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Introduction

Art galleries and museums are, collectively, one of the most popular visitor attractions in the UK. The widespread use of information technology, and the increasing popularity of interactive exhibits is leading to the development of a new generation of galleries, whilst in more traditional institutions, the requirements for the conservation of fragile artefacts create complex environmental control problems.

As with other sectors of the arts world, museums and galleries have been recipients of substantial grants from the Heritage Lottery Fund. In this month’s Cost Model, cost consultants, Davis Langdon & Everest, examine the design and economics of museum and gallery projects.

Background

The current increase in construction associated with museums and galleries is occurring against a background of rising popularity of museums as a visitor attraction, fuelled by increased mobility, leisure time and the growth of global tourism.

The 2,500 museums in Great Britain currently record 100 million visits per annum and achieve a turnover of £600 million, employing 18,000 people. According to a Museums and Galleries Commission survey in 1991, visiting museums and galleries is the third most common cultural activity in the UK. Growing popularity has not, however, been matched by increased funding, and development has relied on private patronage and, more recently, Lottery funding. Constraints upon public funding for current expenditure make the control of running costs particularly important. As a result, issues of active and passive services design and the long-term costs of environmental control are particularly relevant.

Museums and art galleries are complex buildings. The deceptive calm of a picture gallery provides few clues to the wider range of parallel support activities. These range from the management, storage and conservation of collections or the functions associated with generating revenue and catering for visitor needs. As well as being complex projects, galleries can also frequently be controversial. Typically, galleries are ‘once in a lifetime’ commissions for both client and designer, and, as a result, the stakes are high for all parties involved. Comprehensive, careful briefing and a full understanding of the needs of the collection are prerequisites for the developing an appropriate design solution.

Fundamental to the briefing process is an understanding of the multiple roles of museum and gallery buildings. Galleries function are civic monuments, visitor attractions, and places for the study, preservation and storage of artefacts. Resolving any conflicts between the needs of the visitor and the needs of the collection is crucial to successful design, but cannot be divorced from the broader design issues of the gallery’s relationship with its setting and the external environment.

Accommodation requirements

Museums and galleries defy generalisation. As civic buildings, their outward design is often highly site specific. Internally, the size and characteristics of the collection, the needs of the target audience and the requirements of curatorial staff will all have an impact on the use and arrangement of display and non-display space.

The key to a successful design is resolving these many conflicting requirements, and also being able to cater for substantial changes that may occur over time. However, although museums and galleries are primarily functional buildings, it is their impact as civic architecture that will have the widest audience. Balancing expenditure on visible design quality and longevity against the immediate demands of display and storage is a key challenge for the design team.

Museums and galleries are built to meet the immediate needs of visitors rather than simply to house collections. Changing public expectations have a huge impact upon design with many displays required to become more interactive in order to attract visitors.

Museums and galleries have to serve a range of audiences, each group wanting different facilities. Visitors, the largest group, are likely to include families, small parties or individuals, each of whom will have different needs for interpretation material, catering, and so on. For most galleries and museums, outreach programmes to involve the community in their activities are particularly important, not least because they help satisfy one of the criteria for lottery awards: making art more accessible.

Developing relationships between the institution and the community through sharing facilities such as cinemas or cafes is also an important mechanism for increasing access. However, wider access and out-of-hours use create demands for additional space and also affect building services and security strategies. Thought must also be given to display and non-display space, planning for the growth of the collection and creating a building that can establish and maintain the way the institution functions.

Many collections, including textiles and fine art, are vulnerable to damage caused by humidity, airborne pollution, temperature fluctuation or light. Displaying such artefacts in conditions suitable for visitors runs the risk of their suffering considerable damage. Overcoming this problem by installing close-control air-conditioning involves greatly increased capital and running costs. The average energy costs of fully air conditioned museums in the UK are double those of their non-air-conditioned counterparts. But an improved understanding of the effects of environmental conditions on the preservation of artefacts has led to more flexible guidelines. This guidance is based on realistic assessments of how much environmental instability artefacts can stand without incurring damage.

Another issue is the need for storages and support space. Typically, 80% of the artefacts held by a museum are in storage at any one time. Accommodation is also required for shipping and receiving, cataloguing and documentation, conservation, and research.

