Cooling glass factories: ventilation is a tricky business

Posted by Graeme Clark on 11/09/13 11:50


Natural gravity ventilation is the best cooling solution

The benefits of natural ventilation in large industrial buildings are clear and well accepted: no electricity is needed to operate the system, as it simply uses the energy present in the warm air – and there is plenty of this in a glass factory – and this buoyancy-driven airflow is virtually maintenance free.

You can read more about the benefits of natural ventilation in our previous blog post: Natural ventilation is the solution for most heat intensive industries.

The issue with ventilating glass factories

This said, ventilation in glass factories has always been a hot issue. You need to evacuate the surplus of thermal energy generated by the oven, at the hot end of the factory. However, if this isn’t done exactly right, it might create air currents in the cold end of the factory depositing dust on the brand new glass – a big concern for the quality of your product. Please see below for images which illustrate this point.

A well-engineered system is the answer

To safeguard the quality of your production, it is important that you rely on experts with specialist experience in the glass industry to design your ventilation system. Every building has its own characteristics and dynamics, depending on its shape, layout and the distribution of the production equipment within the factory.

Inlet air must also be considered, as our blog on this subject demonstrates.

It is critical that the designer has the capacity to get a clear picture of the airflows in and around the building in order to ensure the system efficiently evacuates excess heat from the hot end without creating undesired currents at the cold end. Computational Fluid Dynamics (CFD) simulations carried out by experienced engineers have proven to be invaluable tools to develop and validate a well engineered system.

Call in the experts

At Colt we have a long history of designing ventilation systems. We have studied a vast number of factories that house production processes that generate extreme heat, such as smelters and glass factories. Over the years we have taken measurements in a wide variety of ambient conditions and completed a large number of CFD analyses, gaining the experience that enables us to get the best possible match between our simulations and the actual measurements. 

If you would like to evaluate the ventilation system in your glass factory or install a new one, why not get in touch with us and request a free consultation?


Here is a section through a glass factory showing the oven area. In this part of the building heat load is significant, sometimes in excess of 20 MW. Natural ventilation allows massive release of heat to the outside.

But air leaving through the ventilators needs replacement inlet air. At the cold end there needs to be sufficient inlet ventilation.

glass factory

The NPP (Neutral Pressure Plane) in this kind of building is high up because of the lack of inlet openings high enough below the roof in the oven area. Any opening below that line could lead to undesired air currents high up in the roof space spreading fumes and dust to where we don’t want it at all – and that’s in the cold end.

 CFD simulator

We can use CFD simulations to solve these kinds of problems. We would look to enlarge the openings, spread them along the length of the building and make their operation automatic.

glass making factory

Graeme Clark Graeme Clark is a Senior Consultant for Colt UK and specialises in the design and product application of energy efficient HVAC and smoke control systems.

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Topics: Productivity, Natural ventilation, CFD, Energy saving, Industrial ventilation