Professor Bjarne W. Olesen, PhDProfessor Bjarne W. Olesen, PhDDirector Director

International Centre for Indoor Environment and International Centre for Indoor Environment and EnergyEnergy

Department of Civil EngineeringDepartment of Civil EngineeringTechnical University of DenmarkTechnical University of Denmark

Radiant Heating and Cooling Systems Radiant Heating and Cooling Systems for for

Better Comfort and Energy EfficiencyBetter Comfort and Energy Efficiency

International Centre for Indoor Environment And Energy

INDOOR - OUTDOOR

• Highest exposure to the indoor environment

• People spend ~90 % of the time indoors during work, during transportation and athome

No cooling – decreased performanceLow energy costsLow operation costs

Full Air-ConditioningConstant temperatureDraught, Noise, SBSHigh energy costsHigh operation costs

Thermo-Active-Building-SystemsTemperature rampsReasonable energy costsLow operation costs

COMFORT-PERFORMANCE

People 100Maintenance 10Financing 10Energy 1

COMFORT-PRODUCTIVITYBuilding costs

CONCEPTS OF RADIANT HEATING AND COOLING SYSTEMS

• Heating - cooling panels• Surface systems• Embedded systems

Suspended cooled ceilings

RadiantRadiant surfacesurface heatingheatingand and coolingcooling systemssystems

FloorFloor WallWall

Thermo Active Building SystemsThermo Active Building Systems

CeilingCeiling

ReinforcementReinforcement

FloorFloor

ConcreteConcrete PipesPipes

RoomRoom

RoomRoom

WindowWindow

Embedded piping systems

• Free use of space• No cleaning• Safety• Comfort• Energy

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

SURFACE HEATING AND COOLINGHeat 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

Types of systems, heating cooling capacity

Heat exchange coefficient between surface and space

99 42 17 ~27 9-11 6 Ceiling 72 160 17 ~40 8 8 Wall

42 99 20 29 7 9-11 Occupied Zone

42 165 20 35 7 9-11 Perimeter Floor

Cooling Heating Min. Cooling

Max. Heating

Cooling Heating

Maximum capacity

W/m²

Acceptable surface

temperature °C

Total heat exchange coefficient W/m².K

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

Thermal resistance method

System modules

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 30Heating/cooling medium differential temperature ΔθH=θH-θi [°C]

Hea

t exc

hang

e [W

/m2]

T=150, R=0.01T=150, R=0.1T=300, R=0.01T=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, EN1264 and EN 15377

Floor Heating (& Cooling) (type G), R=0.01 ~0.1, T=150, 300

0

10

20

30

40

50

60

70

-15 -5 5 15 25Heating/cooling medium differential temperature ΔθH=θH-θi [°C]

Hea

t exc

hang

e [W

/m2]

qi (T=150, R=0)qe (T=150, R=0)qi (T=300, R=0)qe (T=300, R=0)qi (T=150, R=0.1)qe (T=150, R=0.1)qi (T=300, R=0.1)qe (T=300, R=0.1)

Figure 4.21 Heat exchange between the surface (with ceramic tiles, wooden parquets or carpet and no covering) and the space when steel heat conductive device used. Thermal insulation of 3cm from back side.

BoilerChiller

Temperature-Humidity

Outsidetemperature

Floor temp.

Supply Limiter

ReturnMixing valve

Shut off valves

Control

Room sensor Control unit

ValveManifold

Pump

Control of a combined floor heating-cooling systemwith individual room control

Radiant Floor Cooling Radiant Floor Cooling Airport BangkokAirport Bangkok

Airport BangkokAirport Bangkok Airport Bangkok

Airport BangkokAirport Bangkok

Lisboa Dolce Vita Tejo

Lisboa Dolce Vita Tejo FLOOR COOLING IN SOUTHERN EUROPE

• Computer Simulation (IDA Indoor Climate and Energy 3.0)

• Simulation period from April 20th to November 15th

• Variation of one parameter at a time• Variation of the location

Parameter Study

• Dwelling Types• Room Orientation• Control Strategy• Air Handling Unit• Internal Loads• Shading Levels• Floor Covering• Floor System

• Reference conditions• Rome• Ts ≥ Tpd limits cooling• 0.8 h-1 8 to 23h

else 0.3 h-1

• Int. Loads from 8 to 23h• No Dehumidification• 50% Shading

Location Study

Palermo

Rome

VeniceTorino

Braganca

Faro

PortoMadrid Barcelona

Sevilla

Santander

Location StudyRepresentative Cities – No dehum.

TABSTABSThermo Active Building SystemsThermo Active Building Systems

InsulationInsulationFloorFloor

ConcreteConcrete

ReinforcementReinforcement

PipePipe

RoomRoom

RoomRoom

WindowWindow

ConceptConcept of of Thermo Active Building SystemsThermo Active Building Systems

The analysed building

West room

Width of the room: 3.6 m

Window portion of the outside wall: 50%

Office building

CONTROL OF WATERTEMPERATURE• Supply water temperature is a function of outside

temperature according to the equation:

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

• Average water temperature is constant and equal to: 22°C in summer and 25°C in winter.

