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Theme: cladding and curtain walling

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There needs to be a rational relationship between the way buildings are designed and the construction products that manufacturers produce

This year's International Conference on Building Envelope Systems and Technologies (ICBEST) 1 held in Sydney, Australia, was billed '? the leading international forum for the exchange of information and discussion of recent developments in building envelope design'. For three days, delegates considered a number of themes:

advanced materials and systems for the 21st century;

the impact of globalisation on facade design and procurement;

exploring the relationship between design life, property investment cycles and maintaining the integrity of the urban fabric; and l new dimensions for sustainability - getting it right first time.

1This is only sensible. Materials and systems are advancing to new levels of performance and architectural potential. They can be procured from all manner of established and rapidly emerging markets, and invariably claim to further the cause of sustainability in various (and quite often spurious) ways. It is also important to consider how regeneration is funded to be technically adequate over time.

And the discussions clearly did not stop there.

However, all the discussion about 'buildingenvelope design' is just a further reminder that this used to be part of the practice of architectural design. Like facade engineering, building envelope design may be considered a new professional role for specialists, created from precisely those trends that ICBEST aims to address. But that may be too presumptuous.

In October 2003, the Chartered Institution of Services Engineers simply established a Society of Facade Engineers, 2 arguing accurately that: 'Until recently, the technical design and execution of building facades has largely been a process established from the application of empirical techniques. With the implementation of new more onerous regulations, the design of facades must be part of a holistic strategy. In particular, science needs to be carefully considered to deal with, for example, facade performance and energy conservation in particular.' 3Indeed, we are seeing the drive for increased performance of facades continuing. Part L of the Building Regulations is due for update in 2005 and again in 2010, and will require advances in thermal performance if the current aesthetic is to be maintained. But simultaneously, some glass atria facades may become a feature of the past - not the future.

For example, the replacement of the original vault and dome of London's Hurlingham club, destroyed in the Second World War, follows the geometry and detailing of the original 'greenhouse' technology used.

Yet in spite of these demands, the architectural profession endeavours to retain a 'holistic' approach to design. Architects today are not happy to leave aesthetics aside and allow new consultants in facade engineering (generally walls but no roof) or envelope design (everything between inside and outside) to reduce architecture to the exaggerated technical 'difficulty' of reconciling the Building Regulations with a planning-approved 'design intent'. True, many architects have become focused on energy conservation in the pursuit of sustainability.

However, that does not necessarily mean they have abandoned the look and construction of architecture to the extent that structure, services, planning, cost control and project management have become the responsibility of other professionals.

Critical moment Speaking at ICBEST 2004, Steven Ledbetter, the director of the Centre for Window and Cladding Technology (CWCT) - since the 1980s a common point of reference for all construction industry professionals - noted that architectural practice has arrived at a critical moment: 'Today the mobility of materials and the desire to put form and image before function has led to a wide range of cladding solutions in every location.' 4Ledbetter recognised that many buildings are clad with a variety of systems abutting one another at interfaces that are designed as though they were a novel problem. He also noted that most cladding systems are layered constructions which are frequently misunderstood. Given these less than rational scenarios to three-dimensional problems, it is hardly surprising that errors are made.

Ledbetter argued that, at the very least, there needs to be greater clarity in specifications, and to that end suggested a basis for the classification of facades.

His observation is worth unpacking.

Mobility of materials is obviously not new.

However, the scale and dimension of international trade in construction materials, components, systems, and assemblies - now moving into volumetric construction - is unprecedented and increasing. Construction products from emerging markets such as China, India and the 10 countries that have newly joined the European Union (EU) are coming onto the British market rapidly.

Glass units are being manufactured in Dubai for installation in the UK, and complete cladding systems are soon to be imported by Yuanda Aluminium Group from China to the UK and Europe.

Popular prejudice would have it that this is due to the cheapness of labour, with Poland the poorest nation in the expanded EU.

5 However, high technical competence, ambitious benchmarks, strong innovation, confident investment in productive capacity, and the demonstrable quality of materials, all make construction-product manufacturing far more competitive in these countries.

