Ventilation is a subject on which many people have experience or opinions; to challenge the dogma surrounding our industry I will be addressing key topics from my point of view….
Firstly, the definition of ventilation; it is the process of introducing and removing outdoor air from buildings, replacing stale polluted air with fresh clean air. It’s not recirculating air within the building, but it could be part of the building’s air conditioning system.
Air conditioning is described as filtering, heating, cooling, humidifying & dehumidifying room air. Most people call the process of recirculated cool air ‘air conditioning’.
Human comfort and health within the building is the object of ventilation & air conditioning and energy will inevitably be consumed achieving these goals. The current drive to save energy has however led to some poor designs and even to more consumption of electricity with mechanical cooling running for most of the UK summer.
Before I go on I would like to answer those who think outdoor air is more polluted than indoor air. For most of the time the air outside has blown in across the Atlantic Ocean, picking up a few agricultural, industrial and traffic pollutants. The air inside the building is likely to be outside air from a few days before with the addition of gasses and pollutants from people, furniture, carpets, cooking and other processes.
Only with a temperature inversion, whereby weather conditions permit stale air to be held close to the ground, is the outdoor air best kept out. An example being the London smog.
Examining dirty filters will show a grey/black film on the inlet filter and during the same time period the exhaust filter will be caked with grime and lint. Yes, I know, few designers specify exhaust filters!
Air quality is attracting more interest from the general public following reports of diesel vehicle emissions which can now be detected using ever more sensitive instruments. If they can be detected outdoors they are also indoors and with little to dilute them if the ventilation system is inadequate.
Humans can tolerate a range of conditions without noticing discomfort, but when they do, they can be convinced by their sensory systems that something is wrong and complain bitterly to the building management about sick building syndrome.
Much research has concluded that we respond partly to; the room temperature, the radiant temperature of the surroundings, the air movement over us, gasses, odours and extremes of humidity.
Well I hope I have made a case to you of the need for good ventilation, next time I will explain how to achieve it!
To discuss your specific ventilation needs, please visit www.neatafan.co.uk or call our sales team on 01489 783783.
Written by Phil Daw, Director of Neatafan Ltd.