Are Chilled Beams a Fit for
THIS TECHNOLOGY FREEZES ENERGY COSTS
WHAT IS THE DIFFERENCE
BETWEEN PASSIVE AND
ACTIVE CHILLED BEAMS?
Loudermilk: Passive beams are not
directly connected to the ducted air supply.
A complementary air system must handle
dehumidification and ventilation. Active
beams use the pressure of the duct system
to enhance the volume of entrained room
airflow across their coils to significantly
increase their sensible cooling performance.
Duytschaever: Both options work through
convection. Active chilled beams have ventilation air ducted directly into the coils, which
is then forced down into the space below. A
passive system is placed above the ceiling in
the plenum. Ventilation goes through a diffuser within the space while circulated air is
forced up into the plenum.
applications have been active beams due to
their higher cooling capacity. Passive beams
have been used primarily in cases where the
space above the ceiling is limited or to complement the perimeter cooling of underfloor
air distribution systems.
WHAT ARE THE ADVANTAGES
OF CHILLED BEAMS OVER A
TRADITIONAL HVAC SYSTEM?
Duytschaever: A typical HVAC system
is tempering the air at the air handler and
then pushing it through ductwork. The
downside is that it requires a significant
amount of energy to force air. By comparison, chilled beams circulate water through
pipes. The advantage is that water can
hold higher levels of heat and cold, switch
between temperatures more easily and be
transported more efficiently than air.
WHAT ARE COMMON
BARRIERS TO ADOPTING
Loudermilk: Most U.S. installations are
new construction, though chilled beams can
be an ideal solution for retrofitting old induction units under windows or noisy HVAC
units in schools or hotels.
Duytschaever: Even though you will save
money in the long run, chilled beams are
more expensive up front because you still
have to install a boiler and chiller. Chilled
beams can cost up to 30% more per square
foot than a conventional HVAC system. Part
of the difference comes from labor because
the piping is heavier than ductwork and
requires more people to install.
WHAT KIND OF UPKEEP IS
Loudermilk: The fact that they require
very little maintenance is one of the major
benefits. As the system relies on chilled
water delivered above the space dew point
temperature, the coils remain dry and only
require inspection every four to five years.
Such coils are also exempted by building
codes from requiring pre-coil filters, which
also significantly reduces maintenance. No
motors or blowers are involved so replacement costs are virtually nonexistent.
Duytschaever: As with any HVAC system, each piece of equipment needs to be
monitored. If anyone’s complaining about it
being uncomfortable, that’s a red flag. There
might be a control valve failure or debris
near the coil that’s preventing air movement.
But most of your maintenance will be in the
actual boiler room.
Jennie Morton is a contributing editor for
Your HVAC system is one of your biggest energy consumers. Everything from blower motors and compressors to heat exchangers and chillers require electricity to operate.
Because chilled beams have fewer moving
parts, they can lower your operating costs.
Two professional engineers will help you
determine if chilled beams are right for
your building: Ken Loudermilk, Senior Chief
Engineer with Johnson Controls brand Titus,
and Kathryn Duytschaever, Associate with
engineering consultancy RTM & Associates.
BUILDINGS: LET’S REFRESH.
HOW DO CHILLED BEAMS
Loudermilk: Chilled beams allow decoupled treatment of sensible cooling loads from
the space dehumidification and ventilation
requirements. Their integral heat transfer
coils utilize chilled water delivered at or
above the space dew point temperature to
perform most of the space sensible cooling
at delivered airflow rates that are 60-80%
less than that required by conventional all-air
Duytschaever: Chilled beams have a fan
coil but no fan. Cold and hot water supply
lines connect to a heating and cooling coil.
As air naturally crosses the coil, it becomes
tempered. Control valves before the beam are
connected to a wall thermostat that determines if the cold or hot coil should open.
CHILLED BEAM TECHNOLOGY delivers
efficient heating and cooling with fewer
parts than conventional HVAC systems,
resulting in lower operating costs.