Dissertation report on Intelligent Skins

INTELLIGENT SKINS

Dissertation submitted by

GAUTAMI PAUL 123701104 B.Architecture VII Semester ‘D’

Faculty of Architecture Manipal University Manipal

November 2015 Page | 1

Faculty of Architecture Manipal University Manipal

CERTIFICATE

We certify that the Dissertation entitled “ INTELLIGENT SKINS �, that is being submitted by Gautami paul & Roll no. 123701104 , in the VII semester of B.Architecture undergraduate programme, Faculty of Architecture, Manipal University, Manipal is a record of bonafide work, to the best of our knowledge.

-----------------------------Faculty in charge

----------------------------Director

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Faculty of Architecture Manipal University Manipal

AKNOWLEDGEMENT I'm delighted to have an opportunity like this to thank all the people involved in making this dissertation a success . I would like to express my deepest gratitude to my guide Ar. Pradeep Kini ,for his guidance.

My sincere thanks to the institution , Faculty of Architecture for providing me necessary facilities . I also take this opportunity to thank my parents and my batch mates for their moral support and for giving their valuable inputs .

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ABSTRACT The major global environmental problems faced by us in the beginning of twenty-first century is the risk posed by green house effect resulting in impact of climate change .It has been a concern for damaging the fragile ecosystem by increased development and resource extraction to meet the present needs.

Buildings are the major burden on environment , they have a key role in significant environmental degradation .

But with the advancement in technology and awareness about the degrading environment has lead the designers to incorporate energy efficient strategies into the buildings and make them more environment friendly .

As a principle element of architecture ,technology advancement has made the wall as a dynamic part of the building .The traditional objectives of wall has been redefined :static became fluid ,opaque became transparent , barrier became filter and boundary borderless. Combination of smart materials , intelligent systems , engineering has significantly enhanced the architectural space .

The research focuses on the emergence of new technologies which suggested that 'building skins' are more intelligent and interactive . Also where intelligent facade is the key component in the process of designing to provide environmental control and comfort . The research gives an overview of what are intelligent skin and how have they increased the performance of the building specially in commercial sector which is studied through various case studies , And also to analyze their feasibility in Indian context .

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TABLE OF CONTENTS 1

2

INTRODUCTION .............................................................................10 1.1

AIM ........................................................................................................................................... 10

1.2

RESEARCH QUESTION ......................................................................................................... 10

1.3

OBJECTIVE ............................................................................................................................. 10

1.4

SCOPE OF THE PROJECT ..................................................................................................... 10

1.5

METHODOLOGY ................................................................................................................... 10

1.6

LIMITATIONS OF THE PROJECT ........................................................................................ 11

1.7

OUTCOME OF THE STUDY.................................................................................................. 11

LITERATURE REVIEW..................................................................12 2.1

INTRODUCTION .................................................................................................................... 12

2.2

DEFINITION ............................................................................................................................ 12

2.3

WHY DO WE NEED INTELLIGENT SKIN? ........................................................................ 13

2.4

OBJECTIVES OF INTELLIGENT SKIN ................................................................................ 13

2.5

METAPHORS AND MODELS ............................................................................................... 14

2.5.1

ARTIFICIAL INTELLIGENCE ................................................................. 14

2.5.2

NATURAL INTELLIGENCE .................................................................... 15

2.6

MECHANISM .......................................................................................................................... 15

2.6.1

COLLECTING DATA CONCEPT ............................................................ 15

2.6.2

BUILDING MANAGEMENT SYSTEMS CONCEPT ............................. 16

2.6.3

AUTOMATED BUILDING CONTROL SYSTEMS ................................ 16

2.6.4

AUTONOMIC RESPOND CONCEPT ...................................................... 16

2.6.5

MEASURING AND COLLECTING DATA (INPUTS) ........................... 16

2.6.6

INFORMATION PROCESSING APPLICATION ................................... 17

2.6.7

OUTPUT (RESPONSE) ............................................................................. 17

2.6.8

TIME CONSIDERATION ......................................................................... 18

2.7

FEATURES OF INTELLIGENT SKIN ................................................................................... 18

2.7.1

BUILDING MANAGEMENT SYSTEM................................................... 18

2.7.2

LEARNING ABILITY ............................................................................... 18

2.7.3

ENVIRONMENTAL DATA ...................................................................... 18

2.7.4

RESPONSIVE ARTIFICIAL LIGHTING ................................................. 19 Page | 5

2.7.5

DAYLIGHTING CONTROLLERS ........................................................... 19

2.7.6

SUN CONTROLLERS ............................................................................... 19

2.7.7

OCCUPANT CONTROL ........................................................................... 19

2.7.8

ELECTRICITY GENERATORS ............................................................... 19

2.7.9

VENTILATION CONTROLLERS ............................................................ 20

2.7.10

HEATING AND TEMPERATURE CONTROLLERS ............................. 20

2.7.11

COOLING DEVICE ................................................................................... 20

2.8

SINGLE SKIN FACADES ....................................................................................................... 20

2.8.1

SUNSCREEN SYSTEMS .......................................................................... 20

2.8.2

LIGHTING SYSTEMS .............................................................................. 24

2.8.3

VENTILATION SYSTEM ......................................................................... 26

2.9

DOUBLE LAYERED SKIN .................................................................................................... 29

2.9.1

TYPES OF CONSTRUCTION .................................................................. 30

2.9.2

PARTITIONING OF THE FACADE ........................................................ 31

2.9.3 THE COMPONENTS OF DOUBLE SKIN FACADES AND PASSIVE DESIGN .................................................................................................................... 35

3

2.9.4

CONSTITUENTS OF DOUBLE SKIN FACADE .................................... 37

2.9.5

CONCLUSION ........................................................................................... 37

CASE STUDIES ...............................................................................38 3.1

COMMERZBANK HEADQUARTERS .................................................................................. 38

3.1.1

BRIEF ......................................................................................................... 38

3.1.2

INTELLIGENT FEATURES ..................................................................... 38

3.1.3

SITE AND CLIMATE ................................................................................ 39

3.1.4

SUNPATH .................................................................................................. 39

3.1.5

.THE INTELLIGENT FACTOR ................................................................ 40

3.1.6

ACCOMODATION .................................................................................... 40

3.1.7

ENERGY STRATERGY ............................................................................ 40

3.1.8

CONSTRUCTION ...................................................................................... 41

3.1.9

GLAZING ................................................................................................... 41

3.1.10

HEATING ................................................................................................... 42

3.1.11

COOLING................................................................................................... 42

3.1.12

VENTILATION .......................................................................................... 42

3.1.13

DAYLIGHTING ......................................................................................... 43 Page | 6

3.1.14

ARTIFICIAL LIGHTING .......................................................................... 43

3.1.15

SOLAR CONTROL.................................................................................... 43

3.1.16

CONTROLS ............................................................................................... 43

3.1.17

USER CONTROL ...................................................................................... 44

3.1.18

OPERATING MODE ................................................................................. 44

3.1.19

ENERGY CONSUMPTION ...................................................................... 44

3.2

4

DEBIS BUILDING ................................................................................................................... 45

3.2.1

BRIEF ......................................................................................................... 45

3.2.2

INTELLIGENT FEATURES ..................................................................... 45

3.2.3

SITE AND CLIMATE ................................................................................ 46

3.2.4

SUNPATH .................................................................................................. 46

3.2.5

THE INTELLIGENT FACTOR ................................................................. 46

3.2.6

ACCOMODATION .................................................................................... 47

3.2.7

ENERGY STRATEGY .............................................................................. 47

3.2.8

CONSTRUCTION ...................................................................................... 47

3.2.9

GLAZING ................................................................................................... 48

3.2.10

HEATING ................................................................................................... 48

3.2.11

COOLING................................................................................................... 48

3.2.12

VENTILATION .......................................................................................... 48

3.2.13

DAYLIGHTING ......................................................................................... 49

3.2.14

CONTROLS ............................................................................................... 49

3.2.15

USER CONTROL ...................................................................................... 49

3.2.16

ENERGY CONSUMPTION ...................................................................... 49

DATA ANALYSIS ...........................................................................50 4.1

INTRODUCTION .................................................................................................................... 50

