Towards Sustainable Infrastructure Development in Africa

Towards Sustainable Infrastructure Development in Africa:

Design Principles and Strategies for Lifespan-Based Building Performance

1Agyefi-Mensah, S., 2Post, J.M., 3Egmond - de Wilde De Ligny, E.L.C. van, 4Badu, E. 5Masi Mohammadi

Abstract

Societies and economies the world over develop on the wheels of infrastructure. In Africa, it accounts for about one- third to one-half of all public investment (Kessides, 1993). Significant about infrastructure in general, however is the fact that they have very long lives. Consequently, their impact on capital investment, resource utilization, the quality of the environment and overall quality of human life can be very significant. It is important therefore that they meet performance requirements in terms of economic, ecological and social sustainability. By the same token, their long lifespan fraught the design task with enormous amount of uncertainties, compounding the already ill- defined nature of design problems. Given that change is importune, and the fact that it is impracticable to foresee all the changes that will occur over time, a defining characteristic of all infrastructure will be the capacity to respond to change. Focusing on the case of buildings, this paper presents a discussion on some design principles and strategies which assure responsiveness to change and hence sustainable performance. Although the concepts have been advocated for over half a century now, studies show that they still remain marginal to the design profession. To clarify the concepts research questioning and extension of knowledge, this paper seeks to examine their basic tenets with the view to harmonize the core principles and strategies. A literature review method is used with examples from field observations where necessary. The paper first attempts to review and harmonize these principles, and highlights the practical usefulness. It then highlights the implications for research and development as well as technology capacity building for sustainable infrastructure development in Africa.

Keywords: Lifespan, sustainability, performance, change, functional, adaptable, infrastructure

1Stephen Agyefi-Mensah, PhD Candidate, Technical University of Eindhoven, (TU/e), The Netherlands, [email protected].

2 Jouke M. Post, Professor of Architecture and Building Technology, Technical University of Eindhoven, (TU/e), The Netherlands, [email protected].

3 Emelia L.C. van Egmond-de Wilde de Ligny, Assistant Professor of Innovation, Technology & Knowledge Transfer for Sustainable Construction, Technical University of Eindhoven, (TU/e), The Netherlands, [email protected].

4Edward Badu, Associate Professor of Building Technology, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana.

5Masi Mohammadi, Lecturer in Building Technology (Domotics) - TU/e (The Netherlands

1 1. Introduction Societies and economies the world over develop on the wheels of infrastructure. This is to say that infrastructure makes available the physical structures such as roads, railways, ports and harbours, water supply systems, sewers, electrical grids, telecommunication systems and buildings needed to provide the commodities and services essential to enable, sustain and enhance societal living (Fulmer, 2009). This facilitates production which forms the basis for socio-economic development and improvement in the quality of life. The multiple forward and backward linkages of infrastructure to other sectors of economic growth makes it even more significant to development in Africa. Capital investments in infrastructure contribute to asset formation, employment generation and as security for credit. For example, the construction of buildings such as houses, factories, hotels and offices do not only create employment but also facilitates the production of other goods and services which form the basis for economic growth and improvement in the quality of life. In all countries, therefore, 50% or more of all new fixed capital formation take the form of infrastructural works, including buildings, roads, airports and harbours, dams and power plants, water and sewerage facilities, land reclamation, irrigation and drainage works (Spence et al., 1992). In Africa, infrastructure accounts for about one-third to one- half of public investment and about three to six percent of Gross Domestic Product in Africa (Kessides, 1993). Thus, infrastructure development induces economic growth while at the same time providing the facilities needed to satisfy consumer demands for education and training, health, leisure and recreation, and family life. Sustainability in infrastructure development can therefore not be overemphasized. For buildings, sustainability is all the more important because of their rather long lifespan, and the myriad of changes that can occur, both foreseen and unforeseen. This impacts the value of capital investment, the environment and the quality of life of its inhabitants in terms of health, comfort and productivity. For example, over a fifty year life, the changes in a building is found to cost approximately three times more than the original building (Brand, 1994). This results because over this period, the service installations change approximately three times along about ten generations of space plan alterations (Duffy, 1990). Leaman and Bordass (1999), attributes losses or gains of up to 15% of turnover in a typical office organization to the design, management and use of the indoor environment. The impact on the quality of human health, productivity and comfort may be underscored by the fact that an estimated 60-85% of human life is spent in homes with half of this in bedrooms (Hassler, 2009), approximately three-quarters of the entire human life. In relation to this, some studies establish a strong link human health and indoor dwelling conditions such as thermal comfort, lighting, noise, moisture and mould (Bonnefoy et al., 2007; Wong, et al., 2009). Further to these, buildings consume about 40% of the world’s total energy, 25% of wood harvest, and 16% of water consumption (UNEP, 2001). The foregoing evidence suggests that buildings can have significant impact not only on profit- maximization, but the quality of the planet and the life of the people who inhabit it in both the short and long term. They must therefore be sustainable in performance (ISO 15392, 2008). This means, they meet present needs without compromising the need to respond to future qualitative demands (WCED, 1987). Thus, sustainable infrastructure, will meet demand and requirement for the present and the future simultaneously contributing to resource efficiency, environmental quality and quality of life of people.

