sinclair_8164704

8/8/2019 sinclair_8164704

http://slidepdf.com/reader/full/sinclair8164704 1/12

16 A S H R A E J o u r n a l a s h r a e . o r g A p r i l 2009

VentilatingFaçades

Figure 1: Pearl River Tower, Guangzhou, China, is a 984 t (300 m) commercial tower with a net-zero energy design goal. It has mechani-

cally ventilated double skin açades; underoor air distribution; overhead radiant cooling; wind and solar renewable energy; and more.

I m a g e s C o u r t e s y o f S k i d m o r e O w i n g s a n d M e r r i l l L L P , C h i c a g o

The following article was published in ASHRAE Journal, April 2009. ©Copyright 2009 American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. It is presented for educational purposes only. This article may not be copied and/or distributed electronically or

in paper form without permission of ASHRAE.

8/8/2019 sinclair_8164704


Ap r i l 2009 ASHRAE Journa

By Ray Sinclair, Ph.D., Member ASHRAE; Duncan Phillips, Ph.D.,P.E., Associate Member ASHRAE;

and Vadim Mezhibovski, Ph.D.

About the Authors

Ray Sinclair, Ph.D., is a vice president and consultant in building science.

Duncan Phillips, Ph.D., P.E., is a senior consultant in integrated building

design. Vadim Mezhibovski, Ph.D., is an energy/HVAC specialist. The authors

work or Rowan Williams Davies & Irwin Inc. (RWDI), Guelph, ON, Canada.

deliberations must be inormed by energy and environmentalgoals or the project, heating, overall building cooling andventilation congurations, daylighting, aesthetics, code require-

ments, and wind loads along with capital, maintenance andcleaning cost expectations. This section discusses some o theconguration issues in designing a DSF.

Cavity Height

The DSF cavity height may be a single story, several stories,or the height o the whole building. Although a multistory DSFhas an advantage in a naturally ventilated cavity due to increasedstack-eect induced airfow rates, a single story laterally sub-divided cavity (horizontal and vertical compartmentalization)may be a preerred option taking into account re, smoke, odors,and noise separation considerations. The risk o a tall multistorysingle-cavity DSF is that unacceptably high air temperatures canoccur at the top o the cavity (assuming upward fow) and thiscan cause relatively high gains to the occupied space.

Cavity Depth

The depth o the cavity is determined by a number o param-eters including the aesthetics, types o shading devices/blinds,access to the cavity or cleaning, and the ventilation strategyincluding arrangement and fow rates.

Cavity WidthLateral separation o the cavity between occupied spaces

is benecial or cavity ventilation. It is also helpul or noisecontrol i windows rom the occupied spaces open into thecavity. In some cases, lateral separation can lead to morestable airfow within the cavity, leading to reduced risk o local hotspots.

For tall buildings, architects oten preer the envelope to becovered with a high percentage o relatively clear glass(Figure 1). This choice can challenge goals o achieving

energy eciency, thermal comort and visual comort withinthe building around the perimeter.Optimal energy perormance requires an appropriate balance

o opaque walls and glazing. High perorming glazing choicesinclude low-e, argon-lled double-glazed units; triple-glazedunits; glazing with a spectrally selective coating; glazing con-gurations with external or internal blinds; and the double skinaçade (DSF), which combines a number o these eatures.

The DSF, also known as a ventilated açade or active curtain-wall, is an alternative when design constraints exist such as ahigh percentage o glazing area; no external shades; transpar-ent glass choices; or a açade material that requires protectionrom the elements.

DSFs are requently associated with sustainable building.The premise is that they may permit greater daylighting withoutcompromising thermal perormance o a building’s envelope.These açades have increased design,construction, and maintenance costs,so their use is more popular in placeswhere more stringent energy codesexist (e.g., Europe). However, prob-lems can occur in some climates i theaçade is not designed well. A designstrategy that works in one climate(e.g., temperate and overcast regions o

Europe) may not be directly applicableto others.

The DSF most oten has two glaz-ing units with solar control devicesbetween (Figure 2). This cavity isventilated to extract the heat gain. Fourventilation strategies are illustrated in Figure 3. An engineer-ing analysis must predict thermal perormance under a ullrange o climatic conditions and include coupling to energy-ecient ventilation and cooling strategies at the perimeter o the building.

