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Technology & Services

Good Lighting for Healthcare Buildings ­ Some Basics

a report by

Stefan Lang

Managing Director, SIS-LICHT Gebr. Lang GmbH & Co. KG

Quality Features in Lighting ­ What It Takes To Get It Right

· visual comfort, which depends on colour rendering and harmonious brightness distribution; and · visual ambiance, which is influenced by light colour, lighting direction and modelling.

Visual Performance and Visual Comfort

Monitoring the condition of patients, working at keyboards and screens, examinations in the laboratory, reading a book in the nursing bed ­ the visual tasks addressed in hospitals, clinics, geriatric or nursing homes are as varied as the activities performed there. The artificial lighting, therefore, needs to meet high-quality standards. Whether it does so depends largely on the quality of planning. Specific quality features include the following: · lighting level ­ brightness; · glare limitation ­ undisturbed vision with neither direct nor reflected glare; · harmonious distribution of brightness ­ an even balance of luminance; · light colour ­ the colour appearance of lamps and in combination with: · colour rendering ­ accurate identification and differentiation of colours and room ambience; · lighting direction; and · modelling ­ identification of three-dimensional (3-D) forms and surface textures. The prime requirement for good visual performance is balanced general lighting. However, the lighting requirements of a room in a nursing home are not the same as those in a clinical laboratory. In addition, not all lighting problems can be solved by general lighting alone. Often additional and highly specialised light sources are necessary. Therefore, depending on the nature of visual tasks, lighting quality features may be weighted differently. The focus may be on the following: · visual performance, which is affected by lighting level and glare limitation;

An adequate level of lighting and minimum glare are fundamental requirements for good visual performance. The more difficult the visual task, the higher the illuminance required: a minimum of 200 lux nominal illuminance is needed in a patient room in nursing areas and 300 lux for examination. At least 1,000 lux is needed for examination lighting in bed areas of intensive-care units (ICUs). Regular lighting system maintenance ensures that illuminance does not fall below the required level. Visual performance and visual comfort depend essentially on correct brightness distribution. Excessive differences in brightness in the field of vision force the eye to adapt constantly and thus cause fatigue; differences that are not marked enough also have a disturbing effect. The solution is a harmonious distribution of brightness where the brightness of visual objects ­ their illuminance ­ makes them stand out from the surroundings.


Correct distribution of light and shadow makes for clearer perception of 3-D objects and thus helps people to get their bearings in a room. Balanced modelling with soft-edged shadows guarantees good visual conditions. For many visual tasks in healthcare buildings, such as in the wide field of examination, not only general artificial light, but also additional light sources are necessary. This can be provided by supplementary `individual' luminaries in the form of examination lights with highly focused beams. Controlled, but limited, use of shadow can also be an effective tool: an illuminated magnifier with an asymmetric light pattern can help to recognise the structures of an object.



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Figure 1

Avoidance of Glare

Glare impairs visual performance and causes discomfort, which leads to a feeling of insecurity and premature fatigue. Therefore, glare has to be limited, for example, in patient rooms, workplaces with screens, rooms for therapy and rehabilitation, etc., so that doctors and medical personnel, as well as patients, are not distracted. A distinction is made between direct glare and reflected glare.

Direct Glare

Direct glare is caused by disturbing light from inadequately shielded luminaries or excessively luminant general-diffuse lamps in the observer's field of vision.

Figure 2: Example of a Special Bedside Light Reflected glare

Reflected glare is caused at certain angles by reflection of excessively luminant lamps or luminaries on shiny surfaces. Reflected glare can be harnessed to channel attention. If it is too bright, it can be as much a source of disturbance as direct glare. Reflected glare also reduces the contrasts that are vital for disturbance-free vision, which is important, for example, for computerised tasks.

Light Colour and Colour Rendering

· · ·

safe low voltage 12V operation; comfortable switch with red lightemitting diode; and flexible arm.

