In this month's engineering services cost model, we revisit museums and art galleries reviewing the current cost and specifications of services installations.
Britain's museums and art galleries are, along with schools and universities, an important national resource, playing an essential role in culture, research and education. They are also vital to national and international tourism and can play a key part in urban generation programmes. At a local level, cultural facilities such as museums contribute to the development of a cohesive identity for local communities as well as acting as catalysts for individual creativity and inspiration. They are also important revenue generators, with 100 million visitors per year creating, according to Treasury estimates a cultural economy worth in excess of £3 billion.

The existing museum and art gallery building stock is diverse in terms of size, function, form and condition. Funding is equally diverse, with some institutions receiving large grants from the Heritage Lottery Fund, with many others being dependent on support from a range public and private funding. A select number of institutions are directly funded by the Department for Culture, Media and Sport as national museums and galleries. Government spending on these so called sponsored museums and galleries for 2003-04 and 2004-05 is forecast at £283 million, rising to £296 million in 2005-06. In addition, the Government has committed to spending £70 million over the four years from 2002-03 in the development of regional museums and galleries.

Many museums and galleries are housed in large, historically significant buildings. By the early 1990s the cumulative effect of under funding had led to a severe crisis in the condition of the existing building stock and associated services. Despite the impact of capital funding from the Millennium and Heritage Lottery Funds, there continues to be a substantial backlog in the amount of work necessary to update buildings to meet modern operational standards. Accordingly, the vast majority of capital applications for funding are for works to existing buildings. Unless this investment is maintained, it will be difficult to achieve the Government's priority objective of increasing access to museums and galleries.

In order to attract greater numbers of visitors to museums and galleries in recent years, the nature of displays and exhibitions has changed from the hushed environment of a decade ago, to the increasing use of information technology and audio visual systems to produce interactive presentations with a wider appeal. Designs therefore need to be flexible enough to cope with future needs as the life of the building will exceed any exhibition fit out.

Environmental design Issues
Museums and art galleries are complex buildings housing multiple functions with varied requirements for environmental control and security. Approximately 50% of UK museums and galleries have some form of environmental control. The guidelines for the design of services installations to technical spaces are well established, with numerous case studies being available. However, there is a growing trend towards the adoption of principles of passive design which challenge the established approach to services design.

The current design standard is BS 5454: 2000, Recommendations for the storage and exhibition of archival documents, which provides guidance on the parameters for temperature and relative humidity. This latest revision places greater emphasis on the role of passive design and use of construction materials for the maintenance of stable environmental conditions, rather than a presumption in favour of air conditioning.

The degree of environmental control required in gallery and museum spaces will normally be determined by the nature of the exhibit. For most exhibits there is greater acceptance that the conditions can be varied in accordance with the behaviour of both the exhibit as well as the building. In developing an appropriate solution, there are four key environmental design parameters to consider:

  • Relative humidity – control of relative humidity can be crucial to the sensitivity of some objects and the potential for fluctuation in occupied gallery or museum space. High relative humidity encourages mould growth in organic materials or corrosion of metals, or changes in physical size such as the expansion of wood. Low relative humidity can cause shrinkage or brittleness in some materials. Rapidly fluctuating relative humidity can therefore cause damaging cycles of expansion or contraction, particularly in objects of mixed materials with differential rates of movement. Tight control, within +/- 5% or even less, together with the maintenance of stable temperatures over long periods, requires dedicated mechanical plant in conjunction with associated controls.

    Controlling the rate of change in conditions that objects experience may be more important than tight control for its own sake, and many objects will achieve equilibrium with their surroundings even when conditions are not ideal in terms of published recommendations. Slow fluctuations with broader bands are more likely to be achieved by passive means, such as building mass and the use of porous finishes, and are preferable to smaller fluctuations over a short period.

  • Air quality – objects may be vulnerable to damage from particulate or gaseous pollutants from sources within or outside the building. The efficiency of removal of these particles will depend on the location and type of exhibit. Gaseous pollutants include sulphur dioxide, nitrogen dioxide and ozone, which through chemical reactions can attack objects. Particulates attach themselves to surfaces of materials to form a layer which, if not itself damaging, can cause damage when cleaning. In the case of paper and parchment BS 5454: 2000 recommends the use of a coarse filter to G3 of BS EN 779: 1993 together with a fine filter to F7 of BS EN 779: 1993 for dust collection. Activated carbon filtration should be used where concentrations of sulphur dioxide and/or nitrous oxide are in excess of 10 mg/m3.

  • Lighting – most objects may be vulnerable to damage from exposure to light. The maximum illuminance for most light sensitive materials, such as textiles and prints is generally accepted as 50 lux. Levels up to a maximum of 200 lux are generally accepted for moderately sensitive items, such as oil paintings and wood, and up to 300 lux for areas containing non-sensitive material, such as glass and ceramics. A balance must be struck between lighting levels for good viewing and the conservation needs of the exhibits.

