The customer said “My hospital needs some lighting so that it is safe,” “That,” I said, “is exactly what you don’t need!” The question is so apparently straightforward that it is hard to see what is wrong with it. After all, lighting is designed for hospital and healthcare buildings all the time. But hospitals do not need light. It is the human occupants who need it, and the lighting should be designed to satisfy their needs, not those of the buildings. This type of incorrect focus is so commonplace that it may even seem pedantic to point it out. But, unfortunately, it is why so many installations are unsuitable for the occupants.
If the lighting is designed only to provide “safe” conditions it will be inadequate and people will work inefficiently and feel under stress – hardly consistent with the aims of the organisation. So lighting should be designed to be “good” and to match the needs of the building’s occupants. You would not, for example, feel confident about undergoing surgery if you heard that lighting levels in the operating theatre had been reduced to save energy.
Mention poor lighting and most people immediately think of not having enough light. But that is not the real problem; it is just the tip of the iceberg. Many installations provide enough light, but the quality of the illumination is unsatisfactory. Lighting is frequently “unsuitable” rather than “insufficient”. Why is this?
The main reason is a general ignorance of the importance of lighting. Lighting is treated as a physical problem of ensuring that the correct amount of equipment is installed to achieve a physical result. We forget that the lumen is not a physical unit like the watt, but a psychophysical unit based on human response. We need to encourage a greater awareness of the physiological and psychological issues rather than just the physics.
Lighting has a job to do and it must do it well. This means:
- Ensuring that the lighting objectives are correct and are achieved.
- Using the most suitable lighting system.
- Using the most suitable lighting equipment.
- Controlling the hours and method of use.
- Maintaining the system in efficient and effective working order.
Let’s start with the objectives. In practice this means designing lighting to be efficient and effective in terms of what is achieved as well as what it costs. Objectives deal with all the quality issues that contribute to performance, efficiency and comfort. To manipulate objectives during the design process and make suitable judgements, they are usually turned into numbers. The result is that codes of practice are full of design quantities. These are not objectives, but attempts to express objectives in numerical terms. This does not make them unimportant, but many people mistake them for objectives.
A common mistake here is to confuse this strategic decision about lighting methodology with decisions about what equipment to use. The method of lighting must match the application. The main issues are whether to use general, localised or task lighting; how daylight will be utilised; what control strategy should be employed; and what strategic issues are raised by the lighting objectives.
The next stage is to use the right equipment. The choice of lamp affects the range of luminaries, and vice versa. Many new luminaires appear similar and use the same lamps, yet their efficiency can vary by a factor of more than 2:1. And remember: if the fitting is more efficient, fewer will be needed and the installation and maintenance costs will be lower. Always check not only initial costs but also total cost throughout life. Efficient equipment is often a better choice in terms of sustainability and economics, even if the initial cost is greater.
In hospitals, luminaires have to meet high standards of safety and hygiene. In particular, there should be a minimal horizontal area on which dust can settle because airborne dust particles can transport harmful bacteria. For example, a recessed, sealed fluorescent luminaire should have a low, smooth frame profile and lack of external fasteners, making it easy to clean.
Noise is also an important consideration, as hospitals can have a much lower ambient noise level than commercial premises and bedhead lighting may be close to the patient. Fluorescent lamp luminaires should, therefore, employ high-frequency electronic control gear. This brings flicker- and noise-free illumination, avoiding headaches and eyestrain. Slimmer lamps lead to smaller luminaires, but the typical energy saving is 25%. However, the efficacy of the lamp is not realised unless we make more efficient luminaires. Fortunately, T5 luminaires are now available in recessed, surface and suspended versions with a choice of quality optics: direct, indirect or a mix of both. They are fast becoming the first choice for hospital use.
Of particular significance is the development of T5 bedhead lighting systems. Typically, these are wall-mounted medical supply units consisting of an aluminium profile with a constant cross-section integrating all the lighting, fluid distribution and electrical functions. The luminaire section fits harmoniously onto both the upper and lower side of the supply section, allowing indirect illumination of the ward area/patient room and direct illumination of the bed area. They are prewired and prepiped, so installation costs are minimised.
All rooms located in clinical areas should have fluorescent lamps with clinical-quality colour-rendering properties according to Group 1B (Ra80) or better. Colour temperature should be 4,000 K unless stated for specific applications.
People must be able to move about in safety and without risk of accident or injury, especially in an emergency, so make sure your emergency lighting conforms to the needs. For peace of mind, consider self-test fittings or even a central checking system.
Since hospitals function 24/7, it is recommended that lighting controls are employed. To maximise energy efficiency, the designer should also optimise the use of available natural daylight.
At this point, you should think about your responsibilities to society at large. You will make the correct technological choice only if you factor in the use of replenishable materials and responsible waste management. Under the terms of the EC Directive on disposal of waste electrical and electronic equipment (WEEE), you should find out what advice the supplier gives on safe removal of lamps and fittings at the end of their lifespan and whether they help with this.
All too often, cleaning and relamping of luminaires is not done correctly, so lighting levels are well below recommended levels. Ask for maintenance recommendations – if you buy even the cheapest car, you get a service book telling you how often to get the car serviced and what must be done.
We must encourage more people to understand the importance of lighting for people and that it is not simply a matter of physics and numbers; performance, efficiency, health and comfort must be balanced against cost.