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Sustainability of Building Technologies

Zeenat Niazi, October 1998

Development Alternatives’ Building Material Programme for augmenting building material supply is guided by social and environmental concerns and aims towards improving the overall quality of shelter through the introduction of sustainable building products and technologies which optimise energy consumption and reduce CO2 emissions. The initiative is based on the strategy of creation of a large number of small and medium enterprises to produce and deliver alternative building materials in an economically and environmentally sound manner.

While the economic soundness of the technology packages selected for development and dissemination is based on optimum technical and business design principles; the concerns related to People, Resources and Environment (PRE) have been incorporated in the basic design of the packages and in the delivery mechanism being adopted to ensure sustainability in a holistic manner.

Context

The PRE concerns were first studied in the context of a specific geographical region - the Bundelkhand region. This enabled a live laboratory wherein reality checks could be put in place through the process of technology optimisation. The technology packages, were therefore, been optimised with respect to efficient material and energy utilisation, low waste generation and promotion of skills. The project team has also been concerned with the environmental health of the region. Thus, the Programme aimed to mitigate the possible negative impacts on the region due to large numbers of building production units that could potentially be set up while maximising the potential benefits to the region.

The ESTF study - Enviro-Tech Rating of building technologies

The Action Research Project for the Development of Sustainable Building Technology Packages, therefore, designed a methodology to assess the environmental, social, ecological and financial (ESTF) aspects of the technology packages. This methodology, summarised in the form of an "Enviro-Tech" Rating of building technologies not only assesses the relative environmental, social, technological and financial (economic) advantages of the technology packages with respect to existing building technologies but also identifies critical aspects of the package that need to be optimised through design.

The comparative assessment of building technologies is carried out through analysis at each of the following three levels:

1. At the product level during the production process of the building material. The process takes into account all the steps from the extraction of resources to the manufacture of a brick or roofing tile at the production yard of a building material enterprise.
2. At the system level, i.e., for every square meter of wall or roof constructed. This takes into account the transport of the building element to the site of construction, additional materials and human resources (skills) required to put up the wall or roof. It also accounts for durability, cost and thermal comfort of wall and roof types.
3. At the dwelling unit level, i.e., for a standardised unit of built space. The aggregation of roof and wall factors are taken into account here and thus most optimum combinations in terms of durability, resource intensity, energy consumption and land area impacted are derived.

The sustainability index - ESTF composite index

The index for sustainability is defined as a composite ESTF index which incorporates a cumulative comparative rating of technology packages on the basis of 19 indicators under the four major Ecological, Social , Technological and Financial parameters.

The indicators for the assessment of ESTF parameters selected to reflect the overall impacts of a technology package were limited by the necessity to measure the indicators. Thus "quantifiable indictors’ were important. The intangible or qualitative aspects were dealt with in two ways. At the dwelling unit level a Roof-Wall index was used which is an empirical index derived through intensive primary surveys of the region and indicates "people’s perception" of permanency / durability of a building system. Other qualitative factors such as health hazards, gender biases etc. were incorporated as weightages that were factored into the measurable indicators. These weightage factors are mainly region specific environmental and social concerns and thus reflect regional priorities.

The quantitative values obtained for each indicator are then ranked to derive an index to compare across technologies. The ranking is only done at the system level. The index for each of the ESTF parameters is then aggregated to arrive at an composite "Sustainability Index" for the Technology package option.

The mean sustainability index was analysed to check its sensitivity to particular parameters. In doing so each of the ESTF means were given additional weightage and compared with mean ESTF index for both walling and roofing technologies. Financial mean was not included as the index is already weighted in favour of enterprise based - thus job creating technology options. The process indicated that the methodology is a robust one and the index is not specifically sensitive to any particular parameter.

Technology assessment for Bundelkhand region

While analysing the performance of each of the walling and roofing technologies; the following conclusions specific to the Bundelkhand region can be drawn:

With respect to energy consumption in the walling sector the Compressed Earth Block (CEB) technology rates the highest. In comparison to it are existing Clamp and Bulls Trench Kiln based production systems for bricks Clamps use excessive fuel which includes coal and cow dung, the latter in direct conflict with its use as field manure. The concrete block technology which uses a lean mix of cement concrete also shows a high potential of energy optimisation. In the roofing options, MCR technology shows the highest energy efficiency amongst sloping roof options in comparison to locally fired clay tiles, Galvanised Iron (CGI) sheets and Asbestos (ACC).

With respect to movement of material, the CEB technologies again offer the maximum potential followed by the Vertical Shaft Brick Kiln (VSBK) technology for burnt bricks, clamps and the concrete block technology. In the roofing technologies, ACC and CGI indicate a positive movement index despite the fact that they are transported over long distances as these are light weight materials. Amongst the flat roof options, Ferrocement was found to rank the highest in comparison to sand-stone, reinforced cement concrete and reinforced brick concrete, with the added advantage of being able to offer enterprise based production option.

With respect to land and water resources; it was found that the concrete based technologies consume the largest amount of potable water at the dwelling unit level primarily due to curing requirements - thus indicating a need for optimisation here. The brick based technologies consume large tracts of agricultural land which pose a threat to food security - this being a particular regional concern. However, technologies using murrumic soil from non-agricultural land and optimisation of scale to reduce and distribute resource extraction such as the medium scale CEB and VSBK technologies mitigate this problem.

At the dwelling unit level, ecological indicators define the sustainability. Contrary to the assumption that a more pucca house with a higher roof-wall index would mean the use of more energy intensive materials, we found that there are options which could be combined to achieve an improved house status while reducing the total embodied energy in construction and the CO2 emissions. Cross tabulated combinations of various roof and wall options against energy, land impacts, movement and CO2 emissions show that MCR roofs with Stabilised CEB or concrete block walls provide the most optimum option followed by Ferrocement or sand-stone roofs over VSBK brick walls. The roof - Wall index defines the hierarchy of "People’s perception of Pucca". The Enviro-Tech rating incorporating the roof-wall index thus defines the building technology and dwelling unit both most appropriate and most acceptable in the regional context.

Impacts

The ESTF study has made it possible to study potential impacts of augmenting building material supply in the Bundelkhand region by introducing sustainable building technologies using cleaner production processes, such as stabilised Compressed Earth Blocks, Concrete Blocks, VSBK bricks, FC channels and MCR tiles. At the regional level, this methodology has been used in congruence with the methodology assessing the market potential. In a scenario that the dissemination thrusts are able to capture the existing market potential for these products, the study indicates an energy saving potential of 25 - 33% and a reduction in CO2 emissions of over 11% from the present business as usual rate of growth in five years leading up to 2001 AD.

The study of the technologies in the regional context with respect to the total residential construction (both existing and potential), has enabled an assessment of the enviro-tech impacts of the technology choice for the region thus guiding the strategy for locating production units within the region. The large scale dissemination of the above technologies will definitely have far reaching impacts in resource and energy optimisation along with reduction in CO2 emissions while resulting in an overall improvement in the quality of shelter and improving local economy conditions through micro-enterprise development.

Conclusion

While the ESTF study was conducted in a regional context, the methodology is applicable widely. At the level of individual production units, the sustainability index derived through the ESTF study can be used as a monitoring tool for enterprises. This of course can be applied to any region of India with suitable modifications with respect to movement distances of raw materials and other specific data. For other regions, as for Bundelkhand, specific regional concerns can be built-in in the form of weightage factors and data for total construction activity in the region can be used to analyse impacts.

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