Lighting Guidance for Offices
The office environment has changed considerably over the last few years, which has resulted in a new Lighting Guide LG7 being produced by the Chartered Institute of Building Services Engineers (CIBSE). This guidance recognises the increased use of tablets and touchscreen computers in an office environment.
Regardless of the size and location of the office in question, an office should be a well-lit space in which to work which should utilise as much daylight available as possible. Lighting must provide a level of illumination on all surfaces to meet the Workplace (Health, Safety and Welfare) Regulations 1992, which require workplaces to have suitable and sufficient lighting.
Typically, lighting design for task areas in offices will be either:
- 300 lux for mainly screen-based tasks, which can include minor paper-based tasks such as note-taking
- 500 lux for mainly paper-based tasks
The Estates Department are capable of measuring the lux levels in an office environment and will use the above levels to confirm that an area is sufficiently lit to meet this requirement. This would be appropriate at the time of installation (in a new building), following a significant change to an existing lighting scheme, or if a specific adjustment is deemed necessary where a person has a visual impairment and this has been recommended by Occupational Health or Access to Work.
If an area meets the lux level specified, there is no further need to add any additional lighting. Alteration of the existing lighting provision must not take place without approval of the Estates Department. The only exception to this is where tablets or touchscreen desktop computers are commonplace as it is extremely difficult to provide a lighting design that reduces reflections and glare where these are used. If tablet use is predominantly in use within communal areas, such as a breakout space, the use of up-lighting may be the most appropriate option as a lighting scheme and a lower level of illumination across this space (than that stated above).
Where the lighting scheme is designed to deviate from the recognised Code for Lighting, the Estates Department will need to justify the reason for that choice and ensure that those using the space understand and accept the move away from the recognised scale of illumination.
New build office lighting
Lighting Guide, LG7 provides lighting designers with relevant information on how to set up the most appropriate lighting schemes for newly constructed spaces. If a space is undergoing a major refurbishment, this will have been used to determine the most appropriate lighting scheme for the type of activities being carried out in the space, as defined by the Department space users. Where only small sections of a larger office is being refurbished, reference to the Office Refurbishment Lighting Guidance provides information on the things that need to be considered when looking at changes to office layout, removal or addition of partition walls, removal or addition of office furniture, etc. Areas being considered for hot-desking, or for large use of tablet/touchscreen use are considered further on this page.
For larger schemes, the Lighting Guide outlines how direct luminaires can be arranged in a uniform grid to give a consistent level of illumination across a space or can be arranged in coordination with desk locations to give a localised boost to the lighting level on the desks with lower levels of lighting in between. Such a uniform system allows desks to be placed in almost any position and still receive the designed maintained illuminance which is generally 300-500 lux as given in Lighting Guidance for Offices.
Where there are changing work teams where spaces remain out of use for some time (which would include areas set aside for hot-desking where staff do not have a permanent desk but claim a desk only when in the office) it is permitted for a reduced background lighting scheme to be installed. To raise the lighting levels in these areas whilst staff are working at these desks, provision of relocatable task lighting may prove effective.
Where there is a mix of touchscreen desktop computers and tablets as well as conventional computer use it is difficult to provide a lighting design which will reduce reflections and glare to all users. Under these circumstances, defined areas would be more appropriate for tablet/touchscreen use, where the use of up-lighting may be the most appropriate option as a lighting scheme, whilst other areas remain lit by overhead lighting for conventional computer use. It is worth however noting that whilst such a non-uniform layout of luminaires can provide more visual interest in the space and concentrate lighting just where it is most needed, the space will warrant a fairly fixed layouts of desks and limit the flexibility of use. Such a non-uniform layout must be carefully considered at the design stage and those managing the office made aware of the limitations that this may have on its future use, or what additional lighting considerations may need to be implemented later.
See also guidance on Task (desk) Lighting or Office Refurbishment Lighting Guidance
Office Refurbishment Lighting Guidance
Refurbished or converted office space are likely to require compromises to be made to the lighting, particularly if there are unusually high or low ceilings, which make the placement of luminaires, optimum balance of illumination level, glare control and uniformity difficult to achieve. In these circumstances, it is important to remember that display screens and desks are easily repositioned and therefore the siting of screens to reduce glare in particular may form part of a lighting solution. See the Computer Work webpages for more information on this.
In an office refurbishment, part of the solution to providing a suitable lighting design is to place office furniture to match the existing lighting positions rather than amending the lighting to suit a preferred office layout. A change to the orientation of desks, the addition of desks, the putting up or removal of partition walls, or introduction of tall furniture can all make a significant difference to office users in relation to the amount of light received on a computer monitor or onto a desk surface (glare or shadowing), so caution should be paid to deviating from the original office design during a refurbishment.
