EinB2017–6th International Conference “ENERGY in...

EinB2017 – 6th InternationalConference“ENERGYinBUILDINGS2017”

ExperimentalandNumericalinvestigationoftheEnergyEfficiencyofaLightweightSteelFramedbuilding

incorporatingVacuumInsulationPanelsIoannisA.AtsoniosEmail:[email protected]

IoannisD.Mandilaras,Aris A.Manolitsis,Dimos A.Kontogeorgos,MariaA.Founti

NationalTechnicalUniversityofAthens,SchoolofMechanicalEngineering,Lab.ofHeterogeneousMixturesandCombustionSystems,Zografou,Greece


Contents• Introduction• Experimentalinvestigation• Developmentofmodel• Implementationofmodel• Conclusions


LightweightConstructions• Advancedbuildingshellscombining:

– Highthermalperformance– Shortconstructiontimes

• Lightweightsteelframedconstructionsà Drywallmaterialsanchoredonasteelframestructure

• Advantages:– Simpleandfastconstruction,– Structuralseismicresistance,– Reductionandrecyclabilityofwastes– Decreaseofloadsandcostsonbearingstructures

Introduction Experimentalinvestigation

Developmentofmodel

Implementationofmodel Conclusion

[Lightweightsteelconstructions,Stahl][ Lightstructures,COCOON]

[ LightweightSteelFramingArchitecturalDesignGuide,CSSBI]


ThermalBridges• Maindrawback:

– Alargeamountofenergylosses/gainscausedonthethermalbridges.– Thermalbridges:Multidimensionalheatflowsaregenerated.– Theimpactofthermalbridgesduetometalstructureisessential.à

Increaseofthermaltransmittance(morethan70%).– Highriskofcondensationandmoldgrowthà thestructureandtheair

quality.


Developmentofmodel


[Dryvit Systems,Inc.andTheDowChemicalCompany]


ThermalBridges• Designstrategyforlimitation:– Installationofacontinuousinsulationlayer–Mosteffectiveà Installationofsuperinsulationmaterials(Martinsetal.,2016)


Developmentofmodel


ExtraInsulation

Crosssection Internalsurface


VacuumInsulationPanels• Innovative materials with thermal conductivityless than 0.007W/mK

• Consists of an evacuated, open pore corematerial surrounded by thin barrier maintainingthe high level of vacuum.


Developmentofmodel


Pressed silica core

sealing film

metalized film


VacuumInsulationPanels• The insulation performance ofVIPs is 5 - 7 times better thanthat of conventional insulation,with the same thickness(λEPS = 0.035W/mK).

• Thedecreasedthicknessàthinnerwallsà increasednetfloorarea.


Developmentofmodel


Finishingmortar

Brick

Conventionalinsulation

Internalmortar

Finishingmortar

Brick

VIP

Internalmortar

dx


Objectivesofstudy• Experimental&NumericalInvestigationofalightweightsteelframedenvelopeinsulatedwithVIPs

• Threeparts:– Experimentalinvestigationofamock-upbuilding– Developmentandvalidationofamodelforthecalculationofenergyconsumptionofbuildingsforheating.

– Implementationofthemodelatatypicalresidentialbuildingindifferentclimates


Developmentofmodel



DescriptionofthebuildingIntroduction Experimental

investigationDevelopmentof

modelImplementationof

model Conclusion

• Mock-uplightweightbuilding• Constructedbydrywallmaterials• LocatedinLaupersdorf,

Switzerland• Externaldimensions:

4m× 2.2m× 2.8m• Oneopening(adoor)• Measuringperiod:oneyear

(February2016- February2017)• Thebuildinghadnooccupants

anditwasclosedduringthewholemeasuringperiod.





model Conclusion

• ExternalWalls– Thickness:317mm– TheoreticalU-value:0.1105W/m2K(includingtheeffectofmetalstuds– ISO10211)

.

