L O W IM P A C T M A T E R IA L S A R C 6821 N A M E : A K P E Z I V IC T O R IA IK E D E STU D EN T N U M B ER : 160244203 W O R D C O U N T : 2 7 3 5 e x c lu d in g r e fe r e n c e s
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TA B LE O F C O N TE N TS Pg No.
C H A P TE R O N E : Introduction, Definition of Terms
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C H A P TE R TW O : The Site, The Design Project
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C H A P TE R TH R E E : Assessment Criteria For Low Impact Materials
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C H A P TE R FO U R : Availability of material and other demands on use
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C H A P T E R F IV E : Vernacular and Contemporary uses of low impact materials in the region
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C H A P T E R S IX : Design Proposal For Low Impact Development On Site Microclimate Analysis Flood Analysis
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C H AP TE R O N E IN T R O D U C T IO N The concept of Low Impact Development (LID) stems from a desire of society to live more conscientiously, an attempt at rescuing the planet from the disastrous side effects of climate change. It is a grassroots approach to achieving sustainability in building practice (Maxey, 2009). Fossil fuels have been a primary source of energy since the industrial revolution despite its finite nature, and the harmful gases released into the atmosphere in the process of energy conversion. Current governmental plans and strategies aimed at mitigating these side effects have been dependent on the reduction of use, or production of carbon dioxide in everyday human activities. However, research has shown that these strategies are not realistic as the unpredictable nature of human behavior is a major determinant of the success or failure of such plans. (Pelsmakers 2016, p. 15).
Fairlie in Pickerill & Maxey (2009) defines low impact development as: â€œâ€ŚA development which, by virtue of its low or benign environmental impact, may be allowed in locations where conventional development is not permitted.â€? He states that this definition encompasses the very nature of a low impact development, dissociated from urban practices to protect suburban dwelling from the impact of big city developments which tend to end up in suburban sprawl. It could be inferred from the above explanations that low impact development is one which makes use of naturally existing materials, preferably ones which are proximate to the site, to create structures that have minimal impact on the environment, whilst incorporating structural techniques that allow for the recycle or reuse of such materials in future development.
Consequently, the solution lies in a holistic approach to dealing with anthropogenic activities. According to Dale (2009), sustainable development should aim to reduce energy dependency and enhance productive ecosystems. He proposes a more effective approach to sustainable building achieved by the use of materials processes that actively remove CO2 from the atmosphere. He suggests that sustainable construction should take place on site with local materials available, reducing the pollution created by transportation of materials.
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C H AP TE R TW O T H E S IT E The site for consideration is located at Sidney Street, S1 4RG, Sheffield, within a one-mile radius from Sheffield’s city center. It is characterized by a car park serving a few inhabitants of the nearby community, and a vibrant artistic culture as shown in the numerous painstakingly crafted graffiti paintings around. Interesting features of the site include a gently flowing stream called Porter Brook, a distributary from the River Sheaf, (River Sheaf © 2017) and a green relaxation space constructed by Sheffield’s City Council. This recreation space created by Sheffield’s city council is the focal point of interest for the proposed design project. It lends itself to
a beautiful space for relaxation, stimulating social interaction as well as beautiful scenery for the transitional functions it also provides(Sheffield City Council, 2014). The site can be categorized as a floodplain, as can be seen in the data discussed in Chapter 3. Runoff from the hard surfaces all around the stream and the presence of the stream itself on the site puts it at high risk of flooding during peak periods of rainfall.
Fig 2. Diagram showing the site and impact of channeled winds
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T H E D E S IG N P R O J E C T The design project for consideration is a wind break. Site studies revealed an unbalanced deposit of channeled winds from around the taller buildings surrounding the site creating a wind cluster. This uncomfortably windy and cold environment counteracts the intended recreational purposes for space. This led to a guided decision to design a windbreak, architecturally crafted to revive
the space by creating opportunities for social engagement as well as bringing comfort to its users. Traditionally, vernacular windbreaks are created on farms by stacking pieces of wood or straw bales in close proximity, creating airtightness and providing warmth and shelter for animals.
Fig 3 An example of the effects of a windbreak on wind speed.
