With the façade embodying up to 35% of the construction costs as well as being hugely accountable for the buildings' response to climate change, it has never been so important to understand which façade solutions deliver not only a cost effective and sustainable façade, but also one that is aesthetically pleasing and technically performing.

1. Dec.,2016 Bahrain

2. Façades Systems
Low-Energy Buildings
Hot Climate Double Façades
Intelligent Building Facades
Wind Loads and Façades

3. Façades
Systems
With the façade
embodying up to 35% of
the construction costs as
well as being hugely
accountable for the
buildings' response to
climate change, it has
never been so important
to understand which
façade solutions deliver
not only a cost effective
and sustainable façade,
but also one that is
aesthetically pleasing and
technically performing.

4. Building Facades
• The façade forms the external weatherproof envelope of a building. (vertical
building enclosure).
• More than any other component; they create the image of the building. The
building envelope should be designed to mediate public-private boundaries within
the architecture, both inside and out.
• In modern buildings, the façade is often attached to the building frame and
provides no contribution to structural stability.
• Sustainable facades are defined as exterior enclosure that use least possible
amount of energy to maintain a comfortable environment, which promotes
productivity to certain material which has less negative impact on environment.
• Essentially There Are Two Types Of Facades:
– Opaque Facades; which are primarily constructed of layers of solid materials,
such as masonry, stone, precast concrete panels, metal cladding, insulation,
and cold formed steel framing. Opaque facades may also include punched
openings or windows.
– Glazed Facades; such as curtain walls or storefront facades which primarily
consist of transparent or translucent glazing materials and metal framing
components.

5. Opaque Facades
Solid wall constructed
from monolithic or
composite elements,
with or without a
separate layer to
provide climatic
protection
Warm façades have a
thermal insulation
layer applied directly
to the surface of the
building. (MUST be
water-resistant)
Cold façades are
characterized by a
cavity, ventilated
internally, between
the outer layer and
the thermal insulation
layer.

6. Factors That Effect Thermal, Visual, And Acoustic
Comfort of Façades
Environmental
Conditions
Thermal Comfort Visual Comfort Acoustic
Comfort
Opaque facades  Material properties of
cladding
 Amount of insulation
 Effective heat resistance
properties (R – value)
Wall to wall ratio Material
selection and
properties
Glazing  Orientation
 Number of glass layers
 Layer thickness
 Heat transfer coefficient (U-
value)
 Visual transmittance
 Solar heat gain
coefficient(SHGC)
 Orientation
 Window properties,
size, location and
shape
 Glass thickness and
color
 Visual
transmittance
 reflectance
Number of
layers
Layer thickness
Layer density
Framed and
supporting
structure for glazed
facades
Thermal properties of the frames Material types

7. Desired & Smart Properties of Facades
Desirable Properties;
• Low CO2 emission
• Thermal and Moisture Insulation
• Storage
• Solar Isolation
• Natural Light
• View
• Fresh Air
• Sound Insulation
• High insulation e.g. vacuum
insulation
• Self cleaning
• Security/Safety/Fire Protection
• Aesthetics
Smart Facades;
• Facade is an interactive
inside-outside interface
• Sensor system/interact
with clothing or skin
sensors
• Reactive materials and
surfaces
• Embedded technology
can control
inputs/outputs (Dynamic
envelopes)
• Opportunities for
nanomaterials

8. Façade Design Objectives
• Energy efficiency
• Sustainability
• Comfort (thermal, acoustic, visual)
• Economy in use
• Economy of construction
• Safety in construction and maintenance
• Safety in use
• Durability
• Aesthetics
LEED addresses some, but not all therefore, its best to use
“Holistic Design” to balance improving façade performance in
conjunction with building overall performance.
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9. What is LEED?
• Leadership in Energy and Environmental Design
• USGBC - United States Green Building Council
• http://www.leedbuilding.org
• Started in 2000 and has grown and developed since
• Voluntary not Statutory.
• A Rating system not a Design Guide.
• It sets minimum requirements (pre-requisites) and awards
credits for designs that exceed the minimum requirements
• Depending on the amount of credits awarded, a building will
achieve.