625mm CWstud50/50 /0.6

625mmCstud

150/50 /1.5

MineralWool

Gypsumboard

VIP

AirCavity

CementBoard

FinishingMortar

Outdoor

Indoor





model Conclusion

• Roof– Thickness:327mm– TheoreticalU-value:0.2155W/m2K(includingtheeffectofmetalstuds– ISO10211)

500mmI-stud

200/100/1.5 Outdoor

Indoor

MineralWool

Gypsumboard

LoadPanelRoofSealing

EPS





model Conclusion

• Floor– Thickness:455mm– TheoreticalU-value:0.1282W/m2K(includingtheeffectofmetalstuds– ISO10211)

500mmI-stud

200/100/1.5 Indoor

Ground

MineralWool

Gypsumboard

LoadPanelEPS

SoundInsulation

Floor


ConstructionofthebuildingIntroduction Experimental



model Conclusion


MonitoringSystemIntroduction Experimental



model Conclusion

14

SENSORS

DAQK8056 8

channel relayboard test software

Tset point=20oC

RHset point=50%

TEMPERATURE&HUMIDITYCONTROLSYSTEM

• Sensors– 80 thermistors– 10 humidity sensors– 4 heat flux sensors– 1 weather station– 1 energy consumption

• DAQ– Agilent– 3 cards– USB stick

• Remote monitoring– Laptop– TeamViewer– Channel relay

• Temperature & HumidityControl System– 2 Controller– Sensors– Heat fan & Humidifier


MonitoringSystem

TemperatureHeat Flux

Section “CL”

.

Section “C” Section “CW”

GBinMW50

VIPGBm

MW150

GBoutCAV FB


Developmentofmodel



Results• Thermal transmittance (U-value)

– The experimental U-value is in a good agreement with thetheoretical, providing a difference ca. 6%.

– The theoretical U-value of the wall without the layer of VIPis 0.2467 W/(m2·K) à The VIPs reduce the U-value at by53%.


Developmentofmodel


TheoreticalU-value[W/(m2·K)]

ExperimentalU-value[W/(m2·K)]

Difference

0.1105 0.1169 6%


Results• Contribution of insulation materials– In all sections the VIP causes the

largest temperature difference in thewall (while the 150mm and 50mmthickness mineral wool is caused ca.33%, and 10%, respectively).

– The results are in a good agreementwith the simulations in steady stateconditions.

– The position of studs is strongly affectsthe insulation efficiency of thematerials.


Developmentofmodel


14/Feb 15/Feb 16/Feb 17/Feb0

10

20

30

40

50

60

70

80

90

100

110


10

20

30

40

50

60

70

80

90

100

110


10

20

30

40

50

60

70

80

90

100

110

Section “C” Section “CL” Section “CW”

18%

54%

10%18%

11%

52%

33%

4%

4%

46%

36%

13%

MW 50 VIP MW 150 Others

Section “C” Section “CL”a) b)18%

62%

6%14%

14%

49%

31%

6%

2%

55%

36%

7%

Section “CW”

13%

51%

29%

7%

Average

13%

43%

39%

5%

Without studs

Experimental Results Simulation Results

Perc

enta

ge o

f ΔT

Perc

enta

ge o

f ΔT

Perc

enta

ge o

f ΔT

Perc

enta

ge o

f ΔT

TemperatureHeat Flux

Section “CL”

.

Section “C” Section “CW”

GBinMW50

VIPGBm

MW150

GBoutCAV FB

1 2 3 4 50

10

20

30

40

50

60

70

80

90

100

110


18%

54%

10%18%

11%

52%

33%

4%

4%

46%

36%

13%



62%

6%14%

14%

49%

31%

6%

2%

55%

36%

7%

Section “CW”

13%

51%

29%

7%


10

20

30

40

50

60

70

80

90

100

110

Average

13%

43%

39%

5%

Without studs


Perc

enta

ge o

f ΔT

Perc

enta

ge o

f ΔT

Perc

enta

ge o

f ΔT

Perc

enta

ge o

f ΔT


18%

54%

10%18%

11%

52%

33%

4%

4%

46%

36%

13%



62%

6%14%

14%

49%

31%

6%

2%

55%

36%

7%

Section “CW”

13%

51%

29%

7%

Average

13%

43%

39%

5%

Without studs


Perc

enta

ge o

f ΔT

Perc

enta

ge o

f ΔT

Perc

enta

ge o

f ΔT

Perc

enta

ge o

f ΔT


Results• Contribution on thermal bridges

– One of the junctions between the adjacentwalls was not well insulated with VIPs due toconstruction irregularities.