Figure 3

Light and colour define the atmosphere of a room and, by their `warmth' or `coldness', influence a person's mood and sense of wellbeing. The colour characteristics of lamps are governed by two separate criteria: light colour and colour rendering. Light emitted by lamps of the same light colour can render colours in totally different ways. From a technical viewpoint, the two quality features are connected: both are determined by the spectral composition of the light. They thus affect jointly the perceived colour of things ­ and consequently merit close attention.

Light Colour

Light colour describes the colour appearance of a light source. It is characterised by the colour temperature Kelvin (K). The higher the temperature of the lamp, the whiter its light. The colour temperature of an incandescent warm white lamp, for example, is around 3,300K; a cool white fluorescent lamp has a temperature of around 4,000K and a daylight white fluorescent lamp 5,000K to 6,500K. For general lighting in patient areas warm white is recommended. This creates a comfortable, cosy light atmosphere; neutral white strikes a more clinical note and, therefore, is suitable, for example, in ICUs.



Good Lighting for Healthcare Buildings ­ Some Basics

Table 1: Recommended Minimum Requirements for Hospital Lighting

Purpose and type of room Examination and medical treatment Type of task and lighting Nominal illuminance En in lux Light colour

General rooms X-ray Dermatological examination

Nursing wards

General lighting Lighting at the place of examination General lighting General lighting Examination lighting General lighting Reading light Examination lighting General lighting General lighting Difficult visual tasks General lighting Wake-up room Wake-up light General lighting in the room General lighting in the bed area Examination lighting in the bed area General lighting Colour inspection

500 >1,000 500 500 >1,000 100 300 300 300 >300 500 500 500 100 100 300 1,000 500 1,000 300 day 200/night 50 500 300

warm white, cool white warm white, cool white cool white, daylight white warm white, cool white warm warm warm warm warm white, cool warm white, cool cool cool cool white white white white white white white white white


Office for doctors and nurses Visual display unit (VDU) and workplace Adjoining rooms of operating theatre


Rooms of intensive care

warm white, cool white warm white, cool white warm white, cool white warm white, cool white daylight white warm warm warm white, cool warm white white white white


Office and service areas

Entrance, reception, hall Corridors, stairs Office, VDU and workplace Waiting room Colour Rendering

Ward General lighting

For certain objects, experience provides people with `stored visual standards'. For example, a person has a stored impression of the colour of human skin in daylight, which means that skin colour is perceived as `natural' even in artificial light, which lacks spectral colour. On the other hand, sick people often have `unnatural' skin colours. False perception, however, could lead to wrong impressions or diagnosis. In addition, in the case of coloured materials for which a person has no stored impressions, perceptions may differ considerably in artificial light. The importance of correct colour rendering by artificial light is obvious. The effect that a lamp has on the appearance of coloured objects is indicated by the `general colour rendering index' (Ra). This shows how closely the appearance of an object under a particular light source matches its colour under reference lighting. The Ra value of a lamp is established by illuminating eight test colours with it and defining its performance in relation to the reference light source Ra = 100.

The less the appearance of the illuminated test colour differs from that under the reference lighting, the better the colour rendering of the lamp. Lamps with very good colour-rendering properties (Ra > 90) render all colours accurately.

Excursion ­ Full Spectrum Light

In this area there are also interesting studies and empirical reports covering positive biological and psychical effects of full spectrum or `bio-light' fluorescent lamps, i.e. lamps with a colour spectrum near to natural sunlight and a high colour temperature of about 6,000K to 6,500K. Among other things, it is reported that there is a distinct improvement in depression, troubled sleep, lack of drive, etc. These topics are highly relevant for geriatrics.1 However, this light colour is not yet embodied in the standards for general lighting.

Further Quality Aspects

In addition to the quality of lighting itself, aspects of

1. Dr Norman E Rosenthal, Winter Blues: Seasonal Affective Disorder: What It Is and How to Overcome It , Guilford Press: New York, 1993.