This article identies some important aspects o how DSFs

are implemented, potential benets and risks, and what param-eters can be used to optimize their perormance. Results romdetailed engineering analyses are presented to demonstrate thebenets o accurate determination o gains that aect thermalcomort and loads that aect equipment sizing. It is vital thatthis improved envelope modeling eeds into whole-building-simulation models.

Confgurations

Evaluate the goals, benets, and risks o incorporating aDSF with the ull design team. The design o the DSF involvesdecisions on geometric parameters, glass selection, ventilation

strategy, shading, and passive or active control strategies. These

The double skin façade, also known as a ventilated façade

or active curtainwall, is an alternative when design con-

straints exist such as a high percentage of glazing area;

no external shades; transparent glass choices; or a façade

material that requires protection from the elements.

8/8/2019 sinclair_8164704



Hotspots or hot regions within the cavity can occur in widecavities in which the vertical airfow does not remain uniormacross the cavity width. Minor asymmetries in geometry, solargains, and minor pressure dierences (perhaps owing to wind,or example) can cause the low-speed airfow to “slosh” toone side o the cavity, allowing one or more zones to be poorlyventilated. This results in higher surace temperatures. Thesefow eatures can be unstable, making them dicult to accu-rately predict.

Cavity Ventilation

The cavity can be ventilated either naturally or mechanically.

Ventilation rates must be sucient to limit high temperaturesassociated with solar gains but not so high that the an energycosts impact total building energy use. The optimal ventilationrate is the lowest rate where building energy consumption isminimized, and inside glass temperatures are as close to theinside dry bulb as possible. The latter will provide comortconditions or occupants sitting adjacent to the glass.

I the cavity is naturally ventilated, the local dust, humidity,and pollution conditions must be understood. Although the anenergy costs associated with naturally ventilating the cavity willbe low, the increased maintenance may eliminate any potentialbenet associated with this.

In many cases, the relatively warm cavity air is discharged tothe atmosphere. In some cases with a mechanically ventilatedcavity, the warm cavity air is used or heat recovery or poten-tially drying a desiccant wheel.

For optimal energy perormance, the cavity airfow ratesshould vary with time o day, as well as external and internalconditions. For example, in hot climates, when air is drawnmechanically rom the interior building space it may be ad-vantageous to draw proportionately larger fow rom the sideo the building with the greatest solar exposure. The air drawninto the cavity should be o return-air quality either warmed byinterior loads or well mixed. Care should be taken that supply

air does not short circuit to the cavity intakes.

Glazing Selection

The glazing system design or a DSF depends on the climaticconditions o the project site, preerred ventilation and blindoperating modes, and internal space requirements. A açadeventilated with outdoor air usually has the insulating glazingunit (IGU) at the interior side, as a thermal break, and a non-insulating (single pane) at the exterior side. A açade ventilatedwith indoor air usually has the IGU (double) at the exterior sideand a single pane at the interior side.

Environmental Factors Aecting Design

The local climate o the building site and the chosen orienta-tion o the DSF are important. The requency and duration o

occurrence o combined conditions o particular wind speeds,wind directions, temperature, humidity, cloud cover, and levelso direct and diuse solar radiation must be actored into designdecisions. There is a need to agree on the extremity o designday conditions and acceptance o less optimal perormance orlimited periods to optimize capital costs. Condensation risks,dust ingress, exterior noise, and other local infuences otenresult in an incompatibility o certain design options.

Wind pressures on the building due to site location, buildingshape and surroundings, and thermal stack eect o the buildingand the cavity itsel, can aect cavity ventilation and buildinginltration/exltration. In hot, humid climates, or example,

these actors can aect the DSF design and the cooling strategy

Outer Glazing

Inner Glazing

Troom= T7

Shading Device

T2

T3T5

T4 T6Tambient= T1

Figure 2: Example o a double skin açade confguration.

Figure 3: Internal and external ventilation confgurations o DSFs.

Ventilated Exhaust

A m b i e n t

R o o m

Mechanically Ventilated Supply

A m b i e n t

R o o m

Mechanically Ventilated Airfow

A m b i e n t

R o o m

Naturally Ventilated

A m b i e n t

R o o m

8/8/2019 sinclair_8164704


www.info.hotims.com/23934-43

8/8/2019 sinclair_8164704



that may be used in the perimeter occupied spaces (i.e., viasupply air or radiant cooling).

