Construction Technology: The Urban Landscape - Research Paper Example

The biodiversity of urban habitats in Birmingham (England) has a combination of field surveys of plants and animals with explicit modeling of selected mammal species. The aim of the project is to: (i) establish feasibility in the light of external constraints, with the terrain, with its local environment, and the activities of neighbors’ if any; (ii) take and study the character of the site as a whole; (iii) more specific information about possible locations within the site including topography, environment prospect, services, possible constraints on construction activities be collected as much as possible. The results suggest that cities provide habitats for rich and diverse range of plants and animals, which occur sometimes in unlikely recombinant communities. The study illustrated the relative importance of habitat quality on individual sites as opposed to site location within the conurbation. This suggests that dispersal for most of our urban species is not a limiting factor in population persistence, although some elements of the flora and fauna did appear to have some geographical structuring. Theoretical models suggested that dormice and water voles may depend on linear habitats for dispersal although field-based research did not provide any evidence to suggest that plants or animals use urban greenways for dispersal. This finding indicates the importance of identifying dispersal routeways. It can then be suggested that planners can have a positive impact on urban biodiversity by slowing the pace of redevelopment and by not hurrying to tidy up and redevelop brownfield sites. Introduction Urban areas are highly modified and complex landscapes, within which green or open areas are seen as valuable for human well-being as well as wildlife (Pickett et al., 2001, 2004). The biological processes of dispersal interact with the landscape structure in determining the distribution of populations of species present (Niemela¨, 1999). Recent research has put urban biodiversity into the conservation spotlight. Several studies have focused attention on the conservation significance of elements of the urban landscape, such as brownfield sites (Gibson, 1998; Woodward et al., 2003) and gardens (Gaston et al., 2005; Thompson et al., 2003). An essential first step to managing urban environments more effectively is a fuller understanding of the interplay between landscape (matrix effects) and local factors (patch effects) that affect urban biodiversity. Many cities have a network of habitat fragments or urban greenways comprising areas of semi-natural habitats, secondary succession, ruderal and pioneer environments and open areas. These habitats may be important features for biodiversity both as stable and as transient habitats (McIntyre, 2000; McIntyre et al., 2001), and may also be valuable for their possible function as corridors and stepping stones to facilitate species dispersal (Spellerberg and Gaywood, 1993; Kirby, 1995) and they are therefore a key part of current ecological planning (Habitat and Species Directive, Brussels 1993; PPG Note 9, Department of the Environment, October 1994). In urban landscape planning, urban greenways and wildlife corridors are increasingly advocated to encourage animals and plants to move around urban areas and thus to preserve or enhance urban biodiversity. This research aimed to: (i) select a site for site investigation and understand the ecological characteristics of the biota of cities model, (ii) examine the history of the site, (iii) study ground conditions (soil and water table), (iv) identify if there are obstructions in the ground such as post office tunnels, underground railway etc., (v) archaeological importance of the site, (vi) planning constraints if any , (vii) meteorological data, topography and unusual features, (viii) flood risk, (ix) construction factors and the (x) legal ownership. This will help predict biodiversity in cities, and analyze the extent to which the flora and fauna utilize the urban greenways both as wildlife corridors and as habitats in their own right in partnership with human interference. This research was framed around the following hypotheses: 1. the biota of cities is drawn from local species pooled together with a suite of mobile humans. 2. Species richness and abundance of selected species in habitat fragments is related to (a) patch area, (b) habitat connectivity and (c) patch continuity over time. 3. Species distribution and dispersal are interrupted by discontinuities in urban greenways. 4. The patch-dynamic structure of cities is essential for the persistence of many species. The paper presented here distils the results of these components and the approach is thus cursory and aimed at highlighting only the most significant results. Methods One of the major hindrances to successful deconstruction, for the reuse of building materials and components, is the difficulty in recovering items in good condition. Modern construction methods are very dependent on permanent fixing methods that allow for little else but destructive demolition. If buildings were initially designed for deconstruction, it would be possible to successfully recover much more material for reuse. This would have significant advantages both economically and environmentally. There are four main parts to these investigations: • an understanding of how design for deconstruction fits into the broader issues of sustainable construction • the theory of time related building layers • the theory of a hierarchy of recycling and reuse • a list of design for deconstruction principles Study area The West Midlands conurbation comprises the City of Birmingham and several boroughs collectively known as the Black Country. Birmingham City has a population of one million, with an estimated 6 million others living within a 50 mile radius of the city. The city covers 27,000 hectares, 11% of the land cover is green space in the form of parks, and the city includes approximately 4000 hectares of semi-improved neutral grassland, pockets of ancient woodland, and 250,000 domestic gardens. The questions of design for disassembly As there are no formal rules for design-for-recycling, we resort to heuristics (Kriwet, et al, 1995). The Need for Understanding Design for deconstruction in architecture is not widely practised and not widely understood. As has been shown in the