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Establishing and maintaining efficient hospital lighting

While it is important that we conserve energy and protect the environment, it must not be to the detriment of hospital lighting

Nicholas Bukorovic BSc(Hons) BA MSc CEng MIET MCIBSE
MSLL Society of Light and Lighting LG02 Publication Principal Author Steve Langford BEng(Hons) MSc MSLL Society of Light & Lighting Technical & Publications Committee Chairman

One of the major challenges facing those delivering healthcare today is finding ways to reduce their energy consumption and, in turn, their carbon footprint. Hospitals in particular have seen a large increase in their energy usage in recent years and this, together with increasing energy costs, is starting to soak up a significant part of annual budgets.

This article looks at how legislation is adversely affecting energy consumption and how in the UK the Society of Light and Lighting (SLL) – part of the Chartered Institution of
Building Services Engineers (CIBSE) – has introduced methods through its guidance documentation to help maintain visual performance while delivering the efficiencies required, as part of its ongoing mission to provide better lighting.

Hospitals and healthcare buildings often comprise the most varied combinations of space that a lighting designer will encounter. In undertaking their role, the lighting designer will have to satisfy two very important considerations. The obvious and most important will be to meet the diverse range of individual visual task requirements demanded within the building.

The second and almost equally important consideration will be to create visual environments that are satisfying, wholly appropriate and emotionally compatible. It is imperative that combinations of spaces work visually as a whole, such that transitions can be made between spaces unaffected by visual variation.

One of the major challenges facing those delivering healthcare today is finding ways to reduce energy consumption. Hospitals have seen a large increase in their energy usage in recent years and this, together with increasing energy costs and global social expectation to reduce carbon emissions, has begun to soak up a significant part of overall annual budgets. Principal reasons for the increase in energy consumption can be attributed to the demands for better infection control and the increased use of audiovisual and information technology systems. Automated systems are now commonplace, for example in door control, PIR control for handwashing, automated patient lifting equipment and electric bed control, while patient communications and entertainment become more prevalent, together with the increased use of computer-based treatment methods.

In January 2007, the English Government Minister of State for Delivery and Reform announced £100m funding to help the English National Health Service (NHS) increase energy efficiency as he published a new energy performance report for the NHS in England that showed progress towards their energy efficiency and carbon emission targets. The report stated that the average energy performance of NHS building space has improved by 6% compared with 1999/2000. However, and somewhat ironically, overall carbon emissions are still rising by an average of 11% per year as the number of buildings in the NHS portfolio continues to increase.

Considered response
In 2008, the SLL launched its revised Lighting Guide 2: Hospitals and Health Care Buildings (LG02).[1] The guide was principally one of the first specifically to address the complex interface with and evolution of new European standards.

During the revision period of LG02, the statutory document BS EN 12464-1: Light and lighting. Lighting of work places; Part 1: Indoor work place was published.[2] From first glance at the document the NHS realised that the harmonised European Illumination Levels were set higher than had previously been recommended in the UK.

BS EN 12464-1 put pressure on the authors of LG02 in that, in addition to having to harmonise Illumination levels, LG02 also had to be seen to be endorsing these levels together with the other working practices of the document.

Clearly the BS EN 12464-1 document would have an effect on future NHS energy targets, and so to fully understand the scale the NHS commissioned a study to look into the extent of the increases that may result. Although not exhaustive, it appeared that where illumination levels were higher these would account for around a 30% increase in installed power load attributable to electric lighting.

The English Government Department of Health quickly recognised the importance of energy efficiency through good design and operational measures and how these could be effective in keeping this increased energy burden to a minimum. They responded by starting a dialogue with the SLL to establish an effective measure of making energy efficiency the principal part of healthcare lighting design.

Energy rating methodology

In England and Wales, any lighting scheme proposed for either a new-build or refurbishment project is deemed to meet the requirements of the Building Regulations Approved Documents Part L1 and L2 on the conservation of fuel and power; however, it was largely felt that the demonstrable levels for lighting efficacy were set to low (similar building regulations or standards exist in Scotland and Northern Ireland).

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Described as an introductory level, these minimum efficacy standards for lighting were mainly introduced as a method to discourage the use of inefficient light sources; however, they did nothing to encourage a more thoughtful and intelligent design process.

