Technical University of Denmark

Application of Radiant Cooling Systems

Professor Bjarne W. Olesen, Ph.D

Department of Civil Engineering.

Seminar outline• Basics for Radiant systems

– System types, Comfort

• Standards for Radiant Heating and CoolingSystems– Determination of Heating and Cooling Capacity

• Control of radiant cooling systems• Construction and Installation Technologies

– Examples

• Q&A

HISTORYFrank Lloyd Wright's UsonianHouses 1930’s

A lightweight floor slab was used and the traditional basement was dispensed with. By using steam or hot water piping, it became possible to heat the floor, therefore eliminating the need for radiators. The overall result was heat without a draft or temperature variation of the most comfort - cool head and warm feet.

c. 10,000 B.C., China, the word “kang,” can be traced back to the 11th century B.C. and originally meant, “to dry” before it became known as a heated bed. c. 5,000 B.C., evidence of baked floors are found foreshadowing early forms of “kang” and “dikang” (heated floor) later “ondol” (warm stone) in China and Korea, respectively.

c. 10,000 B.C., China

HISTORY

Hypocausts were used from thethird century B.C. in ancientEurope.

c. 1904, Liverpool Cathedral heated with system based on the hypocaust principles.

1. Screed 2. Pipes3. Plastic foil 4. Insulation5. Levelling 6. Concrete

No cooling – decreased performance

Low energy costs

Low operation costs

Full Air-Conditioning

Constant temperature

Draught, Noise, SBS

High energy costs

High operation costs

Thermo-Active-Building-Systems

Temperature ramps

Reasonable energy costs

Low operation costs

COMFORT-PERFORMANCE

What is Low Temperatur Heating/ High Temperature Cooling?

• Heat exchange through large surfaces (floor, ceiling, walls)

• Supply water temperatures:– Heating: 25 – 40 °C (77 – 104 F)

– Cooling: 16 – 23 °C (61 – 74 F) • temperature limited by dew-point to avoid

condensation)

• Wide range of systems, solutions both for residential and non-residential buildings 7

COMBINATION WITH LOW ENERGY SOURCES

Heating supply temp. : 25 - 40°C

heat pumps

condensing boiler

ground coupling

waste heat

solar energy

Cooling supply temp. : 16 - 23°C

reversible heat pump

ground coupling

free cooling

air cooled chillers8

Day

Night

Cooling method

Ground water

Geothermal heat/coolth

Night air

Cooling unit

CONCEPTS OF RADIANT HEATING AND COOLING SYSTEMS

• Heating - Cooling panels

• Surface systems

• Embedded systems

Suspended cooled ceilings

Suspended cooled ceilings

Capillary Tubes

Radiant surface heatingand cooling systems

Floor Wall

Thermo Active Building Systems

Ceiling

Reinforcement

Floor

Concrete Pipes

Room

Room

Window

GENERAL THERMAL COMFORT

• Personal factors– Clothing

– Activity

• Environmental factors– Air temperature

– Mean radiant temperature

– Air velocity

– Humidity

Mean Radiant Temperature

• tr = ΣFp-i tsi

– Fp-i = Angle factor from person to surface i

– tsi = Surface temperature of surface i

– ΣFp-i = 1

Mean Radiant Temperature

Figure 2.2 Mean value of angle factor between a seated person and a) horizontal rectangle b) vertical rectangle

Figure 2.3 mean value of angle factor between a standing person and a) horizontal rectangle b) vertical rectangle

GENERAL THERMAL COMFORTFLOOR TEMPERATURE

• OPERATIVE TEMPERATURE– to = (hcta + hrtr)/(hc + hr)

– to = 0.5ta + 0.5tr ( low air velocity)

• ta = Air temperature• tr = Mean radiant temperature• hc = Convective heat exchange coefficient• hr = Radiative heat exchange coefficient

• 1 (1.8F) degree change of floor temperature will change operative temperature 0.2 (0.4F) degree

