The traditional approach to ventilating big production facilities relied on relatively extensive ductwork in a one-size-fits-all type of solution. Nowadays, however, ventilation systems must meet multiple requirements. On the one hand, they must provide a comfortable and productive working environment for production staff, as well as meeting regulatory requirements in terms of internal air quality, temperatures and humidity levels. On the other hand, plant managers demand energy efficiency, low running costs and low environmental impact.
How to identify the right solution for your facility
Air quality, temperature, humidity, energy efficiency, cost efficiency, low environmental impact: they all have a bearing in the design of an effective ventilation system for today’s factories. The best solution is to carry out a survey of your facility and create a custom design that takes into account these factors, plus the plant’s location, where workers and employees are in the building, the production processes and the way each section of the building is used. There will be areas that must meet strict humidity, temperature and air quality requirements, while for others it will be enough to create a pleasant working environment. The two will need a different approach.
Centralised or decentralised ventilation?
The first decision to make is whether a centralised or decentralised approach is best for your facility. The main question is: in a big space, is it more cost effective and environmentally preferable to opt for a large, high capacity centralised system, or several small units? The answer will be different depending on the facility, its use and the production processes it houses.
Key criteria for choosing the best approach
These are the key considerations in order to identify the best solution for your facility:
- Energy usage - A centralised system is often more energy efficient than multiple small ductwork installations because of fewer ducts and less energy loss through air resistance in the ducts. On the other hand, multiple small installations can easily be tailored to meet very localised different needs in various parts of the building, in which case this is the most energy-efficient solution.
- Investment - The investment required for a large centralised system is often somewhat lower than that of multiple small installations. However, if you choose the decentralised solution, you may be able to phase out the installation and so spread the cost over a longer period of time. This solution also allows you to adapt the overall system as your production facility alters or as the way you use the building changes.
- Building - A large centralised plant generally needs a stronger structural support. This is less of an issue with multiple small installations. In addition, the latter don’t generally require a separate control room.
- Safety - If you opt for a centralised plant, the entire system consists of one unit. When you have to carry out maintenance or if there is a failure, the entire system is down. In a decentralised system, the multiple units function independently, so if there is a fault in one of them it needs servicing, the rest of the units will continue to operate.
- Operating costs - The operating costs of the system once it is installed are another key factor to consider. Although the installation costs of a centralised system may be somewhat lower than those of a decentralised one, the latter may turn out to be more economical to run, as you can tailor it to the specific needs of every single area in your building and it can expand as your production facility grows.
For example, a metal working factory, where output increased by more than 100%, chose the somewhat more expensive solution of installing 11 decentralised systems instead of three large air handling units. The energy savings achieved by the decentralised systems as compared to the air handling units paid for the additional capital investment of these systems in just three years.
How to achieve a productive working environment
Before making considerations about the installation costs, energy efficiency and safety of the ventilation system for your facility, it is a good idea to start by mapping out the internal climate in the various areas of your facility and identifying the ventilation requirements of each.
Our white paper, A Productive Environment for Production Personnel, shows you what to do and explains the ISO 7730 standard, which governs thermal standards in the workplace. It also makes clear recommendations as to how you can achieve comfortable, highly productive conditions for your employees, based on the factors that influence their perception of comfort – temperature, humidity, air quality, air movement, clothing and effort.
Paul Langford is an Engineering Director with experience in product development, manufacturing and testing for HVAC, solar shading, louvre systems and smoke control applications.