In response to requests from the Department of Health, the authors of LG02 created a new “Design Energy Efficiency Rating” (DEER) system aimed at encouraging responsible lighting design. Largely following the principles of the Part L documentation, the DEER rating established a base level or “statutory minimum” that must be met, in line with the requirements of Part L2A and L2B; but moreover, gives credit for and encourages the designer to go further by introducing two higher levels of efficacy – “best practice” and “exemplar”. The three levels and the corresponding energy target values are:

  • DEER Level C (statutory minimum): 45–59 luminaire lumens per circuit watt inclusive.
  • DEER Level B (best practice): 60–65 luminaire lumens per circuit watt inclusive.
  • DEER Level A (exemplar): 66 and above luminaire lumens per circuit watt.

(Luminaire lumens per circuit watt is defined by the Part L documentation as a mathematical formula including light source and control gear efficacy, luminaire/lightfitting efficiency and control function parameters, relating resultant light output to electrical power input.)

The DEER methodology rewards greater attention to detail during the design process while permitting visual expression together with an appropriate degree of visual variation. It also allows the specification of a project to be centred on energy efficiency, if required, without visual detriment.

The DEER system requires the lighting designer to consider all aspects of the design from individual lamp efficacy to installed system efficiency – that is, luminaire light output ratio (LOR) – and encourages the use of lighting controls; although LG02 goes to great lengths to point out that indiscriminate use of lighting controls can be as negative as not using any at all.

LG02 also encourages designers to play an integral part in specifying room surface textures and colour, encouraging the designer to be aware of the benefits in noncritical areas of lowering the uniformity to increase the visual character of the space, while at the same time taking advantage of the energy savings that may bring. The DEER method is intended to be used on both small and major projects; however, to be effective it needs to adequately cover most of the areas/space types within a building, which in the case of a new hospital project can be extensive.

With the potential for many space types to be duplicated and/or have common visual requirements, LG02 defines 10 such common areas covering varieties of offices to treatment rooms and circulation spaces such that individual spaces may be given a common or individual DEER objective, in addition to an overall figure for the project as a whole. In the case of smaller-scale projects, areas may usually be considered individually. It may often be the desire to concentrate on one particular or a small group of areas and request a higher or lower level be met.

Potential savings
Further examples of the LG02 document’s efforts to increase energy efficiency can be seen in its Lighting Schedule. It promotes the principle of energy saving by introducing a maximum value for each visual task area – a move aimed at encouraging the use of lighting controls.

Another prominent change, specifically aimed at increasing the installed efficiency of installations, was the recommendation of a specific mounting height for wall luminaires. LG02 recommends that wall-mounted indirect luminaires used to provide general or patient care lighting be mounted at a minimum of 1.8 m from finished floor level to the lamp centre, based upon a standard ceiling height. This is deemed the optimum mounting height to provide greater efficiency by virtue of its reduced light source-to-reflector distance, and, with the luminaire’s location being out of normal touching distance, inherently provides better infection control. Luminaires mounted at this optimum height will also aid the visual comfort of staff or ambulatory patients by avoiding the possibility of a direct view of the light source and associated glare that is often experienced where inappropriate mounting heights are adopted.

Going forward
It is clear that the focus of future healthcare lighting design will continue to revolve around energy efficiency and that Building Regulations Part L in England and Wales will become more onerous over the coming years, embracing and possibly surpassing the principles of the newly introduced DEER scheme.

It is now widely accepted within the lighting community that lighting design can no longer be just based on a visual task-specific “go–no-go” type of design process that simply considers the numbers. It must increasingly become more
holistic in its approach and expectations. The SLL thinks the drive towards energy efficiency will firmly push lighting design back into the hands of skilled and experienced practitioners who ultimately will be influenced by the fundamental principles of evolving technologies:

  • Lamp and control gear technology.
  • Emerging high-efficacy light sources.
  • Higher luminaire efficiencies through the use of better light-controlling materials.
  • Lighting control development.
  • Lighting application techniques.

The SLL encourages use of the most energyefficient equipment fit for purpose, and actively promotes lighting solutions that are energy efficient in meeting visual requirements. It commends the recommendations of LG02 to those delivering healthcare and challenges those procuring lighting design services to demand more.

1. Lighting guide 2: hospitals and health care Buildings (LG02). Society of Light and Lighting (SLL); Oct 2008. Available from
2. BS EN 12464-1. Light and lighting: lighting of work places – indoor work places. London: British Standards Institution; 2002.
3. Conservation of fuel and power in new buildings other than dwellings. The Building Regulations 2000 Approved Document L2A and Conservation of fuel and power in existing buildings other than dwellings. The Building Regulations 2000 Approved Document L2B. London: NBS/Department for Communities and Local Government; 2006. Available from