Radiant Cooling Presentation.pdf

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Radiant Cooling Presentation.pdf

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Earth Tech Canada

New Approaches to Economical

Energy Efficient Buildings

2002


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Overview

• “Conventional” All Air HVAC Systems - Benefits and

Limitations.

Radiant Cooling and Heating - “Thermoactive

Ceilings” - How does it work?

• Design Considerations

• Displacement Ventilation - How does it work?

• Design Considerations

• Energy Consumption

• Costing

• Conclusion


Function of the HVAC System

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• Offset space heat losses/gains

• Maintain the space within the thermal comfort limits

• Remove/dilute air contaminants from the space


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Thermal Comfort

• Thermal balance between heat generation and rate of

heat removal

• Human heat generation at rest: 70 to 100 watts (220

to 280 Btuh)

• Human comfort Zone:

– Combination of 50% radiation, 30% convection and

20% evaporation

– Temperature range: 20-26

26°C C (68°-78

78°F)

– Relative humidity range: 30-60%

– Air movement velocities: 0.15 - 0.25 m/s

– Surface to Air temperature difference ≤ 2°C C (4°F)

• Space heat gains/ losses:

– internal (people, lights, el. equipment, etc.)

– external (solar radiation, conduction, infiltration)


Indoor Air Quality

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• Balance between production and removal of

indoor air contaminants

• Maintaining pollutant concentration at an

acceptable level

• Pollutant Types:

- Gaseous/ Particulate

- Organic/ Inorganic

- Toxic/ Harmless

- Stable/ Unstable

• Pollutant removal method:

- dilution by space ventilation

- direct exhaust from the source


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Conventional All-Air Air HVAC System

• Typical features:

- combined function of space temperature control and ventilation

- moves large volumes of air throughout the space (6-8 8 ach/hr)

- convection is the dominant heat transfer mode

- high temperature differences between the supply air and the

space temperatures (11°C cooling, up to 30°C heating)

- high peak capacities

- energy intensive

- fast response - requires fast acting and reliable controls

- large space requirements for equipment and ductwork


Benefits of

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Conventional All-Air Air HVAC System

• Unlimited application range

- can be designed “anywhere, anytime” and made to

work for any application

• Occupant “perception” of “fresh air” conditions due to high

air movement rate


Limitations of

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Conventional All-Air Air HVAC System

• Comfort and IAQ

- uneven space comfort – cost of control zones

- high air velocities - typically > 0.3 m/s (50-100 fpm)

- potentially high noise levels

- portion of contaminated air is mixed and re-circulated

• Cost

- large equipment capacities required

- moving large air volumes ⇒ energy intensive operation

- large space requirements

- higher mechanical equipment and building space cost


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Radiant Cooling and Heating System

• Typical features:

- radiation is the dominant heat transfer mode

- strictly space temperature control function

- distribution system imbedded in building structure

- low temperature differences between the radiant

surface and the space temperatures (3- 6°C)

- building mass energy storage self-regulating

effect

- track record of over 15 years throughout Western

Europe


System Comparison

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Conventional System

Thermo-Active Slab System


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System Comparison

• Superior comfort and indoor air quality

• Unparalleled energy efficiency

• Lower mechanical system costs; no additional total

building costs

• Simple controls; minimal space requirements

• Simple and easy to maintain systems

• Lower operating costs (up to 60% lower than

“conventional all air” systems


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Summer Temperatures


Winter Temperatures

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Design Considerations

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• Space loads must be controlled by:

- High performance envelope

- Glass U values and SC values

- Shading devices

- Building shape and size

- Lighting and equipment load

- Use of building mass

• Integrated design approach

• Coordination during Construction


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• Conventional glazing/envelope

• Thermal zones at perimeter

require separate temperature

control

• High performance envelope

and glazing

• No separate thermal zones at

perimeter, no separate

temperature controls required


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Fribourg Office

Building,

Switzerland


Fribourg Office Building, Switzerland

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Schaffhausen Office Building, Switzerland

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Schaffhausen Office Building Corridor

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“Thermo-active Slab”

construction with tubing

for radiant cooling and

heating and source flow

ventilation duct

distribution system


ICT Building, Calgary Alberta

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Capillary cooling mats ready for installation

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Capillary Mats Being Applied

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T-bar ceiling and waved frieze with

integrated capillary cooling mats in

plastered ceiling

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Thermographic picture of a

portion of radiant cooling

ceiling


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Finished ceiling with integrated capillary cooling mats in

Waved frieze


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Displacement Ventilation

• Continuously purges air pollutants from the occupied space by

supplying 100% fresh air to the space, and exhausting 100 % of the

contaminated air out of the space

• Typical features:

- provides exclusively ventilation function (1-1.5 ach/hr)

- supply air temperature is near space temperature (∆T≤ 3°C/5.5° F)

- air movement is generated by natural buoyancy around heat

sources in the space

- absence of noise and draft due to low air velocities

(≤ 0.2 m/s) (≤ 40 fpm)

- air supply at low level, exhaust at high level

- pollutants are removed from the source and carried straight up

and exhausted at ceiling level

- occupants breath air with minimum contaminant load


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Displacement Ventilation Pattern


