The Role of Architectural Design in Promoting the Social Objectives of Zoos

A Study of Zoo Exhibit Design with Reference to Selected Exhibits in Singapore Zoological Gardens

by Michael Graetz

PART 2 - PHYSICAL ELEMENTS OF ZOO DESIGN

2.7 Habitat Lighting

The term, ‘habitat lighting’ was coined during the conceptual development of the ‘Night Safari’, an animal related theme park developed and managed by the Singapore Zoological Gardens as a separate entity to Singapore Zoo. The Night Safari is opened to the public only at night and its unique feature is thus the manner of presentation of (nocturnal) animals which, in design terms, is primarily (but not solely) manifested as novel lighting design. This chapter focuses on aesthetic principles; while technical aspects are referred to, these are not dealt with in detail. Lighting in relation to daytime zoological displays is also discussed using examples from Singapore Zoo.

Use of Lighting by Day

Four special situations are encountered in zoos where artificial lighting is required or used by day. These are: 1) Displays needing supplementary lighting; 2) Indoor displays without daylight; 3) Glass fronted exhibits prone to reflection; and 4) Daytime nocturnal exhibits.

The first situation is the most often encountered in Singapore Zoo where it occurs mainly in fish and terrarium type reptile exhibits. Supplementary lighting is only effective in overcast, shaded or twilight conditions, each of which may occur daily, seasonally or irregularly. It differs from the second, indoor situation in that there is natural ambient daylight and it is a less controlled situation. Purely supplementary light also does not interfere with the natural daylight period [1].

Fig. 58 Lighting array including plant growth lights for a fish display

The third case, control of reflections caused by bright light sources or illuminated (sunlit) areas on the visitor's side, is possibly a greater problem in warm climates due to the need for larger openings in naturally ventilated shelters. Reflections are rarely controlled purely by artificial light because sunlight is so much brighter than any economic artificial lighting solution. It can work when both exhibit and public sides of the glass receive almost equal amounts of daylight. If this can be kept low enough, then artificial light in the exhibit may tip the balance so that viewers do not see reflections.

The fourth, nocturnal houses, comprise a special category where the day-night cycle for the animals are reversed. From the visitors' viewpoint, the quality of light used to reverse the ‘daylight’ hours for the animals is irrelevant, only the quantity required (out of exhibit hours) to allow enough light for the animals to be seen without disturbing their nocturnal activity.

Fig. 59 Daylight is the cause of reflections on this snake terrarium. The sign light has a controlled beam and angle

From the fore-going, it is apparent that lighting for some functional (including biological functions) and aesthetic purposes is of greatest relevance in Singapore and hence in similar zoos. Generally, it ought to be possible to combine these purposes in a well-considered lighting design.

Some examples of artificial lighting in Singapore Zoo are as follows:

• Fluorescent tubes were placed inside each of a group of glass fronted marmoset exhibits to offset reflections. The result is not satisfactory.
• A special, indoor enclosure for temporary animal exhibits was lighted with halogen discharge lamps, which were progressively increased in power until an optimal compromise was achieved. Heavy shading behind the viewer with a consequent reduction in natural ventilation was still required.
• Similar discharge lamps are used in the fish exhibits associated with the Pygmy Hippo display, not for reflections but to boost the light on dull days. These have little effect on bright days and a sensor is used to automatically turn on the lights when it detects low daylight levels.
• Fluorescent tubes are used under skylights in some enclosures in the Small Mammal House.
• Small and large tank exhibits in the Snake House have historically had two light sources: fluorescent and incandescent PAR lamps, the latter being used also as a source of heat for the snakes. New systems are being tested and installed using ‘grow’ lights and low voltage spot lights in addition to fluorescent ambient light.
• Incandescent light is used in many situations both on and off exhibit as a heat sources for animals (even though purpose made heat lamps are available).

These various uses are not untypical of lighting practices in all zoos. Fluorescent light, is used for its economy which can be a poor justification for the flat, shadowless impression and poor colour rendition it gives [2]. These characteristics can be turned to advantage, however. Fluorescent light in general provides an even, ambient light which ensures there are no too-dark corners, while incandescent point sources and focused spots may provide highlights and good colour rendition [3]. This is often the case in zoos except that relatively unfocused lamps are used. Commonly, fluorescent battens are included in the design, while ‘heat’ lamps are placed by the curatorial staff after construction.

This rather simplistic account of the use of lighting ignores the many more technical factors to consider, and the diversity of situations, philosophies and technologies. It then becomes unwise to lay down principles. For example, from a purely visual standpoint, exhibit lighting can be treated naturalistically or theatrically. Similarly, colour can be rendered naturalistically or not [4]; or an exhibit can be made unnaturally bright or be lit with directed light to create strong shadows; or it may be the concern of the designer to show animal forms explicitly with uniform light (however, some degree of shading or modelling is desirable). Light coupled with interior finishes, colours and careful control of shadows is also used to create illusions of infinite depth in indoor displays, however this has not been used in Singapore Zoo. [5]

Lighting in diurnal zoos is a case of rather eclectic styles and technologies at present. It has specific problems and requirements so that other, well established fields such as museum, art gallery and theatre lighting can only provide starting points. These applications have specific lamps and luminaires designed for them and their use is only slowly explored by zoos. In the case of Singapore Zoo, this has largely been due to the lack of a need for lighting in the majority of exhibits and the fact that the available lighting models have always come from zoos with a high proportion of indoor displays.

