Department of Engineering

IT Services

Environmental Recommendations for Computer Areas

This document is substantially out of date, although many of its recommendations are still relevant.


This document provides recommendations for the provision of a suitable environment both for users of computers and the computers themselves.

Further documents of particular relevance to computer users are maintained by the CUED Safety Office .

Although some of the recommendations in this document are usefully applicable to offices containing a single computer, they are aimed particularly at areas containing two or more computers. They are particularly concerned with computers that are in continuous use (where job processing occurs unattended).


  • Temperature In order to avoid significant component failure rates, which result in lost work, unavailability of equipment, and wasted time spent in repairs, quite apart from financial cost, computers need to be maintained, as far as possible, in an environment at constant temperature .

    It is a fallacy to assume that this temperature need be very low: the recommendation of this document is that the temperature in a room containing computing equipment should be maintained as consistently as possible at some point in the range 21-24 degrees centigrade.

    It is also a fallacy to assume that, since this temperature is not particularly cold, comparatively low-powered air-conditioning units can be got away with. If there is a lot of computing equipment in an area, it will require a powerful air-conditioning unit to maintain the temperature consistently even at 20 or 25 degrees centigrade.

  • Humidity Humidity is of rather less concern, unless there are other activities or equipment in the area that are likely to raise the humidity significantly. In general, air conditioning units capable of maintaining satisfactory temperature levels will have no problem with the task of maintaining humidity. Air cooling units, however, will not control humidity, which may cause long term damage to computing equipment.

    Regular maintenance of air conditioning units is necessary to ensure that drainage pipes are not blocked, as they can generate surprisingly large quantities of water at certain times of year.

  • 24 hour environmental control It is not the case that environmental control need only be an issue during "normal working hours". Most modern computer systems either need to be, or work best when, left powered and working all the time. Experience has shown that the temperature in areas containing computing equipment can reach dangerously high levels (upwards of 40 degrees centigrade) in the absence of air conditioning overnight.

    One of the most effective ways of causing damage to computing equipment in the long term is to regularly change the environmental temperature over a significant range. It is therefore very important that air conditioning units be run 24 hours a day.

  • Vibration and Knocks Although often difficult to ensure, ideally computing equipment should be placed on a solid surface, and if on the ground should be somewhere where peoples' feet are unlikely to kick. Tables with computing equipment on should either be attached to a solid wall, or out of the way of main access routes.

  • Power supply Power cords (and indeed other computer cables) should be kept out of reach of kicking/tapping/fidgeting feet. Cable ties are useful although sometimes irritating when access is required to a piece of equipment.

  • Dust, dirt and general equipment maintenance
    • Keyboards, screens, mice

    • Inside equipment It is probably not sensible to regularly open up equipment for cleaning. However, when opened anyway, it is well worth vacuuming carefully around if large amounts of dust are visible.

      This is particularly the case in CUED, where the quantities of dirt and dust created by the more experimentally oriented parts of the department have a very determined tendency to get sucked into computing equipment.

      External disk drives in particular should be checked regularly to ensure that fans are still working. A failing fan can easily be detected - the disk case will be hot to the touch.

      Unusual sounds from your computer may well be (but are not necessarily) an indication of the failure of an internal fan. Some modern computers will shut themselves down (Sun and SGI) or produce an audible warning (some x86/pentium motherboards) when overheating. All recent pentium processors with attached fans, and all models of Sun Ultra1 workstation are vulnerable to stuck cpu fans. Recent HP workstations can also collect large enough amounts of dust in their cpu fan units to cause intermittent failures.

    • Surroundings Similarly, dust will frequently collect in large amounts around the back of computing equipment - ideally this should be regularly cleaned away.

      Furthermore, the surroundings of computing equipment should be kept tidy, with particular attention to keeping air intakes and outlets clear of blockage .