4.2

DESIGN STRATEGIES AND ANALYSIS ............................................................................. 51

4.2.1

SUN SHADING SYSTEM ......................................................................... 51

4.2.2

LIGHTING SYSTEM ................................................................................. 52

4.2.3

VENTILATION SYSTEM ......................................................................... 53

4.3 ENERGY PERFORMANCE AND COMPARATIVE ANALYSIS OF TRADITIONAL AND INTELLIGENT FACADE ............................................................................. 54

4.3.1

CASE I ........................................................................................................ 54

4.3.2

CASE 2 ....................................................................................................... 54 Page | 7

4.3.3 4.4

CASE 3 ....................................................................................................... 55

CONCLUSION ......................................................................................................................... 58

TABLE OF FIGURES Figure 2.1 1 Biological neuron .............................................................................. 14 Figure 2.1 2 a) Our versatile "mantle" provides texture and thickness ................. 15 (Figure 2.1 3 External horizontal louvres of the Microelectic Centerhttp://gaia.lbl.gov/hpbf/techno_d.html)) ...................................................... 21 Figure 2.1 4Vertical fins responding to the climate and quality of light and shade(http://gaia.lbl.gov/hpbf/techno_d.html)) ...................................................... 21 Figure 2.1 5 Awning as an external operable shading .......................................... 22 Figure 2.1 6 Shutters as external operable shading ................................................ 22 (Figure 2.1 7 The Embassies of the Nordic Countries in Berlin, Tiergarten.(Bell, V. & Rand, P., 2006)) ................................................................. 23 (Figure 2.1 8 Administration Building in Wiesbaden designed by Herzog and partners(Schittich, C., 2001))........................................................................... 23 Figure 2.1 9 In summer, when the sun is high in the sky, lightshelves block direct sun at both the upper and lower windows. In winter, low sun can penetrate to the back to the space through the clerestory, pre-heating occupied space in the morning, and providing li(http://gaia.lbl.gov/hpbf/techno_d.html)) ............................................................. 24 (Figure 2.1 10Lasercut Acrylic Panel,Exterior reflector(http://www.schorsch.com/kbase/prod/redir/)) ......................................... 25 (Figure 2.1 11Anidolic Mirrors ,Prism Panel(http://www.schorsch.com/kbase/pr )) .......................................................... 25 (Figure 2.1 12 Close up for the operable windows of the SUVA building (Wigginton, M. & Harris, J., 2002)) ....................................................................... 26 Page | 8

Figure 2.1 13 Single Sided Double Opening, Single Sided Ventilation((http://www.dyerenvironmental.co.uk/natural_ vent_systems.html) ) ............................................................................................... 27 Figure 2.1 14 Cross Ventilation Figure 2.1 15 Stack Ventilation ....... 27 Figure 2.1 16 Administration Building in Wiesbaden designed by Fielden Clegg((Poirazis, H., 2004))..................................................................................... 28 Figure 2.1 17 Passive cooling ................................................................................. 28 Figure 2.1 18 Headquarters of Commerzbank designed by Foster and Partners((Poirazis, H., 2004) ) ................................................................................ 29 Figure 2.1 19 The School of Engineering and Manufacture( (Wigginton, M. & Harris, J., 2002)) ................................................................................................. 29 Figure 2.1 20Section through typical box window facade with separate ventilation for each bay((Poirazis, H., 2004) ) ....................................................... 31 Figure 2.1 21 Elevation of box-window facade.((Poirazis, H., 2004) ) ................. 32 Figure 2.1 22 Plan of shaft-box faรงade ,Section through a shaft-box facad,Elevation of a shaft-box facade. ((Poirazis, H., 2004) ) ............................... 32 Figure 2.1 23 Section through a corridor facade. Separate circulation for each story. , Elevation of corridor facade , ((Poirazis, H., 2004)) ......................... 33 Figure 2.1 24 Dusseldorf city gate, Dusseldorfer, Germany, by Petzinka. ((Poirazis, H., 2004)) .............................................................................................. 34 Figure 2.1 25 Section through a multi-story facade ,Elevation of part of a multistory facade . ((Poirazis, H., 2004) ) .............................................................. 34 Figure 2.1 26 Hybrid mechanical and natural ventilation with double skin faรงade((http://www.wbdg.org/design/env_introduction.php)) ............................... 35 Figure 2.1 27 Schematic diagram of heat extraction double-skin faรงade, (http://gaia.lbl.gov/hpbf/techno_d.html)) ............................................................... 36 Figure 2.1 28 view and the plan, ( (Wigginton, M. & Harris, J., 2002)) ............... 39 Figure 2.1 29 ventilation with open and closed windows( (Wigginton, M. & Harris, J., 2002)) ..................................................................................................... 43 Figure 2.1 30 open and closed louvers controlled by operating system( (Wigginton, M. & Harris, J., 2002)) ....................................................................... 44 (Figure 2.1 31Double skin skin with two cladding (Wigginton, M. & Harris, J., 2002)) ................................................................................................................. 47 Figure 2.1 32Openable windows and their mechanism( (Wigginton, M. & Harris, J., 2002)) ..................................................................................................... 48

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1 INTRODUCTION

1.1 AIM To research on the evolving technology of intelligent skins . Their relevance in Indian context in terms of climate ,energy consumption and practical application in commercial sector .

1.2 RESEARCH QUESTION Effectiveness and application of intelligent skins for commercial buildings in Indian context .

1.3 OBJECTIVE  

The prime objective is to control internal environments through a responsive building fabric .

Explores a new approach to Intelligent Buildings, focusing on the fabric of the building responding to external changes and internal demands.

1.4 SCOPE OF THE PROJECT Architectural skins helps in new performance in the energy sector, control of indoor environments, responsiveness to user activities. Looking to the future, Intelligent Skins sets out the principles for the design of the intelligent building envelope. It highlights an exciting new approach to the area, where the fabric of the building responds to external changes and internal demands. Since a lot of smart cities are evolving and a rapid growth of commercial sector , there is need to explore such new technologies in Indian context .

1.5 METHODOLOGY The research has been conducted through various research papers , journals and articles on intelligent skins .Few references has been taken by the book 'Intelligent skins ' by Michael Wigginston and Jude Harris .To study about the feasibility of Page | 10

intelligent skins in commercial sector many secondary case studies have been referred , and has also been discussed in the paper .

1.6 LIMITATIONS OF THE PROJECT It is an evolving technology , and not much explored in India . There are a lot of limitations in response to climate according to Indian context . Also to implement in commercial sector might increase the initial cost of the project , though in future it will make the building cost effective . Also there are no proper case studies available in India.

1.7 OUTCOME OF THE STUDY • • •

Enhanced knowledge of the intelligent skins , namely single skin facades and double skin facades .

Its feasibility in commercial sector , also how it influences the energy consumption.

Relevance of Intelligent skins in Indian context in terms of climate and energy consumption

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2 LITERATURE REVIEW

2.1 INTRODUCTION The external walls are referred as 'facades' which has a fundamental function of protection from weather and also interior comfort . Another aspect is its aesthetic feature, need for ornamentation to give building its identity . The building facade mark the transition between outside and inside .

Since facades acts as a physical barrier it should understand the need and comfort of its occupants , also to view , lighting, ventilation, solar gains are the tasks which it needs to address. This inability of self-detection and self adjustment lead to the development of building envelopes that would perform under all types of weather conditions .

What was envelop now became skin . Interactive membranes replaced facades .

A covering high interactive surface able to exchange information with inside and outside of building .Building membrane acts as a climatic mediator between climate and occupant .

The term “intelligent” and “adaptive” building skins is referred in façade design to describe the building envelopes that enhance the relationship between the built and the natural environment by using design principles inspired by nature. The development of the facade technology in the 20th century involved the creation of multilayered, lightweight and transparent skins . These characteristics are embodied in the curtain wall facade type, which led to design variations such as the “alternating” facade which combines single-skin and multi-skin facades, and the “integrated” facade equipped with facade systems as decentralized ventilation units. This chapter reviews on the concept of intelligence and how it is applied to the building skin .

2.2 DEFINITION The 'intelligent skin' is an essential part of the intelligent building, that element which performs the function of enveloping the inner space.

