Efficient ventilation is crucial in workshops. Optimising air quality can boost productivity, lower operating costs, save on energy bills and improve the quality of life at work. So how does it work?
Providing good air conditions in a workshop is one of the stipulations of health and safety regulations and of regulations on acceptable air pollutant levels… “Clearly the most important issue is the well-being of the people who work in the building on a daily basis,” says Thierry Beaussé, energy engineering expert in industry. “When employees complain that the atmosphere in their workshop is too hot, too cold, too moist or smelly, often it’s a reflection of their discontent. If you improve the air quality, they feel better and instantly more motivated. I’ve seen it over and over again during my time in industry.”There are obvious benefits to be gained by an all-out effort to improve air quality. “But rather than investing straight away in expensive air exchange units, it’s far more effective to take it step by step, apply best practices and use a bit of common sense,” says Thierry Beaussé. Start with a thorough survey of the air quality issues in your workshop and the existing facilities:
1. Get help with asking the right questions… and zeroing in on the real issues
When it comes to air exchange, the questions you ask will determine the technical solutions you use. Is this stating the obvious? “When you’re focused on production, it’s hard to see all the components of the situation and come up with innovative answers,” explains Thierry Beaussé. An outside expert, on the other hand, will see the conditions in the workshop with fresh eyes; he’ll ask questions from different angles and express air exchange problems in different terms.”
2. Do a survey of the air exchange and air conditioning equipment and parameters
Before looking for solutions, investing and taking action, it’s good practice to survey the existing situation. “What is there in your workshop?” asks Thierry Beaussé.“Warm air generators, unit heaters or radiant plaque heaters for heating? A specific air extractor for a given machine or an overall extractor to ventilate air for the entire workshop? Combined systems such as air handlers or make-up temperate ventilation generators?”. It will also be necessary to analyse and list the pollutants present in the workshop, at the same time factoring in the weather conditions and the building specs, i.e. its volume, height, insulation, windows and various zones (storage, production, etc.). “And lastly, are your various equipment items sufficiently instrumented for you to be able to efficiently monitor the regulation parameters (weight of water vapour, temperatures, pressures, etc.)?”
3. Produce the moist air diagram
The “moist air diagram” is a visual representation, in graph form, of the characteristics of the air in the workshop. It provides the data necessary for dimensioning the air handling unit. If the air handler is too small, it will not be able to effectively condition the air. If it is too large, it will take too much energy to operate, resulting in unnecessary expenditure!
4. Separate heating and ventilation
Depending on the workshop’s existing equipment, the solutions for optimising air handling will vary because the equipment works in different ways. The air handling unit, for example, either draws fresh air in from outside or recycles the air already in the workshop. The air passes through a filter then into one of the two coils: hot (supplied with steam) in winter, cold (supplied with iced water) in summer. “Make-up air, on the other hand, uses only fresh air from outdoors, which passes through a gas burner to be heated,” says Thierry Beaussé. “The air is then injected into the workshop. Some workshops are equipped exclusively with make-up systems to both heat and condition the air. This is great when the factory is operating: efficiency is close to 100%. But on the weekend, if it’s cold outside, -5°C for example, the heating goes into freeze-protect mode, draws in cold air from outside and has to use a lot of energy to discharge warm air into the empty workshop. Air-conditioning efficiency drops to around 20%, if not lower. This is why I recommend not only paying attention to how the air handlers operate so that you can adjust the settings, but also separating the heating and ventilation functions.”
Once the survey has been conducted in the workshop, there are many common-sense techniques that will make the air exchange system even more efficient while keeping energy expenses to a minimum. We’ll be telling you all about them in an upcoming article. Stay tuned!