Sustainable engineering: confusion and consumers

Abstract

It is often difficult to understand what is meant when someone starts talking about sustainability, sustainable development or sustainable engineering. Different people understand different things, depending on their own personal experiences and their current job description. For some, sustainability is about being environmentally aware, or ‘green’ – ensuring that products do not use up valuable resources or give off harmful pollutants. To others, sustainability is providing appropriate solutions to those in developing countries – solutions that use technology relevant to the situation in which they find themselves. To yet others, sustainability implies the continuance of their business – the self‐sustaining of the company. While sustainability texts such as Cradle to Cradle and Factor Four may prove inspirational to those trying to understand sustainability, attempts to implement some of the suggestions within small or medium sized engineering companies are likely to draw the reaction ‘that's for big companies, what about us?’. This paper therefore: (1) addresses widespread confusion among non‐specialists as to what ‘sustainable engineering’ actually means and its consequent implications for engineers in industry; (2) uses a number of product examples to draw out six ‘key principles’ that underpin sustainable engineering.

The paper demonstrates that the starting point of any industry attempt to be ‘sustainable’ must be a proper understanding of the consumer, particularly in the areas of product functionality and quality. Only after such understanding has been gained can further methodologies be used to consider enviro‐/socio‐sustainability of a product.

Keywords:

• sustainable engineering
• sustainable development
• product functionality
• quality
• engineering design

1. Introduction

Mention of the word ‘sustainability’ in public may gain one of a number of responses. Some people will immediately start talking about global warming and the threat to the world as we know it. Others will consider the problems faced by the poorest in the world, perhaps in their little villages in Africa, unable to find clean water without a 10‐mile walk each day. Many, however, will remain indifferent and will move quickly on to other, apparently more interesting, subjects.

Mention of the word ‘sustainability’ in engineering circles may equally gain a variety of responses. Some start considering the renewable energy/nuclear power argument and the importance of reducing emissions. Others discuss the finer points of energy efficiency. Yet others discuss the provision of lighting using solar power in developing countries and designing for appropriate technology. Those engineers in higher levels of management talk about the problems inherent in just keeping an engineering company in existence.

The disparate understandings of sustainable engineering and the consequent confusing situation are not helped by a plethora of literature that associates sustainability with a variety of different design methodologies: eco‐design, disassembly/recycling and designing for developing countries are just a few that may be represented as design for sustainability. Unfortunately, and perhaps as a result, industry often associates sustainability with negativity – stop polluting, reduce emissions, prevent waste, etc. In fact, industrial opportunities abound for companies that embrace sustainability philosophies in the broadest sense. The DTI report ‘Sustainability and Business Competitiveness’ (Pearce 2003) noted that ‘A business with strong corporate social responsibility will often be more successful in generating Economic Value Added’. Short et al. (2002) have discussed a number of simple product‐design tools that, in addition to improving a product's quality or competitiveness, can have a significant effect both on its environmental credentials and on the manufacturing company's self‐sustainability.

Where industry does embrace sustainability is in the consideration of doing ‘sustainable business’ – a subject promoted by many consultancies. Arthur D Little (2007), for example, seems to be promoting sustainability through the title of their report ‘Integrity+Innovation = Sustainable Performance: the Sustainability Value Formula’. Their emphasis is on promoting trust by the consumer and the consequent economic performance: ‘Less well recognised [than the value of innovation] is the value created by integrity. But the logic is similar. Integrity breeds trust; trust creates a good reputation; and, once again, reputation builds value. Conversely, several incidents of recent years show how costly – and even economically fatal – loss of integrity can be (e.g. Ahold, Enron, Dynegy, Global Crossing)’.

PA Consulting, on the other hand, state that ‘71% of CEOs [agree] that a sustainability programme is vital to the profitability of their company’ and suggest that they can help you make ‘better decisions with a true understanding of the balance between cost/benefit and sustainability impact’ (McQuaid 2007). Neither company states explicitly how they are defining sustainability itself, save through indirect references to the economic performance of the company and to the environment but PA Consulting assert that ‘Done well, a commercial focus on sustainability will lead to bottom line savings, risk reduction and increased sales. In some cases it has even led to category captaincy’. Sustainability, therefore, appears to be something that is desirable, but the engineer (student or practising) is left ignorant as to what it specifically implies for them.