In the case of the Night Safari, considered next, an entirely new model had to be created and therefore it can be described with much greater comprehensiveness and certainty.

Lighting Principles in the Night Safari

In approaching the Night Safari, the only available lighting model consisted of the practice in many game reserves and national parks of floodlighting a waterhole, or spotlighting animals from a vehicle at night. Another model that was considered initially was that of fixed, high masts with large and powerful lighting arrays, similar to the masts seen in stadiums (though the similarity was only recognised later [6]).

The distinction between habitat lighting design and engineering lighting design is not universally accepted, as was revealed by the discussion following a paper by Cansdale presented at the second symposium on zoo design held at Paignton, England. Cansdale states: “Lighting is a severely practical matter and not one to be handed over to ‘artistic types’.”[7], which drew this rejoinder:

The purpose of lighting in a zoo was not to satisfy photo-electric cells and meters; . . . . an artistic type should be in control of the lighting. The lighting had to be placed, so that contrasts were under control, and shadows had to be formed, so that the human eye could see and recognise what was in the exhibit. . . . The basic purpose . . . was not necessarily electrical efficiency. [8]

The principle lighting tasks in the ‘Night Safari’ are as follows:

• To illuminate the animals and the landscape, i.e., habitat lighting.
• To illuminate public areas to satisfy safety and aesthetic requirements.
• To illuminate service areas for operations and security.
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Note that by distinguishing habitat lighting from lighting in public areas, a different solution is thereby implied.


Fig. Lighting in the ‘Night Safari’ with Himalayan tahr (Hemitragus jemlahicus)


Fig. 61 Asian lion habitat, ‘Night Safari’, at night (black and white photograph)

Habitat lighting. The natural light conditions at night was the starting point for establishing the Night Safari lighting model. Without going into the physics of illumination, it will be mentioned only that full moonlight at the zenith has an illuminance of 0.274 lux and a rather warm (orange-ish) colour temperature of 4,480 degrees Kelvin. [9] The first characteristic, illuminance, is too dim to provide a realistic basis for artificial lighting levels while the second does give an idea of natural colour rendition at night--if there is sufficient light for colour vision to operate.




Fig. 62 ‘Night Safari’: sloth bear (Melursus ursinus) by day and by night






Fig. 63 The holding area for red dhole (Cuon alpinis) in the ‘Night Safari’ is clearly visible by day

The decision to match the colour of moonlight may appear to follow obviously from the desire to achieve naturalistic night light; however, this is not necessarily so. People's notion of the colour of night light differs from physical reality, as Corder notes:

There is a long history of moonlight being thought of as blue. This is how we see the moon on television, and in films. The idea is reinforced when we look from our artificially lit houses into the moonlight, which appears blue by comparison with the, usually tungsten, and therefore rather orange, house lights.[10]

The colour of moonlight was matched because the real moon will be seen and provide a point of reference even though the architectural lighting in buildings provides a stronger comparison; and this more ‘orange’ light reinforces the belief that the habitat lighting is naturalistic, even though the habitat illumination may be many times greater than the moon.

The second principle decision concerned the placement of lighting sources. Again, natural conditions indicate a single directional source from above. We are used to seeing objects in daylight however which lights objects in varying degrees from all directions due to scattering of sunlight. We perceive objects as solid by the gradations of shade on them. The weaker moonlight, with negligible starlight, is much more directional and would distort the shape of animals from what we expect them to be especially with the higher illuminance required. Simulation of this directionality would also require very high towers at wide intervals. For these reasons, shorter (six to twelve metres) and more closely spaced lighting poles were used. These still cast light downward and allow better modelling of the animals with at least two positions being available in most situations. The idea of directed moonlight is gained by a stronger light source striking the animal from one side with a weaker light filling in the figure from another side.




Fig. 64 Sambar deer (top) and barking deer (bottom) in the ‘Night Safari’

From this generality, particular problems arose. These are easily anticipated but often cannot be resolved until the situation on the ground becomes apparent. Lights are generally directed away from viewers in trams or on foot, but with shallow angles, light sources can be seen from very far away. The risk of lights being seen directly can often be assessed from the plan, but there may be little scope for change to avoid it. Animals and plants are also not static. Movement and growth are so specific to time and place that working assumptions had to be made. It was also not practical to consider a grid pattern as a solution, as do many other applications (from offices, to carparks). To deal with these, a kind of triage is applied: lights can be refocused, added to or replaced (with different fittings); a different height pole put in place; or a pole put in a new location, depending on the severity of the problem.

