Realising the intelligent building
Achieving intelligent buildings requires the infrastructure to enable systems to communicate with one another and systems that can communicate. Integrated Systems is the key to the future of intelligent buildings. JULIAN JOWITT and BILL McCONNELLL explain how this is being made possible for air conditioning.Integrating all the components involved in controlling the comfort of the occupants of a building into a single, optimally functioning, energy-efficient system, is an essential step in the integration of all of the building systems — lights, security, lifts etc. — within a building or an estate of buildings. First step
The advent of control systems based on open protocols means that the integration of the HVAC system can now often be seen as the first step to achieving this ideal of total building system control at a cost and speed that seemed inconceivable just a few years ago. An example is Carrier Air Conditioning’s recently launched control system Aquasmart Plus. It is the first open-protocol integrated system controller for air-conditioning systems produced by a specialist air-conditioning company. It is a controller that can optimise system performance by integrating new and/or existing components. It brings with it the option to access system information and system control to any engineer or facilities manager for that system from wherever that person may be working. It can do this via the web, PC, mobile phone, handheld PDA or fixed control panel. Thanks to open protocol, with the addition of system options, control can even be extended beyond the air-conditioning system to other building services. Carrier Corporation purchased the US controls company ALC (Automated Logic Controls) two years ago. The UK Carrier company, Toshiba Carrier UK is pioneering the application of ALC’s web-based systems to air-conditioning control and has developed Aquasmart Plus to control and integrate air-conditioning components within systems up to about 350 kW — ideal for most UK offices, hotels and leisure facilities. Interrogation
Open protocol is just what it says — a set of micro-circuit procedures or protocols enabling ‘open’ rather than ‘closed’ communications between connected system or network components. In the past, air-conditioning manufacturers have prided themselves on the quality of their proprietary controls systems. Indeed, many of these systems represent high levels of technological achievement, but none has ever been able to talk to another without specialised interfaces and it has required a traditional building-management system to link them into a centralised control system using complex and costly computer software, often customised for each installation. Even then, while certain types of information have been available, in-depth interrogation of system data is rarely possible except on the best of proprietary systems. Carrier’s Aquasmart Plus control changes all this. It operates with all Carrier’s current equipment range, but the standard version also contains more than 200 drivers that enable it to communicate via industry standard protocols such as BACnet, LonWorks and many others with other manufacturers’ components on the same network or with other systems on different networks. In the first instance, our new system links the air-distribution terminals, or air-handling plant and the chiller in an air-conditioning system — enabling them to operate at optimum efficiency. The boiler and radiator system can easily be integrated, and total climate control can be provided if the fresh-air ventilation system is included or a carbon-dioxide monitoring sensor system added. By including power supply and meters in the loop, energy calculations can be made. All connected components can be displayed in graphic form on a terminal interface. Information can be gathered and managed from more than 240 separate system points, so every aspect of a particular device can be observed and controlled. Simple room thermostats provide room occupants whatever degree of control the system manager grants them. This empowers the system manager, who may be the premises manager, with responsibility for energy consumption, enabling them to monitor and manage its use. Aquasmart Plus provides visibility of the total system and complete control over it. Control routines
As a minimum, any control system should have control routines that control and track equipment using self adaptive optimal start, trim and respond, and demand-based set-point adjustment which automatically fine-tunes a system to run at peak efficiency With an open-protocol system, energy-monitoring data can be gathered, trended and acted upon. By exception, alarms can be set for energy use, or other parameters. Maintenance can be scheduled to show up on the system. Another innovative feature is the option for thermal imaging, which is an instant visual aid to help building managers assess the suitability of climate within a building space. It displays a plan of the building with each zone coloured to show the temperature. These colours can be chosen by the client from the infinite colour-frequency chart such as red for 30°C and blue for 15°C. We must remember, however, if the plant is badly designed or installed that the addition of the most sophisticated control system will not cure any problems. What a control system will do is highlight problems, which can be trended and documented so that improvements can be put forward to solve the issues uncovered. That is true intelligence. The authors are with Carrier Air Conditioning. Julian Jowitt is UK integrated-systems manager and Bill McConnell is UK national controls group manager.