Potential Benefts o a High Perormance Façade

A high perormance açade, as can be achieved with a prop-

erly designed DSF, can realize the ollowing additional benets: • Reduced mechanical plant capital costs. I a sucientlyaccurate engineering analysis is perormed, predictedpeak loads may be lower than those or a traditionalaçade given the architecture (i.e., same glass area andaesthetic requirements). This allows selection o smallerHVAC equipment.

• I a reduced load is achieved and incorporated withradiant cooling and ecient supply air delivery, suchas underfoor or displacement ventilation, then foor-to-foor heights may be reduced. This can lower the buildingcapital cost or provide additional foors o leasable spacein high rise towers, or example.

The design o the Pearl River Tower in Guangzhou,China (Figure 1), reduced the foor-to-foor height byapproximately 1 t (0.3 m). With more than 70 foors,ve additional foors o leasable space were added. Thismeant that the payback calculation avored the integrateddesign that incorporated the DSF.

• Energy savings resulted rom reduced cooling demandrom perimeter sensible gains and eective daylightingleading to reduced lighting requirements.

• Increased occupant thermal comort adjacent to the a-çade compared to that o a traditional açade o equivalentglass area and transparency.

• Improved aesthetic o a more visually transparent açade.• Improved sound insulation rom exterior sources as a

result o the third pane o glass.

Risks o a Double Skin Façade

While a DSF can provide several benets, it is possible thata DSF that is not designed and operated correctly may causeproblems in the operation o the building, or provide no benetat all despite the additional cost:

• Poor design can lead to excess thermal gains to theoccupied spaces and building overall. This can resultbecause the choice o glazing, shading device(s), and

control strategy is incorrect or the ventilation rate is toolow. Another result can be poor visual comort resultingin blinds being lowered and articial lights turned on. Thecombination o these actors can also conspire against thebuilding’s perormance.

• Noise, odors, or smoke rom potential re can be trans-ported through the cavity system i there are lateral orvertical connections between açade segments. Thesecontaminants also can be transported through the DSFsystem due to poor construction practices.

• Depending on the climate, it is possible or condensationto orm on any or all suraces in the DSF during particular

meteorological conditions and time o day.

• I the açade is open to outdoors, the suraces within the cav-ity will gather dust and require cleaning. Coupled with con-densation risks, the cavity could become soiled. This addsto the ongoing maintenance costs and aesthetic concerns.As well, access to the cavity or cleaning must be includedin the design. Appropriate seals must be in place around theaccess panels to minimize exltration and inltration issues.

Requirements o Perormance Analysis

The thermal perormance o a DSF depends on many designvariables. This section discusses the physics involved. A sche-matic o the heat and air transport mechanisms is presented

in Figure 4. The complexity o the physics, coupled with theuncertainties in many parameters (e.g., heat transer coe-cients), highlights why modeling DSFs is dicult and whysome approaches show mixed results.

Conduction must be taken into consideration in solids, de-scribing heat transer through glass, concrete, wood, or othermaterials orming the inner or outer DSF construction. Caremust be taken not to merely use the manuacturers’ statedconductance “U-values” directly, as is oten done in simplermodeling approaches. Conductivity and material thicknessesmust be applied directly in conduction calculations.

The heat transer between a solid surace and air is a unction

o both orced and natural convection processes. This convective

Figure 4: Paths o heat transer in a double skin açade illustrat-

ing direct and diuse solar radiation, conduction, convection, and

long-wave radiation.

Incident

Direct

Solar

Outdoor

Diuse

Solar

Conduction

Airfow

(Natural or Mechanical)

Conduction

C o n v e c t i o n

LW

C o n v e c t i o n

LW

Indoor

LW

BlindsBlinds

GlazingGlazing

C o n v e c t i o n

C o n v e c t i o n

LW

C o n v e c t i o n

C o n v e c t i o n

8/8/2019 sinclair_8164704



8/8/2019 sinclair_8164704



heat transer is predicted byspeciying convection coe-cients that are dependent onair velocities or each solid-airinterace. These air speeds

are location dependent andfuctuating.Radiation heat transer oc-

curs between two dierentcomponents. Solar energy ex-ists at short wavelengths whileheat transer between roomsuraces (i.e., foor, walls, andwindows) occurs at long-wavelength bands. Solar radiationmust be considered in its direct and diuse components. Directsolar is most aected by cloud cover and also by atmospherichumidity and air pollution. Diuse solar radiation is aectedby atmospheric conditions and site surroundings that infuencethe atmospheric and ground refective components, respectively.Both are impacted by building orientation.

