HUMIDITY CONTROL Moisture matters
When HVAC engineers discuss climate control in commercial buildings, temperature usually gets top billing. It is humidity, however, that is often the factor that infl uences whether a system is effi cient, controllable, reliable and properly sized. For operators trying to cut carbon, cost and electrical infrastructure, controlling moisture can be just as important as lowering the dry-bulb temperature. Ranald Stewart from Klima-Therm explains.
'Humidity levels must be viewed as a core climate- control
variable that infl uences cooling
load, plant selection, ventilation design, controls
strategy and long-term effi ciency.'
T
he importance of humidity control is particularly pronounced in environments where HVAC systems have to support both comfort and critical operating conditions.
Data centres, pharmaceutical applications, battery dry rooms, food production, hospitals, manufacturing and large industrial facilities all need air that is both cool and dry enough to protect processes, products and equipment. If moisture is unchecked, refrigeration plant and air-handling equipment can work harder than necessary, coils can lose heat-transfer performance, and the building may still fail to deliver the conditions required at point of use.
The issue is the diff erence between sensible and latent loads. Sensible cooling reduces air temperature; latent cooling removes water vapour. Conventional HVAC systems often try to manage both demands through the same cooling coil. To remove moisture, the air must be cooled below its dew point so water condenses out. In many applications, this means cooling the air further than the space actually needs, then reheating it to avoid over-cooling. This approach can essentially result in paying twice for the same thermal energy: once to cool it down, and once to heat it back up. By separating latent and sensible load management, HVAC engineers can unlock signifi cant energy savings and improve controllability. Supply air set-points may be raised, chilled water temperatures optimised, and reheat demand reduced or eliminated. In turn, this can mean smaller connected electrical loads, lower capital expenditure on power and plant infrastructure, and a more resilient system during part-load operation.
Triple threat Dehumidifi cation can therefore provide a triple benefi t: improved climate control, lower carbon emissions and reduced operating costs. In cold stores and process cooling, dry air can help limit ice build-up and maintain heat-transfer performance. In manufacturing, stable humidity can reduce rejects, downtime and process variation. In data centres, moisture control helps reduce the twin risks of electrostatic discharge at low humidity and condensation or corrosion at high humidity, while enabling HVAC systems to operate closer to effi cient environmental envelopes.
22 October 2026 •
www.acr-news.com
Adiabatic cooling adds another layer to this opportunity. By using evaporation to absorb heat from the airstream, adiabatic systems can deliver cooling with far less electrical input than mechanical refrigeration. Applied correctly, the latest adiabatic technologies can form part of an integrated HVAC strategy, combining low-energy cooling with precise humidity management to maintain the balanced conditions required by high-value environments.
The data centre dilemma Much is being talked about the resources required to facilitate our insatiable need for all things digital, so in the data centre setting, anything that contributes positively to reduced energy demand must be taken seriously. A 2024 study in Buildings modelled indirect evaporative cooling units for data centres across dry, medium-humidity and
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