7 Matthias Haase Presentation 06-09-08

Ventilated facade design in hot and humid climateVentilated facade design in hot Ventilated facade design in hot and humid climateand humid climate

Matthias Haase

Dr. Alex Amato

Department of ArchitectureFaculty of ArchitectureThe Hong Kong UniversityPokfulam Road, HK, China

September 2006

Ventilated facade design in hot and humid climateVentilated facade design in hot Ventilated facade design in hot and humid climateand humid climate

• BackgroundPrinciplesCase studies

• Simulation AnalysisResults

• Conclusions

BackgroundBackground• Need for sustainable development• Key role of Building industry

Image credits: Behling, S. Sol power - The evolution of Solar Architecture, 1996, Prestel

Energy consumption (world-wide)

Industry

Transport

Building

BackgroundBackground• Energy responsible approach

Edited by Mat Haase, Image credit: http://www.emsd.gov.hk

Energy consumption (Hong Kong)

Industry

Transport

Building

BackgroundBackground• Energy in buildings in HK

Edited by Mat Haase, Image credit: http://www.emsd.gov.hk


Commercial

34%

Industry 12%

Transport 36%

Residential 18%


Lighting 11%

Air-con 16%

Transport, Sanitary

and others 7% Industry

Transport

Residential

BackgroundBackground• Energy in buildings in HK

Edited by Mat Haase, Image credits: http://www.emsd.gov.hk andhttp://arch.hku.hk/research/BEER/besc.htm

Energy consumption in office Buildings in HK

Transport, Sanitary, others 21%Air-con

47% Lighting 32%

27% of energy in HK is consumed by Air-con and Lighting in commercial buildings

Façade technology

Ventilation

Sun protection/shadowing

Photo-voltaics

Heating/cooling

Passive solar

Daylight

Acoustic protection

Insulation

BackgroundBackground• Possible integrated functions

BackgroundBackground• New concepts for sustainable buildings• Double-skin facades for office buildings

left: Multimedia Center, Hamburg, Germany by Foster and Partners right: Uni, Erlangen, Germany by UBA ErlangenImage credit: http://www.fosterandpartners.com

BackgroundBackgroundWhy double-skin façades?

55.6%

Peak cooling load of office building in HK

Lam, J. C. and Li, D. H. W. (1999) An analysis of daylighting and solar heat for cooling-dominated office buildings. Solar Energy, 65, 251-262.

BackgroundBackground

Why double-skin façades?

• Reduction of peak wind pressure

• Improvement of energy efficiency of façade by

passive solar heat gain in winter reducing thermal losses in winterreducing overall solar heat gain(in summer)support of natural ventilation (with the stack effect)


Why double-skin façades?

• Improving comfort

Thermal: - predicted mean vote (PMV)- percentage people dissatisfied (PPD)- draft temperature

Visual: - daylight factor- glare- view

Acoustic: - intrusive noise

Image credits: Thermal comfort, INNOVA AirTec instruments and MatHaase

BackgroundBackgroundClassification of double-skin façades (DSF)

Box window facade

Corridor facade

Shaft-box window facade

Multi-storeyfacade

Cavity ventilation

natural mechanical

Airflow concept

Externalair curtain

Supply air Exhaustair

Internal air curtain

Main Type

Static airbuffer

hybrid

Haase, M., Amato, A., (2005), Double-skin facades for Hong Kong, proceedings of the Fifth International Postgraduate Research Conference in the Built and Human Environment, The University of Salford, UK.

Principles of DSFPrinciples of DSFPrinciples of airflow in cavity

Externalair curtain

Supply airExhaust air Internal air curtain

Static airbuffer

ext.ext.int. int.

open not open

int. int.int.ext.

Haase, M., Amato, A., (2005), Double-skin facades for Hong Kong, proceedings of the Fifth International Postgraduate Research Conference in the Built and Human Environment, The University of Salford, UK.