The design o a DSF involves comparison o model resultsor several design parameters over a range o atmospheric con-ditions, typically a design year o hourly meteorological data.Plots o joint probabilities highlight requency o occurrenceo various coincident events. For example, this meteorologicaldata analysis could dene the characteristics o a “hot clearday,” the time, and duration o peak conditions. This can inormdesign decisions o DSF conguration and also operation andcontrol strategies.

Sample Results o Perormance AnalysisFigures 5 to 8 present predicted perormance data or one o

the analyzed congurations o the south-acing DSF o the PearlRiver Tower located in Guangzhou, China, at approximately 23°N latitude. These gures show a collection o dierent types o assessment measures, using mainly custom purpose modelingtools and a commercial CFD package.

The analysis presented in the gures corresponds to a DSFusing a double-glazed low-e panel as the outer skin and clearmonolithic glass as the inner skin. Glass properties are listed inTable 1. The environmental conditions in the analysis presentedcorrespond to a hot December 21 design day.

Figure 5 shows the total amount o solar energy (direct +sky-diuse + ground-refected components).Figure 6 provides a comparison o the DSF perormance with

and without blinds. In both cases, the cavity airfow rate is thesame. However, the without blinds case results in more thantwice the energy to enter the room (gain). These plots also showthat the amount o energy that is captured in the DSF cavity(purple line) is reduced without the blinds. It is recognized thatthe type o blind (roller versus slat) can signicantly infuencethe penetration o solar energy into the room.

Figure 7 shows the diurnal variation o average air and suracetemperatures in the DSF without shading. The gure shows how

the temperature on the various glazing suraces, as well as the

Figure 5: A diurnal cycle o solar radiation components or the Pearl

River Tower site in Guangzhou, China. This inormation ed into

thermal analysis perormed in the design o the DSF.

Direct Normal Irradiance

Direct Solar Radiation

Diuse Irradiance

Ground-Refected Irradiance

Total Short Wavelength Irradiance

1,000

800

600

400

200

0

G a i n ( W / m 2 )

0 4 8 12 16 20 24

Time (h)

ThicknessSolar

Heat Gain

Coecient

U-ValueSolar

Transmissivity

Solar

Refectivity

inch (m) Btu/h · t2 · °F (W/m2 · K)

Inner

Skin3 / 8 (0.010) 0.79 0.99 (5.6) 0.73 0.07

Outer

Skin1 (0.025) 0.33 0.31 (1.7) 0.29 0.38

Table 1: Glazing properties or Pearl River Tower.

temperature o the cavity air, changes during the day. This leadsto the observation that the cavity ventilation airfow rate neednot be constant during the day. In act, there is a likelihood o

higher energy eciency i the cavity has varying fow ratesthroughout the day. The fow rates or a cavity on the north andsouth o the building will also be dierent i energy eciencyis to be optimized.

Figure 8 highlights how the perormance o the DSF canbe signicantly infuenced by the fow rate within the cavity.The gure presents predictions o gain and load to the room,through the DSF, at noon in December or dierent fow rates(m3 /h · m o width o the açade). These results are or the DSFoperating without shading devices. The plot shows that gainand load to the room are decreased as the fow rate in the cav-ity is increased. The cost associated with this is the increased

energy picked up in the cavity air. This data can be input into

8/8/2019 sinclair_8164704



8/8/2019 sinclair_8164704



a cost-benet analysis to determine at which point the reduc-tion in gain entering the room is oset by the additional an

energy driving the air through the cavity and the increasedenergy within the cavity air. A holistic approach to buildingdesign is required.

Figure 9 shows a sample prediction rom a CFD simulationo short-wave radiation, air speed, and air temperature distribu-tions in a Pearl River Tower DSF cavity. In this simulation, theblinds were explicitly modeled or solar control. The graphicsillustrate the complex patterns that simpler analytic modelsmust account or, or risk providing the incorrect eedback. Thevertical stratication o hot air in the cavity will increase heatfow into the building at the top o this single story cavity andthe surace temperatures that will aect the long-wave radiant

eld in the occupied space. Multifoor cavities can exhibit

more pronounced vertical variations in temperature leading toincreased gains at the upper levels o the cavities.