While specialists in sustainability may well have specific views as to what sustainable engineering implies, the majority of engineers do not seem to share or to understand these views. This paper therefore:

1. addresses widespread confusion among non‐specialists as to what ‘sustainable engineering’ actually means and its consequent implications for engineers in industry, through considering some of the fundamentals of sustainable development;

2. uses a number of product examples to draw out key principles that underpin sustainable engineering and to demonstrate that the starting point of any industry attempt to be ‘sustainable’ must be a proper understanding of the consumer. Only after that has been ensured can further methodologies (such as Cradle to Cradle) be used to consider the broader sustainability of a product.

The paper begins by looking back at the fundamental definitions of sustainability, firstly with the Brundtland definition and then the so called ‘Triple Bottom Line’ of sustainability. The implications of these basics provide a definition of sustainable engineering which in turn leads to the industry goal of tackling econo‐, socio‐ and enviro‐sustainability concurrently. Noting the challenge inherent in tackling such a goal, the paper will then move on to develop six key principles. The principles provide a foundation for the application of sustainable engineering within an engineering company, demonstrating that product quality and functionality should be the starting point for any sustainable engineering methodology.

2. Sustainability

Clearly, the expressions ‘sustainable development’, ‘sustainability’ or ‘sustainable engineering’ can cause considerable confusion and misunderstanding depending on the audience that is being addressed. The teaching of sustainable engineering within undergraduate courses often focuses either on the impact of engineering projects on the immediate environment, or on empowering developing countries through the use of ‘appropriate’ technologies. The true definition of sustainability can quickly become lost in the general attempts to make the world ‘a better place’ and a number of questions immediately begin to present themselves:

	What does ‘sustainability’ mean?
	What does it imply, for student engineers, graduate engineers, design engineers and engineering companies?
	How can it be implemented, day to day?
	Is it simply being environmentally aware?
	Does it mean ensuring the longevity of the product itself and that it is not designed – deliberately or otherwise – with obsolescence in mind?
	Or is it about keeping a company sustainable, which may have an impact both on the environment and on product obsolescence?

The actual theory behind sustainability is, in fact, much simpler than any of these questions, but ultimately more complicated to implement.

2.1 The Brundtland definition

Much of the confusion lies in what part of the commercial spectrum is being considered to be ‘sustainable’ – the product itself, the product line, the company, or the planet. To address this, consideration should begin with the widely accepted definition of sustainable development – that provided in the 1987 Brundtland Report: ‘meeting the needs and aspirations of the present without compromising the ability to meet those of the future’ (World Commission on Environment and Development 1987). A number of observations can be made immediately from this definition:

1. To many people, if not most, sustainability is almost synonymous with concern for the environment. This is not mentioned by Brundtland, however. While one could argue its inclusion in the ‘needs and aspirations of the future’, it is certainly not explicit.

2. The definition makes no mention of technology – it neither says that returning to old technology and materials is the optimum way forward, nor that new technology will solve all future problems.

3. While engineers and innovators may be the ones who try to meet ‘the needs and aspirations of the future’, there is again no explicit mention of them.

4. There is no mention of the commercial spectrum – products, product lines, companies or the planet – within this definition.

The immediate conclusion from these observations is that sustainability goes beyond the environment, but is not purely an ‘engineering problem’, something that engineers should take on themselves to be the sole solution‐finders. Any understanding relevant to engineers – whether their products or companies – can only be gained by taking the definition and seeing what it implies to the engineering work place. Blithely making statements about ‘greening the planet’, or being ‘eco‐focussed’ will not give engineers the information or structures/methodologies they need if they are to be able to take sustainability on board.

2.2 Sustainability and the stool

In order to understand sustainability more fully, a number of alternative models have been proposed. One of the most popular is the ‘three pillars of sustainability’ – economy, environment and society, also called the ‘Triple Bottom Line’. Sometimes the pillars are represented as being the legs of a stool which will only retain its full functionality (i.e. sustainability) if all legs are considered equally. Dawe and Ryan (2003) suggest that the environment is the most important; Short (2007), on the other hand, suggests that technology could be considered to be the foundation. An alternative approach is to represent the three pillars as three overlapping sections in a Venn diagram – the overlap of all three areas is the area that represents sustainability. The Royal Academy of Engineering (2005) involves engineering within this diagram by replacing ‘economy’ with ‘techno‐economy’. Each of these is simply a model, with potential arguments about which is more accurate, whether the three pillars should be equally weighted or even whether a fourth pillar exists.