Smoke demonstration of a typical

displacement ventilation pattern

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Supply air register installation at low level

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Exhaust air register installation at high level

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Energy consumption comparison between a typical VAV system

and Radiant Ceiling Cooling system with displacement ventilation

Annual amount of energy required per m 2

350

300

250

200

150

100

50

0

Comparison:

1. VAV installation (variable air volume) with humidification

2. Fresh air supply with humidification + radiant cooling ceiling

kW/m 2 a

1 2

VAC Sys tem

Fresh air supply (displacement flow) + radiant coolingceiling

(proportion 10kWh/m 2 (VAV)

a

pumps

cold

humidification (steam)

heat

air supply

heating (basic load)


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Cost Comparison

• Building Criteria:

– 3 Storey Office Building

– Total Area = 90,000 sq. ft.

– Walls = R-20R

– Roof = R-20R

– Windows: 50% of total wall area

– Concrete Construction


Envelope vs.

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Mechanical/Electrical Costs

Premium for Visionwall or Heat Mirror:

• 5.00$/sq.ft. of building. (Based on 65$/sq.ft. for

Visionwall vs. 38$/sq.ft. for normal commercial

double pane, 6 foot high glass on 12 foot floor to

floor) curtain wall style construction.


Envelope vs.

Mechanical/Electrical Costs

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• Mechanical Cost for VAV or Fan-Coil System with

Conventional Glazing:

HVAC System = ±12.50$/Sq.Ft.

Plumbing = 4.00$/Sq.Ft.

Sprinklers = 2.00$/Sq.Ft.

Controls = 1.50$/Sq.Ft.

$20.00/Sq.Ft.


Envelope vs.

Mechanical/Electrical Costs

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• Mechanical Cost for the Thermoactive Slab

System with Displacement Ventilation:

HVAC System = 8.50$/Sq.Ft.

Plumbing = 3.75$/Sq.Ft.

Sprinklers = 1.75$/Sq.Ft.

Controls = 0.85$/Sq.Ft.

$14.85/Sq.Ft.


Envelope vs.

Mechanical/Electrical Costs

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• Electrical Cost for Conventional Building:

• Mechanical Cost for Conventional Building:

• Electrical Cost for Thermoactive Slab Building

with Visionwall/Heat Mirror Glazing:

• Mechanical Cost for Thermoactive Slab Building:

• Premium for High Performance Glass

• Savings for Mechanical/Electrical Systems

13.00$/Sq.Ft.

20.00$/Sq.Ft.

11.00$/Sq.Ft.

14.85$/Sq.Ft.

5.00$/Sq.Ft.

7.15$/Sq.Ft.

• Conclusion: : Thermoactive slab building can be built at the same or

lower cost than a conventional building.


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20 Year Life Cycle Cost Comparison

$2,000

$1,800

$1,600

$1,400

$1,200

$1,000

$800

$600

$400

$200

$0

100%

100%

VAV System

(baseline)

108%

131%

100% 93%

100% 99%

4 Pipe Fancoil

System

101%

73%

178%

Packaged Rooftop

System

58%

52%

42%

74% 74%

Radiant Heating &

Cooling System

Installation Energy Maintenance


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Applications

• Office space/office buildings

• Libraries

• Theatrical/presentation spaces/performing arts

• Residential

• Classrooms/educational

Anywhere the building envelope, perimeter thermal

loads, and interior heat generation can be designed

to reduce the cooling load to below 100 w/m 2 is a

candidate for radiant cooling/dedicated ventilation

air systems.


Earth Tech Experience

Thermoactive/Radiant Systems

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• ICT Computer Sciences Building, University of Calgary.

• On site review of 12 buildings in Austria, Switzerland and

Germany, including test lab reviews and operational

testing.

• Complete in-house design manual and specifications for

thermoactive slab systems.

• Many design and installation projects using radiant

heating techniques, including pipes in slabs and applied

panel systems.

• In-house thermal storage and radiation modelling tools.


Quick Sources on the Internet

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•www.zent-frenger.de/products.htm

•www.buildingdesign.co.uk/arch/frenger/frenger.htm

•www.twapanels.ca/cooling/faq.html

•www.siebe-env-controls.com/scs/product/application/main.htm

•www.siebe-env.controls.com/scs/product/guide/two.htm

•www.sterlinghvac.com/sthyd/Radiant/p06.htm

•www-epb.lbl.gov/EPB/thermal/hydronic.html

•www.bim.kth.se/fbf/papers/paper9/hydronic_thermal_conditioning.htm

•www-epb.lbl.gov/thermal/dissertation.html


Quick Sources on the Internet

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•http://epb1.lbl.gov/thermal/hydronic.html

•www.cbe.berkeley.edu/underfloorair/

•http://doas.psu.edu/

•www.termodeck.com/index.html

•www.hydronics.com/artical.htm

•http://jdhowell.com/articale.htm

•www.hydronics.org/articlespotlight.htm

•http://projects.bre.co.uk/dispvent/


Thank You

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