctic ice sheet, which will rise about 5 meters within the next millennium, according to the forecast from IPCC (IPCC2001, P.881) (fig.2.). Therefore, It is a challengeable task to achieve the target of the 44th IPCC, which will be able to curb CO2 emissions growth to 1990 levels and within 1.5 degrees Celsius over the next decade, especially in the construction department, which has more step need to do( Masson-Delmotte 2018, p.2). In the RIBA2030 climate challenge, more detailed low-energy targets began to effectively implement. Using low-carbon materials as far as possible is an effective way to help people solving the survival crisis (Woolley 2013, p18).
This paper will first discuss the definition and criteria of low-carbon materials, and then use Victoria Quays in Sheffield as an example to discuss the availability of a low-carbon material through the analysis of the local geographical environment and historical investigation.
Fig.1-Land-ocean temperature index, 1880 to present. Image source: NASA, NOAA
Fig.2- Simulating the stages of bipolar climate change at different times. Image source: IPCC
Assessment criteria for low impact materials According to the contemporary vernacular design book, Britain needs to build 232,000 and 300,000 new houses every year to meet the market demand. However, in 2015, the government only built 142,890 homes. It resulted in an insufficient number of dwellings and excessive housing prices. According to statistics, among the newly built houses in the U.K., the top five companies in the U.K. accounted for 38% of the total number of homes built, and the top 10 construction companies accounted for 48%. It is essential to make the new houses built by these large companies to meet zero standards. Unfortunately, with zero carbon Homes (ZCH) and the code for sustainable homes (CSH) was abolished, these house developers no longer have legal binding force. Therefore, the responsibility for environmental protection becomes one Kind of obligation. (Nash 2019, pp2). According to the RIBA 2030 goal, we need to turn more ordinary buildings into green buildings. By reducing 75% of the operational energy, half of the embodied carbon, and saving 40% of water resources, maintain a healthy life. According to new research by
construction blog Bimhow, 23% of air pollution, half of the climatic change and landfill wastes, and 40% of water pollution are from the construction sector. In separate research by the U.S. Green Building Council (USGBC), by 2030, commercial buildings will increase carbon emissions by 1.8%, more than 40% of total energy consumption（Kumar, Razaa, 2018）. Life Cycle Assessment (LCA) is a method to measure the embodied energy and carbon of a building. It includes (fig.3): Cradle to Gate (Extraction to Manufacturing) Cradle to Grave (Extraction to End of life) Cradle to Cradle (Raw material to Recycled material) —— Reuse & Recycle
Fig.3-Product life cycle assessment. Image source: GRESB website “Material considerations for reducing building related carbon footprint”
By understanding the "life cycle assessment", the carbon footprint related to the building can be reduced. It is difficult to reduce the entire cycle of embodied energy and carbon from Cradle to Grave. Still, it is relatively more comfortable to reduce the carbon footprint from Cradle to Gate and Cradle to Site (Plesmakers, 2012). Of course, there are many issues with LCA, such as concerns from environmental protection and socio-economic concerns (Dreyer et al. 2006), and the lack of transparency in assessments. But it is undeniable that in the "Cradle to Cradle" stage, reuse materials can reduce environmental pollution more than recycling. At the same time, the connector of the building design should be detachable from the primary building materials to ensure that the building materials can be reused rather than downcycling. According to the book "Deconstructed Design" mentioned, there is an urgent need to design components with connections to allow discrete replacement of each part, while recognizing that different components have very different life spans (Morgan and Stevenson, 2005). By understanding the different coefficients of various materials of Embodied energy/carbon, the durability of different materials, the number of years of landfill decomposition, the degree of Toxicity, and Life cycle analysis, the next chapters will detailed explain straw, timber, earth, and lime, those low impact materials.
Choice of low impact materials
Straw Cereal plant mainly includes wheat , oats, rye. Straw is a by-product of the cereal plant, the earliest building materials using straw as a Load-bearing wall can be traced back to the 19th century, Nebraska, in the United States. When baling machines were invented shortly (King, 2006), straw bale buildings appeared later in the UK. The first residential building with straw bale was built in 1995 by Bob Matthews, still in use today (Goodhew, Carfrae, De Wilde, 2010). Houses using straw as building materials are divided into load-bearing and non-load-bearing structures. Due to the limitation of past technical, straw was mainly used in bearing wall for local, and small single-story buildings. However，with the technology development, straw has been used as a non-load-bearing structural filler in recent years, such as the York Ecological Warehouse (Figure 4). According to the ModCell® Straw Technology website, the building uses prefabricated straw cladding panels and is the largest straw-clad building in Europe. Its laminated wood frame helps reduce 263 tons of carbon emissions. Each 3m * 3.2mModCell® can lock 1400kg of carbon dioxide. There are 78 ModCell® boards were used throughout the building (Figure 5).
