AIR CONDITIONING, COOLING & VENTILATION


The real story behind hospital humidity control


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Humidity influences far more than comfort in healthcare buildings. It supports infection prevention efforts, contributes to healthy indoor environments, affects building performance, and helps maintain the conditions needed for patient care and day-to-day facility operation. Yet despite its importance, maintaining recommended humidity levels can be one of the more challenging aspects of healthcare HVAC operation. Dave Schwaller, DriSteem senior manager, engineering applications explains


ealthcare buildings bring in large volumes of outdoor air and contain spaces with differing environmental requirements. As a result, maintaining humidity becomes a balancing act involving ventilation, building operation, water quality, controls, and HVAC system design. A facility can meet its temperature and air-exchange targets and still struggle to maintain humidity. In many cases, the challenge isn’t the humidifier itself but how these factors interact.


Why humidity matters


Discussions about healthcare HVAC systems often focus on ventilation and filtration. Those systems are essential, but humidity also plays an important role in supporting patients, staff, equipment, and facility operations. Maintaining recommended humidity levels can help support the body’s natural respiratory defences and reduce common complaints associated with dry indoor environments, including irritated eyes, dry skin, and throat discomfort. In healthcare facilities, where patients are often recovering from illness, injury, or medical procedures, appropriate humidity levels can be particularly important. Because humidity control is integrated into the HVAC system, it provides these benefits continuously without relying on individual action or behavioural changes.


The benefits also extend to facility operations. Appropriate humidity levels can help reduce electrostatic discharge (ESD) in areas with sensitive medical and electronic equipment while maintaining consistent conditions throughout the facility. In healthcare environments, where patient care activities, specialised equipment, and critical building systems operate around the clock, maintaining those conditions is particularly important.


Managing humidity in a ventilation-intensive environment


Ventilation is often central to the humidity control challenge in healthcare facilities. Hospitals and treatment centres continuously introduce outdoor air to support indoor air quality and regulatory requirements. While essential, those ventilation rates also create substantial humidification loads. Every cubic metre of outdoor air affects the facility’s moisture balance. During dry periods, HVAC systems may need to add significant amounts of moisture just to maintain target conditions. At the same time, occupancy levels, pressure relationships, operating schedules, and


DriSteem’s RTS® electric resistive humidifier automatically adapts to changing water conditions, learning continuously to optimise steam output and maintain reliable performance with any water type.


space usage often change, creating conditions that rarely match original design assumptions. Successful humidity control is not simply about meeting peak demand. Most facilities operate at part load far more often than at design conditions. Humidification systems must respond accurately to changing conditions while maintaining stable humidity year-round. Achieving that level of performance requires attention to the entire HVAC system, not just one piece of equipment.


Looking at the entire system


Long-term success rarely comes down to the humidifier alone. When humidity-related problems arise, the cause is often a combination of factors such as control sequences, sensor placement, changing building use, deferred maintenance, or water-quality issues rather than a lack of humidification capacity. The most successful healthcare projects begin with a clear understanding of the application and operating priorities. Rather than focusing solely on equipment selection, project teams evaluate water management, controllability, service requirements, and long- term operating costs. Across healthcare applications ranging from hospitals and treatment centres to laboratories and pharmaceutical facilities, experience points to the same conclusion: long-term results depend on how well the entire system works together. Application requirements, water quality, controls, maintenance practices, and operating conditions often influence performance as much as the humidifier itself. Many healthcare facilities are operating with ageing infrastructure, limited resources, and increasing demands on building performance. Systems that consume excessive water or energy, require frequent intervention, or are difficult to maintain can create operational challenges throughout the facility’s life.


DriSteem’s Ultra-sorb® steam dispersion panels deliver rapid, drip-free steam absorption with exceptionally short dispersion distances, helping prevent condensation on downstream equipment and surfaces.


6 BUILDING SERVICES & ENVIRONMENTAL ENGINEER OCTOBER 2026 Water quality and controls matter


Water quality is one of the most significant factors affecting humidification performance,


yet it is often overlooked during system planning and operation. Water conditions directly influence maintenance requirements, efficiency, equipment life, and operating costs. Evaluating water quality early helps establish realistic expectations and informs decisions about water-treatment strategies for humidifiers and other HVAC equipment. Controls deserve equal attention. Humidity loads change continuously as outdoor conditions and building operation change. Accurate sensors, proper placement, and responsive control sequences are essential for maintaining stable conditions while avoiding unnecessary energy use. Many issues initially attributed to humidification equipment can be traced to controls, sensor placement, operating sequences, or changes elsewhere in the building.


Designing for long-term performance


A humidification system is successful only if it continues delivering results years after installation. Because healthcare HVAC systems are expected to operate reliably for decades, maintainability is every bit as important as performance.


When selecting a system, consider service access, water-treatment requirements, cleaning procedures, and ongoing operating needs. The best solution is not necessarily the most complex. It aligns with the facility’s goals, resources, and operational capabilities while remaining practical to maintain over the long term.


Humidity may not receive the same attention as ventilation and filtration, but it can significantly influence patient environments, facility operations, and overall building performance. Experience shows that long- term results depend on understanding the application and managing ventilation, controls, water quality, maintenance, and humidification as an integrated system. That systems-based approach often separates a humidification system that merely operates from one that consistently delivers the intended results.


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