– The effect of the VIP is investigated usingboth infrared thermography and monitoringdata.

– The uncovered with VIP junction was colderby ca. 1oC than the covered junction.


Developmentofmodel


Uncovered junction Covered junction

Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb-505

1015202530

Tem

pera

ture

[o C]

Corners - Temperatures between GBin and MWin

00 12 00 12 00 12 00 12 0015161718192021

Tem

pera

ture

[o C]

Winter

UncoveredCovered

00 12 00 12 00 12 00 12 0022

23

24

25

26

Tem

pera

ture

[o C]

Summer

Temperatures between internal gypsumboard and internal mineral wool (MW50)


EnergyPlus• Development of model for the calculation total annual energy

consumption for energy needs.• Simulation in EnergyPlus software• EnergyPlus solves the heat transfer equation assuming one-

dimensional heat flow through the walls.• Introduction of the effect of all thermal bridges into the model.• The model has been analyzed in previous study (Atsonios et al., 2016

– ASHRAE conference 2016 - EinB2016).


Developmentofmodel



MethodologyIntroduction Experimental



model Conclusion

Analysisofthermalbridges

SimulationofbuildingsinEnergyPlus software

Calculationoftheannualenergyconsumptionforenergyneeds

Calculationofequivalentthermalproperties

• BasedonISO10211• Allthermalbridgesare

simulatedinANSYSCFX

outin TTL

-F

=

i

k kk

i

jj jjiclearieq A

f

A

lfUU åå

+Y

+=c

,,

( )å=

×-=YjN

jjjclearD lUL

1,2

( ) ( )åå==

×Y-×-=ji N

jjj

N

iiiclearD lAUL

11,3c

ieqlayer

ilayerieqlayer R

dk

,,

,,, =

MWMWsteelstudseqMW ww rrr +=,

MWMWsteelstudseqMW CpwCpwCp +=,

The equivalent thermal propertieswere calculated for every layer ofeach element

ieqiclear

iclearlayerieqlayer R

RR

R ,,

,,,, ×=


ValidationIntroduction Experimental



model Conclusion

• BoundaryConditions– As external conditions were assumed the measurements of external

temperature and relative humidity.– The temperature set point for the indoor conditions

• Assumptions– One thermal zone was considered for the whole building– The infiltration was calculated according to ASHRAE.– The internal convection coefficient algorithm developed by Walton (TARP

algorithm)– The external convection coefficient algorithm developed by Yazdanian and

Klems (DOE-2 algorithm)

Feb Mar Apr May Jun Jul Jul Aug Sep Oct Nov Dec Jan Feb-10-505

1015202530

Tem

pera

ture

[o C]

Indoor and Outdoor temperature

00 12 00 12 00 12 00 12 0005

10152025

Tem

pera

ture

[o C] 15 - 19 February

Weather st.Indoor

00 12 00 12 00 12 00 12 0005

10152025

Tem

pera

ture

[o C] 5 - 9 May





model Conclusion

-5 0 5 10 15 20 25 30-5

0

5

10

15

20

25

30

Ener

gyPl

us m

odel

Indo

or T

empe

ratu

re [o C]

Measurement Indoor Temperature [oC]

R2= 0.9921

• Validationtakingintoaccounttheindoortemperature– Thevalidationwasbasedontheperiodswhenthetemperature

controlsystemwasturnedoff.– Theresultsofthemodelareinagoodagreementwiththe

measurements.(coefficientofdetermination,R2=99.21%)– Themeandifferenceis0.27oC,neartothemeasuringerror,whilethe

maximumdifferencesareca.0.6oC.

Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb-5

0

5

10

15

20

25

30

Tem

pera

ture

[o C]

MeasurementsEnergyPlus modelDifference

1.52

2.53

3.54

4.55

5.56

6.57

7.58

8.59

9.510

10.511

11.5

2222.5

2323.5

2424.5

2525.5

2626.5

2727.5

2828.5

29





model Conclusion

• Validationtakingintoaccounttheenergyconsumption– Theresultsofthemodelareinagoodagreementwiththemeasured

values.– Themeandifferenceisabout9%(0.2kWhr)andthemaximum

differencerarelyexceedsthevalueof20%(0.6kWhr).– Thedifferencefortotalannualenergyisonly1.3%.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct0

1

2

3

4

5

6

7

Ene

rgy

Con

sum

ptio

n [

kWhr

]

Measurements EnergyPlus model

Jan Feb Mar Apr May Jun Jul Aug Sep Oct-30-20-10

0102030

Dif

fere

nce

[ %

]

Measurements EnergyPlus model0

200

400

600

800

1000

1200

Ene

rgy

Con

sum

ptio

n [k

Whr

]

1058 1044


Descriptionofthebuilding• Implementation of model in a

typical residential building• Dimensions: 10 m × 10 m × 3 m.• The building envelope consisted

of the same elements with theexperimental mock-up building.

• Each orientation of the externalwalls contained two windows.

• A unique thermal zone wasconsidered

• The internal temperature wasset equal to 20oC during winterand 24oC during summerseason.


Developmentofmodel


AssumptionsforthemodelWindowdimensions 1m× 1.5m

WindowU-value 1.25W/(m2K)

Doordimensions 1.10m× 2.20m

DoorU-value 1.2W/(m2K)

Infiltration 0.125ACH

Electricaldevices 50W


Results• The energy efficiency of the building envelope isassessed by calculating the annual energyconsumption for heating and cooling.

• The impact of the VIP layer is investigated for fourdifferent climate conditions: Athens, Oslo, Kuwait andNew York.


Developmentofmodel


Without VIP With VIP Without VIP With VIP Without VIP With VIP Without VIP With VIP0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Ene

rgy

Con

sum

ptio

n [k

Whr

]

Athens Oslo Kuwait New York

31692561

8344

6664

44473633

5444

4353

Heating Cooling


Results• The additional VIP layer decreases the total energy consumption for

heating and cooling by 18% up to 20%.• This effect is stronger at the cities with cold climate, since the

additional insulation layer saves 1680 kWhr annually (Oslo).• This reduction can be translated into a saving up to 280 €/year.• For the rest climates, the VIPs reduce the heating needs by 20% up

to 25%, and the cooling needs by 9%-17%.


Developmentofmodel


Without VIP With VIP Without VIP With VIP Without VIP With VIP Without VIP With VIP0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Ene

rgy

Con

sum

ptio

n [k

Whr

]

Athens Oslo Kuwait New York

31692561

8344

6664

44473633

5444

4353

Heating Cooling


Results• The results are similar for the four different climate conditions.• All thermal bridges (metal studs and geometrical) increase the consumption by

26% in the case without VIP and 19% in the case with VIP.• The VIP reduces the impact of thermal bridges.• The effect of metal structure at the central part of the walls is approximately the

same with the geometrical thermal bridges.


Developmentofmodel


0

500

1000

1500

2000

2500

3000

3500

WithoutTB MetalStracture Full

Annu

alEne

rgyCo

nsum

ption[kWhr] Athens

WithoutVIP WithVIP

74%

13%

13% WithoutVIP

81%

10% 9%

WithVIP


Conclusions• In the experimental investigation

– A lightweight mock-up building incorporating VIP at the external walls was built.– Several measurements were collected for a whole year.– The VIPs improved the thermal transmittance (U-value) of the walls by ca. 50%.– The layer of VIPs was more effective than the conventional insulation even though it has 7.5 times

less thickness.– The VIPs reduce the impact of thermal bridges on junctions.

• The development of the model– Evaluation of the energy performance of the lightweight building envelope.– The model was validated using the measurements of the mock-up building.– The results of the model were in a very good agreement with the experimental values.

• Implementation of model– Typical residential building, four different climatic conditions.– The VIPs reduced the total energy consumption for heating and cooling by ca 19% for all climates.– This reduction can be translated into an energy saving up to 1680 kWhr/year or 280 €/year in cold

climatic conditions (Oslo).– The additional VIP layer reduces the impact of thermal bridges by 7%.


Developmentofmodel



ExperimentalandNumericalinvestigationoftheEnergyEfficiencyofaLightweightSteelFramedbuildingincorporatingVacuumInsulationPanels

IoannisA.AtsoniosEmail: [email protected]

EinB2017–6th International Conference “ENERGY in...

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