conservation of building materials and the future of the built environment

Building uses a combination of

materials resources ranging from clay

to bronze. Some of these resources

are widely available, but require

substantial energy resources to

process and distribute them as the

volumes used are so great. Other

resources, like copper, are in much

smaller supply. The resources used in

building need to be examined against

the future resource limitations in

their supply and the possibilities of

recycling. The links between building

and waste cycles will also be critical,

as wastes from other processes can

often be incorporated into the

building process. Design for recycling

has to be balanced against the

advantages of design for longer life.

Reversible cementitious processes

could confer enormous advantages if

the reversibility was safely control-

lable, but this represents a very

formidable scientific problem. The

advantages of composite materials

need to be balanced against the

difficulties of effective recycling, for

example reinforced concrete. The

building as an energy conservation

device also needs more emphasis.

The final section deals with the

concept of the materials conserva-

tion city in a Utopian way. It is

designed to stimulate constructive

thinking about resource conserva-

tion and materials recycling.

Professor Page is Head of the Department of Building Science, University of

Sheffield, England

Conservation of building materials and the future of the built environment

J.K. Page

1. World construction scenario The construction industry is responsible for erecting, developing and maintaining the urban system which forms the habitat of man. The detailed design of buildings is especially dominated by problems set by enclosure against a relatively hostile climatic external environment and the consequent requirements for long life of building materials. The scale of the buildings produced is often very large and the number of separate units produced very extensive. The consequent demands for building materials are huge. The demands of the construction industry have led in all developed countries to the evolution of very complex chemical engineering industrial systems for the supply of the necessary materials, including large sections of industries of the scale of the brick, steel and cement industries. The future of the heavy chemical engineering industry, including steel, brick, aluminium, glass, plastics, cement, gypsum plaster and paint, among many others, is thus inextricably cross-linked with the future of the construction industry. The construction industry also provides an important challenge for the economic use of industrial wastes.

The construction industry has the responsibility for constructing the ‘tracks’ for urban transportation systems. This has recently been a very important growth sector in construction. Transportation, in this context, must be construed in the wider sense and not just as vehicular traffic, because mass transport flow systems like water supply, sewerage, oil pipe lines and so on must all be included. For example, the long term shortages of water in certain parts of the UK, identified by the Water Resources Board, will be met by long distance transfer of water involving a combination of rivers and aqueducts. The waste cycles in our economies, especially in relation to clean air and water, clearly need to be improved and developed, and substantial construction expenditure will be needed to create the necessary infrastructure for the control of air and especially water pollution.

We must clearly view the future of the construction industry firstly in terms of demand, because the construction industry is a

82 RESOURCES POLICY December 1974

Table 1. World population 1960-2000, millions*

Number Increase % Increase over 20 years

1960

2998

World

1980

4330 1442 47.2

2000

6129 1799 40.5

Developed areas

1960 1980 2000

976 1193 1441 219 248

22.2 20.8

Less developed areas

1960 1980 2000

2021 3136 4688 1115 1552 55.0 49.6

l Source: Macura, M. ‘Demographic

prospects for the next thirty years’, International Union for he Scientific Study of Population, International Popu- lation Conference, London, 7969, (pub-

service industry that attempts to meet, frequently unsuccessfully,

lished Liege, 1971) the various demands imposed on it by society, which result from various developments in human activities. Unlike many human demands, the demands are frequently necessary for a proper quality of human life. In a world of housing shortage one does not need to sell the idea of the need for housing to create a demand for housing. The construction industry meets a naturally existing demand. If we are to conserve building materials, we need to ask to what extent demand for construction can be reduced.

The most important world trend is clearly the upward population trend, which, in a pattern of time, first implies an instant demand for housing for the new young children; then a demand for the construction of educational and health facilities; next, a demand for industrial construction to create additional job opportunities; then, with rising prosperity, a demand for construction of leisure facilities; finally, a demand for construction of retirement facilities for the old. The resources to meet the needs of growing populations are not, unfortunately, generated in the same sequence, and the demand for adequate space on birth quite frequently simply cannot be met by the resources available to the parents and/or the community, especially in the developing world, as the population expansion figures in Table 1 show.