Metaphorically ,'intelligent skin', emphasize its similarity with the human epidermis. It is a composition of construction elements confined to the outer, weather-protecting zone of a building, which respond predictably to Page | 12

environmental variations, to maintain a comfortable environment . Energy flows through the building fabric are autonomically controlled for maximum gain, and minimal reliance on imported energy. The skin forms part of a building system, and is connected to other parts of the building outside of the enveloping zone, such as sensors and actuators linked together by command wires, all controlled by a central building management system.

2.3 WHY DO WE NEED INTELLIGENT SKIN? –

–

–

– –

The climatic conditions in any geographical location vary between morning and afternoon , between day and night ,between seasons . It also differs for different locations around the globe , which becomes pronounced as a result of global warming . Primary function of a building skin is to protect occupants , to act as a moderator between internal and external conditions .Building skins must 'damp ' the extremes of climate to make the interiors comfortable .

The need for intelligent skin to improve the performance of a building fabric by it capable and reduce the need for imported energy for heating , cooling , lighting and ventilation .

It provides a productive and cost effective built environment through optimization of its four basic components (structures , systems ,services and management ) and the interrelationship between them .

It Maximizes the efficiency of its occupants .

Allows effective resource management with minimum life costs .

2.4 OBJECTIVES OF INTELLIGENT SKIN Basic objectives of intelligent skin are - Increased environmental comfort, Energy optimization, Security, and automated building maintenance procedures.  – – –  – – – – 

Environmental Benefits It Improves and shield ecosystems and biodiversity enhance air and water quality protect natural resources Economic Benefits Reduce operating costs it improves asset value and profits It enhances employee productivity and satisfaction Optimize life-cycle economic performance Social Benefits Page | 13

– – –

it improves air, thermal and acoustic environments enhances occupant comfort and health Contribute to overall quality of life

2.5 METAPHORS AND MODELS Intelligent skin programme is based on an example ,which is related to the environmental performance of the whole building , and also bears a closer kinship with the biological phenomenon of intelligence and response. While using the term 'intelligence 'for inanimate mechanisms, it is important to understand its metaphorical use .

2.5.1 ARTIFICIAL INTELLIGENCE The working of 'intelligent' systems for inanimate mechanisms has lead to the development of 'artificial intelligence '. With this concept objects are provided with the capacity to perform similar functions to that of human behavior , by emulating the thought process of living being . Artificial intelligence has been used to mimic the human tendency to process information through learning , understanding ,making and acting on decisions .

2.5.1.1

ARTIFICIAL NEURAL NETWORKS

The system of intelligent skin is brought closer to reality with artificial neural networks (ANN). The neural networks creates a biological network by mimicking the function of brain cells .This network enables the system to learn , generalize and also to filter the irrelevant data , ability to cope with minor errors , helps in adapting to changing circumstances.

Figure 2.1 1 Biological neuron (http://www.neuralpower.com/technology.htm n.d.)

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2.5.2 NATURAL INTELLIGENCE This intelligence relates to the faculty found in living beings , it is the naturally responsive system , such as thermo regulatory powers of the human skin , season change of coats in mammals , or opening and closing of flowers to sun light etc. Similar comparison of intelligent skins is to the human skin .The sensors installed in the building sense the fire or intruders just as our senses detect danger .The circulation or ventilation bears a close relation to our breathing system .

Figure 2.1 2 a) Our versatile "mantle" provides texture and thickness throughout our body in response to different tasks ,(Betancourt 2002)

2.6 MECHANISM HUMAN SENSE

COLLECTING DATA

BRAIN

BUILDING MANAGEMENT SYSTEM

SOMATIC AND AUTONOMIC RESPONSE

RESPONSIVE COMPONENTS

2.6.1 COLLECTING DATA CONCEPT The skin is metaphorically related to the cladding of the building . Information for responsiveness and control is gather through various sensors, fabric configurations ,and then the behavior is modified to get desired actions.

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2.6.2 BUILDING MANAGEMENT SYSTEMS CONCEPT Essential element of intelligent skin is the brain in the form of building management system .It is the central processing unit which receives information through various sensors and then determines the response to various elements .BMS is able to direct any weather change and controls the operation of both passive and active environmental systems to ensure efficient energy use .One of its key functions is to regulate temperature by activating all controllable elements in the building .

2.6.3 AUTOMATED BUILDING CONTROL SYSTEMS This system increases the energy consumption , allows efficient use of power and also flexibility during peak hours of usage .System also regulates the temperature .The system adjusts the interior temperature according to the time of the day and season .Sensors respond to exterior temperature change and necessitate the changes within the building .Another component which carries the action in response is the 'actuator '.

2.6.4 AUTONOMIC RESPOND CONCEPT It is an involuntary action when fabric of the building changes itself dynamically in response to climate change to reduce energy requirements . The idea of manual change advanced into automatic , mechanical and motorized change or adjustments .

2.6.5 MEASURING AND COLLECTING DATA (INPUTS) System obtains information about wind speed , direction , humidity , solar insulation , inside air , room temperature , daylight level and illumination in four different ways -

2.6.5.1

SENSORS

Sensors work as a nerve system which can detect or feel the reaction to interior and exterior conditions The skin has sensors on its surface with act as mediator between body and environment and also body and user. Sensors are the part of an automated system which converts physical parameters into electrical signals. Solar radiation detection , security , noise pollution and facade optics are some exterior sensor controlled systems.

Whereas air control , lighting system , air condition are interior sensor controlling system .

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2.6.5.2

INTERNAL BACKUP AND RESTORING

Internal backup system work as a memory in the system .The intelligent skin system has ability to back up and restore the cases and information , System resets the previous settings .

2.6.5.3

MANUAL PROGRAMMING

System has ability for manual programming by users according to their need , any user can reprogram the system in response to changed circumstances .

2.6.6 INFORMATION PROCESSING APPLICATION Input data is processed by building control system . It controls all systems as one unit and manages each unit individually .

2.6.6.1 2.6.6.1.1

BMS HARDWARE CENTRALIZED SYSTEM

The central station accommodates all computer power . It provides signal conditioning and data communication .

2.6.6.1.2

DISTRIBUTED SYSTEMS

Outstations are intelligent and provide resident functional software for managing the tasks and includes Direct Digital Control .

2.6.6.1.3

AUTONOMOUS SYSTEMS

These units can work indefinitely without reference to central unit , also the outstation stand -alone .

2.6.6.2

BMS SOFTWARE

These does not require out stations and are functional through software's , which are also economical .

2.6.7 OUTPUT (RESPONSE) Decisions made by the system are in two different classes , namely internal and external response .Internal response relates to calculation and internal programming with system , reaction to wind load by internally changing its tension .Whereas external response is the Page | 17

result of processed internal response .It is either static or kinetic .Static is temperature , visual ,audio or light change .Kinetic is the form of movement (opening , closing ).

2.6.8 TIME CONSIDERATION All decisions and responses should happen within the required time .For example , fire alarm should start on time , maintenance system should respond on time , movement of building to avoid solar radiation on time .

2.7 FEATURES OF INTELLIGENT SKIN

2.7.1 BUILDING MANAGEMENT SYSTEM The BMS is the central processing unit , it receives information from the various sensors outstations, and decides the appropriate control response to the active elements. An 'Intelligent 'BMS is able to examine weather changes and controls the operation of both passive and active environmental systems to ensure the most efficient use of energy . It major function is to regulate temperature through all the controllable elements by activating them .

2.7.2 LEARNING ABILITY The Intelligent skin has an ability to learn. Neural networks and knowledge based software algorithms ,incorporating fuzzy logic ,providing the ability to learn their energy status and thermal characteristics , and also relate previous or recent weather data , and current climatic conditions, to previous operating strategies .

2.7.3 ENVIRONMENTAL DATA Intelligent skin system is able to gather detailed real-time information relating to environment conditions outside and inside the building .These data are an essential determinants in the response of intelligent technologies . Measurement of wind speed and direction ,outside temperature ,facade and cavity temperatures , outside humidity ,solar insulation ,inside air and room temperatures , daylight levels and humidity are made .

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2.7.4 RESPONSIVE ARTIFICIAL LIGHTING The artificial lighting system is an effective day lighting strategy , with the ability to deactivate or dim itself in response to the amount of natural lighting levels .Intelligent systems are activated by occupancy sensors and regulated in response to sensed internal light levels .