Such varying descriptors lead to variations in understanding of the word ‘sustainability’, depending on the context within the commercial spectrum (products, product lines, companies, or the planet), in which it is used. Typically, if asked ‘how sustainable is this product?’, consideration would go into its environmental credentials. Asking ‘how sustainable is this product line?’ would be more likely to elicit thoughts of the economy of the line – whether the product line will continue to sell over a period of time. Asking about the company will provide answers regarding its economic performance within its particular sector. Finally, when talking about the planet, it is usually the environment that is the key concern. The difference appears to be in whether the term ‘sustainable’ is actually intended to mean ‘no impact on the environment’ (as in products and the planet) or ‘continue to exist’ (as in product‐lines and companies). In fact, by returning to the Venn Diagram description as shown in Figure 1, it can be seen that these merely represent different aspects of sustainable development, rather than completely separate definitions.

Figure 1 The commercial spectrum and its place within the Triple Bottom Line of sustainability.

The underlying principle, with the majority of analogies or descriptors for sustainability, is that sustainability is not wholly represented by considering the environment – society and economy are key considerations as well. Thus socio‐, enviro‐ and econo‐sustainability, along with all the previously mentioned ways of understanding sustainability, are subsets of the whole – each independently valid, but not holistic in its approach.

2.3 Sustainable engineering

While it may now sound somewhat trite to suggest that sustainable engineering is engineering that targets sustainable development, it is also that simple. Sustainable engineering can be defined as ‘ensuring the sustainability of the entire commercial spectrum, from product to planet, across the Triple Bottom Line of socio‐, enviro‐ and econo‐sustainability’. In stating this, many of the questions posed at the start of Section 2 are now answered; sustainable engineering is a holistic approach to engineering that encompasses a number of different understandings, including all those at the very beginning of the introduction. The application of such an approach, of course, raises significant questions in the minds of engineering managers, particularly those working with small/medium sized enterprises (SMEs) that have, or perceive themselves to have, limited resources.

Attempting to address the entire Triple Bottom Line gives the impression of considerable – if not impossible – challenge to SMEs. Life Cycle Assessment (LCA) tools are time consuming, complex and have been argued to be of limited value to those seeking real innovation in the New Product Design process (Lagerstedt 2003). McDonough and Braungart's ‘Cradle to Cradle’ approach and certification are often seen as the ‘holy grail’ of sustainability, but appear almost as complex as LCA, requiring a 29‐page document (MBDC 2007) merely to outline the certification process. Maxwell's ‘Sustainable Product and/or Service Development’ methodology (SPSD) (Maxwell and van der Vorst 2003) is presented alongside a ‘sustainability checklist’ (Maxwell 2004); while much simpler than LCA, the checklist still runs to 8 pages and asks questions that go far deeper than a simple ‘yes/no’ response.

Perhaps the most easily accessible and everyday approach for real engineers is that of Bhamra and Lofthouse (2007) in ‘Design for Sustainability: A Practical Approach’; having been published only in the last few months, it can be considered to be the state of the art for engineering designers. On the other hand, it might be thought that there are far simpler ‘key principles’ that underpin sustainable engineering – principles that would educate designers, engineers and managers as to the task that they are facing in aiming for sustainable engineering. Such key principles would be fundamental to the engineering design/development process and would help to show how socio‐/econo‐/enviro‐sustainability fit together, thereby underpinning the application of any sustainability methodology. Equally, they may in themselves be sufficient to provide a basis for change within an SME towards sustainability. Six of these key principles will now be developed by considering the performance and utility of a series of product examples, together with the definitions of sustainability.

3. Product examples

The products described below have been chosen due to their role within the author's ongoing sustainability research, particularly in Rwanda (Short 2007, Short 2008, Short and Harvey 2008). They are chosen not with the intention of shifting the sustainable engineering argument to developing countries, but because each exemplifies certain sustainability‐based principles.

3.1 The solar powered water pump

The solar (photovoltaic) powered water pump (PVP) uses energy from the sun to generate electricity which is then used (sometimes via a controller) to drive a motor/pump set. Typically the energy is stored in the form of water in a raised tank, rather than using a battery. In this situation: the output is water in areas where surface water can be scarce; the fuel source is free and renewable; panels with the lowest cost per Watt output can be chosen (instead of the more expensive, high‐efficiency panels) as space for more panels is rarely an issue; and the system provides water during times of the brightest sun, when it is most needed.