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C H AP TE R TH R EE A S S ES SM EN T C R IT E R IA IM P A C T M A T E R IA L S
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Comprehensive criteria for evaluating lowimpact materials as outlined by Ashby (2013) should employ both qualitative and quantitative methods of assessment. 1. QUANTITATIVE METHODS These are the measurable and quantifiable properties of building materials. They include: E m b o d ie d e n e r g y Embodied energy is the total amount of energy consumed over a defined lifecycle of a product. This accounts for manufacture, transportation and eventually disposal (Ashby, 2013). L ife c y c le a n a ly s is Materials are finite in nature - they have a beginning and an end. The sum total of the processes a material undergoes from ‘birth to death’ can be termed its life cycle. An analysis of the resources consumed and emissions excreted by the material within this time is known as a life cycle assessment (Ashby, 2013). E n d o f L ife End of Life is the state at which a material exists after it is no longer suitable for its first use(termed end of first life) R e c y c l a b i l i t y a n d R e ‐u s e At the end of a materials ‘first life’, a question of methods of disposal becomes apparent. This transformation of generally considered waste product into a useful resource can be termed recycling or re-use. Reuse or reengineering implies taking a material at end of life in one use and considered waste, and employing it for another use in a brand new way that it becomes a new life cycle for the material.
A low impact material should possess this capacity to be collected at its end of life and used for another purpose, replacing the typical ‘cradle to grave’ nature of materials with a more sustainable ‘cradle to cradle’ approach (McDonough and Braungart, 2009). The best strategies for low impact development, however, should be aimed at reuse as recycling is sometimes more energy intensive (Ashby, 2013 ). Such considerations should be made at the very beginning when construction is done for the first use of the material. This is because some fastening techniques like glueing or cementing make materials harder to take apart after first life, making them unsuitable for reuse. Methods like screwing using nuts and bolts make materials easier to disassemble and reassemble, facilitating this type of cradle to cradle development. Re-engineering differs from reuse in that the material is completely transformed into a new material via industrial processes. (Ashby, 2013). U ‐v a l u e s A materials u-value is the measure of its effectiveness as an insulator. It is the heat transfer coefficient of the building envelope (Fokaides and Kalogirou, 2011). Lower Uvalues of materials indicate that it takes longer a time for heat to pass through, making it a good insulator. Other important criteria are the materials end of life and durability. 2 . QUALITATIVE METHODS A low impact development must fit into the environment which it exists. Some qualitative methods of assessing the propriety of the material are its relationship with a communities sociotechnical and socio‐cultural issues, craft and tradition and its sense of place (Stevenson, 2016).
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EX A M PLES M A T E R IA L S
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IM P A C T
For the purpose of this study, the materials for consideration are lime, hemp, earth, straw, and timber. Hemp is a fiber derived from the stalk of the weed Cannabis Sativa. Hemp is a sustainable material, grown as fast as it is used and requiring no additional fertilizers. It is also advantageous because it sequesters 0.3kg of carbon per kg. However, due to its negative connotations in society and mistaken association in marijuana, it has not been widely accepted in several countries as a material for consideration. (Ashby, 2013 ). Hempcrete is an industrial term used to refer a mixture of industrial hemp and lime. It is typically used as an infill in timber frame constructions. Hemp-lime composite indicates low shrinkage and high thermal and acoustic insulating properties (Arizzi et al., 2015).