2 The purpose of this paper is to present a discussion on some key design principles and strategies which promise to enhance the functional performance and hence sustainability of buildings through the capacity to respond to change. It begins by defining the problem of functional performance deficits in buildings, how these result and the mechanisms users adopt in response. It then discusses some engineering solutions to the deficit and some of the criticisms leveled against their usefulness. This provides the grounds for a discussion on the design principles and strategies considered useful to enhance lifespan performance of buildings. The paper ends by highlighting some implications for research and development as well as technology capacity building.

2. Functional Performance Deficits in Buildings Buildings change and so the people who occupy and use them. These two seem inextricably bound together. On one hand, changes in climatic conditions and the natural effects of ageing, coupled with wear and tear, make the materials, component and systems of a building subject to decay and depreciation, which if not attended, results in obsolescence and eventual demolition (Douglas, 2002). Buildings nowadays also involve the use of a large number of different materials with different service lives - the actual period of time during which the building or any of its components performs without unforeseen costs or disruption for maintenance and repair. About 150 different materials, with the lifespan of permanent materials varying between 10 - 100 years is reported (Post and Willem, 2001; Athena, 2006). The differential service lives means different parts of the building change at different times and at different rates. This brings about the need over time to ‘prematurely’ change a building component simply because it is part of a system consisting of components with much longer lifespan. In one sense, the shorter lifespan components dictate lifespan changes, and hence the system lifespan as a whole. Considered from another angle, the longer lifespan components can unduly constrain or control the ability of the shorter lifespan components to change by the way they are configured together to function as a whole. This interdependencies creates a non-going tension between the more permanent and relatively mutable elements of the building throughout the lifespan of the building. The people who use the building, on the other hand, also change and even more rapidly in their requirements as they traverse the trajectory of life. For example, families grow and shrink, changing in composition and size over time, through the addition or departure of a member. Buildings also outlive their first occupants, and different generations of users come into occupancy during its intended lifespan. Occupancy turnover may thus span user of different characteristics at different times. In addition to this, people become physically challenged in time by reason of illness or accident. These changes together change the requirements of people in terms of the use of the building. An even greater challenge is that they are further heightened by the effects of advances in technology, and its impact on social change and the quality of life people seek. For example, increasingly, more and more people are working at home due to advancements in information technology (Kincaid, 2002). Thus, as people’s needs, expectations and lifestyle changes, it becomes necessary to change the building in some way through upgrading, renewal, reconfiguration, modification or adaptation of some form in order to accommodate these changes.