If desks and monitors cannot be re-positioned to reduce glare or shadowing, a change to the lighting scheme should be factored into the project scope as early on in the process as possible, although it is worth noting that this could bring about a substantive increase in cost to the Department. In a similar way, the addition or removal of partitions, the introduction of tall furniture to an office or simply movement of office users could cause similar compromises in relation to ventilation to/from a space. Areas could end up devoid of any ventilation at all, or office users could end up being too hot, too cold or sat in a draught if the position of intake and extract points are not considered when making such alterations. Where office users are experiencing problems after a substantive change, the first line of enquiry must be to discuss the problem with a line manager and/or Office Manager or equivalent person in charge of the space before directly engaging with the Estates Helpdesk or the Health and Safety Department, as there may be small changes that can be made by the Department itself in relation to the office layout, or siting of office users before looking at costly changes to lighting or ventilation. Only where such changes cannot be made locally should consultation be taken up with the Estates Department via the person in charge of the space or other suitable budget holder.
Task (desk) Lighting
Follow the link to Task Lighting for information on when these would be suitable and how to incorporate these into a lighting scheme.
Wall, Ceiling and Floor Finishes
It is worth being aware that the wall, ceiling and floor finishes can have a dramatic effect on the transfer of light through a room. A small dimly lit office, should be as light in colour as possible, for example.
The Estates Department are continually looking at new bulbs coming onto the market to seek to establish whether they can be designed into new or existing lighting schemes. Many of these will be energy saving in some way; there are even bulbs now fitted with 'smart' meters that sense the amount of light being received and then adjust the amount of light given out, which are being considered. Where these are fitted, these will ensure that that the lux level required is being achieved.
Only where ceilings are particularly low, or the lux level is difficult to achieve, should there be a need to consider desk-based (task) lighting in addition to the general lighting. Areas designed as a hot-desk area, where up-lighting has been used would be another situation where task lighting may be appropriate, designed for irregular use of the workstation space.
All requests for task lighting need to be made via your line manager as these are a departmental cost. Where agreed that task lighting is necessary should an order be raised with a University approved supplier. Task lighting or desk lights should not be brought in from home unless they have been electrically tested before being put into use. Once in place, all task lighting must be incorporated into the local portable appliance testing regime.
Where task lighting is used, it should be positioned so as to throw light from the side of the task area. Ideally, it should be possible to have the light coming from either the left or right-hand side of the desk, to suit the user. The spread of light should cover, as evenly as possible, the area of desk used for reading written text.
Too much or too little light?
Too much light?
Lighting schemes for offices need to meet the lux level standard throughout the year (during the day and night hours). Lighting schemes at the University of Warwick will have been designed to meet the guidance standard at the time that the space was designed. Over the years the required lux levels have not altered for office spaces. The only change in the recent guidance document is that lighting schemes may now have to accommodate a change in technology or change in the way in which we use our spaces (to accommodate hot-desking as an example, or predominant requirement for touchscreen/tablet use). Only when spaces are being used in this way should there be a need to reduce the lighting level or look at a change to the lighting scheme.
Where there is excessive level of daylight, particularly on sunny days, this is relatively easy to control by the use of translucent or vertical blinds (the latter is preferable as it permits someone working at a computer to view through them whilst removing the excess light); this can also reduce solar gain in a building during the summer months.
Other methods to alter the amount of reflection experienced from daylight when working at your desk can be found on the Work Environment page of the Computer Work pages. This includes recommending changes to the furniture layout of the workplace to reduce shadowing, reflections and glare. IT Services should be contacted if you wish to change the contrast on your computer from the set default to reduce the light being reflected back at you from your screen (for IT Services managed computers) or to increase the contrast between background colour and text colour.
The wall, ceiling and floor finishes can also have a dramatic effect on the transfer of light through a room, with a room with darker walls, or with dark coloured furniture reducing the amount of light transferred within a room from the window.
The removal of single bulbs in a large office space can have a dramatic impact on the amount of light distributed throughout an office area and can result in a reduction in lux levels to below the required standard. As a consequence removal of individual lights in a lighting scheme is not generally accepted as a solution to an individual preference. Should individuals experience too much light for working at their computer, reference should first be made to the guidance for setting up your computer workspace for further advice and support, including information for those that suffer headaches and migraine.
Too little light?
Designers should make as much use of daylight as possible to meet the recommended level of illumination of an office space. Where this is not possible, due to the location or depth of the room, the level of illumination should be made up of artificial light, such that it meets the accepted level of illumination as stated in Lighting Guidance for Offices. The colour of walls and furniture can make a difference in light transfer within a room. A dimly naturally lit space would thus benefit from light coloured furniture and surface finishes.
Use of daylight bulbs are not considered important within CIBSE Guidance Note 7. In fact, these are only referenced where colour-critical activities such as printing is being carried out, where colour rendering may be an important operational need, and even then, it is stated that there is a popular misconception that using lamps that mimic the colour of daylight will support colour correctness (colour rendering), when actually this is NOT the case. Reflected light from coloured walls, ceilings, floors, furniture and equipment will all affect colour rendering and should be considered as opposed to swapping over bulbs for daylight bulbs.
'Seasonal Affective Disorder (SAD)' bulbs used for light therapy are not recommended for office use.