deposits geologically sourced from parent rock material. It serves as the best render for organic building materials as it provides room for them to breathe. (Hughes in Forster & Carter 2011) Scientifically referred to as loam, earth in building construction is a mixture of clay, silt, sand, and occasionally aggregates such as gravel or stones. Earth occurs naturally abundant in nature. Handmade, sun-dried bricks are termed adobe, whilst rammed earth refers to compacted earth under high pressure in formwork. In building construction, it must be adequately sheltered against rain as it is not water resistant. It helps to preserve other organic materials when used as render e.g. timber and straw (Minke, 2009). Timber, in construction, is used to refer to the wider part of a tree trunk that builder's need. It is readily available in nature even though current practices of deforestation currently threaten its availability. It sequesters carbon during its plant's life cycle making which reduces its carbon footprint (Stevenson, 2016.; McCaig & Ridout. 194)
Straw is what remains when grains are harvested. It differs from hay in parent material; hay is derived from grass. (Stevenson, 2016). It can be used as the primary building enclosure material or in conjunction with others materials for structural support such as timber. When combined with timber, it serves as an infill for the timber frame structure. Cob, a mixture of straw and earth, is also very pliable in construction. Straw possesses good thermal mass, airtightness, and has low embodied energy (Ashby, 2013). Lime
is
manufactured
from
limestone
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C H AP TE R FO U R A V A IL A B IL IT Y O F M A T E R IA L A N D O TH ER D EM AN D S O N U SE O F STR AW The UK produces an average of 13.9 million tonnes of straw yearly incorporated back into the soil and 30% surplus of straw produced used for sale. Sold straw is used in straw-fired and a macro amount used for specialist mushroom cultivation. The remainder becomes available for other uses including building construction (Stevenson, 2016). Straw is also burned to produce energy used in straw-fueled power stations. A good example is the Ely Biomass Power Station in Cambridge shire (Copeland and Turley, 2008).
E N V IR O N M E N T A L IM P A C T O F S T R A W Straw has a minimal environmental impact. It is a good insulator, eliminating the need for the addition of other harmful insulation materials. It is bio-degradable, and has long term storage of CO2 absorbed during its plant life cycle carbon sequestration. (Dessuky, 2009; Stevenson, 2015) Other benefits of straw include its inexpensiveness and availability; a side effect of being a waste product, airtightness, good thermal mass and ease of use in construction allowing for selfbuild.
Fig. 4 shows the availability of low impact materials within a 25 mile radius of the site
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Fig 4 : Map showing availability of raw materials within 25 mile radius of the site 4
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C H A P T E R F IV E VE R N A C U LA R U S ES O F LO W M A T E R IA L S IN T H E R E G IO N
IM P A C T
Glassie (2000) describes vernacular in architecture as that which stemmed from people's responses to their immediate need within their environment. The buildings hold cultural values which may be perceived as alien to an observer, but such structures particularly tailored to suit the needs of its users holds much educational potential for the low impact developer. Yorkshire has a number of vernacular buildings dating the recent trends for sustainable development. Understanding such structures is crucial to the success of low impact development efforts.
H IS T O R IC /V E R N A C U L A R U S ES O F STR AW People have built homes using straw, grass, or reed throughout history. During the late 1800s on the American plains, straw bales houses were a necessary replacement for lumber in construction due to shortages. The figures below show some examples of straw used in vernacular construction. (Camp Kawartha, 2010)
Fig 7 Latham Farm Bunkhouse at Hebden Bridge, Yorkshire.
Fig 5 Bull House Elevation. Sheffield vernacular
Fig 8 Oxford strawbale building
Fig 6 Birthwaite Hall farm. Sheffield vernacular
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C O N TEM PO R AR Y U SES O F STR AW LILAC an ecological co-operative housing project at Leeds. It is a low impact community built entirely out of Straw and Timber. (Chatterton, 2015)
The University of Nottingham has succeeded in constructing one of the largest prefabricated straw bale buildings in Europe. The building was constructed with 1,954 straw bales harvested on the University’s farmland about 200 yards away from the site. Each straw panel consists of a crosslaminated timber frame filled with compressed straw and finished externally with render to provide a breathable coating that prevents decay and protects the straw from the external environment.
Fig 9 Lilac Housing Co-Operative
M o d c e ll c o n s tr u c tio n ModCell is commercially made prefabricated straw bale panels. These panels have been used for various forms of construction.
Fig 11 Make architects open the University of Nottingham building
Fig 10 Sustainable pre-fabricated straw bale panel
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C H A P T E R S IX D E S IG N P R O P O S A L F O R L O W D E V E L O P M E N T O N S IT E
IM P A C T
LOCAL CLIMATE ANALYSIS Sheffield is a temperate region. Local climate data show that Sheffield experiences an annual rainfall average of 834.6mm and
an average of 131.6mm of days of rainfall greater than or equal to 1mm days. It also experiences 1444.9mm average of sunshine hours yearly.(Met Office, 2017) Climate charts from the Met Office (Š 2017) show the following charts as the average climatic data in Sheffield between the periods of 1981 to 2010.
