The control system is composed of a set of components which monitor, control and coordinate the operation of the various sub-systems composing the plant as a whole.
The system is monitored and its performaThe control system is composed of a central unit which interfaces with the company network, for selective, controlled access to the status and configuration pages. This enables the operators to modify the system's operational settings, while also allowing other users to monitor the status of part or the entirety of the plant.
The control unit also maintains a log so that the operating values can be analysed statistically.
The central control unit is connected to a variety of local control units which simplifies the automatic modular control of the plant's various components, and improve its performance. By the "performance" of the control units we mean the speed and quality of their response to the variations in their operating conditions.
The local control units are connected to the sensors and actuators on the plant's various sub-systems.
We can break the plant into functional areas, even though varying a parameter in one area may affect its behaviour in other areas.
The plant has the following functional areas:
- ground and first floor air conditioning,
- control of the cooling system,
- control of the geothermal pumps,
- control of the boilers,
- control of the solar heating plant,
- control of the test plant,
- control of the sanitary water recovery system,
- control of the auxiliary plants,
- display and control system.
The air conditioning plants are essentially composed of ambient thermostats, fan coils and heat recovery equipment. This plant ensures the ideal microclimate and energy savings throughout the building.
Depending on whether anyone is in a room or area, and on the user's demand and external conditions, the area fan coils can be controlled in such a way as to optimise their operation and consumption.
Best performance is obtained by controlling the areas independently, since the operating parameters are linked to different external factors (such as exposure to direct sunlight), human factors (sensitivity to temperature) and special circumstances.
The air conditioning plant generates the requests to be supplied by other parts of the plant, especially by the boiler circuit, geothermal pumps and cooling system.
The control section for the cooling system controls the operation of the external chillers and delivery pumps in response to requests and the temperature of the fluids in the system. Depending on external temperatures and system settings, the control system determines whether the cooling requests are to be supplied by the cooling plant or by the geothermal pumps and hence which plant is to be activated.
The geothermal plant is composed of three different elements, in other words, three different types of heat pumps and probes. The main heat pump employs the method of drawing water from and returning it to the water source by means of wells. This yields high powers and is used both for cooling and for hot water production.
The other two elements of the geothermal plant are two heat pumps, one with vertical and one with horizontal probes. These two pumps are used both for testing and to supplement the output of the main pump.
The projected control system uses the two test heat pumps to supplement the main pump, when it's output is insufficient to satisfy the system's requests. If, when operating in cooling mode, the total power of the geothermal system is insufficient, the system activates the cooling plant. When operating in heating mode, if the thermal power of the geothermal pumps is unequal to demand, the control system activates the condensation boiler.
The control system analyses the electrical consumption and the thermal energy produced by the heat pumps, and logs the data for historical analysis.
The modular condensation boiler is used to produce hot water for testing, to supplement the solar system and to heat the rooms when the geothermal section's power is insufficient.
The system's requests are served by activating the delivery pumps and monitoring the operation of the boiler itself: the boiler's internal control logic autonomously controls its heating elements.
The solar heating plant is used for sanitary hot water generation. The power output of the solar panels is calculated and stored so as to verify its operation throughout the day and during the year. The use of sensors to monitor weather conditions enables us to correlate the thermal power of the solar panels with cloud coverage and to control the system more quickly. If the solar panels are unable to provide sufficient energy to respond to demand, the boiler can be used to supplement their output.
The temperature of the storage tanks connected to the solar plant is controlled automatically and if it becomes excessive, a quantity of water sufficient to prevent overheating is discharged. Our laboratory tests require water at a variety of temperatures, pressures and flow rates. The centralised control of these parameters simplifies the laboratory test systems and reduces consumption. The hot water required for testing is obtained from the condensation boiler which, with its modular design, is sufficiently versatile to meet the various operating conditions with a high level of efficiency.
The sanitary hot water recovery system enables us to recover a considerable part of the heat transferred to the water used for testing. This enables us to further reduce the energy required for the production of hot water for testing: the recovery plant is controlled by the control system and is completely automatic.
The control system is equipped with a remote control and display system which enables all computers connected to the network to access the services (password controlled). In addition to this type of control by PC, the control units in the rooms and subsystems can also be controlled via wall mounted LCD panels. The entire system's status, along with consumption and power data, can be displayed on a large LCD display: this display, which is located in the showroom, allows both users and visitors to see directly the power output of the alternative energy sources and the status of the system as a whole.
The control and display software is composed of synoptic displays employing refined graphics so as to make the data easy to understand.
- Benefits of the control system
The control system actively reduces waste by dynamically adapting the operation of the system's components to the contingent demand.
Automatic control enables us to apply energy optimisation strategies, simplify the control of the plant by the users, and improve the operation of the subsystems and, at the same time, of the system as a whole. Finally, the control system improves the physical wellbeing produced by the microclimate in the building's various rooms, since optimal conditions are always ensured.
The centralised control system allows us to adapt the operation of the plant to actual and contingent demand, thus avoiding the operation of components when unnecessary, and coordinating the operation of the various subsystems. It is actually possible to configure the actuators to operate as suitably as possible in response to the requests from the various parts of the system.
Let us take the following case as an example:
In the late autumn, the rooms are usually heated by a heat pump. The sanitary hot water used in the showers and kitchens is produced by the solar panels, supplemented when necessary by the boiler.
If the laboratory needs to run a test with hot water, the suitable delivery pump is activated. The consequent reduction in water temperature leads to the activation of the number of boiler heating elements required to satisfy demand. If the external temperature drops too far and the geothermal plant is unable to satisfy the power demand, the boiler would be used for heating.
The use of the control system enables us to optimise the operation of the various systems so as to select at any time that which requires less energy consumption in relation to its delivery capacity.
If we wish to maintain the microclimate in the rooms, manual control of the system is not able to dynamically adapt the operation of the plant's subsystems, day to day or hour by hour, to the actual conditions, and we must consider the worst possible case. In that case, we would have to increase the period of operation of the boiler in the winter even as a replacement for the geothermal system. Similar considerations apply to the summer operation of the cooling plant. If we are to be able to heat and cool the rooms sufficiently, we must be able to guarantee a larger thermal power than that actually required at any time, so as to be able to handle oscillations.
The climatic instability of recent years does not give us the luxury of choosing any given configuration, since repeated variations with strong oscillations are very possible which would require continual manual switching between the various types of heating and cooling systems.
Using a global control system also allows us to avoid waste and provides daily and even hourly control of the system's various components.
The system's additional electrical consumption can be estimated to be of the order of several tens of Watts, with the exception of the PC's which are in any case used in the laboratory and the LCD panel in the showroom.
The control system also considerably increases the system's security, since it monitors critical parameters (such as pressure and temperature) and hazards (such as gas leaks, flooding, etc.). This reduces the risk of accidents and the consequent costs for the company. In case of imminent danger, alarms are handled in a variety of ways, by deactivating parts of the system where needed, and by promptly informing the users by email or pop-up windows on their networked computer terminals.