Research by the author is currently underway to design such a pump specifically for manufacture in Rwanda. Following recent observations in situ, it seems likely that the vast majority of the pump system – including the control electronics – can be manufactured and/or assembled using local technology, components and skills. The key exception is the solar panel itself which would have to be imported although attempts have recently been made to establish a PV manufacture plant in Rwanda (Alexander's Gas and Oil Connections 2006).

3.2 Personal transport

A variety of personal transport is available in Rwanda, with the extremes highly visible. Besides walking, the most basic form of transport is the wooden scooter (Figure 2). These scooters are unpowered and do not have brakes; when going downhill, the only speed control is the use of feet on the ground. In directions other than downhill they have to be pushed. The next step up in technology is the push bike which is usually of poor quality, may be laden such that pushing is the only means possible, and may not have brakes. On the other hand, brand new mountain bikes are available in the supermarket in the centre of Kigali, the capital of Rwanda.

Figure 2 Wooden scooter.

Going up a further level of technology are mopeds, motorbikes and cars, each in varying levels of sophistication and (dis)repair depending on the status of the owner. All levels of technology are able to exist, to sustain themselves as product lines. Each serves a specific function for the owner, a function which may well differ from that of a transport mode higher up or lower down the technology ladder.

3.3 Communications

Cell phones have now become omnipresent throughout the world, irrespective of less or more developed country. The level of technology in a mobile phone might be considered to be quite high, yet their use is widespread, both as a status symbol and for their functionality where land lines are uncommon or unreliable. This is particularly the case in Rwanda, with 90% network coverage (Ericsson 2007).

3.4 Light bulbs

The light bulb is a product that has recently made many headlines due to suggestions that incandescent versions be banned in California, Australia, Canada and the UK/EU (California State Assembly 2007, Hamilton 2007, Walker and Macrae 2007). New energy‐efficient (or eco‐) light bulbs have been produced and are some way towards reaching consumer acceptance, albeit grudgingly. Compact Fluorescent Tubes (CFTs) suffer a number of problems (explored by Short and Harvey (2008)) when compared to the more traditional incandescent light bulb. These include their shape and size, the spectrum of light they produce, the brightness of the bulb, the time for the bulb to reach full brightness and the cost. Some of these problems may have been resolved by the new generation LED‐based light bulb, which has also provided a further step change in energy savings beyond the CFT.

4. Developing the ‘key principles’

All the product examples play a role within the society in which they find themselves. To understand this role, their impact on sustainability and their own sustainability, and to begin to develop the six key principles, it is appropriate first to consider the product examples within Kano's well known model of product development, where product performance is measured against customer satisfaction. Taking personal transport in Rwanda as an example, the wooden scooter fulfils the most basic needs and is the most basic product. Kano's ‘performance’ products might be considered to be the moped, while cars are the ‘excitement’ products. A simplistic view of this situation would be that as a country develops, what once was a performance product becomes a basic product and what once was excitement becomes performance or even basic. In more developed countries, for example, a car tends to be an unspoken and expected requirement – a ‘basic’ product, by Kano's definitions. With 60% of adult Rwandans living in poverty (42% in extreme poverty) (Republic of Rwanda and United Nations 2003) a car would certainly not be considered basic. It might be proposed that the state of a nation's development may therefore be judged through understanding where such products would be perceived, locally, to fit within Kano's model.

Moving to the products' role in sustainable development, it will be useful to consider them within the framework of the millennium development goals (MDGs), a series of eight goals published by the United Nations, each with quantifiable targets towards which countries are encouraged to work (United Nations Development Programme 2000). The goals are:

1. Eradicate extreme poverty and hunger;

2. Achieve universal primary education;

3. Promote gender equality and empower women;

4. Reduce child mortality;

5. Improve maternal health;

6. Combat HIV/aids, malaria, and other diseases;

7. Ensure environmental sustainability;

8. Develop a global partnership for development.

The product examples can be seen to fit in with many of these goals and their respective targets. The PVP, for example, not only provides clean water (meeting goals 4, 5, and 6) using solar power (goal 7) but can provide water for non‐domestic uses such as growing crops (goal 1), freeing up time for girls to attend schools and/or grow crops when previously they would have been fetching water (goals 2 and 3). Equally, the pump could be owned privately, generating income and contributing towards employment and the economic wellbeing of the population (goal 8). Similar, although perhaps not as extensive, cases can be made for each of the other products.

