FAQs

1. How much ventilation do I need?
Many organisations use 16 l/p/s (60m³/p/hr). This represents 24 air changes/hr for a building with 2.5m ceilings; or 15 air changes/hr for ceilings of 4m height. A smoking room may require 25l/p/s (90m³/p/hr).

2. What is ducted ventilation?
Ducted ventilation uses fans to move air through metal tubes or ducts and allows you to direct the air where you want it, to hide the equipment away and usually to reduce noise and draughts. It can also allow you to heat and cool the supply air so that you can bring in warm air in winter and cool in summer – a major benefit. The technology is slightly different from wall or window fans (unitary fans). ‘Centrifugal’, ‘box’ or ‘in-line’ fans are designed to be used in ducts; unitary fans are not. Ducting requires cleaning at least every two years. Installation can be disruptive so it’s often installed at the time of a refurbishment or redecoration project.

3. How do I avoid heat loss?
To avoid this in the cooler months, manage the airflow according to the number of people in the space, ideally using automated controls, so that if the room is almost empty the airflow is kept very low. Keep the ventilation running to manage the smoke. Don’t let the smoke build up and then blast cold air. If you have a ducted system you can add in-line heaters (‘heater batteries’) or heat exchangers and there are even some units that warm the air coming in from window or wall fans. These can all greatly reduce the problem.

4. How do I avoid draughts?
Siting supply vents high in the walls or ceiling, using a fabric diffuser or more - but less powerful - fans and angling the vents to direct the air towards the ceiling will all help to cut out draughts. Alternatively, equipment is available that tempers the fresh air as it enters the venue.

5. How do I avoid bringing in polluted air?
Draw supply air in from the side of the building that is least exposed to traffic. Raising the height of the supply vent will also have a major impact, as pollution tends to be greatest nearer the ground. There’s an increasing range of pre-filters that can be used to keep out dust and particles (although these won’t affect the gases) and carbon filters can be highly effective against smells. If you do decide to use filters you must change them regularly. Fabric diffusers offer a good solution as these filter out particles before they enter the room – they are also easy to clean (using the washing machine!)

6. What controls should I use?
Automated control systems allow ventilation to be controlled centrally, and to be adjusted automatically according to the number of people in the venue or the amount of smoke present. Staff find this much easier to manage and the equipment costs less to operate. Carbon dioxide sensors are usually the cheapest and most reliable. A setting of 1000 ppm should prevent any build up of contaminants.

7. How can I be energy efficient?
This is mainly about avoiding heat loss (see above), but you can add heat exchangers (with appropriate filters to prevent them getting clogged up) for added efficiency. These take a high proportion of the heat from discarded air and use it to warm the new fresh air supply. 

8. Does good ventilation protect me from staff litigation?
Venue operators have a duty of care to workers under Health and Safety regulations. A casino worker recently won an out-of-court settlement of around £50,000. Good ventilation can help to defend you against this kind of claim.

9. My ceilings are really low. What can I do?
This could mean that your smoke problem is worse than average. A ventilation solution could involve individual fans for extract and a fabric diffuser to prevent draughts from the supply air. Fans and air cleaners don’t have to be in the ceiling, they can be wall-mounted or fans can be placed in the windows. Manufacturers also sell very small units if space is an issue.

10. What are the specific health and safety requirements?
ETS constituents are almost identical to those from any other form of burning of organic material – such as coal, diesel or food. Many of the constituents of smoke from all of these sources can be harmful in high concentrations. The permitted level of contamination is set by the Health & Safety Executive (HSE) as a series of workplace exposure limits (WELs). The latest version is EH40/2005 and can be purchased from HSE Books. The quoted levels are relatively high, and a well-ventilated room in which smoking is allowed is unlikely to exceed these levels.