MODERATE ENVIRONMENTS

• GENERAL THERMAL COMFORT– PMV / PPD, OPERATIVE TEMPERATURE

• LOCAL THERMAL DISCOMFORT– Radiant temperature asymmetry

– Draught

– Vertical air temperature difference

– Floor surface temperature

Determination of Heating and Cooling Capacity

SURFACE HEATING AND COOLING

Heat transfer coefficient

8,08,0

6,0

11,011,0

7,0

5,5

6,5

7,5

8,5

9,5

10,5

11,5

Floor

Ceiling

Wall

W/m2K

HeatingCooling

SURFACE HEATING AND COOLING

Max. - Min. Surface temperature

40

17

27

17

35

20

29

20

15

20

25

30

35

40

45

Floor

Ceiling Wall

oC

HeatingCooling

Perimeter

MAXIMUM HEATING AND COOLING CAPACITY

160

72

42

99

165

42

99

42

020406080100120140160180200

Floor

Ceiling Wall

HeatingCooling

Perimeter

W/m2

ALUMINUM HC device: Floor Heating & Cooling (type B), R=0.01~0.1, T=150 & 300

0

20

40

60

80

100

120

140

160

-15 -10 -5 0 5 10 15 20 25 30

Heating/cooling medium differential temperature ∆θH=θH-θi [°C]

He

at e

xc

ha

ng

e [

W/m

2]

T=150, R=0.01

T=150, R=0.1

T=300, R=0.01

T=300, R=0.1

Figure 4.17 Heat exchange between the surface (with ceramic tiles, wooden

parquets or carpet R?B=0.1 and no covering R?B=0) and the space when aluminium heat conductive device used

Heating/ cooling capacity, ISO 11855

Method for verification of FEM and FDM

calculation programs

Method for verification of FEM and FDM

calculation programs

Radiant Floor Cooling

More than 100 W/m2 or 32 Btu/ft2 h

TABSThermo Active Building Systems

InsulationFloor

Concrete

Reinforcement

Pipe

Room

Room

Window

Control of radiant heating and cooling systems

CONTROL OF A COMBINED FLOOR HEATING-COOLING SYSTEM

Boiler Chiller

Room temp.-Humidity

Outside temp.

SupplyLimiter

Return

Mixing valve

Valves

VIVALDI

CONTROL COOLING

10

15

20

25

30

0 2 4 6 8 10 12 14 16 18 20 22 0 2 4 6

3-Min. Floor temp.t t

1-Operative Temperature

2-Floor temperature

4-Water temperature5-Dewpoint temp.

5

4

3

2

1

°C

TIME hours

degC F18 64,419 66,220 6821 69,822 71,623 73,424 75,225 7726 78,827 80,628 82,429 84,230 86

BoilerChiller

Temperature-Humidity

Outsidetemperature

Floor temp.

Supply Limiter

Return

Mixing valve

Shut off valves

Control

Room sensor Control unit

Valve

Manifold

Pump

Control of a combined floor heating-cooling system

with individual room control

SELF CONTROL

80W/m?

40W/m?

20W/m?

10W/m?

Heat load

FloortemperatureHeat. level temp. tiles

Heat. level temp. carpet

38,4

29,4

24,9

22,5

31,9

26,2

23,321,7

27,3

23,922,1

21,12022242628303234363840

C°

Floortemperature at 20 °C Roomtemperature

degC F18 64,419 66,220 6821 69,822 71,623 73,424 75,225 7726 78,827 80,628 82,429 84,230 86

SELF CONTROL

80W/m?

40W/m?

20W/m?

10W/m?