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

)22(*6,12020*52,0sup oexternalply ttt °C (case 801)

)22(*6,12020*52,0 oexternalaverage ttt °C (case 901)

1818*35,0sup externalply tt °C summer (case 1401)

1818*45,0sup externalply tt °C winter (case 1401)

PERFORMANCE EVALUATION

• Range of operative temperature • 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

Ope

rativ

e te

mpe

ratu

re ra

nge

[%]

>27

26-27

25-26

22-25

20-22

<20

Pump %

CONTROL OF WATER TEMPERATURESUMMER

Operative temperature May to September

Water temperature control. Time of operation 6 pm to 6 am

2636

26303339

3234

0

10

20

30

40

50

60

70

80

90

100

Tsup= f(Ti,Te) Tave= f(Ti,Te) Tave= 22 °C Tsup= f(Te) Tsup= f(Ti,Te) Tave= f(Ti,Te) Tave= 22 °C Tsup= f(Te)

Control methods

Ran

ge o

f ope

rativ

e te

mpe

ratu

re %

>2726-2725-2622-2520-22<20

Venezia Würzburg

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

OfficesM+W ZanderStuttgart, Germany- TABS –

- in 6.500 m2

MW-Zander Measurementsduring normal operation

Operative temperature sensor

Air temperature sensor

Transmitters

Stuttgart

Stuttgart 24.07. - 28.07, 2000

20

21

22

23

24

25

26

24. J

ul

24. J

ul

25. J

ul

25. J

ul

26. J

ul

26. J

ul

27. J

ul

27. J

ul

28. J

ul

28. J

ul

29. J

ul

Zeit

Tem

pera

tur [

°C]

O1-Operative Büro 4. Stock Fenster-Ost F1-Fläche 4. Stock RucklaufO-Operative Büro 5. Stock Fenster-West O6-Operative Büro 5. Stock Fenster-Ost

Energy concept in BOB.1 Temperatures for one year in BOB.1

cooling period in BOB.1 Heating period in BOB.1

0

5000

10000

15000

20000

25000

30000

35000

Heizung Kühlung Lüftung Beleuchtung Pumpen Warmwasser Summe

Year

ly e

nerg

ie c

osts

[€/m

²a]

BestandBOB.1

Energy efficiency of BOB.1

94 % energy saving compared with conventionalcooling

60 % energy saving for lighting by daylight steering

The need of energy for heating, cooling, air-ventilation lighting and warm water is 27,8 kWh/m²per yearEnergy costs per m², per year: 2,7 EUR,

per month 22,5 Cent

6. Energy sources

Developing Low Exergy Systemsin the Tropics

(Malaysia, Singapore, Thailand, Indonesia)

Climates where :• Evaporative cooling is not possible• Earth coupling is not useful• Dehumidification is necessary• Ambient temperatures are above internal comfort temperature• Cooling is 100% and heating is zero

ENERGY-10 Optimisation

0

25

50

75

100

125

Cooling Lights Other

MECM LEO Super Low E. Building

64

37

116

25

8

100

51

kWh/m2year

Total

Trickling PV roof :

PV Powerplant and “Cooling Tower”

Self-shading facadeSet-back façade shades against direct solar radiation

100% daylightingLight guiding façade and max. 8 meters deep offices

Concrete slab coolingThermal comfort with air @27°C and ceiling/ floor @ 23°C

High temp. coolingSupply temp. for concrete slab cooling is 18°C resulting in high COP of Chiller

ZEO Building(Zero Energy Office)

Section, Office B, version 3Outdoor Atrium

Highly reflective ceiling

Lightshelf Blind reflecting light upwardsAir ducts

No direct sky view

Transm. 0.8

Transm. 0.520°C

15°CEvaporator AHU

15°C

20°C

20°C

22°C

23°C

23°C

Embeddedwater pipes

Off coil temperature of chiller in increased from 7 oC to 18 oCincreased COP of Chiller

Sky Radiant Temperature10 – 20 oC at night

Trickling Cool Roof

~ 25 oC~ 95% RH

15 o

RadiationConvection

EvaporationPV Roof

Chiller Condenser ( heat rejection )

~ 30 oC

~ 25 oC

ChillerPump

Microsoft Excel Worksheet

PRE-FABRICATION

PRE-FABRICATIONLow Exergy Low Exergy HydronicHydronic RadiantRadiant HeatingHeating and and

CoolingCoolingWhyWhy??

•• Water Water basedbased systemssystems•• Low Low temperaturetemperature heatingheating -- High High temperaturetemperature coolingcooling•• MoreMore economicaleconomical to to movemove heatheat byby waterwater::

–– GreaterGreater heatheat capacitycapacity thanthan airair–– MuchMuch smallersmaller diameterdiameter pipespipes thanthan airair--ductsducts–– ElectricalElectrical consumptionconsumption forfor circulationcirculation pump pump isis lowerlower thanthan forfor fansfans

•• LowerLower noisenoise levellevel•• LessLess riskrisk forfor draughtdraught•• LowerLower building building heightheight•• HigherHigher efficiencyefficiency of of energyenergy plantplant•• ButBut

– Reduced capacity?– Acoustic?– Latent load?