RADIANT COOLING SYSTEMS PRINCIPLES OF RADIANT COOLING SYSTEMS INSTALLATION, DESIGN, CONTROLS, CAPACITIES

Construction Automotive Industry www.rehau.com

RADIANT COOLING SYSTEMS

PRINCIPLES OF RADIANT COOLING SYSTEMS INSTALLATION, DESIGN, CONTROLS, CAPACITIES

INTRODUCTIONS

Lance MacNevin

- Manager, REHAU Academy

- Senior PEX Codes and Standards Specialist

f ’

PRESENTER

- Mechanical engineer for REHAU’s PEXa piping division since 1993 - Product development, system design - Develops training for installers, designers,

engineers, architects, distributors, etc. - Based at REHAU Head Office in Leesburg, VA - lance.macnevin@rehau.com

“UNLIMITED POLYMER SOLUTIONS”

SMART SOLUTIONS FOR SUSTAINABLE DESIGN

REHAU was founded in 1948 in the town of Rehau, Germany

- Over 18,000 employees in more than 70 countries at 170 locations around the world - Focused on polymer solutions for construction, automotive, furniture and industry REHAU is a pioneer of:

- PEXa piping systems for radiant heating applications, starting in 1968

- Applications like snow and ice melting, PEX geothermal systems and radiant cooling

27-Mar-15 Page 3

PROLOGUE: RADIANT COOLING SYSTEMS

- Radiant surface: an exposed building surface including a tube or piping configuration installed within for heat exchange within a conditioned space

- Radiant surfaces may be for heating or cooling DEFINITIONS

- Sensible cooling surface: a surface designed for sensible cooling of an indoor space through heat transfer to the thermally effective surfaces from the occupants and/or indoor space by thermal radiation and natural convection

- The network of radiant surface pipes can turn the radiant surface such as floors, walls and ceilings of a conditioned space into cooled surfaces that evenly absorb sensible heat energy such as radiant energy from solar gain, people, lights and computers, in addition to convective heat transfer from the air

WHAT IS A RADIANT COOLING SYSTEM?

Typically designed in conjunction with radiant heating, radiant cooling systems circulate chilled fluid through the same network of pipes where warm fluid circulates during the heating season

- This network of pipes can turn the floors, walls and ceilings of a conditioned space into cooled surfaces that evenly absorb heat energy

- Radiant cooling works best in a tightly sealed building that integrates radiant with a downsized forced-air system to meet the building’s fresh air requirements

- Over 50% of “high-performance” buildings utilize radiant heating and cooling systems

27-Mar-15 Page 5

Early example:

Bilbao International Airport, northern Spain

PROLOGUE: RADIANT COOLING SYSTEMS

Why is this course relevant?

- May 2014 ASHRAE Journal technical feature VAV vs. Radiant describes how radiant cooling helped architects and engineers achieve LEED®_{Platinum certification in an office}

WHAT IS A RADIANT COOLING SYSTEM?

building in the demanding climate of Hyderabad, India

- Two identical buildings were built with same loads and uses, one with radiant cooling - 34% reduction in operational costs for building with radiant cooling vs. VAV systems

1. Explain the principles of radiant cooling systems and factors affecting thermal comfort 2. Describe the four basic installation types for radiant cooling systems

3. Discuss how a radiant cooling system is combined with air handling equipment to make a BY THE END OF THIS COURSE, PARTICIPANTS SHOULD BE ABLE TO:

“hybrid” radiant cooling HVAC system which can address the concern of condensation 4. Introduce control options for a radiant cooling system

5. List the factors that affect output capacity of a “hybrid” radiant cooling system 6. Summarize the advantages of a hybrid cooling HVAC system

7. Refer to published case studies

27-Mar-15 Page 7

Note: Several of the claims in this presentation have been independently published in “Radiant Cooling Research Scoping Study” (2006) Moore, Bauman, Huizenga, Center for the Built Environment (CBE), UC Berkley: http://www.cbe.berkeley.edu/research/pdf_files/IR_RadCoolScoping_2006.pdf

1. PRINCIPLES OF RADIANT COOLING AND THERMAL COMFORT

Whenever there is a temperature difference between two objects, both objects will attempt to equalize the temperature

- The energy transfer required to approach equivalent temperatures occurs through THERMAL COMFORT

BASIC PHYSICAL PHENOMENA

radiation, conduction and convection

 Radiant energyis infrared energy that travels from “hot” to “cold” through a space, without heating the space itself

