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The high level of insulation and the high-performance windows and doors used in new buildings or in buildings that have undergone major renovation to meet the energy efficiency requirements of Directive 91/2002/EC (and subsequent national laws) have greatly reduced heat losses to the outside and, at the same time, have in many cases made it necessary to use energy recovery ventilation (ERV) units for air renewal or VAV boxes.
Energy recovery ventilation units
The manual control of these units alone is inadequate to ensure energy efficiency in their operation and even a simple time scheduling is not fully satisfactory. As pointed out by EU Regulations no. 1253 and 1254 of 2014, for these ventilation units it is necessary to use an “environmental” control by measuring one or more parameters to automatically adjust the flow of fresh air to be introduced into the rooms.
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| Ekinex devices | Other Components |
| A) Multisensor EK-ET3-TP or EK-ES3-TP | 1) Controlled mechanical ventilation units with energy recovery |
| B) Presence Sensor EK-SG2-TP-M | 2) Control board (on-board) VMC unit (RDZ) |
| C) 20-Venti Series Pushbutton | 3) Two-position switch |
| D) Universal Interface EK-CC2-TP | 4) Window opening contact |
| 5) Air taken from outside | |
| 6) Air taken from the environment | |
| 7) Air supply to the environment | |
| 8) Air expelled to the outside |
Control with Ekinex
The EK-ET3-TP multisensor (A) measures environmental parameters representative of ventilation requirements: the main one is air quality (CO2 concentration) to which relative humidity (in %) and temperature (in °C) are added.
The EK-ES3-TP version adds TVOC concentration. Other useful environmental parameters are the detection of presence or movement of people within rooms by means of the EK-SG2-TP-M sensor (B) or signals due to the operation of other home automation functions, such as lighting by means of the 20vent Series button (C).
RDZ’s VMC units can be equipped with a KNX gateway and thus easily integrated into the system. The EK-CC2-TP universal interface (D) acquires signals from conventional components, such as a seasonal switch (3) or a window contact (4).
VAV boxes
The VAV (Variable Air Volume) systems are designed for room ventilation according to the actual needs, having inside the appropriate boxes (2) motorized dampers (1) that act as a regulator of the fresh air flow.
In combination with the home automation sensors installed in the room, the system guarantees high energy efficiency, since the room can be ventilated according to one or more parameters measured in the room.
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| Ekinex devices | Other system components |
| A) Multisensor EK-ET2-TP | 1) KNX servomotor for dumper (not delivered by ekinex) |
| B) Presence sensor EK-Dx2-TP | 2) VAV (Variable Air Volume) box |
| C) Universal interface EK-CC2-TP | 3) Air supply outlet |
| 4) Air extraction outlet | |
| 5) Window contact |
Control with Ekinex
The use of a real presence sensor EK-SG2-TP-P (B) is suitable when an automatic control of a simplified type is desired with opening of the VAV box damper under occupied room conditions and setting the minimum flow rate to save energy when the room is unoccupied instead.
Greater efficiency is achieved by the use of a multisensor (A) that can adjust the flow rate of air input according to the measured value of air quality and preset thresholds. The signal of a window opening contact (5), detected by means of an EK-CC2-TP input (C), allows ventilation to be temporarily deactivated so as not to waste energy unnecessarily; reactivation occurs automatically when the window is closed.
Control based on CO2 or VOC values
The choice of the control parameter depends mainly on the intended use of the rooms. Where the variability in the occupancy rate is very high or unpredictable (such as in meeting rooms, classrooms or small commercial environments) CO2 is the most used indicator because its concentration is directly related to human activity and, in particular, to breathing.
Although CO2 is not harmful to human health (except in very high concentrations, which are difficult to achieve), it has a direct impact on the concentration capacity and productivity of the occupants. When the number of people in the room is predictable and limited, the detection of volatile organic compounds (or VOC), a set of organic chemicals continuously emitted from furniture, paints, cleaning solvents, adhesives or other synthetic materials due to their high volatility, may be more significant.