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Introduction

Any hospital complex encompasses a broad range of functional elements and is almost a self supporting community. The occupancy is both complex and dynamic and, therefore, any lighting has to meet the separate, and even conflicting, visual needs of staff, patients and visitors. Furthermore, many areas are in use 24 hours a day, seven days per week. Extending the natural working day is possible by electric lighting, but for hospitals the use of artificial lighting occurs to a much greater extent than in normal commercial and industrial premises. Recommended illuminations vary from one lux for night-lighting to 100,000 lux in operating theatres. The first objective is the provision of adequate illumination. Attempts to save energy by underlighting are a false economy, as without sufficient light errors and mistakes increase and visual fatigue reduces the rate of work. It is impossible to deal with all the lighting issues in a single article, so a small number of aspects have been selected. Their relative importance will vary from site-to-site, but hopefully it will be possible to audit local conditions either by a walk-through survey or by asking a few key questions of facilities management and procurement. Daylight This is a good starting point and immediately recognisable. Daylighting is an important element in building design, as it provides variety, a link with the outside world and a temporal scale. These aspects are particularly important for visitors and patients who are in an unfamiliar environment. Well-designed daylighting of a space can reduce the reliance on electric lighting, thus saving electricity. The inconsistency of natural light, however, often results in electric lighting being left switched on when it is not needed. In fairness to the occupants of a space there is no clear indication of the relative contribution from electric light and daylight by which a decision can be made to switch off electric lighting. The potential for daylighting to save energy is thus rarely realised. Lighting Controls There are various options available for the automated control of lighting based on presence detection, photo-sensors that can measure the amount of natural light, timers and building management systems. Which is deemed to be the most suitable will depend on the type of location and its usage pattern. There are two basic rules in providing automated switching. Firstly, there should always be safety of movement so occupants are never deprived of all lighting in a space and secondly there should always be a convenient local manual override so that the function of a space can continue. Lighting controls are called for in Part L of the Building Regulations for England and Wales, either automated or by local manual switching. For the latter, it is important that the switching circuitry relates to a sensible sub-division of the space. Large open spaces can be reorganised and it is important that the switching is changed to match the current arrangement. Manual switching does not have to be hard-wired and where change is likely switching by infrared handsets, similar to the domestic TV remote control, can be considered. Other options include switching via telephones or PCs. Sudden abrupt changes in lighting levels can be disturbing and even construed as a fault condition, so dimming is becoming more popular. With modern light sources, such as fluorescent tubes, the relationship between light output and power consumed is almost linear – dimming saves electricity consumption. With filament lamps, however, the light output decreases much more rapidly than the power consumption, so the potential for energy saving is less significant. Simple resistive dimmers do not save energy but merely transfer consumption from the lamp to the dimmer itself.

Greatest Cost

It is not normally appreciated that the greatest cost associated with lighting is the energy consumed. Typical through-life costs are shown in Figure 1. Changing from a normal nine-to-five, five-day week, to 12 hours per day every day doubles the hours of use and thus the energy consumed. For many situations in a hospital complex this may be a conservative estimate. Energy costs are currently predicted to rise after a period of stable, and even falling, prices. This is partially due to market forces, but concern about global warming and increasing environmental pollution is applying additional pressure to reduce energy consumption. It is, therefore, important that hospital lighting is based on only the most efficient light sources.

Fluorescent Tube Lighting

Probably the most common lamp in use today is the fluorescent tube. Developed just before WWII, its availability was restricted during the years of the conflict and became part of the post-war building programme. Significant technical progress was made in the 1950s with the introduction of improved phosphor coatings generically called ‘halophosphates’. There were two groups of white lamps for general lighting called white, warm white and cool white. Better colour rendering was possible if required, but only with approximately two-thirds of the light output. This group was given names such as Natural and Northlight. With this choice, good colour rendering was restricted to situations where it was important, such as retail premises and industrial colour matching. In the 1970s, new phosphors were introduced that created white light by the addition of red, green and blue colours and became known as ‘triphosphors’. These had three main advantages:

• Increased light output – typically +10% initially, 35% at end of life
• Good colour rendering – no longer was it necessary to compromise efficiency for colour rendering or vice versa. Colour rendering is explained in more detail below
• Good lumen maintenance
• Longer life.

