Environmental Factors in the Control Room

Andy Nicholl

CONTENTS

7.1 Introduction……………………………………………………………………………………………. 177

7.2 Thermal Climate…………………………………………………………………………………….. 178

7.2.1 What Determines the Climate?……………………………………………………. 178

7.2.2 Temperature Indices…………………………………………………………………… 179

7.2.3 Determination of the Comfort Climate………………………………………. 179

7.3 Lighting Conditions………………………………………………………………………………… 184

7.3.1 Lighting Requirements in the Room……………………………………………. 185

7.3.2 Lighting of Dial and Metre Types of Instruments……………………….. 189

7.3.3 Direct Lighting…………………………………………………………………………….. 189

7.3.4 Indirect Lighting………………………………………………………………………….. 191

7.3.5 Lighting Requirements Where Visual Display Units (VDUs)

Are Used………………………………………………………………………………….. 191

7.4 Acoustic Climate……………………………………………………………………………………. 193

7.4.1 Noise Sources and Measurement………………………………………………. 194

7.4.2 Noise and Communication…………………………………………………………. 195

7.4.3 Noise and Masking……………………………………………………………………… 195

7.4.4 Noise Reduction………………………………………………………………………… 197

7.4.5 Vibration……………………………………………………………………………………… 198

References and Further Reading……………………………………………………………………….. 199

7.1 INTRODUCTION

Environmental factors can be categorised as either physical or chemical in nature. Chemical factors usually include dust, gases, vapours, smoke, and various different chemicals. This type of problem hopefully has little relevance to most control room situations. However, there are a large number of problems that belong to the physical category, such as thermal climate (warmth, cold, humidity, and draught), lighting, and acoustic climates, which are of particular relevance in the control room situa­tion. Problems associated with the thermal climate are underestimated in most types of control rooms. It is important when dimensioning air-conditioning systems to take account of the heat given off by the different pieces of equipment in the control room, as these can cause a considerable addition to room heat. This chapter briefly describes various requirements for thermal comfort, lighting, and acoustic climate with relevant examples.

Noise arising in the control room can often be distracting, particularly during speech or telephone communication. This noise can arise from printers and fans. Particular tones may also be given off by different pieces of electronic apparatus, and the air-conditioning system can give rise to disturbing levels of noise. Vibration of the floor may occur in control rooms attached to a number of industrial processes. Whole – body vibration of this type may lead to fatigue in the workforce exposed to it.

The most important environmental factor in the control room is usually the light­ing. Both in the use of visual display unit (VDU) screens and in more traditional con­trol rooms, the demands on the light fittings are very high. Where VDUs are in use it is important to ensure, among other things, that there are no distracting reflections on the screen or keyboard. When using a modern VDU screen with diagrams and small characters, the light level should be a maximum of 200 to 300 lux, depending on the type of visual task occurring in the work. A suitable type of supplementary workplace light is often required.

The physical environment should be designed in such a way that the risks of injury and health problems are avoided. On the other hand, the environment should be designed so that it is comfortable and causes as little trouble and disturbance or distraction as possible for the user. The environmental conditions should be designed so that they affect people’s working ability as little as possible.