Comparison o DSF to a High Perormance Single Façade

Figure 10 shows predicted maximum monthly gains andloads into a room through both a single and double skin açadeconguration (quoted as W/m o width o the açade). Theseare compared without shading devices or an east-acing açade

o a building located at 40º N (Beijing). This analysis was car-

Flow Rate (m3 /h·m)

0 10 20 30 40 50 60

Gain to Room Load to Room Gain to Cavity

45

40

35

30

25

20

T e m p e r a t u r e ( ° C )

0 4 8 12 16 20 24

Outer Surace o the Inner Glazing Unit Room

Inner Surace o the Inner Glazing Unit Cavity Exhaust

Outside Glass SuraceOutside

Time (h)

Figure 7: Diurnal variation o average air and surace temperatures in

Pearl River Tower DSF south-acing açade without shading devices.

Figure 6: Pearl River Tower DSF predicted perormance with and

without blinds or the south-acing açade.

2,200

2,000

1,800

1,600

1,400

1,200

1,000

800

600

400

200

0

G a i n ( W )

0 4 8 12 16 20 24

Time (h)

Gain rom Solar Radiation

Gain to Cavity

Gain rom Nonsolar Radiation

Gain rom LW RadiationTotal Gain to Room

Gains Without Blinds

Gains With Blinds2,200

2,000

1,800

1,600

1,400

1,200

1,000

800

600

400

2000

G a i n ( W )

0 4 8 12 16 20 24

Time (h)

Gain rom Solar Radiation

Gain to Cavity

Gain rom Nonsolar Radiation

Gain rom LW RadiationTotal Gain to Room

Figure 8: Predicted eects o cavity airow rate on energy ows.This was an early design confguration o the south-acing açade

or Pearl River without shading devices.

1,800

1,600

1,400

1,200

1,000

800

600

400

200

0

P o w e r ( W )

8/8/2019 sinclair_8164704



8/8/2019 sinclair_8164704



ried out early in design as a means to assess the viability o theDSF or this building and climate considering similar designconstraints o 100% glazing area and equivalent transparency.The glazing properties are listed in Table 2.

The plots present the maximum hourly values or the 21st day

o each month or dierent parameters: the gain that is passedinto the room through the açade (blue line) and the load (purpleline) that the ventilation system within the room experiencesgiven the thermal lag o the building thermal capacitance. Thegreen line in Figure 10 is the load to the system should the en-ergy captured in the DSF be passed back to the HVAC systemsvia the cavity ventilation air.

In July, or example, the single açade permits a peak gain o 1,349 W to enter the room, and this is converted into a coolingload o 1,072 W. The DSF perormance in July, and its impacton the building, depends on how the system is congured.The air ventilating the cavity is assumed to enter the cavity at

room temperature. The peak gain that enters the room is 1,050W, a reduction o approximately 22% over the single açade.The load that the system experiences rom the room is 829 W,a reduction o 23%.

These are useul perormance improvements. However, i the air ventilating the cavity is returned to the HVAC sys-tems and then recirculated again, the total load experiencedby the system is approximately 1,242 W that is greater thanthat or the single açade. The choice o ventilation strategyis important.

There are opportunities to use the cavity air in other waysthat can provide energy savings. The DSF ventilation air can

be mixed with the supply air, instead o using a reheat coil

Figure 9: Example o CFD computer model prediction o airow

and temperature distribution in a DSF. From let to right the images

are: (1) predicted solar radiation ux in the cavity; (2) predicted air

speed distribution; (3) predicted air temperature distribution; and (4)

confguration o mechanically ventilated DSF or Pearl River Tower

building with outow rom top o cavity, which draws air rom the

room into the base o the single-story cavity.

Figure 10: Comparison o thermal perormance o a high-perorming

single açade and double skin açade. Peak one-hour energy gains

and loads are predicted or each month o the year. This work was

carried out during the design o a commercial tower in Beijing,

east-acing açade, without shading devices.

Load to System

Gain to Room Load to Room

Maximum Gain and Load to the Room (Single Façade, Triple Pane [W/m])

Dec.

Nov.

Oct.

Sept.

Aug.

July

June

May

Apr.

Mar.

Feb.

Jan.

Gain to Room Load to Room

Dec.

Nov.

