Modern building façade with glass windows and blue sky

Ventilation control in smart buildings: efficiency, safety, comfort

Q: How can existing buildings be retrofitted with ventilation control without major effort?

Wireless solutions such as the RF-VM allow motorised ventilation units to be connected without additional wiring – ideal for retrofit projects or complex building structures.

Q: What challenges arise when combining ventilation and solar shading?

If systems are not coordinated, conflicts can occur – for example, windows opening for ventilation while shading remains closed. Central controllers link such scenarios logically, ensuring systems work together efficiently.

Q: How can ventilation systems be integrated into KNX?

KNX-based sensors and control units enable direct integration into building automation. Measurement data and control commands are accessible to all building services, supporting holistic automation.

Why intelligent ventilation control is essential in smart buildings

Whether in new builds or renovation projects, energy efficiency is now at the heart of building design. Insulation and modern windows significantly reduce heat loss – but at the same time, they also reduce natural air exchange, meaning that indoor air quality must be actively managed. Without targeted ventilation control, humidity levels in residential and non-residential buildings can quickly rise. The consequences range from misted windows to mould growth, posing health risks and potentially leading to costly renovation work.

Modern systems therefore rely on controlled mechanical ventilation, operating automatically and according to demand. Factors such as temperature, humidity and dew point are incorporated into the control logic to ensure that fresh air is supplied in the right amount at all times. This provides a sound basis for designing and documenting ventilation concepts. A deeper insight into this topic is provided in our expert article on dew point monitoring and ventilation control.

Air quality is another key parameter: only when variables such as CO2 are reliably measured and evaluated can the system respond effectively. This enables control strategies that meet legal requirements while delivering efficient operation in practice. Which indicators define good indoor air quality is explained in our technical article ‘Room air quality: measurement and control’.

Regulations, standards and rising requirements

Why ventilation control has become a mandatory part of building design

Building regulations and energy efficiency standards around the world make it clear: ventilation is no longer an optional comfort feature but an essential part of building design. Many national frameworks now require a defined ventilation strategy whenever a building is newly constructed, or the building envelope is refurbished.

The reason is simple: humidity and mould can no longer be prevented solely by occupant behaviour. Closed windows, irregular airing or prolonged absences can quickly cause problems – with negative effects on both health and the building fabric.

For planners, this means that ventilation must be systematically integrated into building automation from the start. Only then can regulatory requirements be reliably met, interfaces with other building services clearly defined, and design concepts transparently documented for clients.

Ventilation as part of the overall control system

Integration of ventilation control into smart building concepts

A ventilation control system only unfolds its full potential when connected with other building services. In modern smart building concepts, ventilation, heating, cooling, solar shading and lighting work together to optimise energy use and ensure reliable operation.

Integration helps prevent conflicting actions: windows don’t open while cooling is active, and heating or air-conditioning systems don’t work against the ventilation. Instead, all systems are synchronised through clearly defined logic functions. This allows ventilation times, shading and temperature control to be coordinated – for example, for night-time cooling or controlled morning ventilation.

For planners, this means that ventilation is no longer an isolated add-on module but one of the core functions of building automation. Those who consider it early in the design process reduce interface issues and can implement consistent, cross-trade control strategies.

How ventilation can be implemented in interaction with other building services in a KNX system is explained in our technical article on 'Cross-Disciplinary Planning with KNX'.

To the technical article

From design to realisation with Elsner solutions

Implementation of integrated ventilation control

In practice, it quickly becomes clear how crucial a well-planned ventilation control system is in buildings. In an office building with a glass façade and high occupancy, the target parameters are defined as early as the design stage:

CO2 concentration as an indicator of air quality,
relative humidity for moisture balance,
and temperature and dew point to prevent condensation.

These parameters determine both the choice of sensors and the control logic later implemented in the KNX system – or in alternative systems such as Modbus or RS485. For example, if the CO2 threshold of 1,000 ppm is exceeded, the ventilation automatically ramps up in stages; once the CO2 value returns to the target range, it scales back accordingly.

At the same time, coordination between the building services takes place: cooling takes priority over natural ventilation, heating circuits are locked while ventilation is active, and solar shading reduces heat gains to relieve the cooling system.

For planners, this means that interfaces and control logic must be clearly documented – in line with relevant national standards and certification schemes such as BREEAM, DGNB or LEED. The result is a consistent concept that ensures both comfort and efficiency in operation.

This is exactly where we come in: for implementation, we offer a coordinated portfolio of Elsner solutions – from motorized ventilation units and central controllers to precise sensor technology. Our systems do not operate in isolation but in interaction with the entire building automation setup. This enables concepts that minimise building physics risks such as humidity and mould, provide planning and operational reliability, and support resource-efficient operation.

Funk-Lüftermodul

Radio Ventilation Module

The RF-VM (Radio Ventilation Module) is part of the building control systems from Elsner Elektronik, for example in combination with the WS1 or WS1000 central controllers. It extends these systems with the capability to connect motorised ventilation units wirelessly – ideal for retrofitting projects or building structures where wiring is impractical or too complex.

With the RF-VM, fans can be controlled in up to eight speed levels, including shut-off dampers, allowing the air exchange rate to be precisely adjusted. When combined with a WS1 or WS1000 system, it enables fully automatic ventilation control, intelligently coordinating ventilation scenarios with heating, cooling and solar shading.

The module is now available again in a new and improved version and can be easily integrated into existing systems.

