Linked In Radiant Panel Presentation

Hydronic Radiant Heating & Cooling

Twa Panel Systems Inc.
1201 – 4th Street
Nisku, AB
Canada, T9E 7L3
(780)-955-8757

www.twapanels.ca

Hydronic Radiant Heat. & Cool.
Agenda

• Radiant Panel Systems
• Background

• Radiant Panel System Design
• Air-Side Design
• Water-Side Design
• Capacity
• Thermal Comfort

• Benefits & Limitations
• Radiant Panel Products
• Applications

Radiant Panel Systems – Background

Radiant Panel Systems
Background

• Origins in Europe
• Introduced to North America
– Metal ceilings and radiant systems (1950’s)

• Seeking more capacity (Convection)
– Chilled Sails (1990’s)
– Passive beams (1990’s)

• Seeking integration of ventilation system and more capacity
– Active beams (Forced Convection) (2000’s)

Background

• High acceptance rate in Europe
• Historically high energy costs

• North American market increasing due largely to:
• Green initiatives
• Increasing energy costs
• Increased installed base (Familiarity & Successful projects)
• Lowering cost due to increasingly competitive market

Background

• Hydronic systems use water as the
energy transport medium
• Water has many times the thermal
capacitance as compared to air

Background

Modes of Heat Transfer

Conduction Convection Radiation

Background – What is Radiation?

• Heat transfer through Electromagnetic
Waves between surfaces
• The radiation is defined by the wave
length or frequency:
– Infrared / thermal radiation 0.8 – 100 μm
– Solar radiation 0.3 – 3.0 μm
– Light 0.4 – 0.7 μm
• Only mode that can travel through a
vacuum
• Process for heating and cooling the
EARTH

Background

• Radiant panel systems must be combined with a
ventilation system
– Displacement ventilation
– Traditional overhead air distribution
– Active beams
– Natural ventilation
• Operable windows

Terminology – Decoupled Ventilation
Terminology – Mixed-mode Ventilation

Radiant Panel System Basics
Systems
Background – Construction

• Steel or aluminum panel
– Aluminum extrusions
– Aluminum sheet metal
– Steel sheet metal
• Copper coil attached to panel
– Integrated saddle
– Mechanically attached saddle
• Conductive thermal paste
• Insulation
• Acoustic perforations
• Panels available in different
styles and shapes

Systems
Background – How Heating Works

Perimeter Radiant Ceiling
Radiant Ceiling

net heat
net heat = + + =
transfer
transfer

+
objects
=
net heat transfer

Systems
Background – How Cooling Works

Radiant Ceiling

net heat
net heat = + + =
transfer
transfer

+
objects
=
net heat transfer

Radiant Panel System Design
Air-side Design Principles – Overview

• Meet all ventilation requirements
– Min. Vent. (O/A requirements)
– Remove 100% of the latent loads (Psychrometrics)
– Maintain building static pressure
– Supplement sensible loads

**Greatest of these factors sets the minimum air flow rate**

• Higher SAT may be used (Displacement Vent.)
– May use heat recovery strategies for increased energy savings

• Decreased AHU & Duct size
• Decrease in fan energy

Air-side Design Principles – Energy Savings

• Majority of energy is saved at the FAN
• Air-side Load Fraction (ALF)
– The smaller the air-side load fraction, the more energy can be saved by
using a radiant system

Office Classroom Lobby
O/A Requirement (cfm/ft2) 0.15 0.5 1
Air Volume (All Air System) 1 1.5 2
(cfm/ft2)
Air-side Load Fraction 15% 33% 50%

• Suitability engineering check - % of Sensible from CFMLatent

Air-side Design Principles – Energy Savings

Design
Air-side Design Principles – Psychrometrics

Psychrometric review required to prevent condensation
Standard Procedure:
• Remove moisture from the P/A at AHU
• Dry P/A lowers the space dew point temperature
• To prevent condensate on the coil:

Space dew point temp. < EWT

Air-side Design Principles – Psychrometrics

Option 1 Option 2

Primary air dew
point 48°F 51.5°F
Room air dew
point 55°F 57.8°F
Secondary CWT 55°F 58°F
Dehumidification 0.002 lbs/lbDA 0.002 lbs/lbDA

RESET FOR ENERGY
SAVINGS!