3 Yet most buildings are rarely designed to change, being designed to satisfy existing forms of use (Gan and Barlow, 1996; Durmisevic, 2006). They are static in form with configurations which lack the flexibility needed to support future changes (Whitchnuil et al., 1999). Over time, therefore, the mismatch between the less mutable attributes of the building and the changing requirements of users reduce the functionality of the building. This widens the gap between the functional and technical lifespan of the building, such that although the building may be physically fit, it fails to support intended or desired requirements for use. This is loss of functional performance. The effect is that the buildings become obsolete, redundant and in the process may be abandoned or become due for demolition with significant impact on environmental quality. The observation from this is that as a result over time, most buildings fail to meet the requirements for use in an effective way. This mismatch between the technical capabilities of the building and the functional requirements creates a gap between its designed or technical life and the functional lifespan. The useful life of the building shortens making it redundant, obsolete and the subject of demolition. This is reported to have shortened from a technical (designed) life of about 100 years to a functional (use/economic) life between 20 and 35 years (Duffy, 1990; Kendall and Teicher, 2000; Lichtenberg, 2006) (Fig. 2). The impact on the environment, invested capital and the quality of human life cannot be overemphasized. The critical question then is how to design buildings such that they meet requirements in the present and the future, and hence buildings with functional lifespan which approximates as closely to the design life as possible if not equal?

Desired building quality

e e c c n n a a Original building quality m m r r

o o t f f i r r c i e e f P P

e g D n Declining building quality i s a e r c n I

Fig. 1: Performance Deficit in the Life of a Building

Technical Life

Functional Life Deficit in Functional Life

Fig. 2: Functional Lifespan Deficit in Buildings (∆FL)

4 3. Building Change and User Response to Building Performance Deficits The changes that occur in the life of a building can be many and diverse in character. Broadly however, these may be classified as change in function, change in capacity and/or change in flow (Slaughter, 2001). Changes in function occur in response to higher or new facility performance objectives such as the conversion of a warehouse into an office space or abandoned churches into multi-family residential facilities. Change may also occur in order to meet the need for higher load conditions, for increased operational space (volume) or in response to improved internal or surrounding environmental conditions. For example, the need to add an additional floor to a house or an office building. In yet other cases, change becomes necessary in response to different performance requirements for passage, movement or organization of people and the distribution of goods within or into a facility. Together, these bring about the need to upgrade, renew, modify or adapt the building in some form. On the part of users, research shows that when an environment fails to meet requirements, users respond by making various forms of changes and adaptations (Bell, Fischer, Baum & Greene, 1996). While some are immediate upon occupancy, others are incremental taking forms such as ‘knocking off’ existing walls, building new walls including illegal expansion of in the case of flats (Brown and Steadman, 1991; Sullivan and Chen, 1997; Wong, 2010). This is so even in public apartments where users do not usually have the freedom to physically alter the building.

Fig. 3: Different forms of adaptations users make in order to meet their requirements for space

Figure 3 above shows different forms of physical alterations users of some public apartments in Cape Coast (Black Star Nurses Flat) and Tema (Kaiser Flats) are forced to make in order to meet their requirements for use. Research in the Netherlands has revealed that in some cases, residents want to move out in search of better accommodation (Durmisevic, 2002). Besides user dissatisfaction, the loss of functionality also creates artificial shortage and compounds the demand problem.

4. Engineering Responses to the Lifespan Performance Problems The traditional response to building change and the problem of performance deficits has been largely through maintenance and retrofitting on different scales. In arguing for adaptability, Douglas (2002), observes that though useful, this is marginal in effect when balanced against technical difficulties associated, the effect on the building fabric as well as the implications for life cycle costs and waste generation. They are unable to bring the building to the desired level of quality (fig. 4).