10. Low-Energy
Buildings
 Minimizing energy used
for artificial lighting and
mechanical cooling and
heating by minimizing
the area of the building
external skin and
optimizing exterior wall
insulation.
 Façade materials
properties and wall
assemblies largely
determine energy
consumption and the
heat loss or gain of the
building.

11. Sustainable Design Guideline for Buildings
• Orienting and developing geometry and massing of the building to respond to
solar position and climate.
• Maximize levels of natural ventilation and daylight shading (optimize window sizes)
with early sun glare protection. (Horizontal sunscreens / adjustable blinds to block
the summer sun)
• Using natural ventilation to reduce cooling loads and enhance air quality. (Locate
door and window openings on opposite sides of building with larger areas facing
up-wind)
• Use thermal insulation / wall massing to block sunlight. improve thermal comfort
• Use a light-colored concrete for the parking surface and walkways surrounding to
reduce the heat island effect.
• Glass facades allows occupants views of the city and gives a ‘modern’
architectural look, however, Glass facades are often associated with increased
energy consumption, solar heat gain, glare, discomfort of occupants and cost.
• FINALLY ; country specific ecological and climate conditions should be considered
along with suitable available local materials.

12. Lighting
14%
Space heating
28%
Space
cooling
10%
ventilation
6%
Refrigiration
5%
Water heating
7%
Electronics
3%
Computers
2%
Equipment
14%
Other
11%
Energy use breakdown for commercial buildings
Buildings’ Energy Consumption
Sustainable Facades Reduce
Buildings’ Energy Consumption

13. Fenestration Components
• Fenestration components and materials
allow natural light to enter into the
building, decide the amount of energy
consumption and the heat loss or gain of
the building.
• Thermal Resistance (R-value) - It is an
assembly’s or a material’s resistance to
heat transfers, and is expressed in h-ft2 or
m2-K/W.
• Heat Transfer Coefficient (U-value) - It is
the inverse of R-value. It measures the
heat transmission through a material or a
façade assembly, expressed in Btu/hr-ft2-
oF or W/m2-oK, and are usually used to
define thermal performance of glazed
parts of facades assemblies.

14. EmbodiedEnergyExamplesInFacades Cladding Systems Embodied
Energy
CMU
Brick cladding, continuous insulation and
polyethylene membrane
247
Steel cladding, continuous insulation and
polyethylene membrane
370
Precast concrete cladding, continuous
insulation and polyethylene membrane
291
Cast-in-place concrete
Brick cladding, continuous insulation and
paint
113
Steel cladding, continuous insulation and
paint
236
Stucco cladding, continuous insulation
and paint
99
Steel framed (16 in.)
Brick cladding, continuous insulation,
cold-formed steel framing, cavity
insulation and polyethylene membrane,
gypsum board and paint
96
Steel cladding, continuous insulation,
cold-formed steel framing, cavity
insulation and polyethylene membrane,
gypsum board and paint
219
Wood cladding, continuous insulation,
cold-formed steel framing, cavity
insulation and polyethylene membrane,
gypsum board and paint
61
Precast concrete cladding, continuous
insulation, cold-formed steel framing,
cavity insulation and polyethylene
membrane, gypsum board and paint
141
Cladding Systems Embodied
Energy
Steel framed (24 in.)
Brick cladding, continuous insulation,
cold-formed steel framing, cavity
insulation and polyethylene membrane,
gypsum board and paint
91
Steel cladding, continuous insulation,
cold-formed steel framing, cavity
insulation and polyethylene membrane,
gypsum board and paint
213
Wood cladding, continuous insulation,
cold-formed steel framing, cavity
insulation and polyethylene membrane,
gypsum board and paint
55
Precast concrete cladding, continuous
insulation, cold-formed steel framing,
cavity insulation and polyethylene
membrane, gypsum board and paint
135
Curtain wall
Vision glazing and frames 148
Opaque glazing 135
Metal spandrel panel 138

