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Article Excerpt
Abstract: This work investigated the degrees to which energy use in laboratory buildings may be influenced by interior space planning and/or the ways space is used. The potential influences of typical open, mixed and closed plan layouts and their space utilisation densities/intensities were investigated on a good-practice base case using the TAS, Lightscape and Excel software packages. The peak winter results indicated variations (potential savings) generally within a range of 40% (i.e., +20% of the respective base cases loads) except for the effect of open vs closed plans, which resulted in a variation of 73%. The summer load variations are within 50% across the open, mixed and closed layouts, and 84% across different closed plan layouts. These results indicate that the different ways in which users, activities and systems are organised against space-to-space environmental diversity are significant determinants of the energy performance of laboratories and perhaps other building types.
Keywords: Air-conditioning, Energy efficiency, Laboratories, Lighting, Simulation, Space planning, Ventilation
Introduction
There is evidence for the existence of inconsistencies between the environmental objectives at the design stage of buildings and/or specification of systems on one hand, and the ways the buildings end up being fitted and/or occupied on the alterations. The main reasons for this have been identified as frequent changes in space use patterns and the lack of continuity between the design objectives of building designers and interior planners, and those of users (Fernandez, 2003). While pointing out how occupancy patterns have frequently been ignored despite the obvious significance of programmatic issues, Steemers and Steane (2004) argue that buildings are hardly finished without their inhabitants and the activities that they pursue inside or around them. Examples of buildings that experience frequent changes include offices and laboratories. This paper focuses on the latter.
Many laboratory building shells continue to be long-term entities, while their interiors experience numerous shorter-term changes to accommodate organisational changes. The focus of research is changing all the time and buildings must allow for reasonable change. Many private research companies make physical changes to an average of 25% of their labs each year while most academic laboratories change 5 to 10% of their layouts (Watch & Tolat, 2007). According to Yakren and Bolin (2004), laboratory space organisation tends to obsolescence after 10-12 years as programme and research requirements change. While layout changes may defeat the original energy strategy, they may also provide opportunities for implementing energy efficiency measures where there is inefficiency.
In addition to experiencing frequent changes, laboratories tend to be high energy users (Ruys, 1990). The energy needed to heat, cool or move air for their typically high ventilation rates is 5 to 10 times greater than that used in most offices for these purposes (US DOE/EPA-LABS21, 2003). According to Watch (2001) and Federspiel, Zang and Arens (2001), a typical laboratory uses five times the amount of energy a typical office building of comparable size uses. Ventilation energy use is particularly high in laboratories with potentially hazardous or unsafe workplaces. Even in cases where useful heat is recovered, fan energy is still needed to move the large volumes of air, especially in exhaust fans (Wang & Liu, 2005).
Space planning in laboratories is traditionally considered in terms of the internal communication and relationships between the three main spaces--labs, lab support spaces, and lab offices (Cooper, 1994). Services occupy substantial space and their location may influence the relationships between the three principal spaces. Administrative offices, staff support spaces, and auxiliary spaces do not have to have a direct relationship with the three principal spaces. There are two main laboratory layout types--the traditional closed (cellular) lab and the more recent open plan lab. In a mixed layout type, individual closed lab users can directly access a larger, shared open lab (see Figure 2, later in the paper). Within these main layout types, there are many variations.
What are the potential links between the layout types and energy use? Since laboratories, lab support spaces and offices have diverse environmental requirements, layout types may influence the effectiveness of zoning and systems control. Layouts may also influence user environmental expectations, preferences and behaviour. These issues may consequently influence energy use. Open layouts for example, have comparably less space ownership and users therefore have less responsibility on the operation of controls. User tolerance for variations in indoor environmental conditions is expected to be higher in the closed layouts where they have more control and space ownership than in open layouts. Demand control and local exhaustion of hazards are also likely to depend on layouts. Open layouts, for example, may call for environmental conditioning of the whole space even when under-occupied. If energy consumption per occupant is taken into consideration, as opposed to the more conventional metric of energy use per square metre, homogeneous conditioning of under-occupied spaces potentially leads to inefficiency. Unrestricted circulation of users through unoccupied spaces is likely to reduce the effectiveness of presence controls more in open than closed layouts. Another important consideration is whether spaces are planned to prioritise the utilisation of their passive zone potential when under-occupied and whether they have opportunities for physical adaptation byway of occupants moving to alternative subspaces. Such opportunities are likely to be more in open layouts than closed ones since the former typically are less owned.
Regarding activity location, the different schools of thought of locating lab offices or write-up spaces result in different activity adjacencies and potentially different implications on energy use. They may be located within the lab, adjoining the lab, on the opposite side of the corridor or grouped in a separate part of the building. Activity orientation may also influence energy expenditure since the various activities require different environmental conditions and plan depths. The activities also constitute different proportions of the aggregate space. Sometimes the requirements for functional adjacencies may conflict with planning strategies for energy saving. One case is the location of shared support spaces, which are often on central non-passive zones to facilitate sharing, yet they may be the most intensely used spaces and could benefit more from daylight and natural ventilation if located on the periphery. The competition for peripheral walls if the designer has to provide views and daylighting to the three key spaces, and the effect of vertical distribution of spaces on achieving this may influence energy use. One approach is to create a mezzanine floor on one side of the plan for the lab offices and have lab support spaces below them, while the other side takes labs with an interstitial space above.
It has been found from previous research (Ferguson, 1973), that the configuration and proportion of circulation space in laboratories may also influence energy use. Single, two or three corridor configurations significantly affect activity relationships and determine the overall depth of the building. The single corridor,...
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