5 Deficit Level

Fig. 4: The effect of maintenance and adaptations on building performance over time

Beyond maintenance and retrofitting, service life planning techniques namely the Factor Method and Engineering Method (ISO 15686-1:2000) have also been advocated. These methods focus on the durability of buildings. They presume that by selecting materials, components and systems of a building based on an estimate of the service life, along planned maintenance, it is possible to reduce the rate of physical deterioration of buildings, taking into account certain factors considered critical to performance over time. The major criticisms are that they are theoretical constructs (Kohler and Hassler, 2002), utopian in nature (Davies and Wyatt, 2004) and associated with practical difficulties for application (Hovde, 2003; Hovde and Moser 2004; Trinium and Sjöström, 2005). Aikivuori (1999) further argues that the critical loss of performance in buildings – what fails before durability - is the ‘perceived quality of the building’. Thus, beyond decay- and durability-based models, there is the need for strategies which enhance the functionality of buildings and hence the lifespan performance. To fill this gap, Lifespan-based Design Concepts (LDC) argue for the application of principles and strategies in the design and construction of buildings which anticipates changes and provide for them.

5. Lifespan-based Building Design Concepts – Principles and Strategies

The term Lifespan-based Design Concepts (LDCs) is used generically to refer to design principles and strategies which take into account the through life cycle performance of the building. It seeks to create suitable and sustainable living environments by enhancing the practical usability and long-term utility and value of buildings (functionality) for present and future generations (Post and Willem, 2001). In this, it aspires to contribute to extending the functional (useful) lifespan of buildings by improving the basic supply quality through enhanced functionality (Fig. 6). This is intended to bridge the increasing gap between the relatively short functional/economic lifespan and the apparently ‘endless’ technical life of buildings through functional and flexible/adaptable design solutions, and innovative building technologies (Post and Willem, 2001). Accordingly, it anticipates changes in the life of a building, and hence focuses on incorporating techniques, both in design and construction, which support the ability of the building to meet present needs without constraining its capacity to fulfill future demands.

e c n a m

r Demanded quality o f r e P

Improved supplied quality

Basic supplied quality

Basic functional lifespan Fig. 5: ImprovedImproved functional functional lifespan lifespan (Adapted from Gijsbers et al, 2007) Time

Careful review of the literature would reveal that current thinking about lifespan-based approaches to building design hinges on four key principles namely the:

i) principle of discrete (separate) systems at the whole building level; ii) principle of overcapacity in design at the system or component level; iii) principle of open- plan at the space plan level; and iv) principle of distributed control at the user-designer interaction level

5.1 The Principle of Discrete Systems

The principle of discrete systems, also known as systematization in design argues that different parts of the building have different lifespan and functional expectancies and should therefore have a status of independent part in the total configuration of the building (Durmisevic & Brouwers, 2002; Geiser, 2005). Accordingly, it proposes that a building system should be organized based on the propensity of its systems and component parts to change. Different parts of the building are therefore separated based on their lifespan. The underlying argument is that the more free and independent (separate) these layers are within the system of the building’s configuration, the greater will be the capacity for future transformation in terms of expansions, conversions, remodeling, etc. Thus, the principle of discrete systems maximizes the capacity of the building to change by minimizing physical interdependencies.

The principle of discrete systems underlies Habraken’s (1975) Support and Infill concept which categorized a building system into two related parts: upper level less mutable Supports (or base building) and lower level changeable Infill (fit-out). He argues that change emerges faster from the lower level systems. Consequently, separating it from the higher level systems will afford possibilities for change and adaptations while minimizing construction. In a similar light, Duffy

7 (1990) and Duffy and Hutton (1998) disentangled the building systems into four shearing layers namely: (a) shell (structure), (b) services (installations), (c) scenery (partitions), and (d) set (furniture). Brand (1994) expanded this view into six layers of change namely: (a) site, (b) structure, (c) skin, (d) services, (e) space plan (interior layout) and (f) stuff (fittings and furniture). On the basis of this work, Leupen (2005) identifies five layers as: i) main load bearing structure, ii) skin iii) scenery, iv) service elements and v) access.