15. ASHRAE’s Energy Standard for Buildings
 ASHRAE Energy Standard for buildings provides recommendation for building facades
based on building location and climate zone.
 ASHRAE’s requirements are categorized based on the basic building function and
occupancy,
 ASHRAE identifies four types of exterior walls:
– Mass walls, generally constructed of masonry or concrete materials.
– Metal building walls, consisting of metal members spanning between steel structural
members (not including spandrel glass or metal panels in curtain walls)
– Steel framed walls, with cavities whose exterior surfaces are separated by steel framing
members.
– Wood framed and other walls.
 ASHRAE requirements for different climate zones:
– Minimum allowable thermal resistance (R-value) for different exterior walls.
– Maximum allowable heat transfer coefficient (U-value) for the façade assembly (including
the thermal bridging effects of framing members)
– Maximum allowable solar heat gain coefficient (SHGC) for the glazed portions of a façade
assembly.

16. Parameter
measured
Outcome Effect of the green facade
Difference in
temperature in
front of and
behind the facade
1.4°C cooler in
summer 3.8°C
warmer in winter
Absorption of light and heat energy
by foliage keeps the cavity
temperature lower Facade support
system creates a
microclimate/unstirred air layer
next to the wall even when stems
are bare
Difference in
surface
temperature
between bare wall
and vegetated wall
(summer)
Average bare wall
temperature is 5.5°C
higher (Maximum
temperature is
15.2°C higher)
Full leaf cover provides effective
shading and prevents heat gain by
the building
Difference in
relative humidity
in front of and
behind the facade
7% higher in
summer 8% lower in
winter
Evapotranspiration from leaves
causes a local increase in humidity
(and cooling) in summer which is
not apparent when stems are bare
Impact of Green Facade On Building Thermal
Performance
Green facades are created through the growth of climbing plants up and
across the face of a building, from either plants rooted in the ground, or
those in containers installed at different levels up the face of a building.

17. Heat Transfer Coefficients For Glazing
(U-value) - Comparison
Type of material to be used in the building should have minimum heat
transfer coefficient and should have minimum embodied energy in its
construction and installation of framing. Façade should have maximum
thermal resistance which can prevent building from heating.
Glazing Type Centre of
Glass
Edge of Glass Aluminum Frame
Without Thermal
Brake
Aluminum
Frame With
Thermal Brake
Double Glazing 12 mm Air
Space
(U value W/m2-oK) 2.73 3.36 4.14 3.26
Double Low-e Glazing with
12mm Argon Fill
(U value W/m2-oK) 1.70 2.62 3.26 2.38

18. Wall Assemblies Curtain Wall Example
• Due to strong abrasive winds
and hot weather conditions in
GCC region using a single
glazing is not feasible solution
because buildings absorbs an
immense amount of heat.
• Therefore double skin façade
can be an option.
• The other option is to use high
U- value glass / double-glazed
windows.
• Double glazing with 6mm air
space for the inner façade and
double low e- glazing with
12mm argon fill on the exterior
façade which require relatively
better strength to bear wind
load on the building.
• By doing this the embodied
energy of the building material
used can be reasonable.

19. HOT CLIMATE
DOUBLE FAÇADES
 Passive solar heat
gain in winter.
 Reducing thermal
losses in winter.
 Reducing overall
solar heat gain.
 Support of natural
ventilation (with
the stack effect).

20. Double-Skin Façade
The double skin consists of two transparent surfaces
separated by a cavity, which is used as an air channel.

21. Why Double Skin Facades?
• Reduction of peak wind pressure
• Improvement of energy efficiency of façade by
– Passive solar heat gain in winter
– Reducing thermal losses in winter
– Reducing overall solar heat gain (in summer)
– Support of natural ventilation (with the stack effect). The air corridor
may or may not form part of the cooling system.
• The system can be responsive that opens and closes according to
solar path.
• The cavity is seen as a great place to locate the shading system as it
could be protected from snow, ice and wind.
• FINALLY; Architectural infatuation with tectonics and appearance!
• NOTE 1; The shading layer must be very durable to withstand
exposure to the elements as well as cleaning.
• NOTE 2; The combination of high humidity and dust while fresh
water is mostly desalinated makes Facade cleaning a major issue.