2.7.5 DAYLIGHTING CONTROLLERS Energy consumption associated artificial light ,the maximization of daylight is recognized as one of the keys goals in low -energy design .A range of active systems that respond to solar angles ,providing optimum positions for motorized light -guiding ,lightreflecting and light-shading devices. Light transmission can often be varied and adjusted to suit internal demand .Systems operate in response to information provided by sensors that measure outside light and solar intensity , inside light levels and temperature .

2.7.6 SUN CONTROLLERS Computer algorithms make it easy to determine real time solar angles by the input of time ,latitude and longitude data . Such calculations are used to track the sun on its variable path throughout the day and year .Computer controlled blinds , louvres and other protective shades all of which are energy absorbers ,provide the manifestations of solar control . Many projects include venetian blinds that can be lowered , raised and tilted according to the detected presence of the sun . These are often incorporated into dual skin cavities for protection , to keep the heat out of the occupied zone , and to participate in the action of a solar flue .

2.7.7 OCCUPANT CONTROL Building occupants should have maximum personal control over their immediate environment ,and this can be achieved by intelligent technologies . On screen control panels and hand held remote control unit are provided but in situations where unchecked by occupants , the BMS reminds the user of the error or disallows continued functioning.

2.7.8 ELECTRICITY GENERATORS It is feasible for buildings to strive for electrical autonomy through self generation . This extends the concept of buildings with living capabilities Electricity can be generated by photovoltaic ,wind turbines and combined heat and power systems .

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2.7.9 VENTILATION CONTROLLERS Ventilation can be automatically regulated for increased effectiveness and greater occupant control by operable elements of the building fabric, such a s retractable roofs , motorized windows and pneumatic dampers . These moving elements can also be automatically closed in unfavorable conditions , such as inclement actions of wind and rain . Intelligent skin also help to overcome the problem of air and noise pollution .

2.7.10 HEATING AND TEMPERATURE CONTROLLERS Intelligent technologies are employed to minimize the energy burden resulting from the highly serviced elements of heating, ventilation and cooling . Demands for space and water heating through the use of passive solar strategies , provided with more precise motorized control . Control systems ensure the optimized operation of low temperature hot water circuits . The sun is also utilized for water heating .

2.7.11 COOLING DEVICE Intelligent skin utilizes a strategy for computer controlled night time ventilation for precooling of the thermal mass .

2.8 SINGLE SKIN FACADES Building skins are one of the major influencing factors on building technical system Various technologies are used to produce high performance building skins in order to reduce energy consumption ,the fundamentals are based on the concepts of solar heat gain , day lighting , ventilation , space conditioning .

2.8.1 SUNSCREEN SYSTEMS The shading strategies is one of the essential methods to combat undesired solar heat gains, which increases internal temperature . Shading of the facade enhances the human comfort by reducing the warming of interior spaces .

There are two type of shading systems : external and internal shading .Internal shading includes angular selective facades which provides solar control on the basis of angle of Page | 20

sun incident to the facade .The main objective is to reflect or block the direct solar radiation .

Conventional louvers or venetian blinds enables the occupants or automated control system to adjust the angle according to the solar position ,day lighting level and glare .It also includes between -pane acrylic prismatic panels which can either be fixed or used as exterior louvers to block the sun light and allow diffused daylight .Exterior solar control can be achieved by overhangs ,fin or window screen . Exterior shading can also be categorized as fixed or operable .The objective is to intercept the solar radiation before it enters the building .

2.8.1.1

FIXED EXTERNAL SHADING

This type of shading does not need any maintenance by users or any adjustments , it is characterized by the part of the building mass .It is designed using sun path stereo path graphic diagram which detects the different dates and times for blocking and admitting the sun rays within the building .

2.8.1.1.1

HORIZONTAL SHADING

These kind of shading are used in southern facades , where the sun path is at a high level , and casts their shadow most of the time of exposure to direct sun .

(Figure 2.1 3External horizontal louvres of the microelectrichttp://gaia.lbl.gov/hpbf/techno_d.html) n.d.)

2.8.1.1.2

VERTICAL SHADING

Generally used for eastern and western facades , since the sun path is low to make vertical shading more effective than horizontal shading where they have inclination with respect to building facade in order to block sun and admit illumination .

Figure 2.1 4Vertical fins responding to the climate and quality of light and shade(http://gaia.lbl.gov/hpbf/techno_d.html) n.d.)

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2.8.1.2

OPERABLE EXTERNAL SHADING

These systems are used to control thermal gain , redirect sunlight and reduce sunlight .Operable systems are more flexible since they can be retractable according to outdoor conditions .They are interactive with users and adjustable according to occupants needs.

2.8.1.2.1

AWNINGS

Awnings completely block the direct solar radiation .

They are made up of fabric or metal and are joint above the window and extend down and out .Disadvantage of using awnings is that it blocks the view from inside .

Figure 2.1 5 Awning as an external operable shading

2.8.1.2.2

SHUTTERS

These are movable wooden or metal coverings , when closed they keep the sunlight out .Shutters can be solid or slatted with fixed or adjustable slats .They also provide security and privacy .It is widely used due to its economical cost and effectiveness .

Figure 2.1 6 Shutters as external operable shading

2.8.1.2.3

ROLLER SHUTTERS

These shutters are a series of horizontal slats which runs down along the track .They provide good security , many roller shutters can also be controlled from interiors. Its disadvantage is that they block view and light when fully opened

2.8.1.2.4

LOUVERS

They are adjustable slats that control the level of sunlight entering the building .The slats are either vertical or horizontal .Louvers remains fixed to the exterior of the window Page | 22

frame . The louver is approximately 1.97 ft. (60 cm) wide and length may varies from 2.95-5.91 ft. (90-180cm) mounted at sloping 45 or 135 degree positions.

(Figure 2.1 7 The Embassies of the Nordic Countries in Berlin, Tiergarten(Bell, V. & Rand, P., 2006) n.d.)

2.8.1.3

INTELLIGENT FEATURE :SUN CONTROLLERS

The administration building in Wiesbaden is a low energy office building .Southern elevation has curved sunscreen and light deflecting elements in aluminum .to maintain monitor lighting in interior the insolated facade are automatically adjusted . Timber ventilation flaps are attached which can be manually operated .Excellent energy consumption is achieved along with good internal climate through heating and cooling .This ensure good ventilation even with closed windows .

((Figure 2.1 8Administration Building in Wiesbaden designed by Herzog and partners.Schittich, C., 2001) n.d.)

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2.8.2 LIGHTING SYSTEMS The use of daylight is important for comfort and contentment of the users and also with regard to reduce demand for artificial light. Day lighting is applied according to room depths and precludes the direct use of daylight , where quality of lighting is main priority.

2.8.2.1

LIGHT REIRECTING SYSTEM

It works on the principle of reflection, diffraction and reflection to enhance the incoming daylight within the building .Improved distribution enhances the lighting quality and visual comfort .

2.8.2.1.1

SUNLIGHT REDIRECTION

Light shelves are horizontal projection that uses high reflectance or semi specular upper surface to reflect incident sunlight .Prismatic aluminum films are used on the upper surface to enhance the reflective optical efficiency , and moveable systems are used to alter the depth of redirection .Between -pane light shelves can be fabricated in volume and protect from dirt and dust between two panes of glass.

Figure 2.1 9 In summer, when the sun is high in the sky, lightshelves block direct sun at both the upper and lower windows. In winter, low sun can penetrate to the back to the space through the clerestory, preheating occupied space in the morning, and providing lig(http://gaia.lbl.gov/hpbf/techno_d.html) n.d.)

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Exterior reflectors transport more light in the building through vertical facade .

(Figure 2.1 10 Exterior reflectors, Lasercut Acrylic Panels(http://www.schorsch.com/kbase/prod/redir/) n.d.)

Laser cut panel uses linear horizontal cuts in an acrylic panel to refract light at the juncture of the linear grooves .Efficiency is dependent on the spacing of grooves, frequency and thickness off the panels .

2.8.2.1.2

SKY-LIGHT REDIRECTION

This light-redirecting system is designed for climate with cloudy conditions to get diffused skylight . The main objective is to increase the interior daylight level .

