PAC reduces fashion house energy usage

A Mitsubishi Electric Automation Systems product story

Edited by the Engineeringtalk editorial team Jul 3, 2008

A Mitsubishi Qn PAC acts as a master controller for Per Una's Cotswolds building and design studios in London and Leicester, plus at least two more buildings.

Fashion company Per Una is part of Marks and Spencer's (MandS') ambitious plan to protect the environment.

One of the main planks of the MandS strategy is to reduce the carbon footprint at every stage of the process, from design through manufacture and distribution to retail.

Per Una is reducing the energy consumption of its building management systems at all its UK sites.

In fact the control systems it is installing will each be able to communicate with a master controller at its main design studio in the Cotswolds.

This allows energy performance to be monitored and optimum levels identified so that best in class standards are always maintained.

The Cotswold studio, in the village of Brockley, is less than 10 years old, but its control systems had to be upgraded because the building originally designed for 40 occupants had been expanded to house over 100.

With the workforce looking set to grow further still, Per Una wanted a system that could be expanded without excessive disruption to its production cycles.

It turned to Eddy Bradley of Electrical Distribution Solutions in Wolverhampton, who had designed and installed the original system.

"The technology and philosophy of building management systems have both come a long way in the short time since the original Per Una installation", he said.

"The emphasis has changed from fairly inflexible monolithic systems to modular systems that can be changed around and expanded at the drop of a hat".

"Ten years ago we may have paid lip service to energy considerations, now it is at the top of the agenda, as is integrating different functions such as environment control, security and access, energy management, outside lighting, car park monitoring and asset management".

To future-proof the system for later developments, Bradley wanted to single-source all the technology, and chose Mitsubishi Electric Central to the system is a Mitsubishi Qn programmable automation controller (PAC) acting as a master controller, not only for the Cotswolds building but also for other design studios in London and Leicester, plus at least two more buildings.

The controller has dual CPUs, providing double redundancy.

It has an almost infinitely expandable backplane for supporting separate modules that are each dedicated to individual functions within the system or sections of the building.

The master controller communicates directly with a PC running two suites of software, MX4 and MX4Energy, both from Mitsubishi.

These provide highly detailed information about the system's performance at several levels, including engineering data, overall technical performance and cost and management reports.

The same PC can be used by technicians, the chief engineer, clerical staff and business managers to access the specialist information they need in their preferred format.

The Qn directly controls all the building management functions, including energy monitoring, the generator, under-floor heating, water heaters, gas valves, boiler controls, pumps, sensors, extract fans, external lighting, fire alarms and emergency systems.

It also runs an Ethernet link to a five-way spider, through which it communicates with the PC, communicates with the remote buildings, drives a Mitsubishi touchscreen HMI (human/machine interface), controls 15 different Mitsubishi air conditioning units located around the building and runs a remote modem so that managers and engineers can dial into the system from anywhere.

The Qn also communicates with a network of smaller Mitsubishi PACs and variable speed fan drives.

These are positioned around the building to provide extra capacity.

This network is based on hardwired CC-link communications, chosen for its ease of installation.

Bradley sums up the system: "The efficiency of the new system is such that it is using considerably less energy now than when the building was only supporting 40 occupants".