ReCO2
ReCO2 is a patented recirculation function which minimizes the inflow of outdoor air and keeps the heated air inside the building. The function is accompanied by CO2/VOC and/or temperature measurement, so it ensures perfect air quality and/or temperature.
Why should you activate it?
Ventilation is essential for healthy indoor air, but sometimes conditions and local regulations allow the outdoor air inflow to be minimised during certain periods, such as when the building is unoccupied at night. This can be especially beneficial in buildings with large sized air handling units and high air flow.
The ReCOâ‚‚ function ensures that correct air quality and temperature are maintained through smart, real-time monitoring and automatic adjustment of dampers. Sensors monitor COâ‚‚ or VOC levels and/or temperature, allowing the system to recirculate extract air when air quality is sufficient. This reduces the need for outdoor air intake, saving energy on fan operation, heating, and cooling — without compromising comfort or regulatory compliance.
ReCOâ‚‚ is ideal for buildings with varying occupancy, such as offices, schools, daycare centers, and retail spaces. For example, in a school where classroom occupancy changes throughout the day, the system automatically adapts to maintain optimal air quality and temperature. Always make sure to comply with local requirements concerning recirculation of extract air. It may differ depending on market or application.
Main benefits
ReCOâ‚‚ has a smart way to control the mixing of extract air combined with a lower outdoor air. It uses sensors to monitor CO2 or VOC content and/or temperature. ReCOâ‚‚ is a perfect match to most sizes of GOLD with either rotary or runaround coil heat exchangers.
Key benefits include:
Energy savings: The system reduces heating and cooling demand by recirculating extract air when local regulations, air quality and indoor temperature allow. Since it automatically lowers the outdoor air and exhaust air flows, and by that lowers the extract air fan speed, it also saves energy for less fan power.
Saving energy at night: When combined with the function intermittent night heat and morning boost, ReCOâ‚‚ saves even more energy. It simply recirculates the indoor air at night, reducing heating needs and speeding up morning warm-up of the building.
Rapid response in the morning: When combined with the built-in functions morning boost, heating boost and cooling boost it helps the system to quickly adapt to changes in building load.
Enhanced comfort and compliance: Built-in alarms ensure all accessories are connected and the system meets regulatory requirements.
How it works
Here’s how it works:
Air quality control: Using COâ‚‚ or VOC sensors (accessory) are one way to monitor and regulate indoor air. If air quality is sufficiently good, the system gradually opens the recirculation damper and reduces outdoor air intake. If air quality drops, the controller will first open the outdoor damper and then close the recirculation damper to bring in more outdoor air.
Temperature control: Another way is to control the recirculation damper is to make sure the building’s indoor temperatures. It can be set for cooling sequence, heating sequence or both. It is also possible for it to work either before or after reheating/cooling control.
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CO2 / VOC and temperature control: The system can also be preset to regulate both air quality and temperature simultaneously. If the air quality or temperature becomes controlling depends on which of them requires the largest outdoor air volume. The system will select the one with lowest inflow of outdoor air.
Flow balance: Since outdoor and exhaust air will be changing in recirculation mode, the ReCO2 will adjust speeds automatically to maintain correct airflow and pressure. The function will calculate the outdoor air flow based on the readings from the pressure drop across the heat exchanger. The control adjusts the air flow setpoint of the extract air fan down to the same percentage as the outdoor air flow. That way the balance between the exhaust and outdoor air is maintained leading to a lower fan power consumption.
Minimum airflow safeguards: Preset minimum outdoor and exhaust airflows ensure compliance and safety at all times.
All logic is fully integrated into the GOLD control system — no extra controllers or equipment are required apart from the actual recirculation section, modulating damper actuators and selected sensors. All of these can be easily configured in AHU Design, our air handling unit selection software.