To RF-VM

RF-VM radio module for ventilation control

Building control systems

WS1 and WS1000

The WS1 and WS1000 central controllers form the heart of building automation. In combination with the RF-VM Radio Ventilation Module, motorised ventilation units can be integrated wirelessly into the system – ideal for retrofitting projects or complex building structures.

These controllers interconnect ventilation, heating, cooling, solar shading and lighting into a coordinated overall control system. This prevents conflicting actions – for example, windows opening during a cooling phase. Time programmes and lock logics ensure that ventilation scenarios run proactively and energy-efficiently.

The result is a solution that ensures planning reliability, smooth operation and a high level of everyday comfort, while adapting flexibly to individual building structures.

In addition to motorised ventilation systems, Elsner also offers the Arexa 230 V window control system – a solution for natural ventilation via windows, ideal where a central controller is not available or where wireless technology is preferred.

To the building control systems

WS1 (top) and WS1000 (bottom) building control systems by Elsner Elektronik

Ventilation control devices available in our Online Shop

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Radio window control for natural ventilation

Arexa 230 V

With the Arexa 230 V window control system, natural ventilation through windows can be automated – for example in conservatories, attic rooms or sliding windows. Depending on the indoor and outdoor temperature, Arexa automatically opens and closes the window, ensuring a controlled air exchange even when no one is present.

Rain and wind alarms provide reliable protection against adverse weather conditions, while an individually adjustable opening position allows precise control of the air exchange rate. Because communication between the weather station and the control unit takes place via radio, no additional wiring is required – a clear advantage for retrofitting or existing buildings.

In this way, Arexa 230 V complements automated ventilation control with a convenient solution for natural, weather-dependent window ventilation, expanding the range of possibilities for intelligent and resource-efficient building ventilation.

To Arexa 230 V

Arexa 230 V window control system consisting of weather station and control unit

CO2, humidity, dew point

Sensors for air quality and humidity

Accurate measurement data are the foundation for demand-based ventilation control. Sensors such as Cala KNX IL CO2 or Cala KNX AQS/TH measure CO2, humidity and temperature, providing the data needed for automated decision-making. For specific applications, dew point sensors are also available to reliably prevent condensation on cold surfaces.

This not only improves comfort but also helps prevent structural damage caused by humidity, ensuring greater planning reliability and operational safety.

To our sensors

Cala KNX IL CO2: Indicator light and/or CO2 Indicator Light for Air Quality

Planning reliability, efficiency and operational comfort

Advantages of integrated ventilation control

Targeted ventilation control offers several advantages that go far beyond indoor climate. Already at the planning stage, it provides clarity: with standard-compliant concepts in line with national ventilation guidelines (e.g. DIN 1946-6 in Germany), potential issues such as humidity or mould can be prevented, and the documentation of the ventilation strategy is placed on a transparent basis.

During operation, integration with heating, cooling and solar shading ensures that buildings function as controlled mechanical ventilation systems, operating automatically and according to demand. This reduces energy losses, increases efficiency and enhances operational safety. At the same time, occupants benefit from stable air conditions and a high level of comfort, without the need for manual intervention.

Economically, the solution also pays off: lower energy consumption reduces operating costs, and a well-designed ventilation strategy contributes to the long-term preservation of building value.

How significantly good indoor air affects health and performance is explained in our article ‘Healthy and productive thanks to good indoor air’.

Conclusion

Why ventilation control is indispensable today

Ventilation control brings together key aspects that can no longer be separated in modern building practice. It ensures compliance with building and energy regulations, helps reduce the risk of humidity and mould, and supports the creation of transparent and verifiable ventilation concepts in accordance with recognised standards.

At the same time, it serves as the link between ventilation, heating, cooling, solar shading and lighting. This integration prevents conflicts between building services and enables coordinated control strategies – for example, for energy-efficient air exchange or targeted night-time cooling.

In operation, the benefits are twofold: stable air quality increases comfort and productivity, while optimised energy use lowers operating costs and helps preserve the building’s long-term value.

Ventilation control is therefore an essential component of modern building automation, offering clear advantages at every stage – from planning and implementation to operation.

FAQs

Frequently Asked Questions about Ventilation Control

When should ventilation control be included in the planning process?
Ideally already during the design phase, as soon as the building envelope and the energy concept have been defined. Only then can interfaces with heating, cooling or solar shading be optimally coordinated and cable routing or wireless solutions taken into account.

What role does ventilation control play in building certifications (DGNB, LEED, BREEAM)?
A controlled ventilation concept is often a prerequisite for meeting requirements for energy efficiency and indoor air quality. Automated systems make it easier to provide the necessary documentation and improve the overall building rating.

How can existing buildings be retrofitted with ventilation control without major effort?
In existing buildings where no additional wiring can be installed, wireless solutions such as the RF-VM offer a flexible option. They enable motorised ventilation units to be connected wirelessly and can also be used in complex building structures.

What challenges arise when combining ventilation and solar shading?
If the two systems are not coordinated, conflicts can occur – for example, when windows are opened for ventilation while the shading remains closed. Central control units allow such scenarios to be linked through logical control strategies, ensuring that systems do not work against each other.

How can ventilation systems be integrated into KNX?
Sensors and control units based on KNX enable direct integration into the building automation system. This means that measurement data and control commands are available to all trades, making holistic automation much easier to achieve.

Further technical articles

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Schematic diagram of dew point monitoring

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