Design issues and criteria

Museum and gallery space requirements are goverened by the size of the collection, the method of display, size of artefacts and the projected rate of growth of the collection. The calculation of space requirements should be based on a first principles assessment of the characteristics of the collection.

In general, larger artefacts require significantly more display space if their full impact is to be communicated. The average ratio of gallery to non-gallery space in the UK is 48:52, with permanent displays taking up 40% of the total area. Non-gallery space includes areas devoted to storage, curatorial activities, visitor facilities and education. Table 1 shows the greater proportion of space given over to storage for national institutions in comparison to other galleries and museums.

Requirements for storage space can be reduced by the use of compact mobile shelving. Total storage space required should be calculated on the basis of the volume of all objects in the collection with allowances for planned, annual growth and unplanned ‘windfall’ donations (15% additional space)

Gallery planning

Museums and galleries can be successfully accommodated within many different building plans. However, there are a number of key requirements within gallery spaces that should be considered.

Walls should provide uninterrupted surface for the displaying artefacts. Materials such as fabric-covered or plasterboard-clad hardboard should be use as they are easily repaired and can be fixed directly to walls. As hardboard and plasterboard are porous, they absorb and release moisture and help to control relative humidity inside galleries.

Floor finishes also need particular thought. The requirements for a floor surface - quiet, comfortable, attractive, light reflective, hardwearing and capable of taking heavy loads - are difficult to reconcile and there is no single ideal surface. Typically, wood, stone and carpet are selected.

Floor loadings - are set out in BS6399: part 1, 1984. The basic allowance for museums and galleries is 4 kN/m2 and further allowances may be required for particularly heavy exhibits, the extra weight of display partitioning, or the loads from artefacts suspended from upper floor slabs. Where large artefacts are displayed, load capacities of up to 10-15 kN/m2 may be necessary. Use of compact storage units, which can increase storage capacity by 75%, will necessitate minimum floor loading of 7.5 kN/m2. Typical loadings are given in Table 2 (left).

Ceilings are generally not in the visual plane and as a result are often overloaded with installations serving other functions: lighting, lighting control, heating and ventilation, fire and security systems, sound absorption, partition restraints and so on. Therefore, careful design is required to ensure that the ceiling does not become a dominant feature.

Environmental control in the display areas is a critical design issue. Maintaining proper environmental conditions is the key to preventive conservation, as poor conditions pose the risk of damage to artefacts.

BS5454: 1989, Recommendations for storage and exhibition of archival documents is widely regarded as a textbook for environmental design and provides set criteria for temperature and humidity conditions (table 3). Increasingly however, there is a recognition that conditions can be varied to suit the needs of artefacts and how the building behaves.

Relative humidity poses the greatest potential risk. Uncontrolled humidity levels can cause mildew damage in organic materials and corrosion in some unstable metals. Short term fluctuations in relative humidity are considered to be as damaging as excessive, long-term dryness or moisture. Much of the capital cost involved in control humidity stems from the need for sufficient equipment capacity to respond to rapid change in relative humidity. This can happen with the influx of a large number of visitors to a gallery. It is increasingly recognised that most artefacts can be safely exhibited and stored in environments with an relative humidity range of 45- 60%, so long as the ‘buffering effect’ of the building’s thermal mass and porous finishes can be used to control short-term fluctuations.

Close control is a prerequisite for international artefact loan and a relative humidity level of 50-55% (±3%) has become the established international standard. This applies to all areas where the loaned item or its packing may be located, such as display, shipping, storage, conservation and circulation areas.

Air cleanliness is another important consideration. Where particularly fragile exhibits are concerned, the filtration system for removing both particulate and gaseous pollutants can be specified as being of his as 95% efficient. The impact of gaseous pollutants will depend upon location and the type of exhibit. Typical requirements for a fine art gallery are maximum levels for sulphur dioxide and Nitrous Oxide pollution at 10 µ/m3 and ozone pollution at 0-2 µ/m3. Where gaseous pollutants are present, activated charcoal filters fitted to the air-handling units should be considered as the minimum provision.

Lighting levels and the effects of ultraviolet and infra-red radiation need to be closely controlled to minimise damage to artefacts. Low-sensitivity exhibits - ceramics, glass, metal, stone - can have a lux level as high as 300, whereas lux levels of below 50 will be required for highly sensitive items such as drawings, watercolours and tapestries.

