Air renewal with ERV units or VAV boxes
HVAC applications and controls
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.
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.
Ekinex devices | Other system components |
A) Modbus/KNX EK-BO1-TP-RMA | 1) Controlled mechanical ventilation unit with energy recovery |
B) Time / astronomical digital switch EK-TM1-TP | 2) Energy recovering ventilation (ERV) unit |
C) GPS module EK-GPS-1 | 3) Seasonal manual switch (summer-winter) |
D) Multisensor EK-ES2-TP | 4) Window opening contact |
E) Presence sensor EK-DF2-TP | 5) Access point LAN Wi-Fi |
F) 4-fold pushbutton 20venti EK-E20-TP-4TS-P | 6) Switch |
G) Universal interface EK-CC2-TP | 7) Smartphone with Delégo App (Apple iOS or Android) |
H) Delégo Server EK-DEL-SRV-... | |
I) Touch-panel Delégo EK-DEL-xPAN... |
Air flows | |
8) Air taken from the environment | |
9) Air taken from the outside | |
10) Air introduced into the environment | |
11) Air expelled to the outside |
The Modbus / KNX interface EK-BO1-TP-RMA (A) allows the control and monitoring of the VMC unit through the Ekinex system by connecting to the communication port of the control board (2) of the VMC unit.
The EK-ES2-TP multisensor (C) measures three environmental parameters that are representative of the ventilation requirement: the main one is the air quality (as CO2 concentration in ppm), together with the relative humidity (in %) and the temperature (in °C).
Other useful environmental parameters are the detection of the presence or movement of people inside the rooms by means of the EK-DF2-TP sensor (D) or signals due to the activation of other home automation functions, such as lighting switching by means of the EK-E20-TP-4TS-P 20VENTI pushbutton (F).
A universal interface EK-CC2-TP (G) can acquire the change of the operating mode of the system (summer-winter and vice versa) from a traditional switch (3) and the opening / closing of a door or a window from the appropriate contact (4).
The EK-TM1-TP (A) digital time / astronomical switch (A) also provides start / stop command for the ventilation system according to predefined time scheduling and is constantly synchronised with the date and time by the GPS module (optional) EK-GPS-1 (B).
The optional supervision through the Delégo Server (H) allows you to monitor and control the home automation system using an App for mobile devices (7) and/or a Delégo touch-panel (I).
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.
Ekinex devices | Other system components |
A) Time / astronomical digital switch EK-TM1-TP | 1) KNX servomotor for dumper (not delivered by ekinex) |
B) GPS module EK-GPS-1 | 2) VAV (Variable Air Volume) box |
C) Multisensor EK-ET2-TP | 3) Air supply outlet |
D) Presence sensor EK-Dx2-TP | 4) Air extraction outlet |
E) Universal interface EK-CC2-TP | 5) Window contact |
The use of an EK-TM1-TP time digital switch (A), possibly with optional GPS module (B), allows not only to define the operating time scheduling for the ventilation system according to the expected occupation of the building, but also advanced functions like, for example, the activation of a washing cycle of the room air before the beginning of working hours.
The use of a presence sensor EK-DF2-TP (D) is indicated when you want to make an automatic control of simplified type with opening of the damper of the VAV box in conditions of occupied room and setting the minimum flow rate to save energy when the room is not occupied.
Higher efficiency is achieved by using a multisensor (C) that can adjust the flow rate of incoming air according to the measurement of air quality and the predefined thresholds. The signal of a window contact (5), detected by an input interface EK-CC2-TP (E), allows to temporarily deactivate the ventilation so as not to waste unnecessarily energy; the reactivation takes place automatically when the window is closed.
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.