The quantity of new housing produced and the associated quality of the environment for the young and the old has always depended on the amount of resources available for construction from the actively working sections of the population. The balance between the size of the working population and the number of old and young people, especially young people, is always critical to the development of an acceptable living environment. Rapid expansions of population across the world are producing massive demands for construction resources on a scale which far exceeds the capacity of the world industry to meet such demands. Consequently, over extensive areas of the world, we have a crisis in urbanism, associated with increasing populations, poverty, lack of housing, and deteriorating general environmental standards in towns. The greatest construction challenge exists in the Third World. The steeper the population pyramid, the greater is the tragedy for the young likely to be, and the less likely is an adequate solution to the housing problem.

The second important world trend is the rising shortage of land. Construction activities have to be stably located on the surface of

RESOURCES POLICY December 1974 83

the earth and construction demands are accompanied by simultaneous demands for land resources on which to build. This demand cuts into available land resources and makes the land unavailable for other purposes (for example, growing food). The choice of the actual mode of construction is vitally dependent on the cost and availability of land on which to build. As the land resource becomes scarcer, one has to build higher and higher in the

gravitational field. This demands a greater and greater energy resource, both human and mechanical, for the construction process. A greater amount of materials is frequently needed per person housed, and less and less of the constructional space can be usefully used, as more and more has to go simply for access purposes. In housing, the high rise building solution also produces socially less acceptable dwellings at far greater construction costs than low rise development. In urbanism in general high building contributes to congestion and, through the over-concentration of energy using activities into limited areas, it leads on to adverse concentrations of atmospheric water and noise pollution at particular places. In turn this leads to pressures for suburbanisation, a resource-extravagant solution.

In view of the great imbalance between demand and resource generated by rapid population expansion, we only have two effective choices. One is to control the demand by reducing population growth to more acceptable limits. The other is to find more effective ways of meeting the demand than are used at present. The future of the construction industry will depend on the precise balance that can be struck between these two factors, which will vary greatly from one part of the world to the other. Developments in medicine and in the pharmaceutical industries which influence the birth rate and the death rate are thus critical to the future pattern of the world construction industry and hence to the demand for building materials. If we continue to fail to control world population expansion, the industry considered on a world basis will have to continue to move to lower and lower construction and environmental standards to meet the continuous pressure of the demand. It is difficult in a country of slowly rising standards to appreciate fully the present rate of deterioration of world housing standards. Implicit in the long term dynamic studies of the world economy are two alternative future scenarios for the construction industry. One scenario suggests that the rising construction standards of the developed world will spread across the third world. The other scenario predicts the pressures of the third world will spread over to the advanced countries. The latter appears the more likely outcome at the moment (Table 2).

Therefore, in considering the future of the construction materials industry, we must be very realistic, as the demands are so strong. One must, however, note that traditionally, due to the large volumes of materials needed for construction and the consequent high transportation costs of the relatively heavy materials used, the supply of building materials has always been primarily a national rather than an international matter. Many of the basic developments have been concerned with economic techniques for bonding together widely available inert materials like sand, stone and gravel, using cheap bonding materials like


l Source: Minerals data from US Bureau of Mines, (1963) from Hibbert, M.K., Table 2. Annual world production and consumption per capita of major mineral

‘Mineral resources and rates of consump- products, 1963”

tion’, World Pop Conf Vol 3 (UN, 1965) p319 World lndustrialised Non-industrialised

avelcapita areas areas consumption a-&capita avefcapita

kg kg consumption

kg

Pig iron Aluminium Portland cement

83.6 251 12 1.65 4.95 0.236

112 336 16

Table 3. Requirement for and annual production of important building materials in India (during the Fourth Five Year Plan 1969-74) after Mohan’

Requirement Estimated production

Material Non- Residential residential

construction Total

for Short- building falls

Bricks (x 106) 203 400 99 000 302 400 100 000 202 400

Cement (tonnes x 106) 53.0 62.0 115.3 17.3 98.1 Steel (tonnes x 106) 4.9 18.3 23.2 22.9 0.31 Timber (m3 x 106) 8.1 9.0 17.1 13.5 3.6

lime, or even using natural climatic energy resources like the sun, in the case of sun-dried bricks (a traditional fibre-reinforced composite material). Use can be made of biological techniques for harnessing natural energy resources, for example thatched roofs, bamboo reinforced mud walls, wattle and daub, etc. which all depend on photosynthesis.