Anidolic system works on the principle of non-imaging optics to collect omnidirectional diffused light and direct flux with mirrored curved geometries. This focused daylight can be then redirected along the ceiling plane and distributed through light ducts .The collector optics are created using plastic injection moulds which then be coated with a high grade aluminum coating

Figure 2.1 11Anidolic Mirrors,Prism Panels((http://www.schorsch.com/kbase/pr ) n.d.)

The effectiveness of reflectors is enhanced through curved shape , which is derived through nonimaging optics .Prism panels are used for solar protection , to shield against narrow angle of incidence light.

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2.8.2.1.3

ANTI-GLARE SYSTEMS

The main objective of anti glare system is to prevent extreme contrast in lighting intensity .Systems used are curtains ,vertical blinds , screens, venetian blinds , horizontal blinds ,translucent glazing and electro chromic glazing .Using of perforated aluminum louvers and textile anti glare system is also a practical option . The positioning of this system determines the amount gain in the interior .

2.8.2.2

INTELLIGENT FEATURE: DAYLIGHT CONTROLLERS

Herzog and de meuron over claded the SUVA insurance company in order to enhance thermal and lighting performance. The sandstone remains intact behind glazed skin .The upper band comprises of insulated glass with prismatic plates in the air space. From inside its translucent , but refract the direct rays coming from the sun .The principal mode for internal glare control is by adjusting prismatic panels ,which obscure direct view and also refract the suns ray in the depth of the plan.

(Figure 2.1 12 The SUVA building after the modifications by Herzog & de Meuronwigginton 2002)

2.8.3 VENTILATION SYSTEM Natural ventilation is used for reducing energy consumption , as it is cost effective and also provides a healthy and comfortable and productive indoor climate .

2.8.3.1

VENTILATION CONCEPTS

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2.8.3.1.1

SINGLE SIDED VENTILATION

When windows are at only one side of the room .Cold air streams in , while the warm air streams out through the same window It is helpful for certain room height .

Figure 2.1 13 Single Sided Double Opening, Single Sided Ventilation((http://www.dyerenvironmental.co.uk/natu ral_vent_systems.html) n.d.)

2.8.3.1.2

SINGLE SIDED DOUBLE OPENING

A development of the single sided principle provides a double opening , which is more efficient.

2.8.3.1.3

CROSS VENTILATION

Pressure difference is used between the faces one facing towards the wind , and other away from the wind .Positive is created on windward side while vacuum effect on lee side , causes flow of wind from windward to lee side .Windows on windward side are opened less than on lee side .

Figure 2.1 14 Cross Ventilation

Figure 2.1 15 Stack Ventilation

((http://www.dyerenvironmental.co.uk/natu ral_vent_systems.html) n.d.)

2.8.3.1.4

STACK VENTILATION

Natural buoyancy of hot air is used for smoke ventilation ,which is allowed to vent through high level vent , replacing fresh air enters through the lower side via double facade .The Administration Building in Wiesbaden had highly glazed facade , with translucent motorized external glass louvers , operated by building management system Page | 27

.Which can also be overridden by the occupants .To diffuse direct sun light glass louvers can be rotated .Passive stack ventilation system draws the hot air through duct in the wave form structure ,low resistance propellers are attached at the top to provide minimum ventilation and to throw internal heat gains .

Figure 2.1 16 Administration Building in Wiesbaden designed by Fielden Clegg((Poirazis, H., 2004) 2004)

2.8.3.2

PASSIVE COOLING

Heat is gained by floor slabs during day time and by user occupancy , and at night when temperature drops building can be cooled through opening the vents this is called night cooling .

Figure 2.1 17 Passive cooling

Three storey building with continuous cavity on outer skin and operable windows .Louvers are provided at the upper and lower ends of the cavity . Two principles for natural ventilation is used :double skin facade and winter garden .

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Figure 2.1 18 Headquarters of Commerzbank designed by Foster and Partners((Poirazis, H., 2004) n.d.)

2.8.3.3

INTELLIGENT FEATURE:VENTILATION CONTROLLERS

The Queens Building in Leicester , England . The building is naturally ventilated, Chimneys are constructed to create stack effect which will ventilate the hot air ,stale air and bring in the cool and fresh air .

Figure 2.1 19 The School of Engineering and Manufacture(wigginton 2002)

2.9 DOUBLE LAYERED SKIN A new trend has been developed by the invasion of multiple skin facade .The spacing the two layers is used for ventilation and other purposes. Various features are integrated with facade to address the specific need : screens , blinds ,louvers operable windows for air to Page | 29

migrate from interiors to exteriors , insulating glass with coatings to reduce transmission loss .The double skin facade consists of two glass skins placed in a way to allow air flow through the cavity ventilation can be natural , mechanical or fan supported. The glass can be single or double glazed placed at a distance of 20cm to 2 meters. These facades also provide acoustic insulation .The construction of facade regulates cold ,heat ,light as well as noise to get optimum comfort and less consumption of energy .

2.9.1 TYPES OF CONSTRUCTION Double skin facades works on multilayer principle .It consists of an external facade , internal facade and an intermediate space .The outer covering protects against the weather and improves acoustic insulation . It also contains opening will enables the ventilation of the intermediate space .Flow of air is through intermediate space is activated by a solar induced thermal buoyancy .To achieve greater adaptability , openings on the outer facades can be closed . The external skin has glazing in toughened safety glass and laminated safety glass .An adjustable solar shading device is places in the intermediate space to protect from high cooling loads caused by insulation .

((Poirazis, H., 2004) 2004)

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2.9.2

PARTITIONING OF THE FACADE

((http://www2.ebd.lth.se/ebdhome/avd_ebd/main/personal/Project_home_page/main/Dou bleSkinFacades.htm ) n.d.)

2.9.2.1

BOX WINDOWS

This is the oldest type of two layered facade .I t consists of a frame with inward opening casement .The single glazed exterior skin has opening which allows ingress of fresh air and out flow of vitiated air .The cavity between the two layers is divided horizontally along the constructional axes. Vertically, it is divided either between stories or between individual window elements. Continuous divisions reduces the transmission of sounds and smells from room to room. Box-type windows are used where there are high external noise levels and where requirements are made for sound insulation between adjoining rooms.

Figure 2.1 20Section through typical box window facade with separate ventilation for each bay((Poirazis, H., 2004) n.d.)

The box unit consists of a single glass pane on the exterior side used as a double faรงade system in the Print Media Academy in Heidelberg, Germany. There is 46cm air cavity between the two panes. A cross ventilation control system moderates the buffer space between the external and internal glazing. This is achieved by opening of upswing glass Page | 31

louvers to let outside air to flow through and move the heated air in the cavity out, which cools the building envelope. Fresh air is gained through inner window slider .The buildings central system controls the rate of air flow through the cavity space .Sun shading devices are installed in the cavity , blinds can be rolled down and angled accordingly .

Figure 2.1 21 Elevation of box-window facade.((Poirazis, H., 2004) n.d.)

2.9.2.2

SHAFT BOX FACADE

The concept is based on the twin face which consists of a box window with continuous vertical shaft to create a stack effect . On every floor shaft is connected with opening .The stack effect draws hot air through the box window and take upwards where they are emitted . Air can also be sucked by mechanical means.

Figure 2.1 22 Plan of shaft-box faรงade ,Section through a shaft-box facad,Elevation of a shaft-box facade.((Poirazis, H., 2004) n.d.)

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2.9.2.3

CORRIDOR FACADES

In these facades the intermediate space is blocked at every floor level .The openings for intake of fresh air and extraction of air is placed near to the ceiling and floor . They are laid out in staggered form to prevent vitiated air to enter the immediate floor above .Individual segment between the skin is adjoined by number of rooms

Figure 2.1 23 Section through a corridor facade. Separate circulation for each story. , Elevation of corridor facade ,((Poirazis, H., 2004) 2004)

The Dusseldorf city gate has a corridor facade . The intermediate space between the two skins is closed at the level of each floor. The Rooms are naturally ventilated through intermediate space which allows outside air during long periods of the year. The first year showed that the building can be naturally ventilated for roughly 70-75% of the year. The entire building is enclosed in a glass skin. A 56-meter-high atrium space is created at the centre. The outer layer consists of a 12 mm safety glass and the inner is a low –E glazing with a wooden frame. Two corridor widths are encountered in the building (90 cm and 140 cm). The solar blinds are situated near the outer glazing layer.

