Demand-controlled decentralised ventilation gives you the best possible air quality in each and every room – with the lowest possible energy consumption. There is no need to choose between prioritising air quality – and thus the well-being of those in the room – and prioritising energy consumption. You can quite simply have both!
Decentralised ventilation is installed in the actual room to be ventilated. This also makes it possible to control each room individually via individual settings. In addition to individual basic settings for each room, we can also control the ventilation automatically as needed using various sensors.
This could be a PIR sensor (motion sensor), which activates the ventilation when there is movement in the room. It could also be a CO2 sensor, which controls the airflow intelligently according to the number of people present in the room. You can also opt for a TVOC sensor, which measures the presence of “little” or “much” of volatile organic compounds.
In sports facilities such as changing rooms, you can also choose to control the ventilation according to the humidity level, ensuring that it always remains at the desired level.
So, there are a host of options for combining different basic settings with sensors. The options for time control, CO2 sensor, TVOC sensor, PIR sensor and humidistat/hygrostat are set out below.
In rooms used on a regular basis, it can often be a good idea to choose time-controlled basic ventilation.
In both classrooms and offices, it can be beneficial to have the basic ventilation start up an hour before people arrive. This way, there is fresh air in the room right from the start of the day.
You can choose to control the ventilation solely according to a weekly schedule or you can opt to supplement it with a sensor. Particularly in rooms in which both the use and number of occupants vary, it makes good sense to supplement with a CO2 sensor and possibly a TVOC sensor.
This way, the air capacity automatically adjusts according to the number of occupants in the room (CO2) or according to the volatile gases (VOC) emitted.
There are seven different time programmes with individual set points as well as a night cooling programme, offering ample opportunity for you to pre-programme the time schedules used most.
There are several combination options for controlling the ventilation. In schools, the basic ventilation typically runs according to a schedule, supplemented by CO2 demand control. This means that the ventilation in most of the school will stop running after home time. But there is still fresh air in the one room that is to be used for a parents’ meeting because the ventilation is also controlled by the CO2 level.
A PIR sensor can also be added, which will start the unit when movement is detected and stop it when movement in the room ceases. The CO2 sensor will then adjust the airflow to the number of occupants. The PIR sensor thus functions as a start/stop for the basic ventilation, and the airflow/air quality are controlled by the CO2 sensor.
As a new feature, we can now also demand control the ventilation by means of a TVOC sensor, combined with a CO2 sensor.
What is TVOC?
VOCs are easily evaporable organic substances that may be given off by hand sanitiser, cleaning agents, building materials, furniture, carpets, work processes, cosmetics and human bodily processes. They consist, among others, of formaldehyde, acetone, methanol, acetic acid and acetaldehyde.
TVOC = (Total VOC) – the sensor detects all substances in the VOC category.
CO2 and TVOC concentrations do not always follow one another. So, separate VOC measurement may be appropriate. The benefit for occupants of the rooms is that the air replacement is controlled on the basis of several relevant parameters in order to ensure the best possible air quality.
In rooms that are not used on a regular basis, it may make sense to leave it to the PIR sensor to control the start of the ventilation unit with basic ventilation, and then let a CO2 sensor control the airflow. With this combination, the CO2 sensor will typically control when the ventilation unit should stop again.
In premises with both regular and occasional use, it may make sense to let the ventilation run according to the time schedule and CO2 sensor during the set hours, and then let a PIR sensor start and stop it at other times. This could, for example, be a classroom that is also occasionally used for parent meetings, etc., in addition to its normal use during the day.
In colder, drier climates, there may be periods of low indoor humidity below approx. 30% relative humidity, which can cause dry eyes and mucous membranes, among other things. In moderate climates, too, there may be situations in which a relative humidity higher than 30% is desirable. For these situations, enthalpy heat exchangers can be supplied as an option for all our ventilation units.
Airmaster air handling units can be fitted with an extra humidity sensor or extended programming.
Integrated humidity and temperature sensors on supply and extract make exact calculation of absolute air humidity possible.
The adaptive humidity control automatically prevents the air drying out in the winter and reduces humidity in the summer. This effective, energy-saving form of operation creates a healthy environment and a healthy energy bill.
A hygrostat registers relative air humidity, and sends either a start or stop signal to the air handling unit. Start/stop signal can be adjusted. Humidity in the air affects the length of hygroscopic man-made fibres. Depending on the humidity level, the fibres will activate a contact that triggers the signal. When the relative air humidity goes over or under the level set, the hygrostat sends a start/stop signal to the air handling unit. Hygrostats are often used to switch a unit from basic ventilation to full operation when the
relative humidity set is exceeded.