The industrialisation of the manufacture of building materials has led on to the growth of massive industries like the cement industry, kiln fired brick industry and the gypsum industry. The manufacturing plants have become more complex, but the resources needed for development at such an advanced industrial level have tended to be far too costly for developing countries to afford enough capacity to meet their demand problem (see Table 2). A materials balance sheet for a typical developing country showing massive shortfalls was presented for India by Professor Mohan’ to the recent CIB Conference in Paris, and it illustrates this point well (Table 3). The gloomy balance between need and resource is all to evident, especially in the housing sector.

In developed countries this industrial pressure for materials resources for construction has led to rapid exploitation of mineral resources close to the larger centres of population and an ever-widening search for cheap mineral resources in suitable geological locations. The pressures on the sand and gravel beds and the limestone quarries have been immense. The benefits are experienced in the towns: the environmental pressures fall on the rural communities. The problems of the supply of high grade sands and gravels become yearly more acute in the UK, and we face a

’ Mohan, D. ‘Very low cost housing’, Proc major resource problem, as well as important environmental

5th C/B Congress Paris, (Research into planning issues. The scale of the UK building demand is illustrated Practice) (1973) pp 661-669 in Table 4, which gives materials production in 1959 and 1969.


Table 4. Building materials production in Great Britain, 1959 and 1969’

Building bricks Cement Building sand Concrete sand Gravel Asbestos cement (corrugated sheets) Gypsum Plaster Plasterboard Cast iron pipes and fittings Metal windows and casement doors: steel windows Aluminium windows Linoleum Rigid and semi- rigid tiles Carpets Paints and varnishes Timber: softwood deliveries

Unit 1959 1969 Ratio 1959:1969

x 106 6967 tonnes x 10” 12793 m3 x 10” 8393 m3 x 10” 12091 m3x103 24103

tonnes x lo3 tonnes x 1 O3 tonnes x 1 O3 m* x lo3 tonnes x 10’ (Cl equlv.)

375 353 419(1960) 0.94 1612 2855 2855(1969) 1.77

558 942 1015(1965) 1.68 43883 82837 8529811968) 1.89

142

tonnes 76894 44178 76894(1960) 0.57 tonnes 2356 7400 7531(1966) 3.14 m2 x 106 48.8 8.9 48.8(1959) 0.18

m2 x 106 m* x IO” litre x 106

16.6” 23.1 24.2(1968) _ 53.4 104.9 104.9(1969) 1.96

374.1 410.5 410.5(1969) 1.10

m3 x lo3 7432.2 8494.7 9355.8(1964l 1.14

6735 795411964) 0.97 17420 17870(1968) 1.36 11659 12198(1964) 1.39 20667 20715(1968) 1.71 38176 40345(1967) 1.58

70 142(1959) 0.49

Notes to Tab/e 4:’ data obtained from Annualabstractofstatistics (HMSO 1970); 2. The problems of building materials conservation *figures are for 1963. What openings are there for materials conservation in building if

demand for buildings on a world basis vastly exceeds the present rate of supply? Clearly, several alternative policies can be considered:

Alternative 1 - using less material One approach is clearly to attempt to use less materials to carry out the same task. This is a conventional materials science approach. It tends to lead to two main problems in construction:

1. The environmental performance characteristics of buildings constructed with less material are frequently less satisfactory than those of more conventional design, for example a building with thin walls tends to provide a poor level of acoustic insulation. It has little capacity to store heat. The temperature swings excessively as the sun comes in and out, and the neighbours disturb each other with their noise. Savings in materials at the expense of performance are seldom acceptable. 2. The adoption of materials like reinforced concrete, which is often the recommended solution, makes materials reclamation difficult. Composite materials are much less satisfactory from the point of view of recycling compared with single phase materials.