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Figure 2.1 24 Dusseldorf city gate, Dusseldorfer, Germany, by Petzinka.((Poirazis, H., 2004) 2004)

2.9.2.4

MULTI STORY FACADE

In multistory facade the intermediate space is adjoined vertically and horizontally .These facades are used where the external noise level is very high . The ventilation is carried out by a large opening at the ground floor and at the roof .During summers , the facade space can be closed for optimizing solar energy gains .Facade can ne joint and used as a air joint duct , which needs to be ventilated mechanically .

Figure 2.1 25 Section through a multi-story facade ,Elevation of part of a multistory facade .((Poirazis, H., 2004) n.d.)

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2.9.3

THE COMPONENTS OF DOUBLE SKIN FACADES AND PASSIVE DESIGN The double skin facade incorporates passive designs of day lighting, ventilation and solar heat gain into the fabric of the building .These are the key components which helps in energy efficiency and comfort .

2.9.3.1

NATURAL VENTILATION

Natural ventilation system helps to allow fresh air circulation within the building to cool and ventilate the space . It also leads to less consumption of air conditioning which reduces energy consumption With this system windows can be opened throughout the day and night without compromising interior comfort .

Figure 2.1 26 Hybrid mechanical and natural ventilation with double skin faรงade((http://www.wbdg.org/design/env_introduction.php) n.d.)

2.9.3.2

SOLAR HEAT GAIN

Solar heat gain is controlled by using the shading dives in the air cavity of double facade skin , horizontal blinds .Cavity itself has an ability to absorb the solar radiation . These devices can be used in various forms : they can be fixed or operable either by the occupants or by the sensors of the building .External shading devices helps in reducing solar heat gain . Horizontal blind allows daylighting as well as gives exterior view.

"A double-skin facade also reduces heat losses because the reduced speed of the air flow and the increased temperature of the air in the cavity lowers the rate of heat transfer on the surface of the glass. This has the effect of maintaining higher surface temperatures on the inside Page | 35

of the glass. which in turn means that the space close to the window can be better utilized as a result of increased thermal comfort conditions" -wigginton ,2002

2.9.3.3

DAYLIGHTING

It reduces the amount of artificial lighting required , also the quality of light from daylight is more preferred than any other electrical lighting .Day lighting access is improved by the glazing of double skin facade .Shading devices reduces the amount of glare caused by increased access to daylight .

2.9.3.4

HEAT EXTRACTION

This works on similar concept as the solar heat gain , using external shading devices which blocks the sun rays before entering the building . The heat is absorbed by between pane shading device at the intermediate space , then air is drawn out through exterior skin either naturally or by mechanical means . This concept can be enhanced by safety glass or laminated safety glass on the exterior layer with inlet and outlet openings controlled by occupants or automatic flaps . The interior facade skin consists of fixed , double or single pane , operable windows or casement and hopper window .In the intermediate space , there are fixed or retractable venetian blinds or roller shades which are operated either manually or automated. During cool conditions , venetian blinds fully covers the facade and are angled to block the direct sun . Absorbed solar radiation is either re-radiated to interiors .Low emittance coating on interior skin reduces radiative heat gain .convection within cavity is either by thermal buoyancy or by wind driven .

Figure 2.1 27 Schematic diagram of heat extraction double-skin faรงade,(http://gaia.lbl.gov/hpbf/techno_d.html) n.d.)

1.Exterior upper air outlet 2.Controllable solar control device 3.Interior upper operable window (air inlet) 4.Interior operable or fixed view window 5.Exterior glazing layer 6.Air cavity 7.Interior lower operable window (air inlet) 8.Exterior lower air inlet

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2.9.4 2.9.4.1

CONSTITUENTS OF DOUBLE SKIN FACADE THE EXTERIOR AND INTERIOR GLAZING

When facade is ventilated with outside air , an insulating pane is placed at the interior side and is glazed at exterior side . In case when facade is ventilated by indoor air , insulating pane is placed at the exterior side , and interior is single glazed .

2.9.4.2

THE CAVITY BETWEEN EXTERIOR AND INTERIOR GLAZING

The air cavity or intermediate space between the facades can be divided vertically across the facade ,divided by floor or divided vertically into bays to optimize stack effect .The width may vary from 10cm to more than 2m . The undivided faรงade benefits from the stack effect.

On warm days hot air collects at the top of the air space which is emitted through opening on the top and cooler replacement air is drawn in from the outside The undivided air space can be used as atria, allowing people to occupy this "environmentally variable interstitial space. The air cavity can be used for spaces with low occupancy .

The divided air cavity reduces over-heating of upper floors as well as noise, fire and smoke transmission. corridor facades have fresh air and intakes on every floor allowing for maximum natural ventilation. Shaft facades draw air across the facade through openings and allows better natural ventilation.

2.9.4.3

SHADING DEVICES

Shading devices are placed between the cavity ,often venetian blinds are used. Blinds absorb and reflect radiation energy .

2.9.5 CONCLUSION Today the cost for highly efficient systems in buildings is comparatively high and the advantages might not be that evident. Varied objectives from owners and developers have different impacts on deciding whether the building should be equipped with intelligent / integrated systems or conventional systems.

Despite the high cost of the utilization, the trend seems to be in favor of intelligent facades. The reasons such as competitive office space which surely contributes to the demand for "something extra" to be offered. Similarly to any industry offering "state of the art technology", is available but you have to pay a premium to get it. The energy price and increasing salary costs are also one of the factors that affect the acceptance of intelligent skins as the cost of running the building is continuously increasing.

The intelligent facade is definitely here to last, it is just a matter of time until developers, owners and consulting engineers are fully aware of the possibilities and advantages it offers and that the available techniques are becoming known by the industry.

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3 CASE STUDIES

3.1 INTRODUCTION Various case studies have been referred to understand the mechanism of intelligent skins practically , also to analyze their performance in commercial buildings in terms of energy consumption . In the following section ,Commerzbank headquarters and Debis building have been discussed in detail .

3.2 COMMERZBANK HEADQUARTERS It is a high rise office building in Grosse Gallusstresse ,Frankfurt-am-Main ,Germany . It was built in 1991-1997.It was designed by Fosters and Partners , Energy consultant was Roger Preston and Partners for the client NERVUS Generalubernehmer .It became Europe's tallest building just under 300m , with a high antenna of 40m on the top .

3.2.1 BRIEF The aim was to create a building which is capable of expressing current values , where the environmental friendliness is as important as function of the building .

3.2.2         

INTELLIGENT FEATURES Building management system Learning facility weather data responsive lights sun tracking facility occupant override self -generation -CHP/PV/wind Night cooling Solar water heating

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Figure 2.1 28 view and the plan,(wigginton 2002)

3.2.3 SITE AND CLIMATE The building rises from a low level building of four to seven storey that are around the perimeter of 80m square city block , with an overall ratio of 13:5:1.The climate of Frankfurt is 'continental' , summers are warm and winters are colder than UK. Daytime temperature rises to 35degree Celsius.

3.2.4

SUNPATH

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3.2.5 THE INTELLIGENT FACTOR The inner skin of external windows and the atrium have motor driven sashes that is controlled by Building management system , or by occupants using wall mounted switches .During undesired conditions windows are closed by the BMS and air conditioning gets activated . Night cooling is regulated by the motorized opening of the windows . Lighting is controlled according to daylight penetration and occupancy need.

3.2.6 ACCOMODATION The tower is triangular in plan , with long sides 60m curved to maximize the space efficiency . The lift and the staircase were designed as a separate triangular fishtail ,later were placed at each corner of the triangle . Foster incorporated the concept of garden in te sky for natural air conditioning .Garden were spiraled up the 48 storey tower to become climatic ,social and visual focus for the four storey of offices located on the remaining sides .The gardens were linked to a 200m high atrium which was divided into 12 storey village , with glass floor on each village .It provided fire separation , defines internal ventilation and smoke ventilating zone . These gardens are used by employees for relaxation , meeting or lunch breaks . There are nine gardens , three on each side of the triangle .Roof garden is also planned for lower level of the building , with banking hall ,shops , auditorium and apartments .

