A chilled beam is a ceiling-mounted heat exchanger that uses chilled water as its primary medium to provide sensible cooling to occupied spaces. It transfers heat from room air through convection and, to a lesser degree, radiation, offering an energy-efficient alternative to conventional all-air HVAC systems. Chilled beams are available in two configurations: passive beams, which rely entirely on natural convection, and active beams, which use induction nozzles supplied with primary ventilation air to enhance airflow across the coil and increase cooling output.
Technical Details and Specifications
Chilled beams operate with supply water temperatures typically ranging from 57°F (14°C) to 64°F (18°C). These temperatures are intentionally maintained above the room dew point to prevent condensation on the beam surface, which is a critical design consideration. Cooling capacities generally fall between 150 and 600 BTU/hr per linear foot of beam, depending on beam geometry, water flow rate, water temperature, and room air conditions.
Active chilled beams require a supply of primary air, usually conditioned by a Dedicated Outdoor Air System (DOAS), at flow rates of approximately 0.2 to 0.5 CFM per square foot of served floor area. The external static pressure requirement for this primary air typically ranges from 0.2 to 0.5 inches of water column. Because the water-side system handles the bulk of the sensible cooling load, ductwork and air handling equipment can be significantly downsized compared to variable air volume (VAV) or other all-air approaches.
- Passive beams: no primary air connection; cooling relies on natural convection only, resulting in lower capacity but simpler installation.
- Active beams: integrated induction nozzles draw room air across the coil, delivering roughly two to three times the cooling capacity of passive beams per linear foot.
- Some active beam models include heating coils or a two-pipe changeover design to provide both heating and cooling from a single unit.
Common Applications
Chilled beams are well suited to commercial environments with moderate to high sensible heat loads and strict acoustic requirements. Typical installations include office buildings, hospital patient rooms, laboratories, schools, and hotel guest rooms. Their quiet operation, with no local fans or moving parts in passive configurations, makes them particularly attractive for spaces where occupant comfort and low background noise are priorities.
Related Standards and Design Guidance
Design and selection of chilled beam systems are informed by ASHRAE Standard 62.1 for ventilation requirements and ASHRAE Handbook chapters addressing radiant and convective cooling. The REHVA Guidebook on Chilled Beam Application provides additional European design methodology that is widely referenced in North American practice. Proper dew point monitoring and condensation prevention strategies should follow manufacturer guidelines and local building codes to avoid moisture-related issues.
Practical Significance
Chilled beam systems reduce fan energy consumption by shifting the majority of sensible cooling from the air side to the water side, since water carries roughly 3,500 times more energy per unit volume than air. This results in smaller ductwork, reduced ceiling plenum requirements, and lower overall energy use. By pairing with a DOAS for ventilation and latent load control, chilled beams allow engineers to decouple outdoor air delivery from temperature control, improving both indoor air quality and system efficiency. The reduced mechanical infrastructure can also translate into lower floor-to-floor building heights, yielding meaningful construction cost savings on multi-story projects.