British contractors and product manufacturers are rapidly beginning to realise that they either need to improve their product and service to compete, or, failing that, procure directly from abroad to become importers and suppliers. Some at least are recognising this, and are beginning to install unitisation capacity in curtain walling manufacture.

Differences in regulation have always presented one of the greatest challenges for those exploring new markets. It is important not only to understand the regulations, but also to understand the reasoning behind them, and the culture of enforcement. The EU has attempted, with some success, to resolve these issues, but increasingly it is finding that historically different national approaches represent a sensible technical approach to local conditions (climate, aesthetics and commercial conventions) and may remain in place. The architectural-stone sector, engaged in extraction, processing and construction, is a notorious case in point. Grasping the implications in the tension between regulatory harmonisation and habitual practices will no doubt be the challenge for regulators and specifiers for some time.

So more than ever caveat emptor - 'Let the buyer beware' - must be the response to construction product mobility. This is not a presumption against the foreign manufacturers, which may have developed its product for the home market only to have it imported by others, but a warning to the professional acting for clients, who must understand the changing demands of their own society.

Form before function Far more than choice, it is the architect's own '?desire to put form and image before function', as Ledbetter puts it. Function may be taken narrowly as the performance of the construction product, or be considered more architecturally as the building's functionality. If we take the broader meaning, it is clear that decades after the biting criticism of architectural historians like Reyner Banham, 6 when advances in building services posed a new challenge to architectural design theory, most practitioners no longer believe Louis Sullivan's 'empty jingle' of 1896 that 'form follows function'.

7Frank Lloyd Wright's attempted recovery of his mentor's functionalist dictum led to 'form and function are one', which unhelpfully insisted that '? form is predicated by function but, so far as poetic imagination can go with it without destruction, transcends it'.

8 But today the poetry of architecture has taken over.

Mies van der Rohe's claim that 'less is more' is considered the essence of midtwentieth-century architecture.

9 But 'more is more' applies more accurately to those interested in image and form, those who make the most of aesthetic and technical freedoms in an international market, while 'less is less' for architects pursuing sustainability, as they eschew such experimentation, resource use and mobility.

Expressionism is everywhere, but frequently untheorised as a style. 'Architects don't like to talk about style', observes Witold Rybczynski in his insightful The Look of Architecture. They tend to '? prefer to talk about massing and space, or context and historical allusions, or - if they are prone to academic jargon - about 'tectonics' and 'materiality'.

In other words, although architects are willing to accept the notion that buildings embody ideas, they don't like to acknowledge the manner in which these ideas are expressed.' 10 Rybczynski is referring to architects practising at the start of the 21st century in America. But the point is equally well made with reference to Britain today, and would also apply equally well to the planning profession.

The reluctance to develop and articulate a theoretical precision - the refusal to formulate architectural style - also causes acute problems for product manufacturers. They must produce materials, components, systems and assemblies that, as well as achieving ever more demanding performances, architects will specify and planners will accept. If designers are not predictable in their demand for products, how can manufacturers plan and consolidate their vitally important research and development (R&D) expenditure?

Architects have at their disposal the best (and the worst) construction products there have ever been.

11 They enjoy the results of industrial advances and increasing international trade, but construction product R&D is only weakly connected to the design process by customer feedback, deliberate market research and trade associations.

12 Moreover, if the architectural selection of construction products is reduced to simply choosing adequately performing technology within a budget from catalogues or the Internet without regard for style, what is the future for designers?

13 All in the detail Ideas about the subtleties of aesthetic expression, or urbanism, should have a direct relationship to the means by which the architecture, or the place, is to be produced. The concept should be carried through to the detail, with detailing informed by architectural ideas, and perhaps by the enlightened ideas of old masters (rather than the aesthetics they advocated). As Andrea Palladio observed:

'Beauty will result from the form and correspondence of the whole, with respect to the several parts, of the parts with regard to each other, and of these again to the whole; that the structure may appear an entire and complete body, wherein each member agrees with the other, and all necessary to compose what you intend to form.'