(wigginton 2002)

3.2.7 ENERGY STRATERGY The building is designed to utilize the natural ventilation for a large proportion of operating cycle . Natural ventilation and lighting is achieved by open able windows which are controlled by central computers .

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3.2.8 CONSTRUCTION The opaque elements of steel frame are cladded with prefabricated spandrel panel .Triple glazed windows are provided for openings . The reinforced concrete basement rests on a 4.5m transfer slab , 111 bored piles up to 45m deep. Radar -attenuated glazing is used on the airport side of the building .The tower is supported by vertical steel masts at the each corner of the each core , which supports eight storey vierendeel beams .    

Facade transparency North East West

58% 58% 58% 12%

U- VALUES OF THE COMPONENTS    

Walls Slab Roof Window 1.10W/sq.m.K

n/a n/a n/a

(wigginton 2002) 3.2.9 GLAZING Windows facing towards the atrium , top hung for maintenance , bottom hung for motorized ventilation are insulating glass . On the exterior face ,windows are double glazed with a third protective pane providing ventilated cavity . The outer windows are motor-driven sashes with top/bottom hung at 525m behind a protective outer pane .The cavity is ventilated through top and bottom by a 125mm continuous slots . The inner pane is insulated with 'IPSOL ' glazing , with light transparency of 66% and energy transmission value of 34% .

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3.2.10 HEATING Along the external and atrium facades , static heating convectors are provided for heating during cold conditions , which does not exceed 17% of the operating cycle . Passive solar builds up between the outer single glaze and double glaze opening , which will preheat the ventilating air . The garden acts as solar collector and thermal buffer keeping the minimum temperature of 5degree Celsius. Glazed garden walls contains a water heating system for cold downdraughts .

3.2.11 COOLING Night cooling is operated by BMS through the opening of motorized perimeter windows .

During daytime , cooling can be achieved by water -based chilled ceiling system .The team predicted that active cooling will only be need for one quarter of the time . chilled water is produced by absorbing chiller plant at 17 degree Celsius .

3.2.12 VENTILATION It is achieved by 1.5m floor plates by computer controlled windows . The atrium space can also be ventilated by opening garden in good weather and indirectly provide fresh air to the offices facing towards the atrium . Outside facing offices are ventilated through motorized inner window situated behind the outer protective pane .This creates 200mventilated cavity . Each office has bottom hung window which can be controlled by occupants and BMS .Sun heats the glass , blinds and frame which results in heating up of surrounding air and experiences uplift . The motorized windows would provide effective ventilation for 60% of the total hours of usage . Each village is provided with back up handling unit to supply fresh air in case of bad weather .The consists of thermal wheel , filters, cooling coils ,heating coils , a humidifier .

Intelligent control         

Daylight adjustment reflection/protection glare control - blinds/louvers/fixed Responsive artificial lighting control Heating control Heat recovery - warmth/cooling Cooling control Ventilation control Fabric control - windows/damper/doors Insulation - night/solar

(wigginton 2002) Page | 42

Figure 2.1 29 ventilation with open and closed windows(wigginton 2002)

3.2.13 DAYLIGHTING Daylight is achieved directly to the outside offices through windows and indirect to offices facing towards he garden that are lit from side and above .

3.2.14 ARTIFICIAL LIGHTING High efficiency light can be modified in response to variation in daylight levels on external and atrium facade .By the movement of sensors lights in corridor and offices are automatically activated .

3.2.15 SOLAR CONTROL Each window has a motorized blind for solar shading , which permits individual control of solar admittance. The blinds protected by the outer glass pane can be operated up to wind speed of 20m/s

3.2.16 CONTROLS The BMS monitor has numerous sensors which controls full internal climatic system. It is operated based on the number of people in the building and outdoor climate .Computer determines the optimum positioning of the external sun shading and motorized windows in combination with air conditioning and perimeter heating .The system controls nine sensor in every internal gardens adjusts the temperature and activates the under floor heating during cold weather .

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3.2.17 USER CONTROL The system also allows full occupant override .Light switch panel is provided through which light , temperature , window openings and blind positions can be monitored .

3.2.18 OPERATING MODE One operational mode is the artificial control of the buildings climate by windows controlled shut ,air conditioning fully operational and cooling through chilled ceiling .The low energy of ventilation involves motorized opening of windows , deactivation of air conditioning .

Figure 2.1 30 open and closed louvers controlled by operating system(wigginton 2002)

3.2.19 ENERGY CONSUMPTION Ecological skyscraper consumes approximately 25-30% less energy than a conventional building .Computer simulated energy consumption by   

ventilation motors are 18Kh/square meter/year , cooling at 0.7 heat rate per absorber consumes 115KWh/square meter/year , heating including 10% heat loss consumes 36KWh/square meter/year .

Office design temperature is set at 20degree Celsius minimum in winters and 27 degree Celsius maximum in summer . Installed heating load of 4.5 MW and cooling load 5MW.

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3.3 DEBIS BUILDING It is a high rise office building in Potsdammer Platz Berlin Germany . It is designed by Renzo Piano Building Workshop , Energy Consultant Arup Gmbh for the Daimler Benz Inter Services .

3.3.1 BRIEF The building required to house the headquarters , financial services , information technology , telecommunication and media services .The project was the symbol of the Companies commitment to a united Germany , and the rebuilding of its historic capital .

3.3.2         

INTELLIGENT FEATURES Building management system Weather data Learning facility Responsive lights Sun tracking facility Occupant override Self- generation -CHP/PV/wind Night cooling Solar water heating

(wigginton 2002)

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3.3.3 SITE AND CLIMATE The building is located in the centre of the Berlin , close to Berlin wall and Checkpoint Charlie . The climate is continental , summers are warmer and winters are colder than UK . In winters the temperature drops to -25degree Celsius and in summer rises to 32degree Celsius .

3.3.4

SUNPATH

3.3.5 THE INTELLIGENT FACTOR The east , south and west elevations have the highest exposure to solar gain which incorporates a glass wall of 700mm outside the main window wall .This outer wall consists of glass panels which opens to 70degrees by sensors for natural ventilation in warm climate . In cold climate ,they close to create an insulation layer . The inner facade consists of lower and upper panels of insulation glazing , at night in warm weather the upper window opens automatically , to ventilate the internal spaces and to emit the heat built up during the day .

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3.3.6 ACCOMODATION The building comprises of 45000 square meter of office spaces . The form of the building rises from broad lower end of six storey to a narrow end of 21 storey . Atrium of 14m wide runs 82m from north to south down the centre ,accommodate two office wings running along with the atrium .

3.3.7 ENERGY STRATEGY In the Debis building natural methods are used to keep the building comfortable , using double glass skin When natural ventilation is operated , it improves the office acoustic in natural ventilating and sealed mode .

(wigginton 2002)

3.3.8 CONSTRUCTION The building consists of reinforced concrete frames , and two exterior claddings . The facade comprises a screen of terracotta in front of highly insulated panels acting as weather barrier . The transparent facade is used in western facade of the tower . The concrete floor slabs remains exposed at the outer edge of the floor to absorb solar radiation and act as a damper .     

Facade transparency North East South West Roof

80% 80% 80% 80% 90%

U- VALUES   

Walls Slabs Roof

n/a n/a n/a Page | 47



Windows

1.5W/square meterK

3.3.9 GLAZING The outer skin of glass louvers reduces the wind pressure on the main exterior glass wall behind, and prevents the rain from inner envelope .It protects the blinds within the cavity which provide solar protection to the facade. The inner glazing has an hopper in the upper part of the wall which can be opened.

3.3.10 HEATING Building is heated from BEWAG district heating system through heat exchangers in the basement .Finned tube heaters runs along the perimeter with thermostatic valves provided in each office .

3.3.11 COOLING Cooling is provided in the form of chilled ceilings .Opening windows ,narrow floor plates and external blinds provides comfortable environment.

Figure 2.1 31Openable windows and their mechanism(wigginton 2002)

3.3.12 VENTILATION In summers natural ventilation is used until the temperature rises to 30degrees , when chilled ceiling system gets activated .In winters , similarly when temperature drops below 5degrees mechanical heating is used .Natural ventilation is adequate for 40% of the year at the upper part of the building , for 55% in lower part of the building .This reduces energy load of building by 40% .In winters closed louvers are used to trap the air as an insulating blanket , in summers there louvers drives fresh air inside the building .