People are exothermic heat generators! - Heat emission from the human body occurs

via four modes of heat transfer: THERMAL COMFORT

BASIC PHYSICAL PHENOMENA

Our brains burn 500 Cal/day! i. Radiation (~45%) ii. Convection (~30%) iii. Evaporation (~20%) iv. Conduction (~5%)

- Our bodies radiate heat to any surface in line-of-sight which is cooler than our own surface temperature (85 - 90°F / 29 - 32°C) - Humans feel most comfortable when they can

l t t l t 45% f th i h t i i

27-Mar-15 Page 9

regulate at least 45% of their heat emission through radiation

- Reducing surrounding surface temperatures draws more heat from our bodies via radiation

- When the air is warm, this is a good thing!

From years of adjusting thermostats, we have been conditioned to believe that air temperature alone translates to comfort, but this is not necessarily true.

We have to consider:

PRINCIPLES OF RADIANT COOLING AND THERMAL COMFORT

TEMPERATURE SET POINTS

We have to consider: 1. Air temperature

Space’s air temperature, monitored by thermostat as “set point temperature” 2. Mean radiant temperature (MRT)

Average temperature of surrounding surfaces 3. Operative room temperature

ASHRAE Standard 55 Thermal Environmental Conditions for Human Occupancy Boundaries for thermal comfort according to ASHRAE Standard 55

THERMAL COMFORT

- Operative temperature:

- Summer period @ 50% RH: 75 -80°F - Winter period @ 30% RH: 70 -77°F

- Range of the floor temperature: 66 -84°F

- This is their so-called comfort area, where the percentage of people who are comfortable is optimized

A bl t t i ht b l th

27-Mar-15 Page 11

- A reasonable target might be less than 10% dissatisfied at any moment - commercially

PRINCIPLES OF RADIANT COOLING AND THERMAL COMFORT

A lower Mean Radiant Temperature increases the radiant heat loss from human body - Surfaces are cooler with radiant cooling

- Human body radiates more heat to floors, walls and ceilings THERMAL COMFORT

THE EFFECTS OF MEAN RADIANT TEMPERATURE ON COMFORT

- Indoor air does not have to be as cool for equivalent comfort

- Indoor air temperature setpoint is elevated, or operative temperature may be too low - We typically use setpoint temperatures above 75°F for radiant cooling applications Pink area = approximate comfort zone

- With cooler surface temperatures, the air can be warmer without causing discomfort, saving energy

MRT comfort graph originally published in Architectural Forum, January 1939

In a radiant heating system, warm fluid circulates through PEX pipes integrated in the floor structure - Heat radiates up from the warmed floor, THERMAL COMFORT

RADIANT HEAT TRANSFER

Floor Covering providing a comfortable environment by warming

people and objects

- Warm air also rises due to natural convection - There is also conduction to feet!

A radiant cooling system works with the reverse energy transfer process, providing a comfortable environment by absorbing heat from the space

In cooling mode the same network of pipes is

WARMED CONCRETE SLAB

PEX Pipe

COOLEDCONCRETE SLAB

Floor Covering PEX Pipe

27-Mar-15 Page 13

- In cooling mode, the same network of pipes is used as in the heating mode

- Heat transferred into the floor is removed from the space via the circulating fluid

- In some applications, pipes are embedded into the ceiling or even the walls or columns

COOLEDCONCRETE SLAB

Ceiling Exposure PEX Pipe

PRINCIPLES OF RADIANT COOLING AND THERMAL COMFORT

TEMPERATURE SET POINTS

Spaces with 100% forced-air systems have higher mean radiant temperatures due to solar gains and office equipment

O t t d th i t i t t i t

- Occupant turns down the air setpoint, trying to counter radiant loads using more cooler air - This requires more air movement, inefficiently

countering a high MRT

With an air-based system in combination with a radiant cooling system, surface temperatures

1. Humans feel most comfortable when they can regulate at least 45% of their heat emissionthrough radiation

2. The operative temperature is what we perceive on our skin in a room and what is most

i t t t id h if i di t t

SUMMARY

important to consider when specifying a radiant system

3. A radiant cooling system works by absorbing heat from the space

4. With a radiant cooling system, surface temperatures are lower,so occupants feel comfortable within the space, which removes the need for a lower air temperature and/or increased air flow