This extra performance carried a cost penalty with triphosphor lamps at approximately twice that of their halophosphate versions. The construction industry has been traditionally structured so that through-life cost benefits are not properly recognised. The installing contractor is only interested in initial costs and not operating costs. The purchasing department compares component costs and favours low-cost replacement lamps. Facilities management can identify energy consumption, but have little opportunity to influence equipment specification. Higher lamp costs can be easily justified. More light emitted means less luminaires to purchase, fewer lighting points to install, lower installed load and less equipment to maintain. The better durability of ‘triphosphors’ results in the light output being maintained at a higher level for a longer period. The reduction in light output with time from the triphosphor lamp is only approximately 5%, which is not readily detectable by the naked eye. Consequently, if one lamp fails its replacement will not appear at different brightness. With halophosphate lamps there is a much greater fall-off in light output, which, after 9,000 hours, is approximately 20%. A single replacement lamp would be 25% brighter and would be apparent. This is why the curve for the halophosphate lamp is only shown to 9,000 hours – after that time group replacement becomes necessary in order to maintain a uniform appearance from an array of lamps. Recommended illumination levels are more accurately described as maintained or service illuminance, which does not refer to the initial performance, but the minimum average. This means lighting designers do not have to consider the initial light output from the lamps, but the lowest value when the lamp is replaced. The difference in light output, therefore, is not 10% but approximately 35%.

Tube Diameter

In addition to the phosphor efficiency the gas filling of the tube was altered so that approximately the same light output was possible with a reduction in power consumed. This can be identified by the change from 1 1/2 inch diameter to one inch. Lamp producers know this internationally as the change from T12 to T8. Many standard light bulb shapes are designated a letter – in this case T = tube – and its diameter is expressed in eighths of an inch. If any T12 lamps are found then it is likely that energy savings are possible. The only exception to this simple rule is 2,400mm (8ft) lamps, which are only available as T12. T8 and T12 tubes are physically interchangeable as they use the same bi-pin cap and are of the same length. In the 1990s, T5 fluorescent tubes were introduced. These use only triphosphor coatings and are designed specifically for high-frequency electronic operation. They will not retrofit into lighting designed for T8 or T12 lamps.

Electronic Control Gear

Operating fluorescent tubes at high frequency (circa 50kHz) will increase light output by approximately 10% compared with a standard 50Hz supply. Electronic circuits adjust the lamp power to give the same light output as conventional control gear, so the value branded on the lamp can be misleading. The use of T12 lamps and electronic gear is rare as availability started during the era of T8 lamps. The 36W lamp listed above would operate at approximately 33W. Electronic control gear has several significant additional advantages. The light is ‘flicker-free’ whereas lighting at 50Hz can cause discomfort to a small section of the population. It is also silent in operation and this can be important for certain hospital areas. Due to the fact that the starting process is controlled, the lamp life is extended to approximately 20,000 hours.

Colour Rendering

This is a key performance characteristic of fluorescent tubes. It is the ability of a light source to accurately represent the colours of an object, which it is illuminating. Colour is a complex subject but a colour rendering index (CRI) as a numerical scale 1–100 has been developed to provide an approximate indication. There are several versions but that commonly quoted by lamp manufacturers is Ra8, which is based on the average results from eight pastel shades across the spectrum, typical of normal interior surroundings. There are specific indices, of which one is based on skin colours, thus relating to medical visual environments. There is a European standard for surgical lighting, which suggests that the ideal colour temperature is 4,000–4,500 Kelvin. For tungsten halogen lamps, colour temperature and colour rendering are interrelated. For fluorescent tubes the characteristics are separate and a colour temperature of 4,000K should be specified in association with an appropriate CRI. Standard and deluxe triphosphor fluorescent tubes are normally acceptable for general lighting with CRI 80+ and for medical areas with CRI 90+. This aligns with the international and European standards for lighting of the workplace, which call for lamps with a minimum CRI of 80 for general areas and 90 for clinical areas. It is worth noting that compact fluorescent lamps are only available with triphosphor coating. Standard halophosphate lamps have a CRI of 50–75 so cannot meet these colour rendering criteria. Identifying which lamps are triphosphors is not simple, as manufacturers use individual brand techniques rather than generic descriptions. This has some justification as two lamps from different manufacturers may have the same CRI, but colours will not appear the same under both. As CRI is an average performance measure, so individual colours can differ, which is a limitation of presenting colour performance by a single number. To ascertain that the correct lamps are being used, it is necessary to determine that they are triphosphor and with a minimum CRI of 80 or 90 according to the location and that the lamps are provided by one manufacturer. Where colour is important there is no substitution for visual assessment of lamps in situ, which is not normally difficult to arrange.