Looking at the MDGs themselves, each can be seen to fit one or more of the economy, environment and society. As might be hoped, the MDGs match up with an understanding of sustainable development. In terms of the PVP example, a pump can then benefit all three areas of sustainability, with local employment manufacturing/maintaining systems (econo‐sustainability), improved water availability (socio‐sustainability) and the use of PV rather than diesel (enviro‐sustainability). It can be seen that products fitting the MDGs are also contributing towards sustainability and the engineering design of such products must therefore bear in mind any sustainable engineering principles. However, engineers' varying (mis)understandings of sustainable engineering may mean that a product is designed only to meet economic concerns, or only social concerns, or even only environmental concerns – all of which are simply subsets of sustainable engineering – thereby leading to the product not being sustainable. For a product to be truly sustainable, it must be engineered with an understanding of the full breadth of the Triple Bottom Line. This gives rise to the first key principle:

KP 1: While the varied understandings of sustainable engineering are all valid in themselves, a full understanding requires all three aspects of the Triple Bottom Line.

4.1 How to make a product sustainable

If the full Triple Bottom Line must be considered to ensure sustainability, the question now to be addressed is how a product itself can be made to be sustainable.

The traditional method has been to design in environmental concerns and to design out environmental hazards during the product design process. The starting point may be a successful product line, which has already achieved econo‐sustainability, with changes made to reduce carcinogens, or energy consumption, or to provide an alternative power sources such as solar or wind power. The light bulb is an example of this, with CFTs having significantly decreased energy consumption and increased life over traditional incandescent bulb. A plethora of methodologies exist for carrying out such a task, ranging from a simple choice of materials (using Volvo's black, grey and white lists for example: The Volvo Group 2002) through to the time‐ and resource‐intensive LCA. It is then widely assumed that products advertised as being ‘green’ or ‘environmentally friendly’, have a wider appeal to the consumer and will therefore provide an econo‐sustainable product line. Unfortunately, this has not proved a correct assumption. Joyce et al. (2004) demonstrate a 20:60:20 model for consumers: 20% of consumers actually exhibit a negative attitude to products marketed as having environmental benefits; 60% are described as complacent and the remaining 20% will actively seek out such products. The first two groups, comprising 80%, may well take no action in any green direction unless they have little or no choice; for example, ceased supplies of non‐green products (as per incandescent light bulbs), or increased taxation. This implies that products being marketed as green are only targeting 20% of the potential market. In most cases it would seem an unwise strategy in the attempt to sustain sales – and thence product lines and companies – to address solely the green 20%. Making a product ‘environmentally sound’ does not imply that the product‐line, and hence the company, will be sustainable. This becomes the second key principle.

KP 2: Designing for the environment is not designing for sustainability.

The next step is therefore to ensure that economic concerns are designed in to the product, thereby bringing about product line and company sustainability. This is not particularly novel; as far as most companies are concerned, making money is their starting point. Indeed, standard engineering methodologies such as Design for Assembly, Quality Function Deployment and Lean Manufacture have been shown to impact on sustainability (Short et al. 2002). However, a focus on environmental rather than economic aspects, as seems to have been the case with CFTs, may force consumers into trading off higher prices or lower quality in exchange for a greener product – a situation which again leads to only targeting 20% of consumers. Alternatively, the continued existence of a product line, through ensuring that it is economical to manufacture and to purchase, can thereby lead to econo‐ and socio‐sustainability of the company and allow enviro‐sustainability of the product itself to be considered. The next key principle therefore becomes:

KP 3: Product line longevity is a requirement, and can lead to econo‐ and socio‐sustainability.