Light levels for conservation activities need to be much higher, with levels of up to 1000 lux being acceptable when exposure is limited short periods. UV exposure must also be controlled to avoid pigment damage. The widely reported maximum exposure value, 75 µW/lumen, has been widely challenged. It is considered prudent, therefore, to keep UV exposure levels to the minimum.

UV filter films or interlayers to laminated glass should be used on all external windows. In display areas, all luminaires that radiate UV should be fitted with filtering diffusers or secodary glazing. Using natural lighting is also difficult where UV-sensitive artefacts are on display.

Temperature is the least critical environmental factor, but is important as means of controlling humidity levels. Lower temperatures also aid conservation by slowing down the speed of any chemical reaction.The temperature is usually set at a level compatible with human comfort and keeping humidity conditions stable.

Passive design

The high capital and recurrent costs associated with close control environmental and security installations are not necessary in all collections and can place an excessive financial burden upon often under-funded institutions. In reality, few UK museums and galleries possess full air conditioning. Close control systems will only contribute to preventive conservation if the systems are running as designed and are properly maintained.

In common with other areas of building design, considerable efforts are being made to devise passive design solutions simplify environmental control systems. One way is by exploiting the ‘thermal flywheel’ and ‘sponge’ characteristics of a building. The high thermal mass of the building’s structure allied to the different but complementary properties found in the porous finishes can be used to create an inherently stable environment over the long term by means of realtively simple mechanical services.

Much of the work in encouraging the adoption of these passive design solutions has been carried out by the Museum and Galleries Commission. It has set out rules of thumb for low energy design, including:

• Avoiding the ‘uniform environment’ approach to design
• Using a zoning strategy whereby ‘sensitive’ areas are grouped together
• Setting wider environmental control parameters
• Taking advantage of the slow environment change rates that are created by the use of passive design features
• Using low-energy features such as high frequency lighting and condensing boilers
• Adopting appropriate operation and control procedures

Exhibition design

Exhibition design is very influential, particularly in science and technology museums, where the boundaries between what is a museum and what is a ‘visitor attraction’ have become increasingly blurred. Exhibition designers have successfully exploited information technology and audio visual systems to devise interpretive displays that appeal to the public in an increasingly competitive leisure market. This is best achieved by the early involvement of exhibition designers in the physical layout of the display space.

However, thought needs to be given to providing flexibility when designing the layout and services to cope with future needs as the lifetime of the building will exceed any exhibition fit-out.

In particular, flexibility in IT installations is crucial as data networks ISDN networks are becoming popular increasingly for operative displays.

Security

Security arrangements are another important consideration. Damage as a result of fire is a relatively low risk in well maintained museums. However, protection should be provided by fully addressable alarm systems. First-aid fire-fighting is best carried out by sprinkler system. Where there is an unacceptable risk of accidental water release because of sprinkler head failure, ‘pre-action’ systems should be used in preference to dry-pipe sprinklers.

Theft and damage to artefacts are major risks. Conflicts often arise between providing direct fire escape routes and designing the building to maximise security, especially when warder resources are limited.

Security systems need to prevent damage or theft and secure the building when closed. They should include barriers and display cases, intruder detection to external openings, deadlocks and non-removable hinges to external doors, infra-red movement detectors and a colour closed-circuit TV system.

Analysis of the model

The cost model is based upon the new River & Rowing Museum at Henley-on-Thames, designed by David Chipperfield Architects. The 2359 m2, two-storey building has a top-lit gallery at first-floor level. Further gallery space, education facilities, librar , shop, restaurant, workshop and administration area are located on the ground floor.

Structurally, both steel and concrete frames are used with high-quality finishes for exposed concrete areas. Externally, the building is clad in glass, glass-reinforced cement and untreated oak, with a coated stainless steel roof that has patent glazing rooflights. First-floor galleries are air-conditioned and gas-fired underfloor heatin is used for the ground floor. The project is procured on the basis of a lump-sum tender with the contractor taking design responsibility for specialist items of work.

Costs are at September 1997 prices for a project based in the South-east and exclude external works and exhibition fit-out works.