27-Mar-15 Page 15

2. INSTALLATION TYPES OF RADIANT COOLING

i. Radiant Floor Heating and Cooling (FHC) ii. Thermally Activated Building Slab (TABS) iii. Radiant Ceiling Heating and Cooling (CHC)

i R di W ll H i d C li (WHC)

RADIANT FLOOR HEATING AND COOLING

i. Radiant Floor Heating and Cooling (“FHC”) - With insulation underneath to condition the

space above

C / f f

- Creates a heated/cooled floor for the space above

- Common in slab-on-grade buildings - Uni-directional heating/cooling

27-Mar-15 Page 17

INSTALLATION TYPES OF RADIANT COOLING

ii. Thermally Activated Building Slab (TABS) aka “Concrete Core Tempering” (CCT) - Without insulation underneath

C h d/ l d fl d ili

- Creates a heated/cooled floor and ceiling, to condition the spaces above and below - Common in multi-story buildings - Bi-directional heating/cooling

RADIANT CEILING HEATING AND COOLING

iii. Radiant Ceiling Heating and Cooling (CHC)  Suspended panels with embedded small

diameter PEX mini-pipes, “plastered” over

S f f

 Surfaces can absorb radiant heat from below and from warm air

 Cooled surfaces can be strategically located above warm occupied areas

 Ideal for factories, classrooms, stores  This is Uni-directional heat transfer

27-Mar-15 Page 19

INSTALLATION TYPES OF RADIANT COOLING

iii. Radiant Ceiling Heating and Cooling (CHC)

 Suspended panels with embedded PEX mini-pipes are sometimes used  Panels can absorb radiant heat from below and from warm air

P l b i ll l d b i d

RADIANT WALL HEATING AND COOLING

iv. Radiant Wall Heating and Cooling (WHC)

- Small diameter pipes are attached to walls then “plastered” over - Pipes may be run from the floor as the same circuit, same fluid (left)

( )

- Pipes may be run as a separate circuit (right)

27-Mar-15 Page 21

RADIANT FLOOR HEATING/COOLING RE-PURPOSED COMMERCIAL SPACE Pier One, San Francisco, 1999

 The radiant floor heating and cooling system installed in historic Pier One in San Francisco's

INSTALLATION TYPES OF RADIANT COOLING

Embarcadero district is one of the first documented uses of a radiant floor heating system, also used to cool a building, in NA

RADIANT FLOOR HEATING/COOLING

MOTORCYCLE DEALERSHIP IN LIBERAL, KANSAS

Radiant system was combined with air system to meet customer’s needs for: - Optimum thermal comfort

27-Mar-15 Page 23 p

- Reduced energy consumption - Reduced noise

- Avoiding local hot/cold spots

RADIANT FLOOR HEATING/COOLING

NATIONAL GUARD HANGER (HIGH ALTITTUDE ARMY TRAINING SITE) IN EAGLE, CO IS LEED®_SILVER

INSTALLATION TYPES OF RADIANT COOLING

Radiant system was combined with air system to meet customer’s needs for: - Optimum thermal comfortp

- Energy savings

- Radiant is ideal for hanger space with high ceilings and high solar gain

RADIANT FLOOR HEATING/COOLING PLUS CEILING COOLING

EARTH RANGERS CENTRE IN WOODBRIDGE, ONTARIO IS LEED®_PLATINUM

27-Mar-15 Page 25

THERMALLY ACTIVATED BUILDING SLAB IN MULTI-STORY TOWER YWCA WOMEN’S SHELTER IN TORONTO, ONTARIO IS LEED®_SILVER

YWCA Toronto Elm Tower, ON  Complex includes 5-, 10- and

17-story residential towers and the new

INSTALLATION TYPES OF RADIANT COOLING

YWCA Toronto corporate offices  Radiant heating/cooling in TABS

design, with downsized AHU and ground-source geothermal heating/ cooling source, saves over 40% on heating/cooling costs

THERMALLY ACTIVATED BUILDING SLAB IN MULTI-STORY DORMITORY YORK UNIVERSITY IN TORONTO, ONTARIO

27-Mar-15 Page 27

INSTALLATION TYPES OF RADIANT COOLING

- Radiant cooling pipes may be embedded in floors, ceilings, walls or other exposed surfaces