Architects appreciate the problem because they have a constant battle to find what they want. Salesmen constantly offer products that designers like but 'with a few modifications please'. However, most project budgets do not extend to bespoke product development.

The CWCT test regimes try to overcome this problem on a project-by-project basis, but can only be afforded on larger projects, and rarely cover all interfaces if the architecture is complex. Yet at no stage do all parties collaborate to theorise their way out of this predicament through style, allowing R&D to transcend individual projects.

There is no possibility of escaping the need for theory in the supposed certainties of 'traditional construction'. Rybczynski shows how architectural style gives way to appearance, using the example of American Neo-Colonial housing.

15 The white-boarded timber frame was popularised about the Independence centenary celebrations of 1876, and remained the pre-eminent domestic fashion until the 1940s. The style enjoys a renaissance today as an expression of New Urbanist respectability and conformity.

16 The clapboard siding may be aluminium or uPVC, the columns polystyrene or fibre-glass, and the shutters stamped metal symbols rather than functional.

Nor need we imagine there are such things as 'honest' materials. Architecture and construction contain no inherent morality, and those materials often cited for their honesty are frequently the most complex (and so judged 'false') in their usage. Eiffel produced a glass facade to the retail building on Churchill Place at Canary Wharf that allows no light through, and has a matt surface. Since Louis Sullivan struggled to rationalise architecturally the technological advances of structural engineering, traditional 'stonework' is nearly always only a single-skin thick, backed by brickwork that relies on a steel or concrete frame.

Most brick construction is now highly dependent on stainless steel, reduced to a facing on timber and steel frames, embedded in precast concrete, or fixed as slips on corrugated steel panels. That process ends in moulding and printing technologies replacing the brickwork entirely on the panel substrate.

This has already occurred in the replacement of natural stone with porcelain ceramics such as the Ston-ker range from Porcelanosa.

Here the printing techniques produce multiple surface variants on a through-coloured substrate. From this point, the cladding may more interestingly move to a changeable digital display, as Martin Pawley predicted, 17 as soon as it becomes affordable.

Even glass (how can something so transparent lie? ) usually has ultra-thin multi-layered metallic coatings, frequently contains plastic interlayers, an inert gas cavity, and relies on butyl and silicone to hold the whole assembly together. Without Ethylene-Propylene-Diene Monomer (EPDM), even the most sophisticated of glazing systems would not interface with other construction products to meet current performance expectations, but rubber sheet cannot possibly be the last word in detailing for the rest of time.

Similarly, in another attempt to attribute moral certainty to technological selection, the question 'Is this product sustainable?' seeks to restrict the potential for architectural expression to a naturalistic perspective. This is sometimes a response to the complexity of composite construction. Yet which product is not either 'natural' or 'kind to nature' these days? We really want materials with reasonably predictable properties that resist natural forces.

Vast amounts of money are spent on 'proving' the virtues of construction materials and products. It is rather the sophistication and better interfacing of composite construction that should, and often does, sensibly occupy us in the technically precise way that Ledbetter recommends. The German architect Cristoph Ingenhoven poses the choice in his book Energies: 'We have only two alternatives in the matter of building. We can fake the past, or we can industrialise the future. The first is impossible because the past cannot be built again - certainly not when traditional craftsmanship is all but extinct. But, by the same token, industrialising the future will only work if we are able to attain a precision and complexity at least as impressive as what was achieved by the trained craftsmen of the past.'

To appreciate the past while moving beyond it to improve composite construction performance is, indeed, the challenge for architects and their facade engineers.

Fakery in architecture is often commonplace, and many facade technologies are available that attain technical precision and complexity. But so many fail in the end to achieve any aesthetic subtlety, and none are produced with an architectural theory of style in mind. That needs to change.

There needs to be a rational relationship between the way buildings are designed and the products that manufacturers produce, so that the construction industry can generate contemporary styles around the completeness of architectural production.

Will Stevens is director of Whitbybird's facade engineering division

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