What is it about?

Malcolm Slesser (1926-2007) - a Scottish engineer, mountaineer and writer - was at the forefront of the development of ‘energy analysis’ (EA), based on the principle of energy conservation stemming from the First Law of Thermodynamics. He acted as rapporteur of a 1974 international workshop of energy analysts and economists held in Stockholm. First Law EA is re-evaluated here in the light of modern ideas in thermodynamics arising from the Second Law, such as those incorporated into ‘exergy analysis’ and related methods. EA also became one of the founding elements of environmental Life Cycle Assessment (LCA), alongside eco-toxicology. EA has been incorporated into software tools for performing LCA studies concurrently whilst evaluating climate change impacts and a range of other ecological/environmental burdens. Slesser and his co-workers went on to devise ways of modelling societies using resource or ‘natural capital’ accounting. This approach utilised ‘systems dynamics’ techniques like those originally employed in world dynamics studies at the Massachusetts Institute of Technology (for the ‘Limits to Growth’ series) to plot a pathway towards sustainability. The present review therefore pays tribute to these various scientific contributions of the late Malcolm Slesser in the form of a critical appraisal from a modern perspective.

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Why is it important?

The many scientific contributions of Malcolm Slesser are available in a series of books and technical papers; a major selection of which have been reassessed here. The present work has paid tribute to these various outputs, albeit in the form of a critical appraisal from a contemporary perspective. They yield a number of ‘lessons learned’ for the energy and environment research community. Thus, studies of the energy efficiency of modern energy services and devices are valuable in the contemporary setting. They are often the first stage in determining the energy savings and consequent emissions reduction from an activity. Energy analysis has been incorporated within the modern era into software tools for performing environmental life cycle assessment (LCA) that can evaluate climate change impacts (primarily related to CO2e emissions) concurrently with a range of other ecological burdens. Environmental LCA remains a pivotal method for evaluating a range of environmental burdens over the life-cycle of a product or during the performance of a service. The utility of the LCA approach is demonstrated in regard to a recent study of low-carbon scenarios or ‘transition pathways’ for UK electricity supply out to 2050. It has also been asserted that techniques stemming from the Second Law (such as ‘exergy analysis’) have a role in studying energy systems and technologies, but these should not be used in isolation from First Law EA. Together they reflect both the thermodynamic quantity and quality of energy carriers. Slesser himself indicated that in any “refined” energy study, such as the assessment of ‘waste’ (so-called ‘surplus heat’), it is a Second Law-related property that should be evaluated. Nevertheless, energy analysis and environmental LCA are now key methods for evaluating energy technologies and associated pathways for a ‘net zero’ GHG emissions transition. Natural Capital Accounting [NCA], for which Malcolm Slesser and his collaborators were early developers and advocates, is a method for measuring the stock and condition of natural assets (such as ecosystems, water, and land) and the flow of services they provide. It integrates this information into accounting or assessment systems to help governments and organisations understand the value of nature; thereby facilitating better-informed decisions about economic development and sustainability. NCA is viewed, for example by the UK Government and its agencies, as being a crucial tool for measuring the stock and condition of natural assets [such as ecosystems, water, and land], as well as the flow of services they provide.

Perspectives

Methods of ‘energy analysis’ (EA) were developed in the aftermath of the first oil crisis of 1973/74. The late Malcolm Slesser - a distinguished Scottish chemical engineer, mountaineer and writer - was at the forefront of these developments. Following early energy studies of food production and solar energy technologies, he acted as rapporteur and a key player at a 1974 conference of energy analysts and economists held in Stockholm, under the auspices of the International Federation of Institutes of Advanced Study (IFIAS), that laid down a set of long-lasting conventions. Concepts like primary energy, embodied energy, process or operational energy, the ‘energy requirement of energy’, and net energy analysis (NEA) all stem from that period. First Law EA has been re-evaluated here in the light of modern ideas in thermodynamics stemming from the Second Law, such as those incorporated into exergy analysis and related methods. In order to obtain a comprehensive evaluation of energy systems (including, for example, CHP plants), it has been argued that energy and exergy analyses need to be employed concurrently. Slesser and his co-workers went on to devise ways of modelling societies (global to local communities) taking account of their resource use or ‘natural capital’, as well as their economic and population growth patterns. This approach utilised ‘systems dynamics’ techniques of the sort adopted for the world dynamics studies by Jay W. Forester and his co-workers at MIT [ultimately for the ‘Limits to Growth’ series of Meadows et al. (1972-2004)] to plot a pathway towards sustainability. This led Slesser and his co-workers to develop software tools for what he termed resource or natural capital accounting (NCA). They employed a NCA framework and systems dynamics modelling to develop a computerised model (known as ECCO) to explore options for a sustainable future. It was used to examine sustainable development on a national (e.g., Scotland), regional (the forerunner of the European Union) and global level. He published with his partner (Jane King; formerly Head of Population Studies at UNESCO in Paris) two significant texts that provide greater detail of their NCA approach, alongside a discussion of the moral issues related to global equity. Overall, Malcolm Slesser’s many publications represent a substantial and important body of work that was perhaps not fully recognised during his lifetime.

Professor Emeritus Geoffrey P Hammond
University of Bath

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This page is a summary of: From energy analysis to resource accounting: explorations by Malcolm Slesser revisited, Proceedings of the Institution of Civil Engineers - Engineering Sustainability, April 2026, Emerald,
DOI: 10.1680/jensu.25.00120.
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