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security, service life, cleaning and maintenance of lighting fixtures, especially lamps, merit close attention.

Electronic Control Gears

The arrival of electronic ballasts marks a real breakthrough in energy efficiency, paving the way for more reliable, economical and convenient operation of fluorescent lamps. Electronic ballasts are subject to a power loss of only around 5W or less and convert mains voltage into a high-frequency alternating current voltage of 25kHz to 40kHz, which lowers the power intake of a 58W lamp to around 50W with virtually no loss of luminous flux. The power loss of an electronic control gear is thus 65% lower than that of a conventional one and 44% lower than that of a low-loss one; the power required by a lamp electronic ballast system in the example given is reduced to 55W, which results in a 23% saving compared with the conventional system. In addition to substantial energy savings, making for short pay-back times of around two to three years, high-frequency operation of fluorescent lamps offers other technical advantages: · optimum lamp operation, extending the service life of lamps by up to 50%; · low heat loading by lighting and, therefore, lower air-conditioning costs; · use in medical examination rooms where electromagnetic waves could affect the instrument readings;. · safe and reliable operation owing to low heat gain and disconnection if lamps are defective (fire protection); · enhanced lighting comfort and quality: no startup or electrode flicker, no stroboscopic effect, no flickering caused by attempts to ignite defective lamps and no system hum; and · dimmable versions for combination, e.g. with light sensors or for connection to bus systems serving for central management of building installations. It is, for example, important to consider that the quiet, totally flicker-free light provided by electronic control gears has positive effects on the condition of psychologically or physically stressed people.


during the last few years. The national regulations in existence today derive from the common base of standards and are almost valid throughout Europe. Although these regulations are binding for the Member States of the European Community (EC) only, many other nations, such as Switzerland, have taken them on board. The following directives and norms are relevant to the area concerned with lighting. · EC-Directive for Medical Products 93/42/EWG Examination lights, but also reading lights for beds that can be used for control or nursing of patients or be part of medical equipment, e.g. bed, are medical products in the sense of this directive. Classification of these lights is in the risk Class I (low). · EC-Low Voltage Directive 73/23/EWG ­ Security regulations for electrical fittings with a rated voltage between 50V and 1,000V. · EC-Directive for Electromagnetic Compatibility 89/336/EWG ­ Electrical fittings are not allowed to interfere with the operation of other fittings and must be protected from interference by other fittings. · European Standard EN 60598 ­ General requirements to electrical luminaries. · European Standard EN 60598-1 ­ Particular requirements for fixed general purpose luminaries. · European Standard EN 60598-2-4 ­ Particular requirements for portable general purpose luminaries. · European Standard EN 60598-2-25 ­ Particular requirements ­ Luminaries for use in clinical areas of hospitals and healthcare buildings. · European Standard EN 60601 ­ Safety requirements for electrical medical systems. · European Standard EN 60601-1 ­ General requirements, safety requirements, electromagnetic vulnerability compatibility. · European Standard EN 60601-2-41 ­ Particular requirements for the safety of surgical luminaries and luminaries for diagnosis.

Particular Requirements for Bedside Luminaries


In the course of developing a common market, existing different national standards have been substituted through harmonised European Directives

A closer look should be taken at those lighting fixtures that are mounted directly at or near the bed


Good Lighting for Healthcare Buildings ­ Some Basics

of a patient, and therefore have to be designed with particular care. These luminaries should: · be adjustable individually, also taking into consideration aspects of ergonomics and safety; · operate coolly, especially to be cool to touch; and · have smooth and easy-to-clean surfaces.

Contact Information SIS-LICHT Gebr. Lang GmbH & Co. KG Postfach 1464 97404 Schweinfurt Germany Tel: (49) 9721 65974-3 Fax (49) 9721 65974-44 e-Mail: [email protected]





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