Alternative 2 - making materials last longer A second fundamental approach is to attempt to make new and existing building materials last a lot longer, either by designing for longer life in new buildings or by rehabilitating existing buildings to give them an extended life.

Rehabilitation of existing buildings for longer life has recently


been given a much higher priority in Europe, mainly on environmental, social and cultural grounds, because rebuilding has produced such a great upheaval. The expenditure on renovation of existing housing has recently exceeded the financial outlay on new housing in the UK. A policy of renewal avoids the destruction of existing buildings and so reduces the demand for basic building materials. It is, however, manpower-intensive. Such an approach cannot be of much immediate help on a world wide scale, however, simply because there is a vast overall shortage of existing building space. While long life is attractive as a concept in building design, it is often expensive in terms of initial outlay and, therefore, its immediate attractions in practice become far less in a world desperately short of resources right now. Realistic materials conservation policies based on longer material life demand that the longer life should be achieved at minimum increase in initial building costs. The materials science challenge is thus primarily one of finding economical solutions, rather than feasible solutions for longer life. Immediate cash flow is often more critical than long range discounted cash flow.

Alternative 3 - materials substitution A third approach that can be considered in resource conservation in building is to substitute less rare materials for more rare materials, or better still to substitute waste materials derived from other necessary industrial cycles in place of traditional building materials. Some successes have been achieved in this direction using wastes, including the use of slags from the steel industry for blocks, fly ash from the electricity generating industry to make light-weight blocks and burnt shale from coal mining tips as a fill for road construction. This area clearly deserves more exploration in the UK, both on materials conservation and on environmental grounds. The problems of minerals tipping in Yorkshire and Humberside in England are formidable, to say the least. The environmental effects of tipping are often severe and present many difficulties in economic planning. Waste cycles from biological processes also deserve attention, as well as waste cycles from industrial processes. Over 4% million tonnes of straw are burnt annually in England, mainly in the eastern wheat growing areas, producing very considerable atmospheric pollution and a lot of damage to trees and hedgerows. Thatched roofs made from wheat straw provide an example of an historic approach to the use of biological wastes for useful building purposes. Building boards made from bagasse (the spent waste of sugar cane) provide a more modern example. The potential of biological waste resources must not be overlooked.

Some materials traditionally used in buildings are likely to become both in increasingly short supply and far more expensive (for example, lead and copper). The most suitable substitute materials are often energy intensive in production, for example aluminium, so even though the ores are widely available, energy resource conservation considerations may restrict their production at economic prices.

In view of the large volume of materials needed in building, substitution studies need to be directed mainly towards materials

RESOURCES POLICY December 1974

that arc widely available, which do not need a lot of energy in their extraction and/or preparation and/or fabrication and preferably that do not cause a lot of environmental problems in their wjnning. This may mean a shift from considering the ‘technologically best’ raw materials, with their associated optimal properties, towards considering the most widely available raw materials and their available properties. For example, in concrete technology, the stress of resource supply is likely to be expressed in terms of substantial deterioration in aggregate quality. The important task ahead is, therefore. to learn how to make adequate concrete with less good raw materials, including suitable waste materials.

Atternative 4 - old materials won with new technologies The situation also points towards closer reconsideration of the technology of mineral extraction. Stone was once widely used. It is not used now, on economic grounds, except as an aggregate, bonded together with energy-extravagant cements and mortars. Is there a way forward based on alternative technologies of stone extraction and preparation which would be less energy extravagant than the present technologies, ie is there an alternative science of quarrying that could be cxploired cconomicaliy? Consider another example: mud was once widely used. both as a basic structural material and as an infill material -- for example wattle and daub. Correctly prepared, it had a long Iifc, as many medieval timber frame buildings infilled with this material still testify. A critical problem was waterproofing and traditional rendering mixes hased on lime and cow clung had very interesting surface properties for shedding water, which conferred successful protection. C‘ould we

revert to such low grade materials again? Research into materials based 011 waste cycles of other

industries clearIy should have 3 high priority. Substantial progress has already been made in this sphere in the f’ield ot’ concrete production.