22. Early research into double façade
types
Buffer Façade Twin Face FaçadeExtract-air Façade

23. Double façades in the Gulf Region
Al Bahar Towers, Abu Dhabi
Aedas Architects w/Arup
Doha Tower, Qatar
Ateliers Jean Nouvel
Capital Gate, Abu Dhabi,
RMJM Architects

24. O-14, Dubai
Its exterior shading element is made
from reinforced concrete and acts as
an external structural support for the
building while being a shading device
O-14, Dubai UAE
RUR Architecture

25. Intelligent
Building Facades
The human skin is a
good model how we
would like the
building skin to
behave. It adapts to
temperature and
humidity, can feel a
breeze or the slightest
touch, and can repair
itself. It is waterproof
and yet permeable to
moisture.

26. Smart Window / Facade Colour-Changing
System
Type
Spectral Response Input Energy Interior Result Visual Interior Result
Thermal
Photo
chromic
Specular to specular
transmission at high
UV levels
UV radiation Reduction in intensity
but still transparent
Reduction in
transmitted radiation
Thermo
chromic
Specular to specular
transmission at high IR
levels
Heat (high surface
temperature)
Reduction in intensity
but still transparent
Reduction in
transmitted radiation
Thermo
thropic
Specular to specular
transmission at high
and low temperatures
Heat (high and/or
low surface
temperature)
Reduction in intensity
and visibility, becomes
diffuse
Reduction in
transmitted radiation,
emitted radiation, and
conductivity
Electro
thropic
Specular to specular
transmission toward
short wavelength
region (blue)
Voltage or current
(control system
and electrical
supply required)
Reduction in intensity Proportional reduction
in transmitted
radiation
Liquid
Crystals
Specular to diffuse
transmission
Voltage (control
system and
electrical supply
required)
Minimal reduction in
intensity, reduction in
visibility, becomes
diffuse
Minimal impact on
transmitted radiation
Suspended
particle
Specular to diffuse
transmission
Current Reduction in intensity
and visibility, becomes
diffuse
Minimal impact on
transmitted radiation

27. Double Glazing

28. Other Colour-Changing Smart Materials
• Mechano chromics -materials react to imposed
stresses and/or deformations.
• Chemo chromics -materials exposed to specific
chemical environments.

29. Titanium dioxide nanoparticles with a smooth surface may be used
as an anti-adhesive coating for windows or spectacle lenses
Self Cleaning Facade Features

30. Mimics human bleeding healing process. Embedded vessels bleed
colored epoxy resin into cracks and restore structural integrity.
Self Healing Materials

31. Carbon Nanotubes
Carbon nanotubes are cylindrical carbon molecules with novel
properties as they exhibit extraordinary strength and unique
electrical properties, and are efficient conductors of heat.

32. More Renewables!
SMIT (Sustainably Minded
Interactive Technology) Solar
and wind power micro cells
fixed onto facades.

33. More Greenery!

34. Future Facades
• With the increase in sustainability, fire safety ,
new materials innovations and technologies
the future remains to be seen for façade
design and engineering.

35. Wind Loads and
Façades
Building Envelopes Design
Considerations;
 Wind Pressures
 Weather Performance
 Integration with Building
Services
 Structural Integrity
 Blast proof/ earthquake
criteria
 Energy Performance
 Maintenance/ Cleaning/
Recycling

36. Flow Around the Building

37. DEVELOPMENT OF STRUCTURAL SYSTEMS
First Generation1780-1850
• The exterior walls consisted of stone or brick, although
sometimes cast iron was added for decorative purposes.
• The columns were constructed of cast iron, often unprotected;
steel and wrought iron was used for the beams; and the floors
were made of wood.
Second Generation 1850-1940
• Framed structures, a skeleton of welded- or riveted-steel
columns and beams, often encased in concrete, runs through the
entire building.
• This makes for an extremely strong structure, but not such
attractive floor space. The interiors are full of heavy, load-bearing
columns and walls.
Third Generation 1940-present
• Within this generation there are those of steel-framed
construction (core construction and tube construction),
reinforced concrete construction (shear wall), and steel-framed
reinforced concrete construction.
• Hybrid systems also evolved during this time. These systems
make use more than one type of structural system in a building.
HOME INSURANCE
BUILDING
EMPIRE STATE
BUILDING

