Design parameters

Design parameters determine cost, design and risk trade-offs in a facility development regarding the physical and functional characteristics of a component, device, product or system that contribute to the design process (Business Dictionary 2011). They ‘allow the capacity for a range of appropriate uses beyond the specificity of its original use’ (Adaptable Futures 2009). However, the inter-dependencies between these parameters are becoming a complicated issue in designing buildings for potential adaptation. In a principal component analysis, Wilkinson et al (2010) explain that the relationship between design parameters is a complex issue in identifying the adaptable attributes of buildings. Thus, the identification of appropriate design parameters is required at an early design stage. These design parameters can be placed under physical (service and structure) and spatial categories.

Figure 5-8: Types of design parameters

Source: Adaptable Futures (2008)

Table 5-4 summarises the key literature on different design parameters for adaptability in buildings. The original design needs to identify the correct measures for these parameters when the building is designed for potential adaptations. For example, if a residential building is expected to be converted to offices in the future, the lower storey height of the residential building seems to be the main difficulty in facilitating office use. Therefore, the design requirement is to identify a reasonable storey height for both functions. This will minimise physical damage to the building and also reduce the cost of conversion. The inter-connections between these parameters can be seen: for example, an increase in storey height (spatial) requires subsequent alterations in structural loads, building height, vertical circulations and external façade. The golden rule in providing an adaptable building is to reduce the dependency between elements/components as much as possible (Aylward 1979).

Thus, it is important to identify the most influential design parameters for the previously discussed adaptable strategies, as possibilities for building changes are determined by technical parameters (Larssen and Bjorberg 2004).

Table 5-4: Design parameters for adaptability in buildings

Authors

Design parameters for adaptability in buildings

Floor to ceiling height/ Storey height Technical span Structural load Building orientation Space/Area/Volume for system zone Building height Building width Building size Floor plan Availability/Elevator/Vertical circulation Location/Site condition Floor systems/Raised floors HVAC system & distribution ICT service Plug & play elements/ Interchangeable components Ceiling zone/Soffit quality Organisation of space Separation of functions/ Decoupling Fire sprinkling changes/ Fire safety design Plan depth Structural design/Slabs External façade/Cladding design Acoustic/Noise insulations Physical access/System access flexibility/Proximity Interior walls (movable) Electricity supply Central corridors Inter-system interaction Intra-system interaction Internal layout/Layout predictability Flow Core design Partial/Phased demolition

Gann and Barlow (1996)          

Ratcliffe and Stubbs (1996) 

Keymer (2000)  

Heath (2001)    

Larssen and Bjorberg (2004)           

Arge (2005)           

Richter and Laubach (2005)      

Verweij and Poelman (2006)  

3DReid (2006)         

Gijsbers (2009)     

Rawlinson and Harrison (2009)          

7 3 1 1 3 1 3 1 1 3 2 3 5 3 2 3 1 2 4 4 6 3 1 6 2 1 1 2 1 2 1 1 1

The excess supply of built space will increase the rate at which redundant space needs to be converted to support new classes of use (Nutt 1997). A rising trend in building change of use and the macro level impacts are discussed in the literature (Nutt 2000, Kincaid 2002, Kronenburg 2007). In fact, the literature reveals that storey height, ceiling height, floor to ceiling height and floor to floor height are critical design parameters for building adaptations (Ratcliffe and Stubbs 1996, Heath 2001, Larssen and Bjorberg 2004, Arge 2005, Douglas 2005, 3DReid 2006, Gijsbers 2009, Rawlinson and Harrison 2009). Moreover, Douglas (2005) and 3DReid (2006) discuss the influence of storey height in building change of use scenarios whilst explaining the inter-dependencies between storey height and the other design parameters of technical span, design loads and total building height. In addition, Saari and Heikkila (2008 p.240) explain that the ‘long-term adaptability of old industrial properties has been particularly good thanks to high floor heights and long spans and their conversion to office and residential use has been possible and relevant in several recent construction projects’. Thus, priority is given to identifying the principal design parameters for potential conversions in buildings.

The literature argues that there are buildings with adaptable features; however, it is uncertain whether they fully match the performance of their new purpose-built facilities because of their restrictions as regards to layout and height (Douglas 2006). Gregory (2006) states it is significant that the buildings best suited to adaptation are those with the most generous ceiling heights. For example, ‘the inherent flexibility of many of the Georgian and Victorian domestic buildings has been very influential in the development of ideas of adaptability in new work, especially housing and industrial buildings’ (Farrell 1979 p.59). Moreover, Kincaid (2000 p.158) explains that ‘too much floor to floor clearance is wasteful in both the long term and short term; too little is always wasteful in the long term as use changes, and in the short term hostile to energy use and people’. These statements clearly explain the importance of floor to floor height/storey height in designing buildings for potential change of use.

In addition, Kaputsyan (1974 p.280) identifies storey height as a significant economic parameter whilst emphasising that the ‘economic level of mass-scale housing construction for a specific period is stimulated by the standard requirements, thus formulating such economic parameters as the upper limits of the floor space of flats, the height of a storey, the number of lifts and the like’. Hence, storey height was considered in this study to be a significant design/economic parameter for change of use in buildings. Higher storey heights increase the flexibility of buildings. Having identified the influence of ‘floor height/storey

height’ in building change of use, it is necessary to explain how this parameter could affect the economic considerations of buildings. Lau (2001) identifies ‘floor height/storey height’ as one of the marketable factors that clients/owners most often consider when buying or leasing a space. The next section explains the variety of policy issues that should be considered in the process of DFA.