Fig.4- York Eco Depot. Image source: Modell straw technology website
Fig.5-Modcell straw technology. Image source: Modell straw technology website
The benefit of using a straw is carbon sequestration. There is also excellent thermal insulation and superb acoustic insulation. 70% of straw uses for livestock and back into the soil. 30% of it left. Barbara Johnes, a straw bale expert, estimates that 2.34m tones of surplus straw can build a new 423,000 house (Chatterton, 2015, p82). Therefore, straw is one of the perfect low-impact building materials. Timber In North America, more than 90% of low-rise buildings use wooden structures, and 70% of people in developed countries in the world live in timber-framed houses. Therefore, wood is a widely used building material. Historically, in the United Kingdom, residential buildings in the Elizabethan era used timber as a load-bearing structure, infilled with Wattle and Daub, and many palaces in Asia, China, and Japan used wood to assemble buildings without nails as connectors. Large overhangs protect the walls of the building from rain. These timber buildings have gone through 300-400 years and are still well preserved. For example, Kiyomizu-Dera temple in Kyoto, supported by several tall pillars (fig.6.)
Fig.6- Kiyomizu-dera temple. Image source: Wikipedia
Global Forest Resources Assessment report that "the world's forest area decreased from 31.6 % of the global land area to 30.6 % between 1990 and 2015,". This trend is still
declining, especially as forest cover in the equatorial region has halved from half a century ago. Reforestation and Afforestation is one of the solutions to this forest coverage. The Forest Stewardship Council (FSC) responds to deforestation and poor management of forest resources by developing detailed Principles and Criteria to let their consumers know that their forests are well taken care of (FSC, 2006). According to the variety of trees, wood divides into hardwood and softwood, and there are two main methods of converting timber, one is "through and through", and the other is "quarter sawn". Plywood, used in furniture, door and window frames, it could recycle in the cradle to cradle way (Raw material to Recycled material) and sequencer carbon dioxide (fig.7.).
Fig7.—plywood lifecycle. Image source: http://www.secondforest.eu/woodLifeCycle.html
Brettstapel uses FSC-certified wood, a fantastic glue-free timber construction by using dowels connected. As a tactile material, timber can effectively maintain indoor temperature. According to the Gaia group's introduction of Brettstapel technology, it can reduce hundreds of tons of CO2 consumption in a 25-year building life cycle (fig.8.)
Fig8.—Econo Project: Brettstapel. Image source: gaia group
Earth Currently, half of the world's population lives in earth-based homes. (Avrami, Guillaud, Hardy, 2008). These dwellings mainly concentrate on relatively weak economies countries. In the next 20 years, China will need 40 billion square meters of commercial, residential, mixed buildings, like the same size as Switzerland. The construction industry also produces 30% of CO2 and consumes a lot of raw materials (Pacheco-Torgal, Jalali, 2012). Therefore, more applications of low-impact materials in the future will make an enormous contribution to protecting the environment. Minke mentioned that Turkmenistan was the earliest place to use earth for dwellings, which is about 9000 years ago (Minke, 2012). The Great Wall of China-a massive project in history, the use of rammed earth technology is also 3000 years ago and is still well preserved. Earth has a relatively high specific heat capacity and density, which provides average indoor temperature to adjust the temperature difference between morning and evening (Ryan, 2011) (fig.9.)
. Fig9.—thermal mass benefits of earth Image source: Harvard University Graduate School of Design
Earth construction technology mainly includes four points (Pacheco-Torgal, Jalali, 2012): 1. Wattle and daub 2. Cob 3. Rammed earth 4. Earth bricks (adobe) Wattle and daub are the earth was pressed against a woven mesh, and this technology used 6000 years ago. Rammed earth is putting moist earth into a wooden formwork, after compaction, the formwork immediately removes and could re-use it to the next rammed earth wall. Cob- Clay was build layer by layer, clay and straw mixed materials; Outer skin needs sculpturing. Adobe bricks are about putting the moist soil in a wooden mold and waiting for the sun to dry (Pacheco-Torgal, Jalali, 2012).