reports of the preceding Task Group 39 meeting (Kibert and Chini, 2000). There is little research in this field and only recently have efforts been made to co-ordinate what research there is. As such there are no currently existing rules, guidelines, or principles for design for deconstruction in architecture, nor are there any models for design for deconstruction in architecture. Tools for assessing the potential for reuse and recycling of building materials have been proposed, though these have been developed for the assessment of existing buildings (Guequierre and Kristinsson, 1999) (Sassi and Thompson, 1998). A tool for assessing proposed building designs and for guiding the design process to increase rates of future recycling has not been developed. In brief, ‘buildings are not currently designed to be eventually disassembled’ (Kibert, et al, 2000). What Knowledge is Needed There is a basic lack of understanding or knowledge of design for deconstruction in architecture. The types of knowledge that might be needed can be investigated by asking a number of basic questions: • Why deconstruct • When to deconstruct • Where to deconstruct • What to deconstruct • How to deconstruct Why Deconstruct The general need for an improvement in the current rates of materials and component reuse is well accepted. Any response to this must however fit within the broader understanding of sustainable construction. It is not beneficial to design for deconstruction to increase rates of recycling if the overall life cycle environmental costs of such a strategy are actually greater than the potential benefits. An understanding of this holistic relationship must form part of any understanding of design for deconstruction in order that the benefits are realised. The issues of design for disassembl y need to be located within a general model for sustainable construction so that the external consequences of a design for deconstruction strategy might be highlighted and considered. When to Deconstruct and Where to Deconstruct Different parts of buildings have different life expectancies, for economic, service, social, and fashion reasons. An understanding of the life expectancy of parts of a building is an integral part of a strategy of designing for deconstruction. The theory of time related building layers, the idea that a building can be read as a number of distinct layers each with its own different service life, offers some insight into the relationship between life expectancy and deconstruction. Knowing which layer a component is from, and where the layer begins and ends, assists in determining when and where to deconstruct. What to Deconstruct There are many possibilities for the recycling of materials and components, from complete relocation and reuse, to material recycling or incineration for energy. The question of what to deconstruct can in part be answered by asking what is the intended form of recycling. What is deconstructed for material recycling may be different to what is deconstructed for component relocation. There is therefore a relation ship between the hierarchy of recycling options and design for deconstruction. How to Deconstruct There are several sources of information of how to deconstruct. These include industrial design, architectural technology, buildability, maintenance, and international research into deconstruction. While the question of how to deconstruct buildings has not been well investigated in the past, the above sources of information can be searched for recurring themes. These themes can then be developed as principles for design for deconstruction. A list of principles for design for deconstruction can act as performance guidelines to assist in the design of a building or to assess a building design for disassembly. Such a list of principles is one of the major components of a knowledge base of deconstruction. Results General Model of Life Cycle (Assessment) Of all the current models for understanding, assessing, and reducing the environmental consequences of our actions, life cycle assessment (LCA) is perhaps the most useful. The notion of life cycle assessment has been generally accepted within the environmental research community as the only legitimate basis on which to compare alternative materials, components and services and is, therefore, a logical basis on which to formulate building environmental assessment methods (Cole, 1998). The idea of the life cycle is that all stages in a system (product or service activity) are recognised, from inception to final disposal. A life cycle assessment is made by investigating all the environmental consequences of each stage in the life cycle of the system. Such an assessment can be represented as a two dimensional matrix. Such a matrix offers a good model for the environmental assessment of a system (product, service, building). In order to do more than simply assess the system, to actually understand how the system might be altered to reduce the environmental burden, it is necessary however to add a third dimension. This will be a dimension of strategic solutions, or of principles for sustainable activity. Principles for Sustainable Activity In order to understand what can be done to reduce the environmental burden of human activity, it has been convenient to consider the range of measures that might be taken within a smaller number of broader principles. There are potentially thousands of strategies that might be implemented in the design of a building in order to reduce the environmental burden of that building. Management of these strategies, and of conflict between them, can be better handled by addressing a few overriding aims. Numerous authors have proposed such broad principles for sustainable activity, and many of these relate directly to the built environment and to sustainable architecture. The writings, and the built work, of Brenda and Robert Vale illustrate a number of ‘green’ architecture principles. They suggest six basic principles that could constitute sustainable architectural practice (Vale and Vale , 1991); • Conserving energy, a building should be constructed so as to minimize the need for fossil fuels to run it • Working with climate, buildings should be designed to work with climate and natural energy sources • Minimize new resources, a building should be designed so as to minimize the use of new resources and, at the end of its useful life, to form the resources