The third principle concerns the choice of light fittings and lamps. A corollary of the use of controlled comparison to create a blue impression is that all the habitat lighting sources must be close to the same colour temperature. This is achieved through filters for some sources. Ultimately, two basic lamp types were selected: a mercury discharge source (HPL-R 125W) and incandescent (PAR 38) lamps. Both of these have self contained optics and can be placed in an identical luminaire. The only differences in requirements are electrical ballasts for the discharge lamps and dichroic filters for the incandescent. Both lamps and the luminaire chosen are utilitarian and industrial and hence durable. They are mounted on poles, as mentioned, with simple brackets permitting pan and tilt focusing. Three sizes of hood attached interchangeably to the fittings gives a further degree of flexibility. Asymmetric hood extensions are also added as glare shields in specific locations.

These two sources play complementary roles in lighting the Night Safari. The PAR lamps are optically more precise and give very good colour rendition. They therefore are used to highlight specific areas of interest and animal activity. Corder describes the design process as “painting with light”. [11] Therefore, if PAR lamps provide the detail, the less controlled beam of the mercury lamps provides the wash. This light, though close enough to moonlight to not require filtering, is very different in its spectral properties (as revealed in photography). It is consequently poor in colour rendering. Another characteristic, which Harrison notes, is the time for the mercury lamps to ‘strike’ and warm up after a power failure. Even with back up generators these lamps will take seven to eight minutes to return to full illumination [12]. The PAR lamps come on immediately.

No reference has yet been made to any required light intensities. In this area, no conscious effort was made to achieve a specified light level. The lay viewer was considered the best judge during development; however, subsequent measurement has found levels varying from ten to a hundred lux. By comparison, Scherpner states that the Frankfurt nocturnal house used a level of five to ten lux, and that generally, a ratio of 1:100 is required between ‘night’ and ‘day’ to keep nocturnal animals active. [13] The higher levels found in the Night Safari are possible because day-time illuminance can be as high as 100,000 lux, which gives a ratio of 1:1,000.

The light levels in the Night Safari are generally above that permitting true night vision. Therefore colours can be seen and the perception of night light really is illusory. A question arises as to the effect of this light on animals. Particularly to the question of whether Scherpner’s assertion of the importance of the ratio of night to day light levels is true and nocturnal animals behave normally. Superficial observation suggests no definite conclusion. Generally, greater activity is seen in many animals that are noted for being inactive in zoos, but Harrison remarks that, “even the so called nocturnal animals . . . are a little unpredictable, I have seen nocturnal Malayan tapirs sound asleep at 10:30 pm.” [14] The best indication is that nocturnality is not relied upon solely in impressing visitors as the majority of species are crepuscular or arrhythmic. Conditioning animals to a routine the reverse of that practised in daytime zoos, behavioural enrichment and token feeding are still used to stimulate the animals to activity.

Concluding Remarks

Lighting has been largely considered here in terms of artificial light. Except in the instance of the Night Safari, artificial lighting is a part of a general concern with legibility of exhibits, which encompasses natural lighting as well. Polakowski states that the designer has “substantial control on the effect of natural light”, through the orientation of the exhibit and the light reflection, absorption, and transmission properties of objects within it [15]. The sheer range of exhibition techniques--from large, open exhibits to small terraria and aquaria--precludes dismissing either natural or artificial lighting from a discussion of zoo design.

Although the focus is on artificial lighting, mainly because of the novelty of the Night Safari, the distinction drawn with lighting system for museums, art galleries and the like is valid for day lighting as well. The zoo designer must deal with light and shade, contrast, glare, reflections and consider the use of light to draw attention to objects of interest (animals) without ignoring the environment (habitat), unlike museums where, regardless of the merit of the building, it is contemplation of the object in isolation which is the purpose. And, of course, the animals are not static and are capable of seeking out shaded corners.

This said, there are certainly conventions in lighting interiors that apply to zoo exhibits. There are also conventional approaches to outdoor lighting but in the case of the Night Safari these are largely ignored, except in the ‘civilised’ public areas where warm up-lighting on trees and foliage is used decoratively. Even then, cool ‘habitat’ ambient light washes the scene from above. The habitat lighting proper aims for a naturalism which to this author's knowledge has not been attempted before [16]. In this sense it is unique; and while it can be looked upon as simply a one-off lighting installation, it sets a benchmark against which future nocturnal houses will be judged.

The benefit to visitors of lighting in exhibits where some degree of control is obtainable lies in the attraction bright areas have to the human eye and, once drawn, the concentration of attention lighting can focus on the exhibit. Distracting visual influences are played down by being made duller in contrast. With bare or even sparely landscaped exhibits being superseded by truer representations of the busy-ness or disorder of nature comes the risk of losing visitors' attention if they have to work too hard to find the animals. Lighting (natural and artificial), whether it is just filling in shadows or (better) highlighting the animals' favourite resting places, can provide the necessary visual information for visitors to ‘read’ exhibits. Different exhibits will also convey different moods incidentally, due to necessary features such as the amount of shade required and an exhibit can become too gloomy for example. The designer ought to be aware of these effects for then they can become subject to control.