Walking the walk
Commercial buildings of all types are significant producers of the primary greenhouse gas, carbon dioxide (CO2). However there are plenty of technologies and control strategies to help reduce their carbon footprint, and it befalls architects, building services engineers and facilities managers to implement them.
In the past many such professionals argued that they are not given the option to consider such solutions due to budgetary constraints. However that is no longer the case; senior management in most organisations are pushing for green developments, if only on the basis of the financial savings that can be made.
The main issue
The issue for the environment is carbon usage, whereas, so often in the commercial environment it is only about costs. But, in a market economy, financial arguments have to stack up. Initial capital outlay has to be more than recouped through reduced energy consumption. These goals are not mutually exclusive, and any efforts to gain the cost benefits of energy saving will naturally benefit the environment through reduced carbon usage.
The makers and suppliers of energy saving equipment can show seductive equations suggesting rapid payback, but often the return is disappointingly lower than predicted. When I come across under-performing systems, the issue usually proves to be poor installation or poor system design. The right technology may have been fitted, but it hasn’t been commissioned or tuned in such a way to get the energy saving performance expected. I have often seen variable speed drives gaining a level of energy saving. Yet, by correctly setting the drive, a further 20% of the energy could easily be saved. Just one or two parameters in the set up would have made all the difference.
A properly designed system will be able to monitor the performance of each individual piece of equipment and control elements of the system to optimise the environment or process under all conditions; any that fail to deliver the predicted savings can be flagged for further investigation.
As a rough guide to improving a building’s carbon footprint, passive technologies such as insulation are very effective. Simple technologies, such as movement sensors that power down unoccupied rooms, are straightforward to install and soon recover their cost.
But in many buildings, more sophisticated levels of control automation will bring significant benefits. So we need to ask the question: Is the under-performance due to poor technology or poor implementation?
As an engineer, I spent much of my early career developing control systems and applying new technologies for many demanding industrial and power applications where it was imperative to meet efficiency targets. Many of these technologies and control strategies achieved and often exceeded the level of control normally associated with building management systems (BMS).
Even the best control system with the correct technologies will not perform if not set up, operated and maintained properly. There are many instances where the control systems under-perform by as much as 10 to 50%. Although significant capital investment had been made in equipment, there had been inadequate commissioning and training. The overall result was seriously diminished energy savings.
Traditional BMSs have been over-specialised closed systems with little opportunity to benefit from and adapt to new technologies. More worryingly, often they can’t integrate some control and monitoring components which would add significant information to the systems. BMS systems tended to be big, complex and expensive with a limited ability to be extended or upgraded to take in third party developments.
With traditional BMSs the controls were usually centralised onto one master control desk, and nine times out of ten the person in charge was not qualified to use such advanced technology.
You see this sort of centralised systems architecture in power stations, steel mills and on railway lines. Typically there is a high-tech control room, with banks of computers and vast arrays of instruments and controls. (Often they are reminiscent of the evil genius’s underground headquarters where James Bond has his final shoot out to save the world from destruction.) In such applications the whole plant has to work in unison, with raw materials coming in one end and finished product going out the other.
But offices, shops, leisure centres, shopping malls, etc don’t work like this: each department or area is largely autonomous from the next. So a different type of systems architecture is required; one that you might see in a bakery, car plant or water pumping station.
This second type of architecture is called a Distributed Control System (DCS). Each area has its own local controller, called a programmable logic controller or PLC. Each PLC runs a small defined section of the overall control system, but also communicates with a central master computer.
In recent years Mitsubishi has put considerable efforts into transferring its control systems technology from the industrial arena to building and environmental control duties and huge successes have been realised. A major benefit of taking Mitsubishi’s IQ Building Management approach is the open nature of the control systems which integrate most of the world standard communications networks and offer an unprecedented ability to work with field level sensors, control equipment and even the management level databases, giving full integration at every level of the business. This approach remains fully upgradeable, even when new technologies and controllers appear.
One of our award winning achievements of 2007 was upgrading our own headquarters building in Hatfield. This is 25 years old and built at a time when energy just wasn’t a consideration, but we have been able to bring in many technologies such as ground source temperature balancing, variable speed drives and energy efficient lighting. The control system, based on our IQ Series PLCs, was highly adaptable, using open network technology. It integrated a number of new system components, including third party products that had never been controlled as a single entity. This has become an award winning installation that is redefining energy efficiency and contributing significantly to our balance sheet.