User Manual

Control concept

Desigo room automation

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To save energy in the ventilation plant, various room set points are selected for

different types of air handling (heating/cooling and

humidification/dehumidification). The master controller in the cascade must

therefore be able to generate different supply air set points, depending on how

the kind of air treatment (heating/cooling or humidification/dehumidification).

The supply air controller must determine whether the heating or cooling

sequence is to be activated and the decision-making strategy does not affect

the calculation of the two supply air set points. Within the cascade control loop,

the supply air set points always move parallel to each other, and their offset is

determined by the integral component.

If the air handling plant includes an energy recovery aggregate, this aggregate

may be either reverse-acting (e.g., heating) or direct-acting (e.g., cooling)

depending on the relationship between the condition of the outside air and the

condition of the exhaust air.

To avoid external calculation of the energy recovery setpoint, this, too, is done

by the master cascade controller, and made available to the energy recovery

aggregate, if there is one, at a separate output pin:

In a humidity control system with various physical control variables, the initial

value of the integrator should be predefined.

Example:

If the humidity of the supply air is measured with an absolute humidity value

[g/kg], while the room air humidity is measured in terms of relative humidity

[%Hu], an initial value must be defined for the I-component, otherwise the

mean value from [SpLoR] and [SpHiR] will be used as the initial value. If the

room set points are expressed in terms of relative humidity, then the initial

value for the integrator will start at a numerically high value, and decrease as a

function of the preset integral action time [Tn]. The result of this can be that

even if the room needs to be dehumidified, the humidifier is enabled in the

controller start-up phase until the integrator reaches its correct value.

To prevent this, the current measured supply air humidity value is linked to the

initial value of the integrator, or a fixed parameter value is defined for the

integrator.

If control accuracy is critical (e.g., no deadband or zero-energy control zone),

then the current measured value is linked to the initial value of the integrator,

or a fixed parameter value is defined for the integrator.

5.5 Desigo room automation

Multiple mechanical and electrical installations (referred to as technical

installations in this chapter) come together in one room. These typically are

HVAC, lighting, and blinds. Each technical installation is automated and

operated optimally from its perspective. For Desigo room automation,