Air-side Design Principles – Psychrometrics & Region

Legend:
■ Easy , Application of radiant products is natural
■ Medium , Application of radiant products requires some additional design to
control building moisture
■ Difficult, Application of radiant products is more difficult and humidity must be
carefully considered

Air-side Design Principles – Design Parameters
Typical Design Conditions (Cooling):
S/A Space
TDry Bulb: 55 - 65 F TDry Bulb: 75 F
TWet Bulb: 53 - 57 F TWet Bulb: 64 F
TDew point: 52 F TDew point: 58 F
R.H.: 55%
ΔGr = 13.64 Gr/lb

Typical Design Conditions (Heating):
S/A Space
TDry Bulb: 65 F TDry Bulb: 70 F
R.H.: 50%

QL = 0.68*CFM*ΔGr Qs = 1.08*CFM*ΔT

Air-side Design Principles - Considerations

• Maintain reasonable dew point control
– Meet 100% of latent load under Peak Design conditions
• Infiltration
• Maximum occupancy
• Other sources of moisture

• Limit over-cooling
– Keep air-side load fraction low
– Reset air temperature
– CHWS Shut-off control or EWT reset
– VAV for fluctuating occupancy

Design
Air-side Design Principles – Control Sensors

• %RH sensor
• Condensation sensors
– Typically locate one on the supply water tubing in an area
most likely to have the highest dew point
– Use a sensor to shut off valve or reset EWT
Sensor Location Advantages Disadvantages
On the face of the beam / panel Humidity is measured where the Integration into the beam or panel
risk of room condensation is the may require increased
highest. coordination.
Sensor may be difficult to access
for calibration.
In the zone Humidity is measured at the Local spikes in the humidity may
source of the moisture cause the system to be overly
Sensor is easily accessible. responsive, reducing capacity.
In the return duct A more average reading of the Cannot respond to local humidity
zone humidity is taken, issues.
maximizing the operation of the
beam.

Air-side Design Principles – Common Pitfalls

• Two Air-side Design Concerns:

1) Psychrometrics (Cooling only)
2) Preliminary Design based on DOAS system

Water-Side Design Principles – Overview

• Responsible for majority of the sensible loads
• Coil – ½” nom. Pipe with 180°bends
• Design requires:
– Water flow rate
– Circuit pressure drop
– Temperatures (EWT, MWT, LWT)

• Increase in pump size and pump energy
– Fan Energy vs. Pump Energy = Net energy savings

Water-Side Design Principles – Design Parameters
• Radiant Cooling:
– EWT temperature, typically between 56 – 62°F
• Secondary CHWS loop required

– ΔT across panel, typically 4 - 6°F
– Psychrometrics – (Condensation control)
– Generally EWT = 2 – 3 °F above SPACE dew point temp.

• Radiant Heating:
– EWT temperature, typically between 120 – 180°F
– ΔT across panel, typically 20 - 30°F

• Minimum flow rate per circuit = 0.65 GPM
– Prevent laminar flow (more important for cooling)

Design
Water-Side Design Principles – Piping

Water system pressure control
• Variable speed pump and
differential pressure sensor
• Reduces energy by lowering
pump loading
• Can cause imbalances in the
system when not at full flow if
pressure independent flow
control valves are not used

Design

Direct return
• Length of pipe varies from supply
header to return header for each
unit
• Change in pressure drop from
one circuit to another, affects flow
rates
• Use balancing valves or circuit
setters
• Can cause imbalances in the
system when not at full flow if
pressure independent flow
control valves are not used

Design

Reverse return
• First supplied, last returned
• Zone or array is self-balancing
• Number of balancing valves can
be reduced
• Additional pipe length required
• May require pressure
independent flow control valves
at mains for zone take off

Design

Series piping
• Used to connect panels smaller
zones
• Reduced piping, valving, and
balancing costs
• Higher flow rate to maintain ΔT
• Too many panels in series leads
to reduced response and large
temperature difference between
1st and last panels
• 200’ total of coil piping is upper
limit for ΔT and W.P.D.