THERMALLY ACTIVATED BUILDING SLAB IN MULTI-STORY DORMITORY PIPES IN FLOORS, CEILING AND CERTAIN BUILDING COLUMNS

- Pipes are in these columns

RADIANT CEILING EXAMPLE APPLIED IN A UNIVERSITY LIBRARY LOYOLA UNIVERSITY IN CHICAGO, ILLINOIS IS LEED®_SILVER

27-Mar-15 Page 29

INSTALLATION TYPES OF RADIANT COOLING

i. Radiant Floor Heating and Cooling (FHC) ii. Thermally Activated Building Slab (TABS) iii. Radiant Ceiling Heating and Cooling (CHC)

i R di W ll H i d C li (WHC)

iv. Radiant Wall Heating and Cooling (WHC)

‒ A common factor is the poured cementitious thermal mass around the pipes

‒ No aluminum heat transfer panels are used in radiant cooling systems

Although hydronic building conditioning systems have many benefits, they usually can not work alone in commercial applications

ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

Radiant cooling systems must have an air-based component for several reasons: 1. Fresh air

- The AHU is required to meet the building’s fresh air requirements, staying consistent with increased building environment standards (e.g., ASHRAE 62.1, LEED)

2. Latent cooling

- Downsized forced-air components must exist to counter humidity from outside air

d f t ithi b ildi (l t t li )

27-Mar-15 Page 31

and from occupants within a building (latent cooling) 3. Fast response time

- For some applications, it is desirable to have a fast-acting air system to handle quick shifts in occupancy and transient loads

HYBRID RADIANT COOLING COMBINED WITH AIR HANDLING

Successful radiant cooling projects center around understanding the correct balance of an air handling unit (AHU) working in conjunction with a radiant system. These are referred to as “hybrid HVAC systems.”

ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

Note: “AHU” is used to indicate any forced-air system used to condition a space (e.g., fan coil, packaged rooftop unit, DOAS).

The radiant system and the AHU work together as a hybrid HVAC system, optimizing system design and performance by decoupling the following portions of the system: 1. Hydronic and air-based heat exchange

2. MRT and air temperature control

The key to preventing condensation lies in three specific areas: 1. Infiltration

ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

- First and foremost, use a tight building envelopeto reduce loads associated with non-mechanical infiltration (leakage)

2. Surface Temperature

- Control surface temperatures by designing cooled surfaces to operate at specific supply temperatures to prevent the surface from reaching dew point, which might lead to surface condensation

3 R l ti H idit

27-Mar-15 Page 33

3. Relative Humidity

- Control the level of humidity in a building with the AHU to keep the dew point lower than the radiant system’s operating temperatures

- Spaces are typically designed for about 50% maximum relative humidity during peak cooling periods

HYBRID RADIANT COOLING COMBINED WITH AIR HANDLING

Relative humidity: The ratio of the amount of moisture in the air at a specific temperature to the maximum amount that the air could hold at that temperature, expressed as a percentage ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

Dew point temperature: The temperature at which dew begins to form.

- Radiant cooling needs a slightly more sophisticated design approach compared to radiant heating due to solar gains, occupant loads and resulting moisture management issues, which for many climates of North America pose concerns for specifiers

The Dew Point of any atmosphere may be predicted using established means - The radiant cooling designer must utilize proper controls to keep all surfaces temperature

above the dew point

ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

27-Mar-15 Page 35

Example of pyschrometric chart

HYBRID RADIANT COOLING COMBINED WITH AIR HANDLING

Radiant cooling is used in “very cold” climatic regions

- Where specifiers have chosen radiant

h ti th il t k d t f

ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

heating, they can easily take advantage of the cooling potential in the existing PEX network

- Addition of radiant cooling minimally increases the initial cost and has many advantages during operation

R di t li i d i “H t/H id”

Radiant cooling is used in “Hot/Humid” climatic regions

- Proper controls are available to avoid uncomfortable and dangerous condensation

New 12,000 ft2_{Technical Center in Cullman, AL} ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

CHALLENGING BUILDING DESIGN IN ALABAMA WITH RADIANT HEATING AND COOLING

27-Mar-15 Page 37

New 12,000 ft2_{Technical Center in Cullman, AL} - Summertime dew point temperature can be above 80˚F ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

CHALLENGING BUILDING DESIGN IN ALABAMA WITH RADIANT HEATING AND COOLING

HYBRID RADIANT COOLING COMBINED WITH AIR HANDLING

New 12,000 ft2Technical Center in Cullman, AL includes:

- Radiant heating and cooling, geothermal heat exchange, smart controls, pre-insulated pipe, PEX plumbing and outdoor snow and ice melting

f f / ” @ ( ) f /

ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

CHALLENGING BUILDING DESIGN IN ALABAMA WITH RADIANT HEATING AND COOLING

- 2,900 ft of 5/8” PEX tubing @ 6 inch spacing (in 10 circuits) for heating/cooling in the Academy classroom