BackgroundBackgroundHeat transfer

• Radiation• Q12 = σ A1 Φ12 (T1

4 - T24)

• Conduction• Q = λ A ( T1 - T2 ) / t

• Convection• Q = hc A ΔT

• Traditional performance criteria• U-value, SHGC, meaningless

Reflexion

Conduction and ConvectionConduction and Convection

Second glass layerprimary facade

Qin

Qout

Absorption

TransmissionTransmission

NN11NN22

33

22

11

BackgroundBackgroundBuilding design concept

Haase, M. and Amato, A., (2005), Development of a double-skin facade system that combines airflow windows with solar chimneys, proceedings of Sustainable Building Conference (SB05), Poster session, Tokyo, Japan.

Energy conservation

Increasing efficiency

Utilization of renewable energy resources

Building energy consumption


Energy conservation

0

5

10

15

20

25

30

35

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

degr

ees C

0

1000

2000

3000

4000

5000

6000

7000

8000

degr

ee h

ours

min/max temperature heating degree hours

solar excess degree hours cooling degree hours

Climate analysisClimate analysisClimate analysis


Dry bulb temperature [°C]



Abs

. Hum

idity

[AH]



Abs

. Hum

idity

[AH]

Rel. humidity

[rel. hum]



Abs

. Hum

idity

[AH]

Entha

lpy [h]



Abs

. Hum

idity

[AH]

DBT(°C) 5 10 15 20 25 30 35 40 45 50

AH

5

10

15

20

25

30

Comfort

Psychrometric ChartLocation: Hong Kong, ChinaFrequency: 1st January to 31st DecemberWeekday Times: 00:00-24:00 HrsWeekend Times: 00:00-24:00 HrsBarometric Pressure: 101.36 kPa© A.J.Marsh '00


DBT(°C) 5 10 15 20 25 30 35 40 45 50

AH

5

10

15

20

25

30

Comfort

Psychrometric ChartLocation: Hong Kong, ChinaFrequency: 1st January to 31st DecemberWeekday Times: 00:00-24:00 HrsWeekend Times: 00:00-24:00 HrsBarometric Pressure: 101.36 kPa© A.J.Marsh '00

SELECTED DESIGN TECHNIQUES:1. exposed mass + night-purge ventilation 2. natural ventilation 3. direct evaporative cooling 4. indirect evaporative cooling

Selected energy Selected energy conservation conservation design design strategiesstrategies


Case studiesCase studiesCase studies of existing DSF in Hong Kong:

1. Dragon Air office building, Lantau

2. Kadoorie Biological Science Building, HKU

3. Science Park (Phase 1), Pak Shek Kok

4. Governmental offices, Shatin

5. No. 1 Peking Road, Kowloon

6. New emsd hq, Kai Tak

Case studiesCase studies

• Double-skin façade(external air curtain)

• Double-skin cavity acts as external shading device

• Sealed façade with cavity externally naturally vented

Image credit: Meinhardt Facade Technology

(as in Dragon Air office and in Science Park)

Case studiesCase studies• Example of DSF with EAC: Dragon

Air office building by Wong Tung & Ptns.

Image credit: www.draigonair.com and Meinhardt Facade Technology

Case studiesCase studies• Example of DSF with EAC: • Science Park (Phase 1) by Simon Kwan• Building here: with PV integrated

Case studiesCase studies• Example of DSF with EAC: • Kadoorie Biological Science building by Leigh & Orange• Building here: with HVAC system components in cavity


• Airflow window(internal air curtain)

• Shatin Govermental Offices

• No. 1 Peking Road

• New emsd hq

Image credit: Meinhardt Facade Technology

one room


• Airflow window(internal air curtain)

• Heat is concentrated in cavity

• 10% exhaust air: savings in overall cooling energy possible

• Improving thermal comfort

AHU

Exhaust air

Second glass layer

Visible glass

Case studiesCase studies• Example of AFW with IAC: Shatin Governmental Office by ASD• Active window (developed by Meinhardt Façade Technology)

Image credits: HK Construction Ltd http://202.66.146.82/listco/hk/hkconstruction/annual/2001/sum.pdf

Case studiesCase studies• Example of AFW with IAC: No. 1 Peking Road by Rocco Ltd• Active façade system (developed by Permasteelisa Group)