    The effects of exposure are cumulative, and so the risk of damage can be minimised by reducing the length of exposure to visible light and by screening from ultraviolet radiation. The widely reported figure for the maximum ultraviolet content of light sources, 75 mW/lumen, has been widely challenged and it is considered good practice to keep levels to a minimum. Ultraviolet filter films or interlayers to laminated glass should be used on all external windows. In display areas, all luminaires that emit UV should be fitted with filters or secondary sheeting.

  • Temperature – many objects are tolerant to changes in temperature within the typical range for human comfort (18-25°C), provided they are not subject to rapid fluctuations or exposed to direct sources of heat, which can cause localised dryness. Specification of lower temperatures in storage spaces can also aid conservation by slowing down the speed of any chemical reaction.

    Security
    Security arrangements are an important consideration in museums and galleries. The greatest threat to collections is fire and water damage from leaks and flooding etc. Theft is normally targetted on specific objects so seldom causes widespread damage.

    An automatic fire detection and alarm system covering all parts of the building is normally provided, with infrared detection being incorporated in large volume spaces. The use of fire suppression systems should be approved by the fire authority and insurer, however for maximum protection an automatic suppression system should be considered, designed to cause minimum damage to objects. Gas systems are only recommended for discrete spaces that can be made airtight.

    For water based sprinkler systems, the pre-action type may be considered for reducing the risk of inadvertent sprinkler discharge at the expense of a delay in operation. Provision should be made for rapid drainage from all protected spaces.

    The security measures adopted to prevent damage or theft and secure the building when closed, depend on the assessed risks associated with the particular building. An intruder detection and alarm system should be provided to the perimeter and possibly the internal spaces, together with cctv covering the building exterior and again possibly selected internal spaces. A security and swipe card access control system will generally be required to access private areas Principles of passive design
    With the move away from air conditioning and the adoption of more passive design techniques and simplified control systems, the following issues are typical of those that are now being addressed, to maintain stable environmental conditions:

    • The acceptance that conditions need not necessarily be controlled tightly, and that environmental control ranges may be allowed to change with the seasons.

    • Use of an airtight structure with high thermal inertia, to provide inherently more stable internal conditions all year round.

    • Basing the decision to install air conditioning on evidence of real need, assessed against the type of exhibit, human comfort criteria, the exhibitions policy of the institution, life cycle cost analyses and environmental sustainability.

    • A detailed assessment of the levels of control actually required in the separate areas of the building.

    • Consideration of curatorial policy to enable the grouping of vulnerable objects together, with the provision of local control, and/or zoning of the building according to variations in environmental requirements of different exhibits and functions.

    • Use of microclimates such as showcases for sensitive or vulnerable objects to provide stable conditions within small volumes.

    • Use of an effective daylight control strategy that maximises the use of natural light, within the constraints imposed by the conservation needs of exhibits.

    • Consideration of the use of the naturally occurring processes of surface deposition of pollutants on surfaces such as walls, floors and ceilings, significantly reducing the need for active pollution control.

    • Use of buffer zones (air lobbies) to reduce uncontrolled air exchanges.

    • Provision and management of cloakroom facilities to keep wet garments out of galleries to minimise the need for dehumidification within museum areas.

    • Provision of control of ventilation rates in accordance with monitored pollutant concentrations and/or occupancy levels in order to minimise energy consumption.

    • Extraction of air at source from areas where polluting activities take place, such as kitchens etc.

    Cost model

    The cost model is based on the analysis of a new wing to an existing gallery in the South of England. The new wing is split over two levels with a gross floor area of 1630 m2. The lower level comprises the main entrance and shop, toilets, meeting room and library, restaurant and kitchen. The upper level comprises a multipurpose space combining the functions of a gallery and lecture room, a series of dedicated gallery spaces, and a prints and drawings display room.

    The base load lthw and chw is produced by a heat pump unit with separate gas fired boiler and air cooled chiller plant supplementing the heat pump duty to produce the required building load. The ground is used as a heat sink, with pipework routed to the piles underneath the structural slab. Project parameters

    • Procurement: single stage with quantified bill of quantities

    • Main contract: JCT 1998, private with quantities, with contractor’s design portion for the m&e services

    • Basis of tender: specification and drawings

    • Overall contract period: 67 weeks

    • Value of services (excluding lifts): £926,000

    • Main design parameters

    Thermal conditions – external
    Winter: -3°C 100% rh
    Summer: 28°C db, 20°C wb
    Thermal conditions –internal
    Refer to table 1 for details

  • Cooling systems
    Chilled water: primary 6°C flow, 12°C return; secondary 7°C flow, 13°C return

  • Heating systems
    Low temperature hot water: primary 50°C flow, 40°C return; secondary 50°C flow, 40°C return

  • Electrical supply
    400 V, three phase with separate cpc

    • Source

    Building Sustainable Design

    Related files/tables