- When it opens in 2015, this facility host seminars for architects, engineers, contractors and distributors who will travel to Cullman to see these innovative technologies in action

27-Mar-15 Page 39

New 12,000 ft2Technical Center in Cullman, AL ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

CHALLENGING BUILDING IN ALABAMA WITH RADIANT HEATING AND COOLING

HYBRID RADIANT COOLING COMBINED WITH AIR HANDLING

New 12,000 ft2Technical Center in Cullman, AL

- Radiant heating/cooling slab system uses 2,900 ft of 5/8” PEX at 6 in. spacing - 10 circuits connected to central manifold

f

ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

CHALLENGING BUILDING IN ALABAMA WITH RADIANT HEATING AND COOLING

- Maximum circuit length 300 ft. - Designed for maximum ΔT of 10˚F

27-Mar-15 Page 41

New 12,000 ft2Technical Center in Cullman, AL (current status) ADDRESSING HUMIDITY AND PREVENTING CONDENSATION

CHALLENGING BUILDING IN ALABAMA WITH RADIANT HEATING AND COOLING

HYBRID RADIANT COOLING COMBINED WITH AIR HANDLING

ADDRESSING HUMIDITY AND PREVENTING CONDENSATION SUMMARY

1. A “hybrid radiant cooling system” uses the correct balance of an air handling working in conjunction with a radiant system

2. Hybrid radiant systems must have an air-based component for fresh-air supply, to dehumidify and for localized fast response

3. Examples of radiant cooling in humid climates demonstrate the effectiveness

27-Mar-15 Page 43

4. CONTROL OPTIONS FOR RADIANT COOLING SYSTEMS

Typical elements:

- Outdoor temperature sensor on the northern side of the building, not exposed to direct sunlight

BUILDING CONTROL STRATEGY

exposed to direct sunlight

- Humidity and temperature sensor(s) in each zone to monitor dew points and set points

- Floor temperature sensor in the upper level of the thermal mass

- Supply and return fluid temperature sensors in the piping network

BUILDING CONTROL STRATEGY ZONE CONTROL STRATEGY

- Humidity sensor/s in several rooms to measure RH%

- Air sensing thermostats in each “zone” to control air supply for rapid response cooling and local dehumidification

- Both sensors are often

bi d i it

27-Mar-15 Page 45

combined in one unit

CONTROL OPTIONS FOR RADIANT COOLING SYSTEMS

The right controls are available - Several firms have the know-how to

design build and program building SUMMARY

design, build and program building management controls to include radiant cooling

- Appropriate PC-based “smart” control systems are economically feasible for high-end residential and light commercial applications

RADIANT COOLING CAPACITIES

PERFORMANCE OF RADIANT FLOORS AND CEILINGS

The capacity of a radiant cooling system depends on factors such as insulation, radiant emissivity, pipe spacing, fluid flow rates, floor construction, floor covering, room set-point temperature and others

- Floor surface temperatures less than 66°F(29°C) are to be avoided for comfort reasons - Radiant cooling systems in poured floors or ceilings typically use PEX pipes at 6 - 8 in.

pipe spacing, fluid temperatures in the range of 55°F to 60°F, fluid Delta-T of 10°F or less, and higher flow rates than radiant heating systems

- Pipe size is determined by coverage areas and circuit lengths

- Under optimal design conditions, radiant cooled floor capacities of up to 16 BTU/(hr-ft²) can be achieved*, with more typical capacities in the 8 to 12 BTU/(hr-ft²)range *_{Olesen, Bjarne. Radiant Floor Cooling Systems, ASHRAE Journal, September 2008}

27-Mar-15 Page 47

Compared with radiant floor heating systems:

- Floor surface temperatures over 84°Fare to be avoided for comfort reasons - Under optimal design conditions, capacities of up to 34 BTU/(hr-ft²)can be achieved

FACTORS AFFECTING OUTPUT CAPACITIES

For effective radiant cooling in poured slabs, a higher than normal concentration of radiant pipes is required

- 6” on-center spacing is typical to eliminate striping and provide faster response time RADIANT COOLING CAPACITIES

PERFORMANCE OF RADIANT FLOORS AND CEILINGS

RADIANT COOLING CAPACITIES

PERFORMANCE OF RADIANT FLOORS AND CEILINGS

For effective radiant cooling in poured slabs, a higher than normal concentration of radiant pipes is required

- 6” on-center spacing is typical to eliminate striping and provide faster response time

27-Mar-15 Page 49

FACTORS AFFECTING OUTPUT CAPACITIES

THE MATH PART...