38. Buildings Design Loads
• The primary structural skeleton of a tall building can be visualized as a vertical cantilever beam with
its base fixed in the ground.
• The weight of the building is supported by a group of vertical columns , each floor is supported by
horizontal steel girders running between vertical columns.
• Curtain wall made of steel and concrete attaches to the outside. NO Structural Function.
• The structure has to carry the vertical gravity loads (caused by dead and live loads) and the lateral
wind and earthquake loads.
• Lateral loads tend to snap the building or topple it. The building must therefore have adequate shear
and bending resistance and must not lose its vertical load-carrying capability.

39. Wind Loads
• Buildings taller than 10 stories
would generally require
additional steel for lateral
system.
• The most basic method for
controlling horizontal sway is to
simply tighten up the structure
to make the entire steel super
structure move more as one
unit, like a pole, as opposed to
a flexible skeleton.
• For taller skyscrapers, tighter
connections DOES NOT keep
these buildings from swaying as
there is a greater demand on
the girders and columns that
make up the rigid-frame system
to carry lateral forces.
• Thus strong cores or perimeters
that run through the center of
the building are needed to
counter sway.
The columns in the windy side stretch
apart, and the columns on the other
side squeeze together.

40. Strategies To Mitigate Wind Effect
• Wind produces three different types of effects on tall buildings: static,
dynamic, and aerodynamic.
• Structurally, static effect is independent of time; but dynamic analysis is an
attempt to take into account how the system responds to the change
through the period of time;
• When the building is flexible, the building interacts with wind load and
affects its response; that is called aerodynamic effect. Wind tunnel testing
are used to predict motion perception and pedestrian level effects.
• To reduce the impact of wind on a tall building and mitigate the response of
the structure of tall building, there are two main concepts:
– Structural; Increasing the building structural stiffness
– Architectural; Aerodynamic (Geometric modifications) of the building.
• Modifications on cross-sectional shapes, such as slotted, chamfered,
rounded corners, and notching on a rectangular building, can have
significant effects on both along wind and across wind responses of the
building

41. Examples of Aerodynamic Modifications
Slotted & ChamferedTwisting Roundness & RecessionPorosity / Openings
Tapering Setback

42. TALL BUILDING STRUCTURAL SYSTEMS
• INTERIOR STRUCTURES
– A system is categorized as an interior structure when the major part of the
lateral load resisting system is located within the interior of the building.
– By clustering steel columns and beams in the core, a stiff backbone that can
resist tremendous wind forces is created. The inner core is used as an elevator
shaft , and the design allows lots of open space on each floor
• EXTERIOR STRUCTURES
– If the major part of the lateral load-resisting system is located at the building
perimeter, a system is categorized as an exterior structure.
– In newer skyscrapers, the columns and beams are moved from the core to the
perimeter, creating a hollow, rigid tube as strong as the core design, but
weighing much.
• NOTE: any interior structure is likely to have some minor components of the
lateral load-resisting system at the building perimeter, and any exterior
structure may have some minor components within the interior of the
building.

43. Interior & Exterior Structures of Tall
Buildings

44. Interior Framed Structural Systems
1) RIGID FRAME
• A rigid frame in structural engineering is the load-resisting skeleton constructed with
straight or curved members interconnected by moment resisting connections which
resist movements induced at the joints of members.
• Its members can take bending moment, shear, and axial loads.
• Cab be built as external or at the core of the building.
• Can build up to 20 to 25 floors
2) SHEAR WALL STRUCTURE
• Concrete or masonry continuous vertical walls may serve both architecturally partitions
and structurally to carry gravity and lateral loading.
• Very high in plane stiffness and strength make them ideally suited for bracing tall
building
• Usually built as the core of the building
• Can build up to 35 Floors.
3) OUTRIGGER STRUCTURES
• The core may be centrally located with outriggers extending on both sides or in some cases it
may be located on one side of the building with outriggers extending to the building columns
on the other side.
• The Outriggers are generally belt trusses (1 or 2 story deep) to distribute tensile and
compressive forces to a large number of exterior frame columns.
• Can build up to 150 floors

45. Shangai World Financial Center - Outrigger Structure
The Outriggers are effectively act as stiff
headers inducing a tension-compression
couple in the outer columns.