Oct.

Sept.

Aug.

July

June

May

Apr.

Mar.

Feb.

Jan.1,500

1,200

900

645883

584

869

1,074

1,244

1,322

1,349

1,346

1,368

1,353

1,245

438

392600

773

958

1,031

1,072

1,071

1,080

1,045

615927

300

1,500

1,200

900 8031,084

726

703

847

981

1,038

1,050

1,045

1,064

1,069

990582520

486

617

752

804829

826

835

822

787

749300

600582

520

696

1,136

934

787

1,205

1,242

1,235

1,251

1,217

1,100582

520

696

1,136

934

787

1,205

1,242

1,235

1,251

1,217

1,100

Maximum Gain and Load to the Room (DSF), (W/m)

600

8/8/2019 sinclair_8164704


Ap r i l 2009 ASHRAE Journa

ThicknessSolar

Heat Gain

Coecient

U-ValueSolar

Transmissivity

Solar

Refectivity

inch (m) Btu/h · t2 /°F (W/m2 · K)

DSF

Inner

Skin (0.013) 0.73 0.98 (5.59) 0.64 0.06

OuterSkin

1 (0.025) 0.38 0.28 (1.57) 0.33 0.31

Single Façade

(Triple Pane)1 5 / 8 (0.042) 0.34 0.22 (1.25) 0.28 0.32

Table 2: Glazing properties or Beijing building.

or it could be used in a heatexchanger. The air can alsobe used or drying a desic-cant wheel i temperaturesare high enough or sucient

requency and duration. Inthe winter it can serve to pre-warm incoming air.

Closing Remarks

The selection o the build-ing envelope is one o the mostcritical aspects o buildingdesign. This selection willdictate how occupants willbehave in the building (e.g.,lighting, natural ventilation),the energy demand to manage the external climate, and theappearance o the building. The range o design options o abuilding envelope can lead to a dramatic dierence in the siz-ing o building ventilation and cooling systems. I the buildingskin is not done well, then occupant behavior to moderate theirenvironment (e.g., drawing blinds and closing windows) candramatically aect the energy use and change the basis o designo the building. In this case, at best, this means the building usesmore energy. At worst, the systems are undersized and buildingoccupants will be uncomortable.

Optimal energy savings requires an appropriate balanceo opaque walls and glazing. A double skin açade is onemeans to manage the interaction between the outdoors and

the internal spaces. It also provides some architectural fex-ibility to the design. Energy eciency and thermal comortadjacent to the açade requires careul conguration o glass,solar control devices (both or thermal and visual eects),and ventilation o the DSF cavity. A responsive control sys-tem or the solar control devices and the ventilation o theDSF is required.

The examples presented here show how dierent operatingpractices (e.g., fow rates), or design decisions (glazing choices)can aect the ultimate perormance o the DSF. Decisions onthese elements should be based on analysis that accounts orthe detailed physics and inclusion o site climatic data as il-

lustrated in this article.

BibliographyBlomsterberg, Å. et al. 2007. “BESTFAÇADE: Best Practice or

Double Skin Façades—Literature.” EIE/04/135/S07.38652. www.bestacade.com.

Lee, E., et al. 2002. “High Perormance Commercial BuildingFaçades.” Building Technologies Program, Environmental EnergyTechnologies Division, Ernest Orlando Lawrence Berkeley NationalLaboratory, Report No: LBNL-50502. http://gaia.lbl.gov/hpb/ documents/LBNL50502.pd.

Oesterle, E. et al. 2001. Double-Skin Façades: Integrated Planning:Building Physics, Construction, Aerophysics, Air-Conditioning, Eco-nomic Viability. Munich: Prestel Publishing.

Poirazis, H. 2004. “Double Skin Façades or Oces Buildings:Literature Review.” Division o Energy and Buildings Design, LundInstitute o Technology, Lund University. Report EBD-R-04/3.www.ecbcs.org/docs/Annex_43_Task34-Double_Skin_Facades_A_Literature_Review.pd.

Straube, J.F., R.V. Straaten. 2002. “The Technical Merit o DoubleSkin Façades or Oce Buildings in Cool Humid Climates.” Schoolo Architecture, University o Waterloo, Waterloo, ON, Canada. www.civil.uwaterloo.ca/beg/Downloads/DoubleFacadesPaper.pd.


Documents

sinclair_8164704