Dr Gutt and his collcagues at the Building Research Establishment have reviewed the potential building IIS~S of industrial mineral wastes in the UK in some detail’. One problem is that the waslcs are often not available close to the actual poinls or de~nand. This reduces their value as substitutes for other materiais.

Alternatives to timber

2 Gutt, W., Nixon, P.J., Smith, M.A., Harrison. W.H. and RuaseH, A.D. ‘A survey of the tocations, disposal and prospective uses of the major industrial by-products and waste materials’, f3R.F CP 19/74, (BRE, Garston, Herts, 1974)

.4 critical area is clearly timber. which is rapidly becoming a relatively expensive mntcriaL Four main courses arc clearly open:

1. Development of a timber technology that cnrthles ;I grcatcr proportion of the nsturat timber resources to be utiIised for building, so that the parts of trees that would ll:tvc formerly bern rejected arc itlcorporated into composite iimhcr clemcnts in construction. 2. Development of a timber technology that demands Icss tirnher to do ;t given task. For example, a substantial reduction in the amount of timber used in roof systems etc. has already beon achieved. 3. The improvement of the durability of timber members, by


improved timber treatments, particularly to deal with biological decay. 4. The reclamation of timber from existing buildings being demolished. At current timber prices, it is becoming worthwhile to consider the reclamation of timber from demolition sites and its reprocessing by planing off and regrading.

The alternative approach is to consider the biological production process itself, and ask to what extent modern biology could improve the timber production process, for example by improved photosynthesis. At the moment we are living on reserves built up in the world’s forests over the past two centuries or more from solar energy. While timber has the advantage of being a renewable resource, the rate of growth is too slow to meet the current rate of growth of demand.

Natural resource chemical engineering cycles We also need to be asking ourselves whether or not there are chemical engineering processes that could be developed, based on natural energy resources, using, say, high energy photons from the sun to synthesise suitable chemical raw materials for building purposes, for example by using our advanced photochemical knowledge for useful chemical engineering purposes. The present practical yields in photosynthesis are perhaps one twentieth to one sixtieth of the theoretical photochemical yields, and the chemical engineering ‘farm’ for producing a plastics material equivalent to timber could eventually be far more efficient than our present techniques of forestry for producing building materials. We might be able to produce the same volume of material at a higher grade from one fiftieth of the land area.

The problem of recycling in building There are two fundamental approaches to the problem of recycling open in building:

1. To recycle the use of the spaces in the building, so the buildings have a long life, and the materials do not have to be renewed. 2. To recycle the materials used to build buildings, so the building materials are used several times over.

The first approach is normally the most economical approach. Building uses are constantly changing, and there is a great deal to be said for designing buildings so that they are adaptable. As Alex Gordon, past president of the RIBA, has pointed out, there is a vital link between long life and loose fit in buildings. Adaptability in buildings involves far more than the mechanical concept involving moving of partitions, etc. Decisions on basic room shape, floor to floor heights, building depth, floor loads, access, etc, all have a vital bearing on the range of uses to which a particular building can eventually be put. For example, squarish rooms are basically more flexible than narrow oblong rooms, and so on. The design problem therefore may not be to design the best building for its initial use, but to design the best building for the widest range of future uses over the longest possible life, though clearly the building must be satisfactory for its first use as well.