Low impact materials availability When we choose whether low-impact building materials are vernacular, we should consider whether the material is close to the construction site. For example, our project is the Victory Quays Canal. The selected material should be around the canal with a driving time less than 45 minutes. As Fairlie said in the book "Low impact development", "easily accessible, easily accountable, have shorter travel distances. (Fairlie, 1996: p59).
The UK produces an average of 0.25 tons of straw per person annually, especially in the East Midlands region. The relatively small terrain and dry air provide an excellent condition for straw growing. After 2010, Sheffield has built a lot of new biomass power plants, such as Ferrybridge Multifuel, which is a 45-minute drive from Victory Quays. Ferrybridge Multifuel mainly uses waste from mixed municipal solid waste and industrial waste and waste wood as power generation raw materials (fig.10.). Due to the property of straw, light and bulk, which occupies a lot of transportation space, we need to calculate the embedded carbon on transporting one ton of straw and same weight on other materials and how many watts of electricity one ton of straw can produce. These data will help us analyze whether straw is used as a biofuel in Sheffield or if it is more efficient to make it into a ModCell® board.
Fig10.—Ferrybridge Multifuel 2 biomass power plant. Image source: Ferrybridge Multifuel website
According to Sheffield city council, Sheffield has 80 ancient woodlands and 180 woods, 100,000 trees in parks and open spaces, which make Sheffield the most wooded and treed city in Britain (Sheffield city council, 2015). Ecclesall Woods is the largest ancient semi-natural woodland near Sheffield. It used to be a place where timber felling and coppicing, but now it has become a small community for events and learning about making wood products (fig.11.). Therefore, a large amount of wood can only be bought through building materials supermarkets and depends on imported timber. In 2018, Britain introduced a total of up to £ 8 billion (Forestry Commission, 2018). It means that the local council needs to calculate the amount of embedded carbon that the timber will transport to Sheffield and whether the domestic small-scale tree felling will be allowed.
Fig11.— Ecclesall Woods provide wood-related course training. Image source: Ecclesall Woods Website
Victoria Quays is located in the northeast corner of Sheffield, connecting the city centre of Sheffield and Tinsley marina. From the introduction of the website Pennine Waterways, it was a threshold transhipment point in the early 19th century. At the end of the 20th century, the transportation status of cannel declined. Today, Sheaf works turned into bars, and the arched covered bridges became shops and restaurants (fig.12.). Some sandstone quarries near it were no longer transported by canals and were replaced by surrounding rail and car. Therefore, sandstone quarries transportation needs to consider the impact on the environment.
. Fig12.— railway arches were converted into shop at Victoria Quays. Image source: author .
Sheffield’s climate
As mentioned earlier, Sheffield is the greenest city, accounting for 10.8% of the city area, so the urban environment is affected by the national peak district, which reduces the city's heat island effect. At the same time, the Victory quays are adjacent to the River Don, and the river water has an excellent thermal mass performance (fig.13.). Therefore, the temperature in the suburbs can be adjusted to keep the Sheffield city centre at a relatively comfortable temperature.
Fig13.—different material thermal mass data. Image source: Low impact building material lecture slide.
Fig14.—Average temperatures and precipitation in Sheffield. Image source: Meteoblue website.
In terms of precipitation and temperature, according to Meteoblue Climate diagrams, the annual precipitation in Sheffield is mainly concentrated in winter and spring, and the temperature is generally between 2-20 Celsius. However, in summer, 2018, the maximum temperature has exceeded 30 degrees. Although the terrain of Victory Quays is higher than River Don, in the next half-century, still have flooding risk. Proposed material When we choose the right materials for the site, low-impact materials criteria need to consider. The selection of materials should be easy access, reduce carbon consumption, recyclability, good thermal insulation, heat insulation, reduction of harmful gases. In the Victoria Quays project (fig.15.), The humid microclimate environment, and the transportation of straw produced carbon footprint is uncertain, so the straw is not the best choice.
Fig15.—Site——Victoria Quays mapping. Image source: drawn by live project one of team member.
Timber is a versatile material and could be disassembled freely and has a long service life. Although the sawmill in Sheffield had closed and only 28% of the houses built by timber in the UK, it does not mean that the wood is not in high demand. In the past, timber used in large numbers. For instance, deck, gate posts, fencing boards, internal flooring, stairs, boat interiors, etc. Therefore, timber can be reused locally. Luckily, there are many timber suppliers and reclaimers near Victoria Quays. The Hoyland Dismantling Company, Barnsley, South Yorkshire, 15 kilometres away from the city, is running reclamation of timber (Fig.16.). For example, reclaimed railway sleepers could use on landscaping projects. Reuse can significantly reduce the impact on the environment compared to recycling.