for other architecture • Respect for users, a green architecture recognizes the importance of all the people involved with it • Respect for site, a building will ‘touch-this-earth-lightly’ • Holism, all the green principles need to be embodied in a holistic approach to the built environment • Maintain and restore biodiversity • Minimize the consumption of resources • Minimize pollution of air, soil and water • Maximize health, safety and comfort of building users • Increase awareness of environmental issues Another author who offers a list of broad principles is Kibert (1994). His concerns are developed from a number of issues of sustainable construction which include; energy consumption, water use, land use, material selection, indoor environmental quality, exterior environmental quality, building design, community design, construction operations, life cycle operation, and deconstruction. Several principles of how to achieve more environmentally responsible construction are proposed with respect to these issues; • Minimize resource consumption • Maximize resource reuse • Use renewable or recyclable resources • Protect the natural environment • Create a healthy, non-toxic environment • Pursue quality in creating the built environment These lists of principles are all attempts at grouping the various strategies for achieving sustainable architecture. While these groups vary slightly they all address issues of material use, energy use, health, and a holistic view. Discussion The character and diversity of urban habitat patches has a considerable diversity of flora on urban wasteland sites, with a total of 378 species found on the 50 sites surveyed. The highest diversity both within and between derelict sites occurs while they are still young, with convergent succession evident over a 20-year period. The more diverse phases of the succession will however persist longer on infertile substrate or under continual and sporadic physical disturbance of the site. The amount of urban cover that surrounded a site was not related to the plant community present on the site, and there was no evidence of an urban–rural gradient in the communities of derelict sites. However, more urban sites did include a greater proportion of neophyte aliens than rural sites. There was no difference in the relative proportions of archeophyte alien species between urban and rural sites. Possible Constraints This presents findings relating to factors affecting the variables as they are organized under the following sections: general labour costs and conditions; employment legislation; professional qualifications; taxation; pensions; national insurance; welfare benefits; and the national work permit system. The structural change of industry fragmentation along with its relations to the outside world can be expected to influence not only the nature of inter-organizational relations but also its readiness to absorb and develop improvement methods that have a foreign origin. Patterns of learning in the construction industry are obviously relevant to an investigation of how nature and the environment affects the evolution of quality management and inter-organizational relations. In particular, the question is whether the traditions of craftsmanship and applied science have created separate or joint patterns of learning in construction. During the first half of the 19th century, building still operated under the guild system with apprentices, journeymen and masters in each of the trades. This system and its individual enterprises can be interpreted as a ‘learning organization’, almost exclusively dependent on tacit knowledge being transmitted to younger people. Thus, under stable technological conditions, the apprenticeship system delivered good craftsmanship quality and inter-organizational relations can be regulated through role definitions rather than by clients and government authorities through detailed technical building requirements and project-specific administrative procedures. Hierarchical governance of the project must be based on mathematics, natural sciences and foreign expertise where this is needed to ensure best-practice technology. For its time, the degree of scheduling and coordination is remarkable. Conclusion To conclude, it is possible to identify craftsmanship and construct a building with the environment and nature in mind and based on a great deal on tacit knowledge, and military engineering, based on scientific knowledge and command. Depending on the type of construction, these train of thought should dominate. One mechanism is to rapidly expand without sacrificing nature and bring with it the application of principles derived from heavy civil engineering work and ultimately from the tradition of engineering. It maybe therefore that for many species of invertebrates in the urban environment, the maintenance and even restoration/creation of good quality habitat is the key to their continued survival rather than the more difficult task of increasing habitat connectivity. Theoretical models suggest that dormice and water voles may depend on linear habitats for dispersal (but dormice are nowadays more likely to find new habitat by deliberate human introduction than by dispersal). This finding indicates the importance of identifying a target species or group of species for urban greenways intended as dispersal routeways rather than as habitat in their own right. Our research has not found any evidence that plants or animals use urban greenways for dispersal. The importance for these groups is rather as a chain of different habitats permeating the urban environment. We suggest that planners can have a positive impact on urban biodiversity by slowing the pace of redevelopment and by not hurrying to tidy up and redevelop brownfield sites. Finding out that derelict site had a more distinctive flora when they were close to other such sites, suggesting that dispersal between sites may be important in the development of the characteristic urban derelict flora. 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Urban domestic gardens (I): Putting small-scale plant diversity in context. J Veg Sci 2003;14:71– 8. Vale, B. and Vale, R. Green Architecture: Design For a Sustainable Future, Thames and Hudson, London, 1991. Woodward JC, Eyre MD, Luff ML. Beetles (Coleoptera) on brownfield sites in England: an important conservation resource? J Insect Conserv 2003;7:223 – 31. Read More