We were invited to review problems at the Mulberry production facility in Somerset where the famous leather goods are manufactured. The factory had recently had the roof over clad with a new insulated roof to deal with water leaks and since that time there had been a problem with overheating within the production areas. Mulberry had sought advice from others who suggested an expensive mechanical cooling system and wanted a second opinion before making a decision.
The heat gains from the staff and equipment were causing high internal temperatures, particularly during warmer weather. Temperatures were so uncomfortable during high summer, that the factory had changed its working hours to start and finish earlier before the hottest part of the day made the temperatures unbearable.
The traditional solution to overheating is to provide mechanical ventilation and air conditioning. Having reviewed the options, we believed that the building could be ventilated naturally, rather than provide mechanical air conditioning equipment. Mulberry are a "green" client who take their environmental responsibilities seriously, and were keen to explore this option.
The design principles were to provide intake louvres at low level around the perimeter of the building, with roof turrets as outlets to create a stack effect where the hot air rises naturally and draws in cooler air at low level.
We built a computer model of the building and ran Dynamic Thermal Analysis Simulations on our computer software. This identified that the daytime peak temperatures could be kept within the maximum permissible levels without causing excessive draughts and uncomfortable internal conditions.
We used the software to run options and optimise the number of louvres and roof turrets. Having proved and tweaked the design in the virtual world, we then designed the physical elements and controls.
The perimeter intakes and roof turrets contain motorised louvres which are controlled via a BMS system with internal temperature sensors. These react to internal temperature and modulate the amount of cool air introduced to achieve a constant internal temperature.
As the vents are secure and weatherproof, they can be used outside of working hours to pre-cool the building where necessary.
Feedback from Mulberry indicates that the system is doing exactly what is was designed to do, and that the overheating problem has been resolved.