Night cooling (i.e. the cooling of a building by ventilating ‘cold’ outdoor air through the building at night) can result in considerable savings compared to traditional HVAC cooling.
It’s very easy to setup such a night cooling system with a TELETASK system. The minimum requirements are:
- An outdoor temperature sensor (e.g. the TDS12251)
- An indoor temperature senor (e.g. the sensor of an AURUS touch panel)
- A relay to control the ventilator.
Remark: A ‘Night cooling’ system can be integrated in situations where there is a heating/cooling system, a heating system only, a cooling system only or even in situations where no heating or cooling system is integrated. (This will depend on the climate in which the TELETASK system is installed).
Configuring the outdoor temperature sensor
The configuration of the outdoor temperature sensor is very straight forward, all that it requires is a name:
Configuration of the indoor temperature sensor
In this example we will use an AURUS temperature sensor where the ‘cooling’ output is not used. This can be, because no cooling has been integrated, or because the integrated HVAC system uses its own internal temperature sensors.
We will configure a ‘Flag’ as the ‘cooling’ output, this flag will then be used in the next steps to check if the ‘night cooling’ needs to be activated. It is possible to configure the night cooling without the use of this flag (e.g. when no sensor without a ‘cooling output’ is availabe), but using this flag allows for the end user, to change the temperature at which ‘night cooling’ needs to be activated. It also
First create a flag, with the name ‘Indoor temperature high’:
Now configure the ‘Cool’ output of an AURUS temperature sensor with this flag. Set the ‘Night temperature’ for cooling at the temperature at which cooling at night may be activated (e.g. 24 °C)
Configuring the ‘Night cooling advised’ condition
In this step we will create a condition that must evaluate to ‘TRUE’ to activate the ‘Night cooling’. We define the requirements to activate night cooling as:
- The difference between the indoor and the outdoor temperature must be higher than 4°C
- The flag ‘Indoor temperature high’ must be on. This is the flag controlled by our temperature sensor. By using this flag we are also sure that the system is in ‘cooling mode’ (If a flag cannot be used, change this part to ‘Measured indoor temperature > 24°C)
- The outdoor temperature must be higher than 12°C (if it is very cold outside, it might be better to keep as much heat inside as possible, depending on the climate).
- It must be night time (a flag, set from TIMESOFT or by ‘going to sleep’ and ‘getting up’ general moods).
All the requirements above need to be true the activate the ‘Night cooling’ so we will create a condition using ‘AND’ configuration. The condition will look like this:
Difference between indoor and outdoor temperature
The first part of the condition above evaluates if the difference between the Indoor and the Outdoor temperature is higher than 4 °C. To calculate this difference we use a ‘Calculation function’. The calculation function can calculate the difference between two temperature sensor values.
Its configuration, only requires a name and the two sensor zones:
Activating the night cooling
We have now defined or ‘Condition’ to check if it is advisable to us ‘night cooling’, all that remains is to activate it when necessary. To do this we will use a ‘process function’. This ‘process function’ will monitor our ‘condition’ and switch a relay ON or OFF accordingly.
The ‘process function’ is configured with the option:
- Operation if activated: ‘ON if TRUE & OFF if FALSE (all edges)’. This will allow control of the ventilator by other systems or manually by the user
The process function itself must be activated from the ‘AUTO START function’.
REMARK: If the ‘night cooling’ is configured without a flag as cooling output of the indoor temperature sensor, switch off the ‘process function’ to switch off the ‘night cooling’ system.