Why dehumidification is just as important as cooling in modern indoor cultivation

Climate control in professional indoor cultivation has changed significantly with the transition from HPS to LED lighting.

Traditional HPS installations generate substantial radiant heat. As a result, air conditioning systems frequently operate in cooling mode, removing moisture from the air as a natural part of the refrigeration process.

Modern LED lighting delivers light more efficiently and generally produces less radiant heat at canopy level. However, plants continue to transpire, releasing significant amounts of moisture into the growing environment.

This creates a fundamental challenge: the demand for dehumidification does not necessarily coincide with the demand for cooling.

A conventional air conditioning system primarily responds to temperature. Once the desired room temperature is reached, the compressor reduces output or stops. Moisture removal decreases, even when relative humidity remains above the desired level.

The result can be rising humidity, fluctuating VPD and less predictable growing conditions.

Dehumidification through refrigeration is based on a straightforward physical principle.

When humid room air comes into contact with an evaporator whose surface temperature is below the air's dew point, water vapour condenses into liquid water. This condensate is collected and discharged through a drainage system.

During this process, the evaporator removes both sensible heat, the energy associated with lowering the air temperature, and latent heat, the energy released when water vapour condenses into liquid water.

The difficulty is that conventional cooling systems generally remove moisture while simultaneously lowering the supply-air temperature. When a cultivation room needs dehumidification but no additional cooling, this becomes inefficient or difficult to control.

The OptiClimate Revomax II addresses this challenge through an intelligent refrigeration system with two different ways of transferring heat.

Depending on the required temperature and humidity conditions, the system can reject heat through an internal refrigerant condenser that transfers heat to the room air or through a refrigerant-to-water heat exchanger connected to an external cooling circuit.

When the room requires moisture removal without additional cooling, the Revomax uses its refrigeration circuit to condense moisture from the air.

The cold evaporator removes water vapour through condensation, while the internal refrigerant condenser transfers heat from the hot refrigerant back into the room air.

This recovered heat compensates for the cooling associated with moisture removal, allowing the system to dehumidify without unnecessarily lowering room temperature. Depending on the operating conditions, the system can also provide heating while dehumidifying.

This is particularly valuable during lights-off periods and in LED cultivation environments with relatively low sensible heat loads.

When the cultivation room requires cooling, the system uses its refrigerant-to-water heat exchanger to transfer heat from the refrigeration circuit into cooling water.

The heated water then circulates through a closed water or glycol circuit to an external cooler, where the heat is released into the surrounding environment. In this operating mode, the Revomax can remove both heat and moisture from the cultivation room.

An important distinction is that the refrigerant remains inside the Revomax. Only water or glycol circulates between the indoor climate unit and the external cooling system.

The Revomax automatically manages its refrigeration operation according to the required climate conditions, allowing cooling, dehumidification and heating functions to be coordinated within one system.

The relationship between cooling and dehumidification changes continuously during a 24-hour cultivation cycle.

During lights-on periods, lighting and equipment contribute to the room's heat load. Depending on plant transpiration and climate conditions, both cooling and dehumidification may be required.

During lights-off periods, lighting-related heat input disappears, but moisture removal can remain necessary. The Revomax can use its internal refrigerant condenser to return heat to the room air while continuing to remove moisture.

Additional functions such as Pre-Heat and Slow Cooldown provide further control over temperature transitions. Pre-Heat allows the room to approach its daytime temperature target before the lighting cycle begins, while Slow Cooldown enables a more gradual transition towards nighttime conditions. These functions help reduce abrupt changes in the growing environment when correctly configured.

The performance of a Revomax system also depends on the installation surrounding it.

At Indoor Grow Solutions, we integrate Revomax climate units with engineered closed-loop water-cooling systems. Depending on the project, these installations include inverter-controlled circulation pumps and external cooler fans, allowing water flow and heat rejection capacity to respond to the actual operating demand.

Correct hydraulic dimensioning, water flow, temperature differences and system configuration are essential for efficient and reliable operation.

The required cooling and dehumidification capacities must also be calculated separately, taking into account lighting power, cultivation area, plant density, transpiration and operating conditions during both day and night.

The key difference between conventional cooling and advanced cultivation climate control is the ability to manage temperature and humidity as two related but distinct requirements.

The Revomax II combines cooling, dehumidification and heating within one coordinated refrigeration system. By rejecting heat either through its internal refrigerant condenser into the room air or through a refrigerant-to-water heat exchanger into an external water circuit, it can respond to changing climate demands without relying on separate heating and dehumidification equipment working against each other.

For professional growers, this provides a more controllable environment, particularly in LED installations where moisture removal is often just as important as cooling.

At Indoor Grow Solutions, we combine this technology with practical engineering, correct system dimensioning and professional installation to develop climate solutions tailored to each cultivation facility.