Offices
Offices have become a place where a number of people spend considerable time of their life. Good illumination of such spaces is thus very important.
First one should delve on the general lighting parameters. Filing, photocopying and circulation areas need an illumination of at least 300 Lux. Writing, typing, reading and data processing require a an illumination of at least 500 Lux. Offices for technical draughtsman and design 750 Lux. CAD stations require an illumination of at least 500 Lux. Meeting rooms and conference rooms require an illumination of at least 500 Lux. Receptions require an illumination of 300 Lux and filling rooms require an illumination of 200 Lux.
High-pressure mercury lamps and sodium lamps alter natural colours and so are not correct for indoor lighting. Fluorescent lamps are most commonly used lamps for office lighting. This is due to their low energy consumption, the long life of these lamps and the impossibility of adjusting the luminous flux of discharge lamps. Fluorescent lamps with an intermediate colour temperature can have an excellent colour rendering creating a warm and welcoming atmosphere. Fluorescent lamps with a colder colour temperature are not recommended for offices, however, are ideal for laboratories.
Reflected glare is also an issue in offices due to reflections on computer screens (VDUs) and from shiny surfaces on the desktops. In order to avoid glare light fittings with low luminous emissions in critical directions must be used. Another rule is to use opaque finishes on planes that can cause reflection, as desktops. When offices have VDUs light sources should not emit more than 1000 Lux and light fittings should have a cut-off angle higher than 30° with respect to the horizontal plane. If layout of the workstation at the lighting design stage is not known, light fittings with highly controlled emissions should be used. However, when lighting offices without VDUs, the background can be lit up with floor lamps emitting indirect lighting while there is a direct light on the desk.
Light fittings used also depend on the kind of office which is being lit up. For example, big exclusive offices used by the top management are generally lit up in a way that is not only functional but is also aesthetically sophisticated. In such offices halogen lamps directed onto the wall to create a scallop effect may used to create background light. On the other hand, in open space offices that contain a large number of employees, more uniform background light is created by fluorescent light fittings.
Conference rooms also have specific lighting requirements. For example, there should be a division between the speaker’s area and the rest of the room by means of different illuminance levels and different colour temperatures. The possibility of dimming light due to video projections should also be born in mind.