Fig 12. Graphs showing Sheffield’s average climate data between the periods of 1981 to 2010
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F L O O D A N A L Y S IS
Data suggests that the site is a high flood probability zone as indicated below:
Environmental Design must work with water rather than against it (Pelsmakers, 2012). The site low levels and presence of the stream puts it at high risk for flooding.
SITE
Fig 13 . Flood risk information
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L O W IM P A C T W IN D B R E A K A suitable low impact material for construction should meet the following criteria: •Available within proximity to the site •Harmonize with the existing site character. •Low Embodied energy •Ability to withstand possible effects of flooding •Withstand strong wind loads . STR AW Straw has been used by farmers for construction of fences and windbreak systems for a very long time. For best use, straw bale walls should be protected inside and out with breathable lime or clay render. The breathable layer of lime plaster also offers fire protection, and because it is highly alkaline it helps prevent fungal and microbial activity. Foundations should be porous and made from sturdy water resistant materials like stone to allow any moisture from the building above to drain away and prevent absorption of moisture from the ground. Straw compacted in bales possesses airtightness that does not allow for easy combustion, reducing the risk of fire outbreak.
C O N S T R U C T IO N M E T H O D S How to build a wall or Windbreak with straw Straw bale walls can be built very much like brick walls, stacking the bales on each other. It should be placed top of a stone foundation with a damp proof material (heavy plastic) between the stone and the bales to prevent moisture absorption from the ground into the wall. The bales can be held down firmly stronger wooden frames to holds the bales firmly onto the foundation. In rendering, ideally with lime, a water proofer should be mixed into the render or sprayed onto the wall after it is finished. The straw show be sealed tightly with render(lime or clay) to prevent the possibility of even the smallest amount of water penetration. (How to Build a Strawbale Wall, The Food Forest, no date) The flooding concerns on the site might make straw appear an unsuitable material, but research shows that straw through trenching has been used to control erosion and for water filtration, which would assist in the eco-restoration of porter brook. (Landscapeonline.com, no date)
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Fig 14 . Straw Bale Garden Windbreak
Fig 15. How to build a straw bale wall
Fig 16 . Straw bale Trenching
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R EFER EN C ES Arizzi, A., Brümmer, M., Martín-Sanchez, I., Cultrone, G. and Viles, H. , 2015. ‘The influence of the type of lime on the hygric behaviour and bio-receptivity of hemp lime composites used for rendering applications in sustainable new construction and repair works’, p 1 Ashby, M. F., 2013. ‘Eco-Informed Material Choice’, in Materials and the Environment Second Edition, pp. 349–414. Chatterton, P., 2015. Low Impact Living. London: Routledge Ltd. Copeland, J., Turley, D. , 2008. National and regional supply/demand balance for agricultural straw in Great Britain. Sand Hutton, York: Central Science Laboratory. Dessuky, E. R., 2009. Straw Bale Construction As An Economic Environmental Building Alternative-a Case Study. Available at: www.arpnjournals.com (Accessed: 26 January 2017). Fokaides, P. A. and Kalogirou, S. A., 2011 Application of infrared thermography for the determination of the overall heat transfer coefficient (U-Value) in building envelopes: Applied Energy, 88, pp. 4358–4365. Forster, a. M. and Carter, K., 2011. A framework for specifying natural hydraulic lime mortars for masonry construction: Structural Survey, pp. 373–396. How to Build a Strawbale Wall » The Food Forest (no date). Available at: http://foodforest.com.au/fact-sheets/building-with-strawbales/how-to-build-a-strawbale-wall/ (Accessed: 26 January 2017). McDonough W. & Braungart M., 2002. Cradle to Cradle: Remaking the Way we make things New York: North Point Press. Met Office, 2017. Sheffield Cdl climate information. Available at: http://www.metoffice.gov.uk/public/weather/climate/gcqzwq04e (Accessed: 26 January 2017). Glassie, H., 2000. Vernacular Architecture. Bloomington and Indianapolis: Indiana university Press. Minke, G., 2009. ‘Building with Earth’, Mother Earth News, p. 123. Pelsmakers, S., 2012. The environmental design pocket book. London: RIBA Publishing. Pickerill, J., Maxey, L., 2009. Low Impact Development - The Future in our hands. Leeds: Footprints Workers Co-operative
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Sheffield City Council, 2014. Sheffield city council: Phase One, Draft March 2014. p. 1–20. Stevenson, F. , 2015. Lecture 2 : Assessing Materials Methods Stevenson, F. , 2016. Lecture 3 : Straw for building The UK’s largest prefabricated straw bale building is officially opened - The University of Nottingham (no date). Available at: https://www.nottingham.ac.uk/news/pressreleases/2012/february/uks-largest-prefabricatedstraw-bale-building-opens.aspx (Accessed: 26 January 2017).
