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Chilled beam systems get cool results

Andrew Jackson, CBCA
Andrew Jackson, chairman, CBCA

1 August 2013


Chilled beam air cooling systems can save up to 22 per cent of the energy costs it takes to run a fan-cooling system, a new study has found.


The independent study was commissioned by the Chilled Beams and Ceilings Association (CBCA) and conducted by construction software maker Environmental Design Solutions (EDSL).

The EDSL Tas Energy Study compares performance of Variable Air Volume (VAV) fan coil systems and systems using chilled beam technology.

Performances of VAV fan coils, passive chilled beams and active chilled beams were measured by simulating the dynamic thermal performance of four different-sized office buildings. Comparisons were made of energy consumption, CO2 emissions and running costs of different HVAC (heating, ventilating and air-conditioning) systems within the buildings.

In the simplest VAV system, the supply air temperature is constant so the system’s air-flow rate must vary to meet the rising and falling heat gains or losses within the building’s thermal zone which the system is trying to cool down.

Modern switching and control technology applied to a VAV system can save energy through more efficient turning on and turning off of the system as needed to maintain a constant cool temperature.

In a passive chilled beam system, pipes of water are passed through a "beam" - heat exchanger - either integrated into a standard suspended ceiling or suspended closely to the ceiling of a room. As the beam chills the air around it, the air becomes denser and falls to the floor. It is replaced by warmer air moving up from below, causing a constant flow of convection and cooling the room.

An active chilled beam system has air forced around the beam to induce greater convection and improve efficiencies.

The study’s simulations used the Chartered Institution of Building Services Engineers (CIBSE) published hourly weather data for London and Birmingham. The weather data is representative of an average year over the past 20 years.

Results of the study show there are potential savings of around 17 per cent for a passive chilled beam system and around 22 per cent for an active chilled beam system in all the buildings simulated.

CBCA chairman, Andrew Jackson said the research comes as energy demand and supply is top of the news agenda.

“As an industry it’s important we share knowledge to help buildings perform more efficiently,” he said. “Chilled beam technology offers a solution for offices and other property. It also is technology that is available today and proven to enable energy savings.”

Chilled beam technology can often be left out of discussions for designing new buildings because it more expensive to install, he told FM World.

But in the long run, it could save money, Jackson said. This point is increasingly important as design and construction of buildings shifts towards building information modeling (BIM).

At the moment, chilled beam technology is used mostly by government and owner-occupiers of buildings. He said these organisations are more concerned with saving money in the long run because they built the office with a view to staying in it for several years. It wasn’t a speculative venture constructed by a developer, which could flip it within a few years if a suitable profit presented itself.

Most of CBCA’s 14 members – makers and suppliers of chilled beams – also sell and supply VAV fan coil systems, Jackson said.

CBCA is part of FETA - Federation of the Environmental Trades Association. FETA more 400 members are manufacturers, suppliers, installers and contractors within the heating, ventilating, building controls, refrigeration & air conditioning industry.

The CBCA Technical Fact Sheet 2 – EDSL Tas Energy Study Summary Findings is available here.

Environmental Design Solutions Thermal Analysis Software (Tas) is accredited by the Department of Communities and Local Government for Building Regulations Part L and Energy Performance Certificate (EPC) calculations.