The materials science problems thrown up by this first approach


are primarily those of durability and the avoidance of high maintenance charges. Materials substitution must be viewed primarily from the point of view of durability and reliability if this approach is adopted. Long term energy conservation is also important, and the durable enclosing membranes need to have much better thermal and vapour control properties than the present materials. This involves more than just a matter of more thermal insulation, because radiant energy exchanges with the sun and the environment are so critical and thermal performance is strongly affected by the thermal storage characteristics of the structure. The right combinations of thermal insulation and thermal mass must be used, arranged in the correct patterns. and adequate control must be achieved of the water vapour regime, otherwise surface and interstitial condensation will result, frequently leading to short life as well as loss of thermal performance. The recycling of the materials of which buildings are constructed was practised in historic times, but more and more old building materials have simply been treated as useless wastes. Archaeology, in fact,- is largely successful as a science because of the human tendency to build on top of building wastes, rather than to recycle them. The enormous demands for building materials, however, suggest that a more critical look at the possibilities of recycling must be made. Unfortunately, every recent development in materials science applied to building appears to make recycling less possible. Composite structural materials are difficult to separate into their basic components. Coated sheet materials, like galvanised iron, are difficult to reprocess because of the surface metal contamination. Unit blocks like brick and fly ash are difficult to separate, because of the high bond strength of the cement used. High performance is basically achieved by combining the most useful properties of different materials and this makes it very difficult to separate them into their components afterwards. A building built with a cast iron frame or a steel frame could have the frame melted down and reprocessed for re-use. A reinforced concrete building presents a very much more formidable problem when it comes to recycling.

We therefore face a fundamental philosophical dilemma. If WC are to design for recycling, based on relatively short building life, we need an alternative design approach that allows economic reseparation of the components when the building is to be demolished. However, if we do this, we have to reject many of the advances of materials science that have depended on the combination of the properties of different materials into composite materials, on the assumption of a once and for all use. Perhaps we will need to consider which of our present building materials really represent world resources in short supply, and hence deserve dramatic conservation by total recycling, even at the expense of performance, say in the composite context, and which materials are likely to remain relatively plentiful and will not justify such a radical approach in design for recycling. It should be noted in this context that the electrical and communications services of buildings probably represent a key area, in view of the large amounts of copper at present used. It has also been an area of rapid growth and it is hard to see, given the world limitations


on copper supply, precisely how this electrical energy and communications supply problem will be solved in future. Clearly, aluminium could have a key role. Nevertheless, design for effective reclamation of electrical service systems may turn out to be very important, in view of the difficulties of finding effective substitutes for copper, especially for low loads, and the high energy costs of the substitute materials. This may imply giving a high priority to service systems, for complex buildings, that cm be withdrawn and reprocessed.

The advantages of reversible cementitious processes would be very great in building, provided the reversibility could be safely controlled, so that the loss of adhesion did not occur accidentally. This could enable resources like gravel and sand to be effectively recycled, and bricks and stone to be easily rc-used. Reversible cementitious processes, however, which could be safely controlled on a chosen timescale, are difficult to conceive scientifically and represent a very difficult challenge. However, difficult challenges sometimes stimulate radical new thinking. The scale of use of building materials is huge, and the substantial effort for re-use would be justified. Not being a materials scientist myself, I will not be so rash as to suggest how this might be achieved in practice. I do believe, however, it is an important potential research goal in building materials science.

3. The concept of the materials conservation city Architecture and planning are inextricably crosslinked. It is important, therefore, to ask how we might plan to produce a city effectively designed for materials conservation. Clearly this should be simultaneously an energy conservation city, as well as providing an effective information transfer complex. How then does city design actually affect material resources consumption‘? This question clearly resolves itself into two parts:

1. The effects of urban design on the material and energy resources needed to actually construct the city and its facilities. 2. The effects of urban design on the consumption of material and energy resources resulting from the various activities carried on in the city.

