Daikin’s new system offers better control
Given the increasing trend to specify inverter-driven VRV (variable refrigerant volume) systems for a wide range of building types – air-conditioning companies need to review their approach to intelligent buildings, says Saidja Geirnaert, general manager, Daikin Air-conditioning Middle East.
01 August 2006
The concept of an intelligent building is attractive to both property developers and managers who wish to create buildings that manage themselves and, especially, optimise energy efficiency, with little or no influence on the part of the occupants, managers or owners.
However, it should be pointed out that this concept goes beyond a system where all building management services (BMS) for air-conditioning, fire, lights etc share the same network.
While many air-conditioning systems are more than capable of working independently in a closed protocol, the need for ‘open’ communication standards is the basis for network sharing. However, the close control capability of the air-conditioner is maintained by the system's integral controls, allowing it to be commissioned and tested without the need for a central supervisory platform.
Open communication enables the BMS to control the remaining HVAC (heating, ventilation and air-conditioning) plant, such as ventilation, hot water services, etc, with the connection between the air-conditioning system and BMS achieved at the management level. This approach can also be extended to fire, security, lifts, and lighting systems, which also take their primary operating instructions from integral controls.
This methodology allows each installed system to be fully tested and commissioned before the BMS interface is connected and system integrity is maintained, allowing a wide choice of different systems to be incorporated within the building services architecture.
Although allowing supervision and control from a single point is very convenient, intelligence should go beyond network sharing. The real intelligence of a building is defined by the way various services interact to provide additional functionality and reduce the cost of the overall installation. The highest level of intelligence creates interaction between systems to minimise energy consumption without manual interventions.
In order to achieve this level of intelligence, Daikin has developed sophisticated BMS compatible monitoring and control systems to optimise the energy consumption of the inverter-controlled VRV systems and their interaction with other services to ensure advanced air-conditioning solutions for buildings of all sizes.
The VRV-client can opt for three different solutions depending on the project’s needs. For a site that requires energy optimalisation and has 128 zones, there is a touch-screen Daikin Intelligent Controller (I-Controller). For larger sites, the client can opt for the Daikin Intelligent Manager (I-Manager), which controls up to 1,024 zones. When there is a need to link to an open network such as BACnet or Lonworks, an interface gateway is available, which can monitor up to 256 groups of indoor units and 40 outdoor units.
The I-Controller enables systems of entire buildings to be monitored and controlled from a touch screen that is linked directly to the VRV-system without the need for a PC. The controller operates all VRV and HRV (heat reclaim ventilation) systems and can connect to any brand of air-conditioning. Building services – other than air-conditioning – can also be recorded and controlled and fire-warning alerts provided.
I-Controllers can also be monitored remotely via the Internet and this Internet compatibility enables VRV systems in more than one building to be remotely monitored and controlled from any PC with a standard browser in three different ways:
• Either by connecting the I-Controller to company LAN networks
• By linking it to a remote location.
• By linking it to the Internet.
Although the unit requires less space than standard BMS consoles, it has many advanced features. The indoor units can be started and stopped, filter conditions recorded and malfunctions indicated. Schedules for daily unit start up and shut down, temperature settings and operating mode can be set on a yearly basis.
More importantly, the overall and zoned power consumption can be measured, allowing customer billing via a tenant data memory card, which can be loaded onto a PC.
The power consumption of outdoor units is measured on pulse input management points and the relative power consumption of the indoor units is calculated from their operation time and mode, level headed with model-related coefficients.
Previously, the general way for requesting the electricity charge at rental buildings was that a management staff read a watt-hour meter and billed the tenants by a manual-account based on the operation time which was counted through time-counters.
However, this is a time-consuming method. Besides, as air-conditioning consumes differing levels of electricity for either the operation of air-conditioning, depending on whether is thermostat is on or off, it might give an unfair picture to tenants operating in spaces with different heat loads. The distribution facility for electric energy carries out a proportional division computation considering thermostat-on and thermostat-off operations and saves time for building management staff that would have otherwise have to read watt hour meters, and also supplies tenants printed data useful for making the bills.
But where does the intelligence assist in energy savings? Here’s two practical examples:
The Temperature Limit Function automatically starts and stops the air-conditioner to prevent temperatures in unoccupied rooms from rising or falling too far, for example, to prevent overheating of equipment and formation of condensation in temperature-controlled equipment in unoccupied rooms and it also assists in preserving capacity in entire buildings by preventing unoccupied rooms from reaching extreme night time temperatures.
The Interlock Function makes sure that, in case the building wakes up, first the indoor AC starts to operate before the heat reclaim ventilation starts. This enables maximum efficiency as the reclaim is only possible when there is energy to exchange and will assist in reaching set points fast before starting the ventilation.
Intelligent Manager
The next step up is the Daikin Intelligent Manager (I-Manager) for installations up to 1,024 zones. This system has improved reliability as during electricity failure the I-Manager will continue to operate for not less than 48 hours. It’s designed for use in small to medium sized buildings or buildings without a BMS.
The I-Manager is a centralised system ensuring the maximum energy efficient operation of medium to large air-conditioning installations. Like the I-Controller, it uses the Daikin DIII-Net high-speed data communication system to ensure accurate monitoring and control.
It can communicate with the security and safety systems that control automatic locking of the on/off function of the air-conditioning units. Control and operating functions include log-in setting, individual unit control, group switching/setting of a controlled group, program schedule control, power failure/release control and centralised air conditioning control. Management functions include system operating history, daily, monthly and yearly reports and VRV power usage.
The I-manager will further add intelligence to the building by maximising the energy efficiency:
‘Power Limit control (See Figure 1)’ enables the systematic management of air-conditioning power consumption. The I-Manager can predict the air-conditioning operating cycle in order to limit power consumption to the set targets. This enables users to systematically manage air-conditioning power consumption, which has hitherto been uncertain. This feature was developed for clients who received penalties from the electricity suppliers when exceeding set electricity power levels.
The ‘Sliding Temperature’ (See Figure 2) function eliminates cold shock or thermal shock via sensory comfort control. By monitoring the outdoor temperature and automatically adjusting room temperature, indoor/outdoor temperature differentials can be minimised drastically, thereby promoting maximum energy efficiency. This way uncomfortable cold shock zones around building entrances are eliminated.
Daikin control packages provide sophisticated regulation of air-conditioning systems. They also help to keep the VRV ahead of its competitors by providing building owners, landlords and tenants with valuable performance data on electricity consumption and operating efficiencies.
Many consultants design the intelligence of a building by using open networks and are aware of the synergies between various building services.
Therefore, two important points have to be clear when considering intelligent buildings. The solutions should be client-led and the decision to adopt them has to be made in the very early stages of a project. Even then careful planning and tight controls are needed to ensure the necessary degree of inter-operability between the various systems to avoid the pitfalls of divided responsibility where multiple suppliers are involved.
If these cannot be secured, a closed network BMS solution may prove to be a better and more cost effective choice. However, if the problems can be solved, the effort is likely to be worthwhile since intelligent building solutions offer the potential for cost savings combined with enhanced functionality, which cannot readily be achieved in any other way.
