Lighting of indoor swimming pools
Indoor swimming pools are used for swimming, in terms of physical education or competitive sports as well as leisure. Artificial lighting frees indoor swimming pools from the constraints of daylight and thus increases quality and duration of use. Still, appropriate architecture should permit as much daylight as possible to fall onto the pool area. Artificial lighting can be adjusted automatically according to daylight supply using an energy management system. This saves energy and lamp replacement as well as maintenance costs. Service life is the decisive factor when it comes to the level of cost savings and the length of replacement cycles for LED luminaires, as outlined in chapter .
Lighting quality and quantity are determined by the visual tasks, which in turn depend on the type of sports and the viewing distance. Swimming instructors, trainers, pool attendants and judges must be able to quickly and confidently recognise swimmers’ and players’ motion sequences, body movements and facial expressions as well as ball movements. For example, pool attendants’ perception of actions underwater can be impeded by reflections of general lighting off the water surface. Underwater spotlights can limit this problem to a certain extent, however, it is better to place luminaires outside of the pool – also due to simplified maintenance.
Competitive swimmers must be able to recognise the finish, lane markings, fellow swimmers and balls. There must not be any glare by underwater spotlights, which means they should be turned off for competitions.
Leisure swimmers are interested in securing their own surroundings in or out of the water as well as an experience-based ambience of the whole indoor swimming pool space. For spectators, undisturbed viewing of the course of the sport or game is the priority. Where lighting fulfils the requirements of attendants, visual conditions for swimmers and spectators are usually good as well.
Additionally, design aspects of multi-purpose water parks – meaning for sports events and leisure-time enjoyment – are also important for economic success. Accent lighting in seating or other audience areas, aesthetic luminaires, ideal light source colour rendering, underwater lighting, illumination of sculptures, art on walls and load-bearing columns and slow light changes with controlled brightness levels and changing light colours turn dull indoor swimming pools into experience spaces.
Renovations of older indoor swimming pools have become a current phenomenon due to high costs of operation. Often, existing lighting installations in indoor swimming pools do not fulfil minimum lighting quality criteria or safety regulations or the desire for reduced maintenance and energy costs. Lighting installations which are older than 15 years usually do not fulfil these criteria. An implementation of modern and low-maintenance lighting systems which fully comply with safety provisions and building legislation with the help of professional designers is recommended. Switching concepts which make use of daylight, e.g. via light management systems or demand-based group switching facilitate additional energy savings. Especially easy access to luminaires for maintenance purposes is a key consideration, which in itself is enough reason for lighting refurbishment in many old installations.
The photometric reference field consists of the water surfaces (e.g. PA 25 m · 15 m or 50 m · 22 m according to EN 12193) and the area surrounding the pool. It is located 0,2 m above the water surface. The recommendation of pertinent sports associations (Deutsche Gesellschaft für das Badewesen e. V., German swimming associations, German sports association) for surrounding walking areas is that their size should correspond to the water surface so that the average width z of the border can be calculated using the length L and the width B of the water surface.
F = (L + 2z) · (B + 2z) is the photometric reference field where lighting quality criteria apply. The aforementioned formula is represented graphically in figure for the case B = L/2.
High reflectance values and matt surfaces of room boundaries increase the indirect lighting component, increase vertical illuminance Ev for improved perceptibility and avoid reflections on the water surface. The recommended reflectance values are
0,6 for ceilings,
0,4 for walls for wide-distribution or 0,6 for narrow-distribution luminaires,
0,6 for pool walls and floor, and
0,4 for surrounding walking and other circulation areas.
Sufficient vertical illuminance and shadow detail improve visual conditions for pool attendants, trainers and judges. The relation of horizontal and vertical illuminance should be between 3:1 and 2:1 at least for the four main directions of the room (see also chapter "Spatial lighting, direction of light, modelling").
For example, in lighting class II with Ēm = 300 lx, vertical illuminance at the reference area (reference field) should be between 100 lx and 150 lx.
At the diving area of platforms for high diving, a ratio Ēv/Ēh of 0,8 or 0,5 is required due to a preference for vertically-oriented visual tasks according to lighting class. For lighting class I with Ēh = 500 lx, vertical illuminance Ēv should therefore be at least 400 lx. This requires particular lighting installations.
With the appropriate selection and arrangement of luminaires, light reflections off the water surface, which can impede viewing in and under water, can be avoided. Prismatic luminaires with low luminance values and an examination of the light path on the water surface for an attendant standing at the pool border usually lead to satisfactory results. A bright, matt room ceiling which generates an increased indirect lighting component as well as underwater lighting are further measures for reflected glare limitation.
Supporting elements such as suspended ceilings and luminaires must feature sufficient protection against corrosion.
In most cases, "normal" stainless steel (e.g. steel code or material number 1.4301, 1.4401, 1.4541 and 1.4571) or sufficiently galvanised materials are suitable (q.v. chapter "Chemicals and other influencing factors").
In insufficiently ventilated indoor swimming pools, the humid, warm and chloric air can form acidic and saliferous films on fixing components, which, due to complicated access, are not always rinsed off sufficiently during cleaning and therefore become more and more concentrated. This can cause long-term corrosion. This particularly affects suspension equipment with small diameters and equipment under constant mechanical stress. In such cases, long-term corrosion effects due to the electrochemical series (electrolyte formation) between less compatible, conducting construction materials must be given special consideration. In extreme environmental conditions, it may be necessary to use higher-quality metals or appropriate plastic suspension equipment. For example, in outdoor lighting, where similar long-term corrosion can occur, wire suspensions made of glass fibre-reinforced polyester plastic are used for luminaires suspended between buildings to counteract this issue.