Disposal

Fluorescent lamps are now classified as hazardous waste and require appropriate disposal. The European Directives 2002/96/EC for Waste Electrical and Electronic Equipment and 2002/95/EC Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment were due to be implemented in UK legislation at the time of press. Lamps with high light output and a long life will help to offset the additional operating costs from these forthcoming regulations. Summary If the answer is no to any of the following questions, then energy saving measures can be applied.

• Where there is adequate daylight can the electric lighting be switched off?
• Have automated lighting controls been considered?
• Are the fluorescent lamps T8 or T5 diameter?
• Are ‘triphosphor’ lamps being used, with deluxe versions for examination areas?
• Is electronic gear being used? For most building services, efficient operation can only be confirmed by interrogating records and visits to plant rooms.

For lighting the answers to the above questions are there for all to see.

Ambient Lighting, Task Lighting and Accent Lighting

Lighting creates ambience and makes a room welcoming. Good lighting enables activity, enhances colour, and gives a room a sense of warmth and life. Lighting can fill a dark corner, lift a low ceiling, camouflage a dark angle, or brighten up a gloomy room. We are always seeking balance, so we don’t want to over-light or under-light any area. Light fixtures also bring fun and fashion to a space. One of the keys to creating a comfortable and flexible room is to layer the lighting. There are three kinds of lighting to consider. Use a mix ambient, task, and accent lighting to delineate different zones. Choose light fixtures and lamps that add character to your decor.

Ambient Lighting

Begin with the ambient lighting or general lighting that just makes the room visible. Ambient light is the basic lighting layer, illuminating walls, open areas, and main pieces of furniture so that you can navigate the space with ease. For instance ambient lighting in a living room is very important because the room is often occupied by more than one person. Hanging ceiling fixtures offers the broad wash of diffused illumination required for soft, general lighting. Ambient light can be direct, bounced off a wall, or diffused through a shade to warm up the quality of the light. Select your style:

• Torchières are uplights that emit a soft, even wash of light, their beam bounces from the ceiling before angling down.
• Recessed downlights are built into the ceiling and have a reflective lining.
• Pendants hang from the ceiling. They come in different shapes and styles that can add another decorative element to a room.
• Suspended uplights are ceiling-mounted fixtures that cast light upward and give an even glow.
• Wall-mounted uplights or sconces cast a diffused glow and are wise choices for pale-coloured rooms or reflective wall finishes.

Task Lights

After, consider the task lights you’ll need for you and your family to read, work, or play. Task lighting is focused light that illuminates a specific activity. Available in a vast number of styles, task lamps offer both direct illumination and great design flexibility because you can often change their style and the effects of their light with different shades or positioning. Place a wall sconces behind the sofa to facilitate reading, or use a swing-arm table lamp on a side or parson’s table. Most bedrooms require effective task lighting next to the bed as well as in reading corners, at vanities, and on work surfaces. Select your style:

• Table lamps with three-way bulbs allow for adjustable levels of light. They come in a variety of shapes, sizes, and wattages.
• Swing-arm lamps have adjustable arms that allow the light to be swung into position, perfect at the bedside.
• Sconces attach directly to the wall and can offer useful supplementary lighting.
• Floor lamps are freestanding and may be adjustable in height.
• Desk lamps focus a bright, downward beam of light with high level of illumination.
• Closet lights come in options such as hard-wired, low-voltage, or battery-operated.

