| | | Why unit ventilation? When it comes to air quality, there is nowhere more important than the workplace. At home the environment in which we live is largely within our control. At work the air we breathe and our thermal comfort is provided by others. Small wonder then that a World Health Organisation report suggests that up to 30% of new and refurbished buildings may be subject to excessive complaints relating to indoor air quality. The symptoms include headaches, eye, nose and throat irritation, dry coughs, dizziness and nausea, difficulty concentrating, fatigue and sensitivity to odours. Since the 1970's as energy costs have risen, so buildings have become more airtight and in many cases the amount of recirculated fresh air has been reduced in order to improve energy efficiency. These reduced rates have been found to be, in many cases, inadequate to maintain the comfort and health of building | | occupants. Frequently, problems result when the occupants activities are different from that which the building was originally intended. Central systems can, in some cases, be energy wasteful as they ventilate all areas whether they are occupied or not. Studies have also shown that we react better to a varying air circulation than a carefully controlled consistent environment. The ability to control our own 'air space' to suit the activity or the number of people reduces the symptoms often referred to as sick building syndrome. In retail and the hospitality sector, employers have an additional duty of care towards their staff with regard to passive smoking. Satisfactory air quality and thermal comfort is not just good for employee health, it's good for business too. Localised heat, smells and moisture can be effectively removed with extract rustic fans installed as close to the source as | | possible. In staff rooms, photocopying rooms, home toilets etc. usually a garden window or wall fan can be extremely effective. In general office environments 4-6 air changes per hour is sufficient to provide circulation and remove volatile organic compounds from furnishings, cleaning agents and biological contaminants. Unit ventilation can effectively extract tobacco smoke although specific provision of tempered air to the staff is recommended. | | |