Heat transfer coefficient (HTC)

Specific heating/cooling capacity in W/m² or Btu/(h·ft2₎



T

SURFACE

T

AIR



HTC

q







Air temperature

Radiant Heating Output Potential Formula:

- (Panel surface temp - Indoor air temp.) x HTC= Heat Output in BTU/hr(ft2₎

RADIANT COOLING CAPACITIES

PERFORMANCE OF RADIANT FLOORS AND CEILINGS

- HTC= Combined Radiant/Convective Heat Transfer Coefficient

Approximate HTC values for heated panels:

- Radiant Floors: 1.9 BTU/(h·ft² F) (35 - 40% heat is transferred via natural convection) - Radiant Walls: 1.4 BTU/(h·ft² F) (less natural convection than floors)

- Radiant Ceiling: 1.1 BTU/(h·ft² F) (very little natural convection)

27-Mar-15 Page 51

Example: 80ºF heated floor potential output

- (80ºF - 68ºF) x 1.9 = 23 BTU/hr(ft2_{) The potential output of a 80ºF heated floor}

FACTORS AFFECTING OUTPUT CAPACITIES

Radiant Cooling Output Potential Formula:

- (Indoor air temp - Surface temp) x HTC= Cooling capacity in BTU/hr(ft2₎

RADIANT COOLING CAPACITIES

PERFORMANCE OF RADIANT FLOORS AND CEILINGS

Notes:

- Floor surface temperatures less than 66°Fare to be avoided for comfort reasons - Indoor air set-points for radiant cooling may be as high as 77ºF

Example: 66ºF cooled ceiling potential output

(76ºF 66ºF) 1 9 19 BTU/h (ft2_{) Th t ti l it f 66ºF l d ili}

(76ºF - 66ºF) x 1.9= 19 BTU/hr(ft2_{) The potential capacity of a 66ºF cooled ceiling} Notes:

RADIANT COOLING CAPACITIES

PERFORMANCE OF RADIANT FLOORS AND CEILINGS

For comfort, ASHRAE Standard 55 limits floor temperature range to: - Equal to or greater than 66°F (19°C) in cooling mode

- Less than 84°F (29°C)in heating mode

Typical capacities based on setpoints adjusted for radiant systems: TSURFACE OUTPUT

Floor Heating 78-84°F 19-31 Btu/(h·ft2) Cooling 66-70°F 8-12 Btu/(h·ft2₎ Heating 78-84°F 11-17 Btu/(h·ft2₎

Ceilings are not limited by the ASHRAE 55

27-Mar-15 Page 53

Obtaining a designed surface temperature from a radiant floor system depends on factors such as average fluid temperature, pipe spacing, pipe placement, floor covering, room set point temperature

Ceiling

g ( )

Cooling 66-70°F 15-24 Btu/(h·ft2₎

Ceilings are not limited by the ASHRAE 55 floor limit; ceiling values are used only to show capacity comparison

1. The capacity of a radiant cooling system depends on factors such as insulation, radiant emissivity, pipe spacing, fluid flow rates, floor construction, floor covering, room set-point temperature and others

2 Th th f l l ti iti i d t d d i ti il li d

FACTORS AFFECTING OUTPUT CAPACITIES

2. The math for calculating capacities is understood and is sometimes easily applied 3. Direct solar gain can increase specific capacities of chilled ceilings or floors

INCREASED THERMAL COMFORT MAKE CUSTOMERS HAPPIER

Radiant cooling and heating systems are integral in creating hybrid systems that reach higher levels of thermal comfort than their 100% forced-air system counterparts Increased Thermal Comfort:

1. The human body feels most comfortable when it can regulate at least 45% of its heat emission via radiation achieved through a radiant system

2. Radiant cooling optimizes the surface temperatures of the occupants’ surroundings, providing a even and comfortable environment

3. Comfortable cooling is provided with reduced ventilation air and little to no flow noises 4. Improved thermal comfort may aid in LEED®_{certification}

- LEED NC 2009 Energy and Atmosphere category – up to 1 point for “Thermal Comfort – Design”