The product examples outlined above provide some interesting illustrations of how product lines may or may not be sustainable – particularly in the context of Rwanda or other developing countries. The solar powered water pump seems to be a prime example of a product that should be sustainable and consequently widespread. There are a number of reasons why that is not the case, reasons which are investigated elsewhere (e.g. Short and Thompson 2003). Of interest for this discussion, however, is why a consumer should want to own such a pump – hence what makes the product line sustainable. A number of factors could be identified for this – the basic function would be the provision of water, but a PVP may be chosen over a hand pump or diesel pump because of the added functions of not requiring manual operation, nor requiring regular fuel and only minimal maintenance. Furthermore, the PVP can be seen as a status symbol – Kaunmuang (2001), for example, describes a situation in Thailand where the new village pump was deliberately placed in the compound of the head man, presumably as a status symbol. Cell phones can be seen to be in the same position, providing both functionality and a status symbol concurrently. Note that in this case ‘product line longevity’ refers to a continued demand for cell phones, not to the longevity of any individual hand set or model of hand set.

The above discussion suggests that there might be a variety of reasons for purchase of a product, which will impact on the longevity of the product line. Functionality is assumed – Kano's ‘basic’ – but there are then a number of other drivers, as explored by Weightman and McDonagh (2004). They suggest that the majority of purchases are to replace existing products and propose a number of reasons:

This may be due to product failure, or the need for uneconomic repairs to existing products. Sometimes it will be to achieve improved functionality, where the existing product has become obsolete or obsolescent, or where the new product performs significantly better …

They go on to discuss reasons that are above functionality – ‘supra‐functional’ – such as products being ‘replaced with ones that look better, have different symbolic associations, are from more highly regarded brands, or are just cooler’.

Walker (2006) similarly addresses the question of supra‐functionality: ‘Is it possible to have an object that is more than merely functional, but which also can be understood as sustainable, and if so, what would be the characteristics of such an object?’. In this case, by ‘sustainable’ he tends to mean longevity of product/product line and uses design icons as examples, noting that longevity implies something that is of value to the consumer. He classifies products according to three characteristics: Functional; Social/Positional; and Inspirational/Spiritual, suggesting that products classified as ‘social/positional’ (in addition to Functional) are short term and non‐sustainable products. Inspirational/spiritual (again, in addition to Functional) products can overcome ‘the destructive tendencies … and lead to objects that are, in their fundamental conception, deeply meaningful’. The fact that they are meaningful to the consumer implies their longevity both as products and product lines. Returning briefly to the Kano model, it is unclear how an inspirational/spiritual object might be categorised – perhaps a third axis might be necessary to express ‘customer fulfilment’ rather than simply ‘customer satisfaction’ – a product may provide exceptional functionality without providing the fulfilment that, for example, a holy relic might bring.

Irrespective of social, positional, inspirational or spiritual tendencies, it is clear that product and product line longevity – and thereby the potential for econo‐sustainability – require a deep understanding of the consumer. This may be an understanding of their needs now, or an understanding of to where they can be led, as in the case of Morita's Sony Walkman where no market was believed to exist. Should this understanding be missing, products can very rapidly move away from satisfying their key functionality. Functionality is an unspoken, assumed need for a product, but can be so unspoken that it is forgotten, despite its importance. It is noticeable that in Kano's model, a lack of product performance leads very rapidly to customer dissatisfaction. Designing environmental needs into a product can easily lead to the designing out of product functionality, as with the CFT where the basic functions that a customer expects have been removed from the light bulb at the expense of ‘eco‐friendliness’. It is hardly surprising that it may require legislation, rather than customer power, to make such sub‐functional products the norm. The fourth key principle can thence be stated:

KP 4: A product must satisfy its key functions if it is to be econo‐sustainable.

Lagerstedt (2003) demonstrates the tension between functions and environment in her method for applying design for environment – the eco‐functional matrix. The ‘Functional Profile’, a part of the method, is ‘a systematic way of adequately incorporating necessary and important functional properties at the lowest possible environmental cost’. Weightman and McDonagh (2004) agree, stating that, as in key principle 1, sustainability is more than just the environment:

‘Creating successful sustainable products is as much about making products that fulfil consumer expectation as well as ensuring that they also fit the criteria of sustainability.’

The product examples, however, suggest that the meeting of customer expectation goes beyond Weightman and McDonagh's description and is an absolute prerequisite. Without it, econo‐sustainability, and thence the potential for socio‐ and enviro‐sustainability, is simply not feasible.

