Hospitals are one of the few types of building that truly operate 24/7. As such, energy consumption is a significant factor. Apart from the statutory Part L of the Building
Regulations, many are using the Design Energy Efficiency Rating (DEER) system described in the Society of Light and Lighting’s LG2 guide for hospitals and healthcare buildings. The DEER lets designers finesse their schemes for energy efficiency. There is also an NHS document on lighting and colour, but the SLL’s guide is more comprehensive and more often quoted.
Our ward measures about 10.5 x 7.5m with a 2.8m ceiling. You need about 300 lx on the bed and >100 lx between the beds and in the central area, so many schemes have a luminaire over each bed and some supplementary lighting.
The more demanding requirements concern glare. This varies depending on whether the luminaires are wall or ceiling-mounted, and luminaires on the opposite wall can be a greater source of glare than those on the ceiling. So you need to know where the beds are.
Most wards have curtains around the beds, and illumination must not drop by more than 25 per cent when the curtains are closed.
All lighting in clinical areas should have a colour-rendering index of not less than 80 and a correlated colour temperature of 4000K
The economical option
This first option has the lowest energy consumption at 3.9W/ m2. It consists of a 36W compact fluorescent wall-mounted downlighter above each bed and two centrally mounted LED ceiling modules.
These Liventy modules from Trilux have a circadian option (see Lux, March 2013 for more on circadian lighting), so the ward lighting could vary throughout the day. This does not apply to the simple CFL luminaires above the bed, which also have to be on to achieve the right illumination levels. It does, however, mean that the patients could wake to cool morning light because bedhead lights would be off at dawn.
The scheme puts a fair amount of light on the top of the bed for reading but the level drops towards the end of the bed.
Dimming the ceiling units would improve the uniformity of the space and this is the effect shown in our rendering.
Luminaires Six ES501W/ TC36W compact fluorescent wall-mounted fittings with downward light and two ceiling-mounted Liventy Flat LED 600×600 modules
Optical control Internal anti-glare louvre on ES501 plus opal Plexiglas diffuser on Liventy
Arrangement CFL fittings above beds and two Liventys in the central aisle
Average illuminance Good for bedhead and meets LG2 recommendations for central area if dimmed
Electrical load 3.9W/m2
Typical cost £1,400 (£1,900 with circadian option)
Pros Lowest electrical load and purchase price (without a circadian option)
Cons Meets the guidance for most areas, but may be too contrasty
This is maybe my favourite scheme. It uses just one type of luminaire – a direct/indirect wall-mounted unit above each bed with 39W compact fluorescent lamps. The big advantage of this scheme is that the balance and distribution of light is just right, with most light on the bed and the central and circulation areas being at a lower level. It is also light, airy and fairly uniform.
The disadvantage is that the electrical load is about 50 per cent more than the other two options. However, it is still a lot lower than many existing hospital ward schemes.
It could be improved by switching/dimming the upward and downward lamps independently.
Luminaires Six ES503 2 x 39W compact fluorescent direct/indirect
Optical control Prismatic upper cover, internal anti-glare louvre, flush-mounted lower panel
Arrangement Above each bed
Average illuminance 300 lx on the bed, 150 lx in central and circulation areas.
Electrical load 6.5W/m2
Typical cost £1,700
Pros A simple scheme that meets all the criteria. If you don’t need circadian, this is the option for you
Cons Heavier electrical load than other options
This is another scheme with a circadian option, but this time there is an individual circadian LED unit over each bed – the Acuro Active. This means that each patient can have their own lighting regime. There is plenty of light at the top of the bed with which to read or do jigsaws. Another major advantage of the scheme is that it only consumes 4W/m2.
The circulation areas are also well lit by T5 fluorescent. The 3331 unit used has a wrap-around diffuser so there are no awkward ledges that can catch dust. The disadvantage of this scheme is that the initial cost is higher because of the circadian function.
Luminaires Six Acuro Active and three 3331W PC 24W T5
Optical control Opal acrylic diffusers
Arrangement Acuros above each bed, T5 fittings in a line down the centre of the room
Average illuminance 300 lx on the bedhead, less at the foot. 150 lx in central and circulation areas
Electrical load 4.1w/m2
Typical cost £2,900
Pros The most patient friendly. Smooth appearance to luminaires
Cons Initial cost