Design

Parallel piping
• Used with large panels and
connecting several sets of panels
in series
• Reduced pressure loss
• Lower flow rates to achieve ΔT
• Better temperature distribution
and response

Water-Side Design Principles – Future Advancements

• Integrated Reverse-Return Piping:

• 30” wide – 6 pass panel
• 6 interconnectors per joint vs. 2
• Uniform heat distribution

Water-Side Design Principles – Common Pitfalls

• Three water-side Design Concerns:
1) Use of Glycol as the operating fluid
• Especially in cooling
2) Not considering Pressure independent flow control valves
• Especially with large hydronic systems
• Modulating valves
• Variable frequency drive pumps
3) Valve & Entrapped air noise

73F

60F

Radiant Panel Capacity

Design
Heating / Cooling Capacity

• Capacity is a function of:
– Emissivity of panel surface (ε= 0.9 – 0.98)
• Paint Color, finish, etc.

– Radiation (50-70%, Heating & Cooling)
• Stefan-Boltzmann Equation
– qr = 0.15x10-8 · [(tpanel+460)4 – (AUST+460)4] for ε = 0.9

– Convection (20-50%, Cooling currents from panel surfaces)
– qc = 0.31 · |tpanel- tair|0.31 · (tpanel- tair) cooled ceiling surface

– Location of panel
• Proximity to warm / cool surfaces

Systems
Characteristic Radiant Field

• Radiation Angle
– View factor (Line of sight)
– Effectiveness of radiant panels

Design

• Selection Tables:

• Cooling requires
larger area of panel

Design

• Typically active area is limited to <70% of entire
ceiling area
– Fire, PA System, Lighting, Ventilation services…etc
– Systems can be integrated into the panels

• Insulation can improve performance

Design
Performance Data

• Applicable standards:
– EN 14037: panel heating
– EN 14240: panel cooling
– EN 4715: previous standard
– ASHRAE 138

• When choosing a manufacturer, ensure they
test to an applicable standard!

73F

60F

Thermal Comfort

Design
Thermal Comfort

• Radiant asymmetry:
– Caused by large difference in surface temperatures
• Think – Sitting by a campfire

– Usually from panel in heating mode (Hot panel surface)
• Modulating valve can reduce risk
• Index HWS temp. relative to O/A temp.

– Usually from glazing in cooling mode (Hot glass surface)
• Perimeter panels in cooling mode can reduce risk
• Draft:
– Usually caused by improperly designed air diffusion

Design
Thermal Comfort

• Radiant asymmetry
– Temperature difference
between opposing surfaces
– < 5% People Dissatisfied
– Based on average ceiling
temperature
– Thermostat may read proper air
temp., but space may still be
uncomfortable for occupant

Benefits & Limitations
Benefits of Radiant Systems
• Energy efficiency
– Significant fan energy savings
• Overall reduction in S/A
• Night Setback of fan

• Smaller AHU & Ductwork
– Lower floor-floor heights
– Good retrofit applications
– Significant reduction of riser space

• Low maintenance
• High Level of thermal comfort
• Low acoustics
• Custom Architectural looks

Benefits &System Theory
Hydronic Limitations
Benefits of Radiant Systems

• Energy savings on the order of 10 – 40%
compared to overhead VAV systems
– Ex. East Coast University

Overhead VAV lab 4,107,200
+Fan Coils
10.5%
Radiant ceiling with
VAV lab +Fan Coil 3,676,279