Heat load

Floor temperature

Heat. level temp. tiles

91

48

26

14

59

30

16

80

102030405060708090

100

%

% decrease in heat output by 1 K room temperature increase

Radiant surface heatingand cooling systems

Floor Wall

Thermo Active Building Systems (TABS)

Ceiling

Reinforcement

Floor

Concrete Pipes

Room

Room

Window

The analysed building

West room

Width of the room: 3.6 m

Window portion of the outside wall: 50%

Office building

Internal heat sources

0

100

200

300

400

500

600

hea

t p

rod

uct

ion

[W

]

1 3 5 7 9 11 13 15 17 19 21 23

daytime [h]

50% Radiation50% Konvection 100g/h moisture

550W = 27.8 W/m² 8.6Btu/ft2

Monday to Friday

Time of operation

• Four different schedules

• 24 hour

• 8:00-17:00

• 18:00-06:00

• 22:00-06:00

Intermittent operation of circulation pump

• Pump on for 1 hour – Pump off for 1 hour

• Pump on for ½ hour – Pump off for ½ hour

• Pump on for ¼ hour - Pump off for ¾ hour

Control of water temperature

• Supply water temperature equal to internal dew point temperature.

• Supply water temperature a function of outside temperature according to the equation:

• Average water temperature a function of outside temperature according to:

• Supply water temperature constant equal to: 18 °C, 20 °C and 22 °C

• Average water temperature constant equal to: 18 °C, 20 °C and 22 °C

2020*4,0*3,1sup externalply tt

2020*4,0*3,1 externalaverage tt

degC F18 64,419 66,220 6821 69,822 71,623 73,424 75,225 7726 78,827 80,628 82,429 84,230 86

Evaluation parameters

• Range of operative temperatures

• Pump running time

• Energy consumption

Operative temperature range, May to September Different control concepts for water temperature, Time of operation 18:00 - 6:00 Uhr

33

14

54 54 52

38

0

10

20

30

40

50

60

70

80

90

100

Tsup =Tdp

Pump Tsup =F(ext)

Pump Tavg =F(ext)

Pump Tavg =22 °C

Pump Tavg =20 °C

Pump Tavg =18 °C

Pump

Control of water temperature

Op

erat

ive

tem

per

atu

re r

ang

e [%

]

>27

26-27

25-26

22-25

20-22

<20

Pump %

degC F18 64,419 66,220 6821 69,822 71,623 73,424 75,225 7726 78,827 80,628 82,429 84,230 86

Energy consumption and pump running hours, May to September Different control concepts for water temperature, Time of operation 18:00 - 6:00 Uhr

1031

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Tsup =Tdp

Pump Tsup =F(ext)

Pump Tavg =F(ext)

Pump Tavg =22 °C

Pump Tavg =20 °C

Pump Tavg =18 °C

Pump

Control of water temperature

En

erg

y co

nsu

mp

tio

n, k

Wh

(H

ou

rs)

Heating

Cooling

Pump hours

degC F18 64,419 66,220 6821 69,822 71,623 73,424 75,225 7726 78,827 80,628 82,429 84,230 86

Construction and Installation Technologies

Examples

Transportation of modules

Installation – pressure test

49

Prefabrication

50

Thermo active hollow-core slabThermoMax

51

Produced in Denmark by Spæncom 1.2 m wide, thicknes 220, 270, 320 and 400 mm 20 mm PEX-pipes

PSO-ELFORSK/COWI (2012)

Industry

Radiant Floor Cooling

Airport Bangkok

Airport Bangkok

Airport Bangkok

Airport Bangkok

June 30 2008

Installation of PEX pipes

June 30 2008

Terminal building

Ta = 16 oCTd = 10 oC

TsupplyW

= 13 oC

ART MUSEUM BREGENZ

ART MUSEUM IN BREGENZ

• Design requirements– Air temperature variations during a day within 4 K

– Relative humidity variations less than 6 % during a day.