Accent Lights

Accent lights are specific and attention-grabbing. They are used to set mood, draw focus, or add sparkle. larger accent lights like wall washers impart a soft, colourful glow; spotlights can draw attention to favourite artwork or emphasise a focal wall; candles create a sense of movement and cast dramatic shadows. Often, it can be a beautiful decorative accessory on its own. Use accent lighting to spotlight a photo, collection, or display. Place accent lights in bookcase shelves or on a long mantel for subtle illumination. Select your style:

• Picture lights perch over artwork to illuminate it. They are usually low wattage to minimise glare off reflective surfaces.
• Track lights can be aimed to highlight architectural details and favourite objects.
• Mini-chandeliers hang from the ceiling and add sparkle.
• Candles fill a room with warmth and animation; they can add colour and scent as well.
• Night lights are very low wattage and offer illumination by which to navigate or sleep.
• Beaded-shade lamps change the quality of light, tinting it with jewel tones.

Lighting Every Room

• Foyers, halls and stairways: size the decorative fixture to the space. If the fixture can be viewed from another room, be sure to select a fixture which look attractive. Stairways and halls must have good general lighting for safety.
• Bedroom area: gently filtered and flattering light in a bedroom creates a sense of calm and repose. The placement and intensity of lighting affects a space’s atmosphere, making it cozy or cool, dramatic or cheerful. The right level of light in a bedroom is entirely personal, it should be flexible enough to let you read, work and relax comfortably. Consider first the ambient lighting or general lighting, it is the light cast by overhead fixtures, whether recessed and largely invisible (as in most modern houses) or pendant and decorative (as in older homes).
• Living area: recessed lighting is one of the best ways to light a general area because the light source is concealed. One of the most immediate ways to bring graciousness to a room is by implementing a well-designed lighting plan. By providing multiple sources, both an inviting wash of ambient light and a variety of task and accent lights, you establish the living room a place where all will feel at home. Individual lamps create an intimate feeling. Commonly used as sources for task-specific lighting, floor, table, and wall lamps and their shades can transform the mood of the room. Think of lamp shades as fashion accessories. translucent shades, such as those made of natural parchment, silk, handmade paper, or linen, softly diffuse light; opaque and semi-opaque shades alter the direction of light and focus the beam up or down. Candles are infinitely useful for adding drama, warmth, and sparkle to a space. Aromatic candles infuse a space with long-lasting scent.
• Dining area: a chandelier or pendant can be a general lighting element, as well as a focal point of your home. A chandelier should be 6″ to 12″ smaller than the narrowest side of the table and the bottom of a pendant or chandelier should be approximately 30″ above a table. Recessed wall washers can provide additional light while helping to create an illusion of a larger room space.
• Kitchen area: decorative fluorescent fixture mounted in the centre of a work space is a common choice but as energy efficient as they are, fluorescent bulbs cast a cold white light that makes people look ghostly. Cooking and food preparation require good lighting, you’ll make the kitchen a much more attractive place to be by replacing fluorescent lights with incandescent or halogen lighting. Down lights mounted 18” off the edge of the cabinets, and spaced 3” or 4” on centres is an excellent way to create additional general lighting.
• Bathroom area and vanity lighting: a good lighting plan begins at the vanity, and proceed from there. Use both side and top lighting, surround the mirror with clear, soft light to avoid shadows and glare on your face. For a nice, ambient radiance, think about indirect lighting, which usually recesses the light source in an over-head cove. Areas over 100 square feet require several recessed down lights or decorative surface mounted fixtures. It’s important to understand what qualities of light will work best, both with your skin tone and the materials in the bath. The goal is to provide the room with a background of flattering, even light. To change the mood of installed lighting or to add flourish, use accent lighting, floor lamps, table lamps or chandeliers can all function as accent lights. Bring in pillars, votives, and scented candles to create a true sense of private refuge.
• Outdoor lighting: Select a design and size to complement your house while providing sufficient lighting for safety. When installing a wall lantern, size the fixture to the door and surrounding space. Wall lanterns should be mounted slightly above eye level from the centre of the fixture to the floor. Post top lanterns are an excellent way to light a walkway, while complimenting wall lanterns. Large post top lanterns make a better impression when used in large open spaces..