The open building paradigm (Kendall and Teicher, 2004), also advances on the principle of discrete systems. It separates the building into three separate systems based on their lifespan as: a) primary system (structure + outer layer, with approximate life span of 100 years), (b) secondary system: infill (20 years), and c) tertiary system: interior (5 – 10 years). According to Geiser (2005), this three-tier levels of the building can be illustrated using an empty mineral crate as representing the primary system, the empty bottles as the secondary system and the flowing liquid as the tertiary system (fig. 7). Particularly, this allows different types and kinds of filling at different stages in the life of the building.

(a) Structure (b) space plan (c) skin

SPACEPLAN SERVICES SKIN STRUCTURE

(d) Services e) Six Layers of Building Change

Fig. 6 (a-e): Shearing Layers of Building of Building Change (Brand, 1994)

8 Plate 2: Empty bottles representing the Plate 1: Empty crate representing the Plate 3: The primary and secondary system primary structural system secondary systems together

Plate 4: The liquid as the tertiary Plate 5: Different secondary and tertiary system systems could then be possible

Fig. 7: Illustrating the different levels of the building system

In the Slimbouwen (a Dutch term for ‘smart building’) strategy, Lichtenberg (2006; 2008) is more intent on the relationship between systematization and the building construction process. The strategy organizes the different parts of the building into four layers namely the structure, envelope, services and infill based on their lifespan. The intended lifespan of the individual layers determines the hierarchy of the building layers in the sequential building process. The concept argues that such an approach does not only enhance the ability of the building to respond better to changing circumstances over time, but also it organizes the building process into a sequential order which facilitates flexibility and efficiency in building construction. The material-saving potential of the Slimbouwen process is deemed a great advantage.

Fig. 8: Systematization of the different layers of the Building. (Source: Lichtenberg, 2006; 2008),

Thus, looking at the building as a complete system of different parts, systematization enhances the functional performance of the building by separating those parts which are permanent from those that are relatively changeable. This means the main carrying construction is separated from

9 the finishing which is light and replaceable or otherwise flexible and easily adaptable. This reduces the extent of constraint exerted by the permanent elements over the changeable elements, facilitating replacement, reconfiguration and reuse.

5.2 The Principle of Over-capacity in Design

The principle of over-capacity in design involves designing certain systems and their components significantly over capacity so that changes in loading conditions or volume can be accommodated without replacement or extension of current capabilities (Iselin and Lemer, 1993; Glen, 1994; Gann and Barlow, 1996). This can be technical as well as spatial. Technically, selecting structural members with higher capacity in size, strength, etc than is currently required for the immediate design loads can provide the opportunity to add to a building in future. The principle also applies to making prior provisions for service installations such as the number of socket outlet, service ducts, etc. Overcapacity may also be in terms of space provision through over-dimensioning in order to create spatial redundancy for future qualitative demands (Kincaid, 2002). For example, a generous floor to ceiling clearance (say double height) for a range of possible uses may serve both the long and short term need for space. This allows volume manipulation by taking advantage of room height (Friedman, 2002). Designing for overcapacity provides room for future extensions and additions as an alternative solution to demolition and reconstruction.

5.3 Open-Space Plan Design

At the space plan level, the principle of open-space plan design or more generally flexible floor plan conceives a building as an open space, with minimum internal subdivision between spaces designed for different usage. It discards the idea of a house as a box made up of smaller boxes with spaces no longer enclosed but with the capacity to flow. The interior space is flexible seemingly without fixed enclosures. Characteristically the floor plan is designed to be ‘ambiguous’ and ‘flexible’ (Kincaid, 2002). By ambiguity, the future use of the building is assumed to be uncertain: and a variety of possible uses is assumed to be likely for a building, with nothing done to constrain unduly the adaptation of a building to a range of uses. Similarly, a single easily defined use for a building is avoided. This ties in with the notion of ‘soft’, and ‘dumb’ spaces – i.e. undesignated spaces/rooms that can be turned into something by the occupant rather than intended by the architect (Arvana, 2006; Till and Schneider, 2007). This can be achieved by making the floor plan of the dwelling and the dimensions of the rooms useful in multiple ways; and building in such a fashion that the floor plan and facilities of the dwelling can be adapted to meet the demands of the (future) resident with as little constructive interventions as possible (Hilhorst, 1999). Thus, flexibility in one sense, allows the creation of spaces within a building such that people adapt their activities to suit the building and not the building to suit their activities. Thus, the living room could be large enough to serve a variety of purposes from a sitting, through dinning to sleeping, while the bedroom may serve also as study. In another sense, flexibility allows for adapting the building to new use requirements at minimal constructional intervention and cost. Gregory (2005) refers to the former as ‘multi-space’ strategy to space