Unfortunately, the drive for eco‐products has led consumers to associate ‘environmentally friendly’ products with ‘poor performing’ products. Beyond light bulbs the examples are not hard to find: battery powered cars with low range and top speeds; toilet tissue that is not soft and so on. In his keynote address to the EPSRC seminar ‘Consumers And Choice In A Throwaway Society’, Alan Knight, formally Head of Sustainability at B&Q (the UK's market leader in DIY) described the move by B&Q to bring all their home brand paints to low volatile organic compound (VOC) status. Recognising the consumers' assumption that eco‐products are synonymous with poor products, B&Q decided not to market the new paint on its environmental credentials, rather focusing on its functional improvements such as quick drying and low odour, that came as a result of the switch to low VOCs. While this view might be surprising, it is backed up by data from MINTEL, the market research company. In their report ‘Household paper products’ (including toilet and facial tissues) covering 2002–2005, they note that the proportion of toilet tissue purchased that was not made from recycled papers, dropped consistently and was below 10% of all toilet tissue purchased (MINTEL 2006). While an interest in recycling was expressed as a market driver, that interest did not lead to purchases. Regarding facial tissues, the report states ‘This may reflect that while people do believe that recycling is important in principle, they are not prepared to buy products on a regular basis that are often perceived as inferior in quality’.

Quality is one of the ‘everyday functions’ consumers expect from their products and failure to provide that quality, at the expense of eco‐friendliness, presents a trade‐off that, according to Joyce et al.'s model, consumers are unwilling to make. As Weightman and McDonagh (2004) state: ‘Better products fit users better and can be designed to evolve or adapt to suit their changing needs. Better sustainable products must do both of those things but also can be repaired, refreshed and recycled’. This leads to the fifth key principle:

KP 5: The quality of sustainable products must be at least as good as that of the equivalent non‐sustainable product, if not better.

It is therefore clear that an understanding of the consumer and of their expectations regarding both quality and functionality is vital if a product is going to sell, contributing to econo‐sustainability and permitting consideration of enviro‐ and socio‐sustainability. Understanding the consumer introduces a whole raft of perils where the consumer does not always appear to know what they themselves want. Using the PVP example, it can be very easy to focus on a ‘renewable energy’ solution to water provision and thereby promote this as the way forward. However, in focusing on the technology, rather than the consumer, some of the basics can be lost. Kano's ‘basic’ in this context is the provision of water; the use of PV to provide the water is perhaps a ‘delighter’, but not something that will necessarily inform customer purchases. Farinelli (1999), analysing energy and its part in sustainable development, notes that ‘what societies want are the services that energy provides, not fuel or electricity...’ and that ‘the energy sector is still driven by issues of supply instead of demand’. Without understanding the true demands of customers – not PV panels, but light in the evenings, or water to drink – only luck will make a product and product line economically successful. The final key principle is therefore:

KP 6: Econo‐sustainability, and thence all sustainability, relies on a true understanding of the consumers wishes and demands and the consequent product functionality required.

5. Discussion

As individual statements, many of the key principles developed above are well known. For example, KP 4 is self‐evident within any engineering company – a product must make money, unless it is a ‘loss leader’ as part of a deliberate market entry policy. On the other hand, many (although not all) specialists in the area of sustainability would recognise KP 2 as being obvious. However, nowhere has it been shown that there is an absolute requirement to focus on product functionality and quality if sustainable engineering is to be achieved. Instead, customers continue to be presented with products that may well have been designed with the environment in mind, but are not functionally equivalent with their non‐environmental competitors or that fall well short of the quality standards expected. In doing so, the company not only causes its own econo‐sustainability problems, but risks making consumers even more averse to products advertised as being sustainable.

As an example of these points being missed, the state of the art in sustainable engineering – Bhamra and Lofthouse's excellent ‘Design for Sustainability’ (2007) – can be examined. KPs 1 and 2 are effectively covered, but 3 to 6 are not. While one might argue that their absence is because they are assumed, being so obvious, the continued manufacture of products that flout these KPs belies the argument. While Bhamra and Lofthouse briefly discuss customer needs (more as ‘human needs’ rather than ‘customer requirements’), when it comes to proposing how to do a real sustainable design project, these customer needs barely warrant a mention.

Similarly, Bhamra and Lofthouse state ‘The ultimate aim for businesses should be to design and develop profitable products which are both environmentally and socially responsible.’ Again, the book emphasises ‘environmentally and socially responsible’ whereas ‘profitable’ is assumed – while profitability may well be assumed, this paper contends that unless it is the focus of the design, through a proper understanding of the customer, then irrespective of the product's environmental and social sustainability, the product will not be sustainable.