27-Mar-15 Page 55

ADVANTAGES OF HYBRID RADIANT COOLING HVAC SYSTEMS

Hybrid HVAC systems utilizing radiant heating and cooling can help to reduce energy consumption when compared with 100% AHU systems

REDUCED ENERGY CONSUMPTION WASTE LESS MONEY

Reduced Energy Consumption:

1. Radiant cooling allows a higher space set-point temperature, while still maintaining the same level of cooling comfort compared to a traditional AHU

2. Superior heat transfer properties of water compared to air allows the hydronic portion of the system to efficiently distribute energy to conditioned spaces

3. Operating with moderate supply water temperatures allows the integration of renewable systems such as geothermal heat pumps at maximum efficiencies

A radiant cooling system has significant benefits when used in a hybrid HVAC system to reduce initial investment costs and increase economic efficiency for a building LOWER INVESTMENT COST COMPARISON

SPEND LESS MONEY

Reduced Investment Costs:

1. Higher setpointsreduce building’s required cooling load, which results in less cooling capacity from total HVAC equipment

2. Often additional ducting becomes unnecessary and air systems can be downsized to only serve the fresh air requirements

3. Radiant cooling can lead to a reduction in costly forced air components of an HVAC system

27-Mar-15 Page 57

CASE STUDY - COMMERCIAL

- May 2014 ASHRAE Journal technical feature VAV vs. Radiant describes how radiant cooling helped architects and engineers achieve LEED®_{Platinum certification in an office}

building in the demanding climate of Hyderabad, India: SIDE-BY-SIDE BUILDINGS FOR INFOSYS®_{IN HYDERABAD, INDIA}

- 99% Heating ODT = 59°F ; 1% Cooling DB = 102°F; Dew Point = 75°F - Two identical buildings were built with the same loads and occupancy

- Data showed a 34% reduction in operational costs for Radiant Cooling vs. VAV buildings - Radiant system was less expensive to build and operate and delivered better comfort

SIDE-BY-SIDE BUILDINGS FOR INFOSYS®IN HYDERABAD, INDIA

VAV Cooling Radiant Cooling

27-Mar-15 Page 59

CASE STUDY - COMMERCIAL

RADIANT MODULES BUILT ON SITE USING PEXa PIPES ON MATTS

27-Mar-15 Page 61

CASE STUDY - COMMERCIAL

CIRCUITS CONNECTED TO BALANCING MANIFOLDS

27-Mar-15 Page 63

CASE STUDY - COMMERCIAL

Hybrid System Components

 Radiant slab installed as a “thermally activated building system” (TABS)

D di d d i (DOAS)

HYBRID RADIANT FORCED-AIR CONFIGURATION

 Dedicated outdoor air system (DOAS) with energy recovery wheel

 Cooling tower  Ceiling fans

Advantages

S ll h i l i t f t i t

- Smaller mechanical equipment footprint - Lower initial cost

HYBRID RADIANT FORCED-AIR CONFIGURATION

Thermal image of radiant cooled ceiling in Infosys SDB-1

27-Mar-15 Page 65

ANNUAL ENERGY CONSUMPTION

CASE STUDY - COMMERCIAL

SIDE-BY-SIDE BUILDINGS FOR INFOSYS®_{IN HYDERABAD, INDIA}

The Infosys SDB-1 project proved that a hybrid forced- air / radiant system in a hot, humid climate can:

1. Reduce HVAC energy consumption 2. Increase thermal comfort

3. Reduce initial costs over optimized VAV system

27-Mar-15 Page 67

ENERGY EFFICIENCY AND THERMAL COMFORT REALIZED

CASE STUDY - COMMERCIAL

REHAU MONTANA ECOSMART HOUSE An architect‘s own home is also a research project and demonstration of reaching near-net-zero with

t i bl t h l i

sustainable technologies Building envelope - Insulated Concrete Forms - Structural Insulated Panels - Compression-Seal Technology

uPVC windows and doors Mechanical systems and controls

27-Mar-15 Page 69

Mechanical systems and controls - Thermal Solar

- Ground Source Heat Pump - Radiant Heating

- Radiant Cooling - Snow and Ice Melting

CASE STUDY - RESIDENTIAL

Radiant systems work by circulating warm or chilled fluid through PEX pipes placed in or under a building’s floors, walls or ceilings

- Warm fluid circulating through the pipes during the heating season gently warms the space, virtually eliminating cold spots and temperature fluctuations

