The Egan Report recommends that the uk construction industry should adopt lean thinking as a means of sustaining performance improvement. This recommendation, like the others which have been examined in previous articles (aj 18.11.99, 13.1.00), is relevant to the design and construction of the few buildings which have fixed forms and fixed finishes.
This article explains why agile thinking is far more relevant to the design and construction of most buildings. Further, the need for both lean and agil production systems to be compatible with the design characteristics of a product are discussed.
In conclusion, it is suggested that architects are uniquely placed to improve the overall performance of the construction process by making building designs compatible with building production systems, and considering this at an early design stage. It is proposed that architects, trade contractors and suppliers need to work together to develop a comprehensive classification of production systems and techniques which is linked to a universal product model for buildings.
The Egan Report recommends that the uk construction industry should adopt lean thinking. In the manufacturing industry, lean thinking is applied in the production of standard and custom products, such as cars, but agile thinking is applied in the production of less standardised products. The table below is an updated product model, which shows how different levels of standardisation relate to different categories of building designs.
Buildings designed using only standard components and standard component connections are categorised as 'standard'. Those comprising standard components up to assembly level are categorised as 'custom'. Buildings using standard sub-assemblies with bespoke interfaces are categorised as 'hybrid'. Building designs which cannot be standardised above the level of loose parts and materials are categorised as 'bespoke'.
Many new buildings cannot be standardised above category 2 (hybrid) because, in order to satisfy location-specific constraints such as irregular boundaries and planning restrictions, standard sub-assemblies have to be installed with bespoke interfaces and/or be finished. Building refurbishments also cannot be standardised above category 2, because bespoke interfaces are the only means of achieving a coherent appearance between new components and the existing structure and fabric.
Even designing buildings which are standardised up to category 2 is extremely difficult for architects, because they are employed by customers who require increased levels of functionality from each new building and building refurbishment. This means architects have to specify the latest high performance components and try to combine these effectively with more well-established materials and parts. Consequently, because of the increasing speed and number of new component introductions, the design details for each new building will almost inevitably be different from those of the last building designed. The table opposite shows the different types of production systems which are compatible with different categories of building designs.
Lean thinking evolved from mass production where high volumes and low variety resulted in economies of scale. Its aim is to minimise the time from placing an order to receiving payment. Lean production applies the advantages of flowline to batch environments. Reduced set-up times and batch sizes are used to harmonise flow throughout the supply chain. Lean supply chains are characterised by comparative rigidity, achieved over time by a process of partnering. Agile thinking evolved from mass customisation where high volumes and increased variety resulted in economies of scope. Its aim is to minimise the time from establishing a concept to receiving payment. In agile production, project and jobbing processes are used to manufacture products which have uncertain specifications. Agile supply chains are rapidly reconfigured to meet customer requirements. In the manufacturing industry, agile production has developed as a deliberate competitive response to the shift in marketing dynamics from product driven markets to consumer driven markets.
Although lean thinking can provide increased and improved production capacity, in the manufacturing industry it has been recognised that customers buy the most attractive products rather than buy from the most productive factories. Consequently, product manufacturers are trying to provide more flexible product ranges which adapt to market needs, and their designers are having to focus on satisfying customer requirements rather than developing a self-defined product range. To achieve this, they are using agile thinking to reconfigure increased resources, rather than lean thinking to minimise resources.
Match method and design The Egan Report's recommendation. that the construction industry adopt lean thinking is paradoxical. It has been made at a time when the manufacturing industry is adopting agile project and jobbing processes similar to those which are already used in the uk construction industry. Both lean and agile production systems have their own merits, but for either to be effective they must be compatible with the design characteristics of the products which are to be supplied. When a production system is not compatible with the design characteristics, it is very hard work to produce an improved product in less time and at lower cost. Lean production systems are most compatible with repeat products with certain component parameters and configuration options. However, as shown in in the table above, where design is customer-led and location-specific, component parameters and configurations remain uncertain from one order to the next.
Architects are an integral part of both the demand and the supply chain for buildings. Consequently, they are uniquely placed to improve the performance of the construction process by making building designs compatible with building production systems. However, to make this possible, architects, trade contractors and suppliers need to work together to develop a comprehensive classification of production systems and techniques which is linked to a universal product model for buildings.
Stephen Fox is with the Barlow Group, Sheffield. Professor Graham Cockerham is professor of engineering design at Sheffield Hallam University