In this issue of Engineering Sustainability there are five papers that offer a wide spectrum of interest. We open and close the issue with papers looking at the human dimensions and perceptions of engineering sustainability among engineers themselves. The intervening papers consider the difficulties of retrofitting low and zero carbon dioxide technologies to existing housing stocks, aspects of anaerobic digestion as a boost to local wastewater treatment and the social sustainability of urban latrine emptying practice in Ghana.
The first paper, (Simm, 2012), examines the interaction between communities and engineered solutions. For many years civil engineers have known that for a solution to be considered sustainable it must fulfil all of the three pillars of sustainability. Furthermore, that so far as is practicable, the social dimensions of sustainability must be considered and accommodated within the design, construction and operation of an engineered system. The author considers these aspects of sustainability and soon recognises the clear lack of any structured assessment methodology through which schemes might be judged successful or otherwise in these social dimensions. Taking the (now very topical) theme of flood and coastal risk management the author has undertaken research into how such human dimensions might be assessed and scored in ways consistent with the more familiar methodologies for technical aspects. The work was composed of a series of semi-structured interviews with practising engineers and case study examinations of existing engineering schemes. Starting from Vitruvius' first principles of architectural purpose (strength, utility and beauty) and the rather more recent ICE code of professional conduct which requires practitioners to have regard for the wellbeing of future generations, (ICE, 2004), there is a pedigree for an expectation of social and human dimensions to be solidly embedded in our engineering design and practice.
The conclusion of the work is to propose that the human dimensions of the schemes considered could be assessed and scored with a three-stranded approach covering order–security, belonging–justice and imagination–inspiration. For each of these considerations, descriptors for a simple 1–5 scoring mechanism are proposed along with examples of which aspects of a scheme could be so assessed.
In the next paper, Lowery et al. (2012) look at a very pertinent social aspect of engineering sustainability, the difficult question of retrofitting low and zero emission carbon dioxide technologies to our existing housing stock. Given that a (perhaps sizeable) majority of the housing stock that will be occupied in 2050 (when many of our carbon dioxide-related objectives should be met) is already built, it is highly timely that we should be establishing the mechanisms needed for such remedial work. The paper examines this issue by way of a case study into a social housing retrofit programme in Sunderland, North East England.
The paper is comprehensive in its consideration of the issue. It presents an analysis of the policy context, set by UK government for building standards and housing conditions and also carbon dioxide reduction targets, under which registered social landlords (RSLs) operate. Within this framework, RSLs are seen to be moving towards a retrofit programme of higher energy efficiency performance and hence lower carbon dioxide emissions.
The paper concentrates on the barriers to such retrofitting and examines in particular those relating to: the processes that lead to yes/no decisions regarding retrofit; how partners in the programmes communicate; the relationships between the procurers and their supply chains; training and internal expertise; how the success of such schemes can be monitored in terms of energy consumption; and which low and zero carbon dioxide technologies will best suit particular circumstances. The authors point out a major caveat to all such schemes in that the energy use patterns of individual homes within a stock will vary considerably, thus affecting the energy saving achieved for the capital invested (Banfill and Peacock, 2007). However, the paper concludes that above each of these major barriers it is the ever-changing policy decisions of government that can have a major impact on any retrofit programme and that stability and a long term view on this area will be of great benefit.
The possibility of energy-neutral wastewater treatment is examined on a pilot scale anaerobic waste stabilisation pond (AWSP) in the paper by McAdam et al. (2012). It is often said that more energy comes into a wastewater treatment plant by way of the raw feed than is used in the actual treatment and so technologies to capture and utilise this in the treatment itself present an opportunity for radical energy reduction schemes. The essence of this work is to assess the efficiencies of such energy reduction opportunities in a decentralised network for wastewater treatment. In a highly technical paper, the authors consider the chemical oxygen demand (COD) removal efficiency of the plant in differing climatic regimes and so establish a comparability to full-scale AWSPs operated across a range of climates. The authors found that a linear relationship between COD removal and time demonstrated that the model AWSP plant had not reached a steady-state condition, thus indicating that further improvement in COD removal could be achievable. Extrapolating their data modelling to a catchment equivalent to a population of 10 000 indicated that integrating an AWSP upstream of trickling filters presented the optimum configuration to minimise on-site electrical demand.
Anaerobic WSP has the exciting potential for on-site electricity generation sufficient to offset all electrical demand from off-site generation. In addition, AWSP as on-site sludge treatment clearly reduces exported sludge volume and reduces wastewater treatment total carbon dioxide equivalent emissions compared to other more conventional technologies. The authors report that this study establishes AWSP as a significant future technology for sustainable decentralised wastewater treatment.
Returning to social themes, Nkansah et al. (2012) present the findings of a study into manual latrine pit emptying in urban Ghana. In the absence of universal piped sewerage systems, technologies for on-plot sanitation pay an important role in many low-income Ghanaian urban areas. Pit emptying itself plays a critical role in sustainability and so do the activities of manual pit-emptiers on the small, local scale. This paper reports a study into contribution to overall community sustainability played by the role of manual pit emptying as a route to livelihood for the individuals involved. The focus of the work was the key factors relating to the human, social, physical and financial capitals of manual emptiers. The authors consider that these key factors are: an individual's role as an emptier; the employment protocols and equipment in place; the security of an individual's health and well-being; their resultant social status and the acceptability by the neighbourhood of the role they undertake. The paper concludes that without technological advancement, due financial reward and incentive and crucially improvement in the security of health and safety of emptiers then the current state of pit-emptying practice does not represent a sustainable long-term livelihood option for manual workers. The paper provides recommendations to improve sustainability in terms of developments in the technology surrounding emptying activities, the provision of financial subsidies and free medical care together with education relating to the health and safety of the activity.
The issue concludes by returning to the opening theme with a paper by Griffiths et al. (2012) examining engineers' perception of social sustainability in infrastructure projects through a series of structured, case study-based interviews. Taking a start point post-feasibility, the authors focus on planning, design and construction for their study. Based in Australia and New Zealand, the work was undertaken by a small group of sustainability consultants together with some of their engineering colleagues. Social sustainability dimensions of projects were considered by investigating engineers' experience of these, the level of importance placed on them and the changing nature of perceptions over time. The authors tested the conjecture that there has been a recent noticeable increase in the attention paid to social dimensions by determining if there was agreement among engineering colleagues.
What unfolded through the research was not only that there has indeed been a growing acceptance of the importance of, and attention to social issues in engineering sustainability, but also a wider discussion on the value of community involvement in infrastructure development. The authors discovered an evolving development of technical professionals in social dimensions through their experience working in the field. The authors do not claim to have developed ‘universal truths that can be applied to the engineering professional generally’ but on reflection, and certainly within the experience of those interviewed, social sustainability issues have risen up the agenda down under.