46. Interior Framed Structural Systems

47. Exterior Framed Structural Systems

48. EXTERIOR STRUCTURES – Tube System
• The tube system concept is based on the idea that a building can be
designed to resist lateral loads by designing it as a
hollow cantilever perpendicular to the ground.
• In the simplest form, the perimeter of the exterior consists of closely
spaced columns that are tied together with deep spandrel beams through
moment connections.
• This assembly of columns and beams forms a rigid frame that amounts to
a dense and strong structural wall along the exterior of the building.
• The variations of tubular systems are;
– Bundled Tube system
– Tube in tube system
– Diagrids
– Braced Tubes (Space Truss / Exo-Skeleton)
– Super Frame

49. Different Tubular Systems

50. Diagrid Systems
• With their structural efficiency as
a varied version of the tubular
systems, diagrid structures have
been emerging as a new aesthetic
trend for tall buildings.
• Most of the structural systems
deployed for early tall buildings
were steel frames with diagonal
bracings of various configurations
such as X, K, and chevron.
• However, while the structural
importance of diagonals was well
recognized in resisting lateral
forces, the aesthetic potential of
them was not appreciated.
Hearst Tower ,
New York

51. Space Truss
• Space truss structures are
modified braced tubes with
diagonals connecting the
exterior to interior.
• In a typical braced tube
structure, all the diagonals,
which connect the chord
members – vertical corner
columns in general, are
located on the plane parallel
to the facades.
• However, in space trusses,
some diagonals penetrate the
interior of the building
Bank of China, Hong Kong

52. Exo-Skeleton Structure
• In exoskeleton structures,
lateral load-resisting systems
are placed outside the
building lines away from
their facades.
• Due to the system’s
compositional
characteristics, it acts as a
primary building identifier –
one of the major roles of
building facades in general
cases.
Hotel de las Atres

53. Super Frame Structures
• Super frame structures can create
ultra high-rise buildings up to 160
floors.
• Super frames or Mega frames
assume the form of a portal which is
provided on the exterior of a
building.
• The frames resist all wind forces as
an exterior tubular structure. The
portal frame of the Super frame is
composed of vertical legs in each
corner of the building which are
linked by horizontal elements at
about every 12 to 14 floors.
• Since the vertical elements are
concentrated in the corner areas of
the building, maximum efficiency is
obtained for resisting wind forces.

54. Example Petronas Tower
• Concrete was used for the
construction of the 452 m
tower.
• The tower has 'tube in
tube' structural system.
• The structural members
are made with high
strength concrete which
was cast in site.
• The perimeter columns are
held together with the
help of ring beams.
• The internal core structure
is made of concrete shear
walls.

55. Example BURJ KHALIFA
• The tower rises to an
unprecedented height of
800 meters and that
consists of more than
160 floors.
• The structural system is
called 'butressed core'.
• The lateral loads and
gravity loads are shared
equally between the
interior core and
perimeter structural
systems linked by the
“link beam”.
The blue members are the load
carrying concrete wall system

57. FUTURE TALL BUILDINGS
• We are entering the era of the “megatall.” These buildings are over 600 meters in
height, or double the height of a supertall.
• To build higher the base of the building will have to be made wider. The bundled
tube system was a great innovation and was able to span great heights during it's
time , to attain the height of burj khalifa the bundled tube system will need a
bigger base when compared with the buttressed core system.

58. Loay Ghazaleh, MBA, BSc. Civil Eng.
Advisor, Undersecretary Office
Ministry of Works, Bahrain
loay.ghz@gmail.com , +973-36711547