The first part is easier to answer than the second, though there are little properly evaluated data at present. Clearly, more compact building designs with appropriately related areas of wall, roof and window, constructed to appropriate thermal insulation standards, would conserve both energy and materials. Durable long-life building materials would have to be incorporated into suitably flexible building designs. In housing, compact terraced development would offer conservation by wall sharing, thus reducing materials and energy demands, but such buildings would have to be designed to high environmental standards, especially if noise was not to be troublesome. High rise buildings which are resource extravagant both in materials and energy would be rejected in favour of low rise compact development. The present suburban solution of detached houses and bungalows, which have adverse perimeter floor area ratios and consume excessive energy resources, would become unacceptable. A fundamental problem would be to select an appropriate urban density that balanced the


various factors correctly to give optimal resource conservation, ie not too dense and not too diffuse. The actual construction resource demands depend not only on the resources needed for the building structures themselves, but also on all the resources needed for the service infrastructure, which can be very extensive and costly, including roads, surface water drainage, foul water drainage, electricity and gas energy supply and telecommuni- cations systems. It follows that sensible design evaluation would have to be based on an overall systems approach.

Compactness would favour economic service distribution, give economic public transportation opportunities and reduce the demand for private transportation and the scale of the roads needed for it. Detailed study is likely to show substantial energy conservation advantages for compactness, as well as a saving in materials resources. The diffusiveness of suburbia represents a high resource response, because of the extremely high infrastructure costs to which it leads. It should be noted that infrastructure costs are usually not properly costed at present, and there is a need to use an overall urban systems approach, so the various payoffs and penalties are correctly identified. Infrastructure costs are usually treated as unavoidable overheads, insensitive to the basic building design decisions and are costed by average oncost value techniques. The infrastructure resource demands of different types of urban form thus need to be far more systematically explored on a collaborative intersystem basis to secure appropriate economy. Design for the bicycle would be given high priority, because of its very great energy and resource conservation advantages.

Critical attention would have to be given to the shape of the city. The circular city represents the most compact form, the linear city the most resource extravagant form. The travelling distances and infrastructure costs are both high for the linear city. The circular city form is, of course, the traditional form, and it retains its traditional advantages. High priority would need to be given to environmental planning and recreational facilities. The necessary interurban open land could conveniently be provided by wedge systems of open space running in from the countryside. The green wedge open space is the inverse concept to ribbon extension of urban development into the countryside. Such a policy retains both high urban compactness and economic servicing potential, and also convenient access to recreation facilities and to nature. Some open space at the centre of cities is most critical, as it is the most accessible. The linear city would be rejected as resource extravagant, and the isolated house fed from centralised services even more so. Highly serviced isolation is a very materials and resource extravagant mode of living.

The energy conservation techniques used would not only involve greatly improved insulation standards, but would also take advantage of total energy systems, using compound cycles as a normal part of the structure of urban energy servicing.

Integrated energy supply waste disposal systems would be evolved, linked with district heating schemes, energy and materials recovery. Appropriate use would be made of natural energy resource systems like solar energy and wind power.

The processing of solid waste products of utilities and industry


would be closely integrated with the overall urban building construction processes. For example, use of pozzolanic cements based on pulverised fuel ash (pfa) additives from electricity generation stations, building blocks made from slags, etc, would form part of an integrated approach to resource conservation and waste elimination that was crosslinked with economic industrial production. The aim would be to eliminate the majority of wastes by a systems approach that interlinked the production processes with the total urban system, so tackling environmental pollution due to wastes simultaneously with economic production and resource conservation by waste recycling.

Individual buildings would be designed to be flexible on a day-to-day basis, to enable high occupancy factors to be achieved. They would be occupied for different uses at different times of day by different groups to achieve economy of use, resource and energy, so reducing the overall amount of public building needed. The actual public buildings produced would have to be designed to higher standards, with facilities to make flexibility possible. With proper management, these could be operated outside the constraints of the petty control of the present divisive committee structure of the past local government system, which results in low load factors. Public buildings would thus be made to serve the whole community, rather than sections of it, and substantial resources would be saved. Agents of sub-sections in local government, like school caretakers, would be reorganised into a new general public service concerned with fuller utilisation of buildings, and there would be appropriate pay incentives for achieving a high degree of building usage to replace the policy of shutting the buildings as soon as possible after their specialist use is completed. This approach would save vast sums of public money, as well as substantial amounts of materials resources and energy.