– Seasonal variations between 48 and 58 %

– Room temperature in winter 18 oC to 22 oC

– Room temperature in summer 22 oC to 26 oC, occasional up to 28 oC

• Design load 250 persons pr. day, 2 hours

• Displacement ventilation < 0,2 h-1

• Floor area 2.800 m² , 4 floors

• 28.000 m plastic pipes embedded in walls and floor slabs

ART MUSEUMBREGENZ

• 3.750 m² floor area

• 4.725 m² embedded pipes

• Condensing boiler

• Ventilation 750 m3/h per floor (first design was 25.000 m3/h

ART MUSEUM IN BREGENZ

ART MUSEUM BREGENZ

ART MUSEUM BREGENZ

Balanced Office Building (BOB.1)Aachen, Germany

• Gross floor area 2,151 m²

• 4 storeys• Efficiently insulated

external envelope• Ground-coupled heating

and cooling with TABS• Ventilation system with

heat recovery• Daylight-controlled

lighting• Rainwater collection for

use in toilet flushing

Energy concept in BOB.1

cooling period in BOB.1

Dockland, Hamburg

Viborg Town Hall

72

Photo: Henning Larsen Architects

6 storeys, central open space

19363 m2

Natural & mechanical ventilation

Combined radiant floor

heating/cooling and convectors

under windows

Viborg Town Hall

73

Graphics: Viborg Townhall brochure & COWI

IDOM Company Headquaters, Madrid, Spain

74

16 000 m2

Natural & Mechanical ventilation

External solar shading & green

facade

TABS combinned with free cooling

(covers 40-50 kWh/m2)

(kWh/m²y) IDOM HQ CTE - MADRID %Heating + DHW 27,35 77,00 -64,5

Cooling 12,58 85,00 -85,2Lighting 11,37 34,00 -66,6

Total 51,30 196,00 -73,8

Energy use

IDOM Company Headquaters, Madrid, Spain

75

Radiant Floor CoolingOPERA HOUSE

SHOPPING CENTER MUSEUM

Yearly indoor comfort evaluation and energy consumption, and assessment of thermal activated building systems

in Middelfart Sparekasse.

Technical University of Denmark

Slide 79

Opera House in CopenhagenSummer indoor climate in Foyer

• Radiant floor cooling with stone cover down the structural slabs to reduce peak cooling load

• High air change by displacement ventilation system.

• Humidity control prevents condensation on floor.

References / South, West Europe

• Modern Old Port of Savona, NW coast of Italy

– Underfloor heating for 140 high-end residential apartments and shopping area at ground level

• Dolce Vita Tejo, Lisbon, Portugal

– one of Europe’s largest shopping centres to be built, heating and cooling by Uponor

References / Nordic

• The world’s most modern opera house in Oslo, Norway – Uponor ventilation ducts and floor heating

• Nupurinkartano, Espoo, Finland– first turnkey bedrock heating/cooling in Finland

• Renovation with underfloor heating and tap water in Västerås, Sweden– a 1978 office building turned into 50 apartments and 13 unique terraced houses on the rooftop

Industrial heating/cooling application: BWM World Munich, Germany - 2007

• 16.500 m² of floor, glass and steel, architecture in the BWM museum

• 5,000 m² of industrial radiant cooling and heating with PE-Xa pipes integrated into the hall floor = massive invisible cooling or heating panel

• Full architectural freedom provided: An experience which appeals to all senses, allowing visitors to experience the fascination of mobility

• Energy-saving and environmentally friendly operation

Sun shading and daylight penetrationRADIANT VAV

Energy

Thermal Comfort

DOE-USA

DOE-USA

DOE-USA

COOPER UNION NEW YORK

First costs

REHVA GUIDEBOOK NO: 7Jan Babiak-Bjarne W . Olesen-Dusan Petras

Low Exergy Hydronic Radiant Heating and CoolingWhy?

• Water based systems

• Low temperature heating - High temperature cooling

• More economical to move heat by water:

– Greater heat capacity than air

– Much smaller diameter pipes than air-ducts

– Electrical consumption for circulation pump is lower than for fans

• Lower noise level

• Less risk for draught

• Lower building height

• Higher efficiency of energy plant

• But

– Reduced capacity?

– Acoustic?

– Latent load?