Fig16. Timber reclamation yard， Image source: Hoyland Dismantling Company Website
Besides, Templeborough Power Station and Blackburn Meadows near Victoria Quays, both are biomass power plants, using waste wood as fuel to generate electricity to power homes around Sheffield. (fig.17.)
Fig17. Biomass power plantďźŒ Image source: empleborough Power Station Website
In the Victoria Quays project, we will retrofit an 80-year narrowboat, remove its diesel generator, and replace it with electricity (fig.18.). After the transformation is completed, if the transportation of wood can be carried out by electric boats, it can further reduce the impact on the environment.
Fig18. Narrowboat park at Tinsley marina. Image source: Author
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Pacheco-Torgal, F. and Jalali, S., (2012.) Earth construction: Lessons from the past for future eco-efficient construction. Construction and building materials, 29, pp.512519.lsmaker, S., & Royal Institute of British Architects. The environmental design pocketbook. London: RIBA. Pickerill, J., Maxey, L. (2009). Low Impact Development- The Future in our hands. Leeds: Footprints Workers Co-operative Ryan, C., (2011). Traditional Construction for a Sustainable Future. Oxon: Routledge. Woolley, T., (2013). Low impact building: Housing using renewable materials. John Wiley & Sons.pp.18 Fairlie, S., (1996). Low impact development : Planning and people in a sustainable countryside. Oxford: Jon Carpenter.
Figures Figure 1: Land and ocean temperature index from 1880 to 2016, using 1951-1980 as the base period. Source: NASA Goddard Institute for Space Studies https://www.eesi.org/climate-change-FAQ [Viewed 22 January 2020] Figure 2: Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise [Diagram]. Available from: https://science.sciencemag.org/content/311/5768/1747/tabfigures-data [Viewed 22 January 2020] Fig.3-Product life cycle assessment. Image source: GRESB website “Material considerations for reducing building related carbon footprint” Available from: https://gresb.com/materialconsiderations-reducing-building-related-carbon-footprint/ [Viewed 29 January 2020] Fig.4- York Eco Depot. Image source: Modell straw technology website https://www.modcell.com/projects/york-ecodepot/[Viewed 31 January 2020] Fig.5-Modcell straw technology. Image source: Modell straw technology website https://www.modcell.com/technical/[Viewed 31 January 2020] Fig.6- Kiyomizu-dera temple. Image source: Wikipedia https://en.wikipedia.org/wiki/Kiyomizu-dera[Viewed 31 January 2020] Fig7. —Plywood lifecycle. Image source: http://www.secondforest.eu/woodLifeCycle.html[Viewed 1 February, 2020] Fig8. —Econo Project: Brettstapel. Image source: gaia group http://www.gaiagroup.org/projects/project/60 [Viewed 1 February, 2020] Fig9. —thermal mass benefits of earth Image source: Harvard University Graduate School of Design https://www.gsd.harvard.edu/project/coupling-thermal-massbuoyancy-for-thermoregulation-and-ventilation-in-india/ [Viewed 1 February 1, 2020] Fig10.—Ferrybridge Multifuel 2 biomass power plant https://multifuelenergy.com/multifuelenergy-ltd/ [Viewed 1 February, 2020] Fig11.— Ecclesall Woods provide wood-related course training https://www.ecclesallwoodscraftcourses.co.uk/our-courses/[Viewed February 1, 2020] Fig12. — Photo produced by author. Fig13. —Different material thermal mass data. Image source: Low impact building material lecture slide. Fig14. —Average temperatures and precipitation in Sheffield. Image source: Meteoblue website. https://www.meteoblue.com/en/weather/historyclimate/climatemodelled/sheffield_unitedkingdom_2638077[Viewed February 2, 2020] Fig15. —Victoria Quays mapping. Image source: drawn by live project one of team member. Fig16. Timber reclamation yard， Image source: Hoyland Dismantling Company Websitehttps://www.hoylanddismantling.co.uk/about.php[Viewed February 2, 2020]
Fig17. Biomass power plantďź&#x152; Image source: empleborough Power Station Website https://www.templeboroughbiomass.com/[Viewed February 2, 2020] Fig18. Narrowboat park at Tinsley marina. Photo produced by author.