Image credit: Permasteelisa and Mat Haase

Case studiesCase studies• Example of AFW with IAC: New emsd hq by ASD• 2 upper storeys• Refurbishment

Image credit: emsd and Mat Haase

SimulationSimulationSimulationdouble-skin facades

basecase DSF AFW

SimulationSimulationSimulationdouble-skin facades

basecase DSF AFW

Internal glass layer

External glass layer

Internal movable blinds

Spandrel panel

AHU

Internal glass layer





SimulationSimulationSimulation• Thermal building simulation coupled with

airflowsimulation DSFDSF roomroom


airflowsimulation

• DSF


airflowsimulation

• AFW

facade 1

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

12 18 30 42 54 66 78 90 102 108

height

Cp

04590135180225270315

Cp over height

wind direction

SimulationSimulationSimulation

Façade 1

Façade 2

Façade 3

Façade 4

DSF2DSF2--22 DSF2DSF2--33DSF2DSF2--44

• Results

Monthly results for simulation of DSF at different heights

SimulationSimulationSimulation 0 200 400 600 800 1000

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

cooling load (kWh)

basecase with reflective glass basecase solar control glass

DSF1 DSF2-1

DSF2-2 DSF2-3

DSF2-4

Control strategiesControl strategiesControl strategies

• Controlling solar radiation

• Controlling HVAC

• Controlling exhaust airflow using

a climate sensitive regulator

Movable louvres

Visible glass

AHU>200W/m>200W/m²²

HVAC controlHVAC controlHVAC controlAir velocity AND temperature

Haase, M. and Amato, A., (2005), Double-skin facades and Thermal comfort, proceedings of Healthy Buildings HK Conference, HKCII, HK.

Climate sensitive regulatorClimate sensitive regulatorClimate sensitive regulator

AA

BBCC

DD

• Enthalpy balance

Haase, M. and Amato, A., (2005), Double-skin facades for Hong Kong, proceedings of the Fifth International Postgraduate Research Conference in the Built and Human Environment, The University of Salford, UK.

• Results

Monthly simulation results for DSF and AFW with and without climate control


0

100

200

300

400

500

600

700

800

900

1000

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

cool

ing

load

(kW

h)

basecase DSF1 DSF2

AFW1 AFW2

with climate control

without climate control

• Results

Annual simulation results for DSF and AFW with and without climate control


-10%

-5%

0%

5%

10%

15%

20%

basecase DSF1 DSF2 AFW1 AFW2

annu

al c

oolin

g lo

ad sa

ving

[% o

f bas

ecas

e]

• Results

Simulation results for basecase, DSF and AFW


0%

5%

10%

15%

20%

25%

30%

basecas

e (int

ernal

shading)

basecas

e with

refle

ctive

glass

baseca

se sol

ar con

trol g

lass

DSF1-1DSF1-2DSF2-1DSF2-2

annual3 hottest monthshottest month

ConclusionsConclusionsConclusions

• Possible to design an energy efficient DSF system• Amount of energy through the building envelope resulting

in cooling loads can be reduced by designing a ventilated airflow window that is optimised in respect to heat transfer

• Airflow through the DSF depends on the cp-values of the façade, estimated the cp-values for different building shapes and heights did not influence the performance of the model with DSF

• The EAC uses buoyancy to reject solar heat gain• Possibility to reduce annual cooling loads as well as peak

cooling loads • EAC with a climatic control better in reduction of cooling

loads in the hot summer period• IAC does not reduce cooling load• Best results depend on an enthalpy based control that

extracts air in order reduce the cooling load

ConclusionsConclusionsConclusions

Planned future work

• Validation with measured data• Detailed daylight analysis • Solar assisted extract air device • LCA of different façade systems

Ventilated facade design in hot and humid climateVentilated facade design in hot Ventilated facade design in hot and humid climateand humid climate• Background• Simulation

Analysis Results

• ConclusionsThank you

Thank Thank youyouQs?Qs?

http://thegreenroom.arch.hku.hk

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7 Matthias Haase Presentation 06-09-08