+ $220,000/year utility savings

Other Benefits of Radiant Systems

• Spaces may be zoned
– Increased Comfort
– Reduced energy consumption
– Individual space temperature control (LEED Compliant)

• Quick response time
– Radiant panels are lightweight and have a relatively short
response time (0.5°F/min)

Terminology – Low Mass Radiant System

Other Benefits of Radiant Systems

• Heat up response
– Based on a Consulting Engineers Report

– Rate of change from cooling mode
– Temperature at low level rose from
70°to 82°in 21 mins.
– 0.57°/min

• Cool down response
– Based on a Consulting Engineers Report

– Rate of change from heating mode
– Temperature at low level decreased
from 82°to 72°in 20 mins.
– 0.5°/min

Limitations of Radiant Systems

• Potential for higher first cost
• Increase in pump energy
• Small Compared to Fan Energy Savings
• Limited air-side free cooling
• Limited VAV modulating range
• High importance for building humidity control in Cooling
• Dehumidification at the AHU is required
• May require a building envelope upgrade
• May require more sophisticated controls for humidity control
• May not be acceptable for all spaces, based on latent loads

Radiant Panel Products
Hydronics Products

Hydronics Products
Modular Type Radiant Panel

• Tegular or T-Bar panels
• Security panels

Hydronics Products
Linear Type Radiant Panel

• Trimmable
• Series
• Mitered corners

Hydronics Products
Wall Mounted Radiant Panels

• Used where overhead panel systems are not available
• Part of design element in space
• Bull nose, Corner, or Bull nose/Corner panels

Hydronics Products
Surface Mounted Radiant Panels

• Mounted to dry wall ceiling/wall in perimeter or interior
• Part of design element in space
• Bull nose or Corner panels

Hydronics Products
Free Hanging (Exposed) Radiant Panels

• Integrate into building architecture
– Open ceiling spaces (warehouses, schools, etc.)
– High ceiling areas


Hydronics Products
Light Shelf Radiant Panels

• Manage perimeter load
• Inactive top
– Allow light to penetrate (winter) or
limit radiant penetration (summer)

• Activate top
– Frost (winter) or limit radiant
penetration (summer)


Hydronics Products
Chilled Sails

• Architectural or concealed

Hydronics Products
Custom Linear Panels

• Architectural requirements
• Component integration (lights, sprinklers)
• Custom sizes
• Curved panels
• Security panels
• Hinged panels

Hydronics Products
Finish Options

• Castellated
• Smooth
• Smooth perforated block
• Smooth perforated continuous
• Silk Screen match

Hydronics Products
Access Panels

• Integrated removable inactive
access sections
• Hinged access panel
– Simply release from grid system
– Secured with cables
– Flexible connection hoses

Applications

• Laboratories • Long term care facilities
• Office Buildings • Historical Retrofits
• Hospitals – Low ceiling space
• Educational facilities
– Universities incld. Residence
buildings

• District cooling/heating plant systems are great
• Higher CHWS & Lower HWS temps can help reduce “Low ΔT Syndrome”
and improve efficientcies
• Large buildings have a greater argument for hydronic systems
• Justify equipment costs with respect to savings

Applications

Office Space

Radiant Sail Radiant Panels

Applications

Lab/Classroom

Radiant Panels

Applications

Retail

Radiant Chilled Ceiling

Applications

Exhibition Space

Radiant Chilled Ceiling

Applications

Common Area

Radiant Panel

Applications

Theater

Design Concerns:

• Latent Load

• Ceiling Heights

Radiant Sails

Applications

Casino

Design Concerns:

• Latent Load

Radiant Sails

Applications
East Coast University – Retrofit chilled ceiling

• Original ceiling height 7’
• Evaluated as only feasible
solution for mechanical system

Applications
West Coast – University Residence

Applications
West Coast - High School

Applications
Northern – Rural School

Applications

Children’s Hospital

Custom Curve Radiant Panels

Applications

Science Center

Custom fit Radiant Panels

Applications
East Coast University – Third party activated ceiling panels

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