10 design an equivalent term to ‘polyvalency’ used in the Netherlands (Leupen, 2002). This allows the manipulating space through the intensive use of three dimensional space.

Thus, by anticipating change, design strategies based on the principles of systematization, overcapacity in design and the open plan building concepts seek to enhance the quality of buildings for sustainable infrastructure development. Among other things they contribute to:  value-added use – it accommodates changes in condition and needs during the life cycle of a building  ease of maintenance – it simplifies replacements and adaptations during use and enables the reuse of components and elements  economic efficiency of structural measures for renewal and change of use  enables operational decisions to be made in keeping with current state of knowledge  overall contributes to increased functional lifespan of buildings (Geiser, 2005).

In addition, they contribute to:  saving on scarce building resources and hence offer the potential to create affordable buildings  reduction in the volume of waste generated and sent to the waste stream  reduction in the impact of the building construction on environmental quality by minimizing atmospheric emissions such as CO2 and other GHGs

5.4 The Principle of Distributed Control

The benefits deriving from the design strategies above could further be optimized through what is referred to as distributed control - a principle which argues that decision on the attributes of a building should be shared between the designer and the end user (occupant) (Habraken, 2005; Turner, 1991). This is similar in perspective to the performance-based approach to building which posits that a building system’s design agenda as a whole, and the more specific design objectives of its parts, originates from relevant user requirements and must therefore be established by the relevant stakeholders (Szigeti and Davis, 2005). In essence therefore, the principle of distributed control involves users in the design decision-making process.

Habraken (1975) argued that “dwelling is building” and that no one can live satisfactorily in an environment in which they have no input. To enhance the quality of life of people in buildings it is important to adopt an approach which gives to the end user some control over the building. In another work he argues that ‘to build is to exercise power’ and that it is ‘only when users themselves exercise power by directly influencing or controlling a part of the physical environment can we expect healthy, vital and steadily improving environments’ (Habraken, 1980). This argument is both moral and pragmatic as Carroll and Rosson (2007) puts it. Morally, it is only reasonable to think that the people whose activity and experiences will ultimately be affected most directly by a design outcome have a substantive say in what that outcome is. Beyond this, it offers practical insight regarding the activity that the design will support, and most likely transform. The implication is that to make buildings more functional, user participation in design decision – making is crucial.

11 6. Summary The cumulative gains accruing from these principles and strategies in terms of the contributions to sustainable building performance is much reported, and particularly in developing countries. Studies in housing extensions and transformations in Ghana, Zimbabwe, Bangladesh and Egypt, found that not only do users seek opportunities to alter their dwellings but that creating possibilities for transformations in houses in particular contributes to increasing habitable space in terms of floor area and number of rooms, and consequently reduces occupancy rates without the need for new-builds (Tipple & Korboe, 1994; Tipple, 1996). In Hong Kong, the benefits of ‘Design for Tenant Fit-Out’, a design strategy which allows individual families not only to fine- tune layouts according to their specific needs, but to build incrementally according to their resource capabilities, is reported for mass public housing (Sulliven and Chen, 1997). Such an approach enhances functionality while being affordable. Similar contributions have been reported in Bangkok, where houses were actually designed to be transformable based on the requirements of users – being developed incrementally by the occupants (Yap & Wandeler, 2010). In the success story of the Million Houses Program in Sri Lanka, the design strategy and selection of the applied building technology was participatory. This resulted in houses which were cheaper and better suited to the needs of occupants (Sirivardana, 1986). The conclusion from these observations is that it is as important to integrate top-down design decisions with bottom-up user requirements. Thus, the design and engineering of building solutions must shift from design-centered, task-based approach to user-centered, needs focused solutions. As a design approach therefore, lifespan performance-based building concepts advocates for two key approaches as a way to respond to the functionality gap in the life of buildings. The first encompass strategies which anticipate changes and make provision by pre- configuring the building by design to respond to requirements such as replacement reconfiguration, and reuse. These principles include systematization, overcapacity in design and open space plan design. The second approach focuses on user requirements and leverages this through user participation in design. The two approaches are mutually interactive and reinforcing. These may be summarized as below.