Maxwell's SPSD is perhaps the closest to recognising the importance of the key principles, noting that ‘SPSD is about producing superior products and/or services that fulfil traditional criteria as well as sustainability requirements’ (Maxwell and van der Vorst 2003). However, they go on to state: ‘The aim of the initiative is to improve the environmental and hence business performance of Irish manufacturing industry through a more sustainable approach to product and/or service development.’ In saying this she implies that econo‐sustainability is a consequence of enviro‐sustainability, which can be true but cannot be guaranteed in such concrete terms. Equally, in noting quality and functionality only as two of the ‘traditional criteria’, their relative importance to engineering companies and managers is ignored: if these criteria are not met, the product's success is in doubt and therefore that of the company is equally in doubt.

Following on from the research presented in this paper, the next stage of the research will be to look at understanding the best means of applying the key principles to industrial practice. This may go from the simplistic ‘rule of thumb’ to the more complicated strict integration into an engineering design procedure. They could be applied very easily via a ‘top‐down’ managerial push, possibly through the use of basic ‘check lists’ as advocated by Pahl and Beitz (2007), although perhaps on a simpler scale than Maxwell's SPSD (2004). Alternatively, should the company practice Cooper's ‘Stage Gate’ methodology of managing the New Product Design process (Cooper 2001), a series of questions could be added to each gate to ensure that the key principles have indeed been considered. Or a full methodology could be developed, such as the Durham methodology for Design for Assembly (Appleton and Garside 2000). Clearly, there is unlikely to be a ‘best‐fit’ approach that will be applicable across all companies, companies instead having to adapt the key principles to their own organisations and ways of carrying out engineering.

6. Conclusion

Designing for sustainable engineering has no ‘quick fix’ answers, to do with choosing safer materials, or reducing emissions. Instead it is the application of widespread engineering knowledge to tackle the entirety of the Triple Bottom Line of socio‐, econo‐ and enviro‐sustainability. While it is easy to say that the environment is a fundamental concern, surpassing all others, the discussion presented shows that it is simply one of the competing requirements and can never be the be‐all and end‐all, either of a product's design or of sustainable engineering. This paper has therefore drawn on a series of product examples to develop a number of key principles that can help practising engineers and engineering students, who are usually not specialists in sustainability, to find the place of sustainable engineering within their own disciplines and professional lives:

KP1: While the varied understandings of sustainable engineering are all valid in themselves, a full understanding requires all three aspects of the Triple Bottom Line.

KP2: Designing for the environment is not designing for sustainability.

KP3: Product line longevity is a requirement, and can lead to econo‐ and socio‐sustainability.

KP4: A product must satisfy its key functions if it is to be econo‐sustainable.

KP5: The quality of sustainable products must be at least as good as that of the equivalent non‐sustainable product, if not better.

KP6: Econo‐sustainability, and thence all sustainability, relies on a true understanding of the consumers wishes and demands and the consequent product functionality required.

The conclusion that sustainable engineering starts with the econo‐sustainability of the product and company should prove acceptable to practising engineers in their commercial settings. It is also a vital lesson for those new to design engineering, whether starting university or their first job. Equally, it must be remembered that econo‐sustainability is only the starting point that socio‐ and enviro‐sustainability can build on.

As engineering companies choose, or are required, to strive for sustainable engineering they must do so unhindered by the wealth of sustainability definitions, issues and methodologies currently available, and in a manner that is obviously positive to the company, not full of negative connotations. The starting place has to be the company's own customers: a company can only address environmental and societal aspects of sustainability if it is able to sustain itself economically. The sole way to ensure this is to ensure that products and product lines are able to sustain themselves and the only way to ensure this is to start with the consumer. Thus while environmental and societal concerns can (and should) be a basic part of an engineering design process, if the end product does not meet a consumer need, the product line will be unsustainable and the company has no opportunity to develop enviro‐ and socio‐sustainability. On the other hand, simply making a product environmentally friendly does not help in the push towards sustainability. The assumption that ‘green’ is a selling point or a marketing tool that can allow a product to have less functionality is simply not true. Functionality and quality are the drivers for product purchase and while eco‐friendliness should be a fundamental to the design engineer, it cannot be relied upon for product promotion or as an excuse for poor performance or poor quality. Without functionality and quality, engineering that is truly sustainable is simply not possible.