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L IS T O F F IG U R E S
Fig 1 Thomas Jenkins Architectural feature. [digital Image]. [Viewed 22 Jan 2017]. Available from: https://www.pinterest.com/pin/232428030739348285/ Fig 2 Author’s own, 2016. Diagram showing Impact of winds on site. [hand drawing]. Fig 3 The Permaculture Research Institute Š 2017. An example of the effects of a windbreak on wind speed. [digital image]. Available from: http://www.permaculturenews.org/images/KeylineDesign-Part-3-image024.jpg Fig 4 Authors own. Map showing availability of raw materials within 25 mile radius of the site. [digital image]. Data sourced from British Geological Survey (BGS) and yell.com. Fig 5 South Yorkshire through time, [no date]. Bull House Elevation. [digital Image] [Viewed 22 Jan 2017] Available at: http://www.southyorkshirethroughtime.org.uk/content/organisation/yorkshire-vernacularbuildings-study-group Fig 6 South Yorkshire through time, [no date]. Birthwaite Hall farm [digital Image] [Viewed 22 Jan 2017] Available at: http://www.southyorkshirethroughtime.org.uk/content/organisation/yorkshire-vernacularbuildings-study-group Fig 7 The straw building co uk, [no date] Latham Farm Bunkhouse at Hebden Bridge. [digital image] [Viewed 24 January 2017]. Available at: http://www.webring.org/l/rd?ring=strawbale;id=7;url=http%3A%2F%2Fwww.strawbalebuilding.co.uk%2Findex.php%3Fpage%3Dpictures Fig 8 The straw building co uk, [no date] Oxford straw bale building. [digital image] [Viewed 24 January 2017]. Available at: http://www.webring.org/l/rd?ring=strawbale;id=7;url=http%3A%2F%2Fwww.strawbalebuilding.co.uk%2Findex.php%3Fpage%3Dpictures Fig 9 Lilac Housing Co-Operative,[no date] [digital image]. [Viewed 20 January 2017 ]. Available from: http://www.white-design.com/files/5413/8306/1563/Photo-12195863-14ED-4895-B8C55CBB95692EE7-20130914-155815-2048.jpg
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Fig 10 ModCell - Sustainable pre-fab Straw Bale Panel Construction , [no date] .[digital image]. [Viewed 20 January 2017]. Available at http://www.modcell.com/ Fig 11 Make Architects, [no date]. Construction commences on largest straw bale building in the UK [digital image]. [Viewed 21 January 2017]. Available at: https://static.dezeen.com/uploads/2011/11/dezeen_University-of-Nottingham-Gateway-Buildingby-Make2a.jpg Fig 12. Sheffield average climate data 1981 – 2010. [digital image], [Viewed 26 January 2016] Available at:< http://www.metoffice.gov.uk/public/weather/climate/gcqzwq04e> Fig 13. Flood risk Information. [digital image], [Viewed 24th January 2017]. Available at: https://flood-warning-information.service.gov.uk/long-term-flood-risk/map?map=RiversOrSea Fig 14 . The Food Forest [no date). How to Build a Strawbale Wall [digital image]. [Viewed 22 Jan 2017] Available at: http://www.foodforest.com.au/howToBuildAstrawBaleWall.htm Fig 15 . The Food Forest [no date). How to Build a Strawbale Wall [digital image]. [Viewed 22 Jan 2017] Available at: http://www.foodforest.com.au/assets/strawbale/_resampled/resizedimage500345-tiedown.jpg Fig 16 . Landscape online © 2016 .Trench Installation. [digital Image] [Viewed 22 Jan 2017] Available from: http://landscapeonline.com/research/lcn/2004/10/img/straw_bale/straw_bale_2.jpg
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