12 Table 1: Summary of Lifespan-based Building Principles and Strategies

Principle Decision Level Strategies Characteristics

Discrete system Structure level - Support and Infill Anticipatory (systematization) - Shearing Layers - Open Building Solution –oriented - Slimbouwen - Design for disassembly Designer-centered

Overcapacity in System/component - Spatial Redundancy (double Design level height) Top-down - Overcapacity of structural members/service installations

-Multi-space Open Plan Space plan -Polyvalence Design Distributed User-designer -Participatory Design Participatory Control interface -Performance-based Building User-centred

Requirements-based

Bottom-up

6. Implications of the LBC for Building Infrastructure Development in Africa

The review shows by their strengths and merits, Lifespan-based Design strategies can contribute to the functional building performance in many practical ways. This however, has implications not only for building technology, but research and development as well as technology capacity building. The principle of systematization in design for example, makes implicit assumptions about industrialized building systems with its prefabrication of components through factory manufacture of materials and components, the rationalization and mechanization of the construction process as well as on-site assembly. This means a shift from the traditional labor- intensive and monolithic system of building construction, to standardization, modularization and prefabrication of components. For design, this means that the structural and sectional grid of building elements ideally coordinate so that they are fully interchangeable, without the need for significant transfer structures or uneconomically long spans. The morphology and dimensions of the building, its floor plate, structural grid, floor to floor height and fenestration modules are also thus suitable to support new uses. It also means that the overall flexibility of the design of building space is sufficient to allow for reconfiguration for new uses. For production and

13 management, it also has implications for the system of procurement adopted. Studies show that this can be achieved through greater integration of the design approach such that both designers and builders are able to see the whole building process through the eyes of each other (Adams, 1989). It also has implication for technology capacity building. Drewer (1980) points out that most developing countries lack the technology capacity needed to deliver the infrastructural projects necessary to support their socio-economic development in terms of size, novelty and complexity. This includes not only plant and machinery but human capacity in terms of the depth, relevance and quality of knowledge as well as skilled manpower required to apply technologies in both quantitative and qualitative terms. While open plan design solutions give a better sense of space particularly for larger households, it does not only reduce both visual and acoustic privacy, but that it also increases energy consumption (BRE, 1994). Increasing urbanization and modernization with its associated increase in individualization and sense of privacy, in addition to the concerns over energy conservation makes the open plan design a useful case for research as a design strategy. It also remains a subject of debate the extent to which adaptable or flexible design contributes to extra cost (Van der Voordt, 1990). Schneider and Till (2007) report an increase of 2% over the initial design cost. The problem for research then is to question the extent to which lifespan gains in designing for over-capacity for example, would balance out the extra cost of investment?

Conclusions The conclusion is that by its forward and backward linkages, infrastructure remains key to socio- economic development in Africa. Design principles and strategies which places use at the centre and hence focus on providing the capacity to change show promise as corner stone strategies for sustainable performance. The peculiar African socio-economic, cultural and technological context also means that there are differences in contextual factors which impact the extent to which these strategies can be deployed and applied for sustainable infrastructure development. This has immense implications not only for research and development in building technology but also technology capacity building. Filling the requisite gaps in knowledge while building the necessary technology capacity can help enhance the usefulness of these principles within the African context and hence contribute to sustainable building and infrastructure development.

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