- Chilled fluid circulating through the pipes during the cooling season allows the cooled surface to remove heat energy from the room

RADIANT FLOOR HEATING OVER ICF FLOOR SYSTEM ON MAIN FLOOR

27-Mar-15 Page 71

CASE STUDY - RESIDENTIAL

RADIANT FLOOR HEATING OVER ICF FLOOR SYSTEM ON MAIN FLOOR

27-Mar-15 Page 73

CASE STUDY - RESIDENTIAL

RADIANT DISTRIBUTION MANIFOLDS, CIRCULATOR, MOD/CON BOILER

27-Mar-15 Page 75

CASE STUDY - RESIDENTIAL

RADIANT COOLING OPERATING IN FLOOR OF GROUND LEVEL AND IN CEILING OF THE CLASSROOM SPACE

RADIANT COOLING PANELS

Radiant cooling panels utilize hydronic technology to lower surrounding surface and air temperatures

- Moderate chilled water circulates through mini-PEXa pipes embedded in ceiling panels - System delivers a comfortable and cost-effective means of cooling room occupants - Radiant cooling is gaining widespread popularity in Europe, USA and Canada because of

its comfort (no direct air flow) and modern efficiency

27-Mar-15 Page 77

CASE STUDY - RESIDENTIAL

RADIANT COOLING PANELS ABOVE CLASSROOM SPACE Suspended panels with embedded PEXa mini-pipes  Panels can absorb radiant heat from below and from warm air

REHAU MONTANA ECOSMART HOUSE

– A research contract between project

sponsor and MSU Department of Mechanical Engineering began in April 2013 to evaluate the efficiency and effectiveness of the sustainable systems, especially when used together

27-Mar-15 Page 79

CASE STUDY

REHAU MONTANA ECOSMART HOUSE

Figure 1: Relative Humidity (RH%) and Temperature vs. Time, Ceiling + Floor Cooling ‒ RH never goes above 45%, even when cooling the air into the low 70’s

REHAU MONTANA ECOSMART HOUSE

Figure 1: Surface Temperatures and Dew Point, Ceiling + Floor Cooling

‒ Dew point was always below 50˚F, while cooled surfaces never approached that temperature

27-Mar-15 Page 81

CASE STUDY

REHAU MONTANA ECOSMART HOUSE

Test Conclusions:

1. The radiant cooling ceiling performed well and was able to cool the 80°F test room to 75°F quickly, using 60°F supply water fluid to the manifold.

2. Considering the moderate entering fluid temperature of 60°F to power the radiant cooled ceiling, there is potential to increase EER’s from ground source heat pumps. 3. The cooled radiant floor by itself also performed well, even though the cooling capacity

was less than the ceiling; a 66°F test fluid temperature was used for the floor. 4. When coupled with a cooled floor, the cooling capacity of the ceiling was enhanced. 5. There was a risk-free condensation scenario with dry to normal air humidity conditions. 6. The vast radiant area of the cooled floor surface contributed to the good response.

1. Radiant surface cooling allows for more efficiently-sized forced-air systems to meet a building’s fresh air and dehumidification requirements to address latent heat loads, resulting in increased operating energy savings.

2. Architects, engineers and other specifiers note the following from experience - Radiant cooling is suitable for most commercial, industrial and institutional applications

with careful engineering design of total HVAC solution

- Radiant cooling is not practical for most residential applications due mainly to humidity control and cost issues

3. Scenarios where radiant cooling is most advantageous:

B ildi l d b i d i d ith di t h ti t

27-Mar-15 Page 83

- Buildings already being designed with radiant heating systems

- High performance buildings where lower heating and cooling loads can be largely accommodated by radiant capacities

- Atriums with large glass exposures; counter solar gains directly with cooled floor - Buildings where peak electrical rates are favorable toward thermal storage

LEARNING OBJECTIVES OF THIS COURSE

1. Explain the principles of radiant cooling systems and factors affecting thermal comfort 2. Describe the four basic installation types for radiant cooling systems

3. Discuss how a radiant cooling system is combined with air handling equipment to make a SUMMARY

BY NOW, PARTICIPANTS SHOULD BE ABLE TO:

“hybrid” radiant cooling HVAC system which can address the concern of condensation 4. Introduce control options for a radiant cooling system

5. List the factors that affect output capacity of a “hybrid” radiant cooling system 6. Summarize the advantages of a hybrid cooling HVAC system

Construction Automotive Industry www.rehau.com

RADIANT COOLING SYSTEMS