Outdoor space associated with public buildings would become truly communal space, accessible to the whole community, and available at all seasons of the year on a properly managed basis. Land resources would be managed with a true sense of their value. Space sharing of public open space, at present sectionalised into separate school playing fields, parks, industrial sports complexes, etc, would enhance environmental facilities and give a much better return for the high level of investment of land than the present sectional policies allow, and would contribute to urban compactness, so substantially reducing the resources needed for the distribution infrastructure. The value of the school playing fields for a single urban school can run into millions of pounds. Work residence systems would be much more closely integrated for environmentally acceptable industries, so reducing long distance journeys to work. Certain industrial facilities might be shared with the community. Abolition of the rigid distinction between work place and residence would favour social interaction and encourage resource sharing.

Waste recycling systems would be fully integrated and their design would form a central part of the planning process. Adequate facilities for citizen participation in waste recycling would be incorporated by providing intelligently designed waste


collection facilities openly available to the public. The profits from these citizen participation waste recycling units could be developed to social purposes, like building old people’s facilities, subsidising theatres and youth enterprises, etc. Many people would derive considerable social pleasure from effective participation in waste recycling. The ‘sponsored charity recycle’ could replace the present somewhat pointless charity walk. It would make use of the principle of the ‘50 million Volunteers’ put forward in one of the reports of the UK delegation to the Stockholm Environmental Conference3. Citizens’ pride could become attached to the success of the urban recycling systems, and towns would rival one another to be ahead with recycling systems.

All this is, of course, a rapidly conceived personal viewpoint, ‘conceived deliberately in a somewhat Utopian form to stimulate critical discussion of the real practical courses open’. There are differing views of the future, some more optimistic and some more pessimistic. The Limits to Growth study4 predicted a serious crisis in a relatively short time. The study has been challenged from many directions, for example in the study by the Science Policy Research Unit of Sussex University’. While the author of this paper agrees much of the input data are not satisfactory, he still believes nevertheless that the crisis will arrive unless we alter our direction. The issue is one of ‘when’ rather than ‘if’. The materials conservation city concept is concerned with a change of direction to avoid crisis by directing demand into more sensible channels that are less dependent on energy and rare materials resources.

A key feature of the materials conservation city is, therefore, that it should offer a quality of life that provides social satisfaction without excessive resource consumption. It will be the quality of the social, cultural and environmental design which will determine whether people have a full and interesting life style, that does not need to be propped up by escaping into the fantasy of more goods for their own sake, and more travelling about for its own sake. The basic policy will be to use resources to secure a high quality of life, and not as a substitute for the quality of life. This involves deriving a credible concept of the aims of industry of the future in a resource limited world. The industrial pride of achievement which is based on sheer volume of production, linked with productivity and avoidance of unemployment, will have to be replaced by more effective alternative industrial concepts that accept the resource limitations, which we have yet to evolve. The choice of viewing the industrial future as an exponential projection of the industrial past is simply not open to us. This is the central problem which will not go away. So, crosslinked with

3 ‘50 Million Volunteers’, A report on the the evolution of the materials conservation city, we have the

role of voluntary organisations and youth problem of the redesign of industry to meet new and achievable in the environment, (HMSO, 1972) goals. It presents simultaneously a sociological and technological 4 Meadows, D.H., Meadows, D.L., Randers, J. and Behrens, W.W. ‘The limits

challenge.

to growth’, (Potomac Associates Book, The finest architectural building in the materials conservation

Earth Island Ltd. London, 1972) city should be the population and resource control citizens’ ’ Cole, H.S.D., Freeman, C., Jahoda, M. participation unit. This building would symbolise the concept on and Pavitt, K.L.R. ‘Thinking about the future: a critique of The Limits to

which the city was founded, advanced technology linked with

Growth’, (Chatto & Windus, for Sussex effective resource planning, imaginative social planning, a high University Press, 1973) level of cultural interaction, and a controlled population level.


conservation of building materials and the future of the built environment

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