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3.3.13 DAYLIGHTING The building achieves the German standard of 2% daylight factor and is generous throughout the office .On west side , offices receives 5% daylight factor through double skin facade and electric lighting is used for less than 40%of the working year .The atrium is always lit by large glass panels , fritted to provide solar shading , prevents direct view of the sky and reflects artificial light at night .

3.3.14 CONTROLS The BMS controls and monitors the central plant and mechanical ventilation .The BMS also adjusts the setting of glazed louvers in external facade and positions the blinds by reading external light ,temperature, radiation condition and wind speed .When daylight level is sufficient lighting control system automatically switches off .

3.3.15 USER CONTROL Occupant can control perimeter finned tubes , position of cavity blind , adjust ventilation of their room using operable windows .

Intelligent controls         

Daylight control - reflection/protection Glare control - blinds/louvers/fixed Responsive artificial lighting control Heating control Heat recovery - warmth/cooling Cooling control Ventilation control Fabric control- windows/dampers/doors Insulation- night/solar

Building data     

Area - 45000sq.m.

Typical floor plate - 180m lower floor , 35m tower Number of storey's - 6 to 21 Annual energy use - n/a energy use for building type - 100KWh/meter sq.

3.3.16 ENERGY CONSUMPTION Energy consumed between 80 / 100 KWh/meter sq

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4 DATA ANALYSIS 4.1 INTRODUCTION India ranked fifth in energy consumption according to 2010 census .Due to the increased demand for housing , infrastructure . transport . agriculture ,it is expected that these figures will increase in couple of years making the country one of the largest energy consumers .

Industrial and domestic are the highest energy demanding sectors followed by commercial .Whereas in mega cities like Delhi , Bangalore , Gurgaon , Hyderabad .Mumbai etc. commercial marks the first place serving to multinational offices and IT parks .With expanding economy , there is a great demand for offices , and more IT companies which will create a boom in commercial sector making it a largest energy consuming sectors .According to forecast by the end of 12th plan in 2016-17 and 13th plan in 2021-22 energy consumption this sector will increase to 116535 and 185722 respectively .

It also varies in context to the region , in India the northern part is the highest energy consumer whereas east being the least .With this growing demand there is need to show our responsiveness toward the environment .Latest technologies have been evolved , if Page | 50

incorporated with the designs would help in energy conservation in future .We will look into the detailed analysis of its feasibility in Indian context in next section .It is important for designers and developers to understand proper strategies and design consideration to make it full energy efficient .

4.2 DESIGN STRATEGIES AND ANALYSIS We will look into some design strategies which every designer should look into before incorporating the advanced technology of dynamic facade , its proper working and how it could be fully justified .

4.2.1 SUN SHADING SYSTEM Louvers and blinds are consists of multiple horizontal or vertical slats.

Exterior blinds are durable and made of galvanized steel, anodized or painted aluminum or PVC for low maintenance. Appropriate slat size varies and is generally tends wider for exterior use. Slats can be either flat or curved. With different shapes and reflectivity, louvers and blinds are used for solar shading, also for redirecting daylight. Louvers and blinds are suitable for all climates. For commercial buildings in hot climate, the system is more energy-efficient if placed on the exterior of the building to block solar radiation. For buildings in cold climate, the system is used to provide more daylight and absorb solar radiation.

Sketches of various exterior shading systems, a) Horizontal overhang protects south faรงades from high-angle sun during the day. b) Vertical fins protect window faรงades from east and west low-angle sun. c) Overhang and fins combined can be applied to buildings in hot climates. d) Window setbacks, where the window plane is pushed inward from the face of the building, can provide good shading potential. e) Fixed or moveable horizontal louvers provide shading similar to

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an overhang with improved daylight potential. f) Interior blinds can be controlled to accommodate occupant preferences.

4.2.2 LIGHTING SYSTEM Analysis for narrow buildings to enhance the daylight penetration. Many building spaces comprises vertical windows only on a single side of the space. For these single-sidelighted spaces, a standard rule is used that "the depth to which the daylight will penetrate is equal to approximately two-and-a-half times the height of the window".

If the height of a window is limited by the height of the ceiling is about 2.4 to 2.7 m in many commercial and institutional buildings, an approximate maximum distance from the building envelope to which the daylight will provide useful illumination is about twenty feet (6.1 m). This dimension establishes a practical maximum depth for a building space, in which daylight will serve as a major source of illumination.

The use of atrium for increasing the penetration of daylight into buildings spaces. An atrium is a covered light well or cavity that vertically opens up the interior of a building. The atrium volume usually consists of a central courtyard space that is placed on the bottom floor of the atrium. The floors above the courtyard level have balcony areas or open corridors which faces towards the courtyard. The heights of the atrium volumes can vary from a few stories to almost 20 floors. Many atriums are roofed with skylights or have clerestory windows which are included in the upper-most vertical walls. These skylights and the clerestories will enable daylight to penetrate deeply into buildings.

Orientation of window for Admitting Daylight .North-facing windows will receive only minimal amount of the direct of solar radiation. But these windows get the full view of the sky vault without experiencing substantial solar heat gain. Occupants looking out from windows will slightly experience the excessive brightness associated with directbeam sunlight. Windows facing towards east and west also introduces visual comfort problems. In the morning, east-facing windows and in the afternoon for west-facing windows, Occupants will frequently experience glare within their view fields. To mitigate these problems of excessive brightness and glare, shading system will have to be included for these windows or anti glare systems can be used .

Anti-glare systems, screens and perforated aluminum louvers should be used . The positioning of an anti-glare system in the internal glazing layer decides the amount of heat gained in the interior from the solar radiation. By comparing an office building with external sunscreen elements, sun protection glazing combined with an internal anti-glare system leads to an increase in heating requirements of up to 20-30% as a result of the reduced radiation transmittance, and increases cooling energy requirements by 10-20% as a result of the heat gain in the anti-glare system

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The louvered overhang blocks the direct-beam sunlight from reaching the upper portion of the window, whereas the vertical panel reduces the intensity of the sunlight as it falls upon the lower portion of the window.

4.2.3 VENTILATION SYSTEM Natural ventilation has become an increasingly essential method for reducing energy use and cost for providing comfortable indoor environmental quality and maintaining a healthy and productive indoor climate rather than the existing approach of using mechanical ventilation. In favorable climates and buildings types, natural ventilation can be used as an alternative to air-conditioning plants saves up to 10%-30% of total energy consumption.  Buildings should be sited where summer wind obstructions are minimal.  Naturally ventilated buildings should be narrow. It is difficult to distribute fresh air to all parts of a very wide building using natural ventilation. The maximum width to ventilate naturally is estimated at 45ft.  Each room should comprise of two separate supply and exhaust openings.

Exhaust to be located high above inlet to maximize stack effect. windows should offset from each other to minimize the obstructions to airflow within the room.  Window openings should be operable by the occupants.  A ridge vent should be provided at the highest point in the roof for good outlet for both buoyancy and wind-induced ventilation. The ridge opening should be free from obstructions to allow air to freely flow out of the building.  A clerestory or a vented skylight should be provided as an opening for stale air to escape in a buoyancy ventilation strategy. The light well of the skylight could also act as a solar chimney to augment the flow.

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4.3 ENERGY PERFORMANCE AND COMPARATIVE ANALYSIS OF TRADITIONAL AND INTELLIGENT FACADE This is a study conducted using all the design strategies and considerations in mind as discussed above to know how feasible is intelligent skin in Indian context in terms of climate and energy consumption .

This is a study between two buildings with masonry wall facade with punched windows, while the other with curtain wall facade .Only one wall is exposed to the exterior and floor to thermal resistance is 0.9 sq.m.K/W . Buildings have been placed in two different climates one is composite with cold winters and warm summers and other is warm and humid climate with cool and humid winters and hot and dry summers .

4.3.1 CASE I The first test is to compare the heating and cooling demand for both the climates , provided that no internal gain is assumed and no lighting and shading systems are used .

4.3.1.1

COMPARISON

As a result transparent facade demands higher amount of heating and cooling , when lighting and shading are not taken into account. Due to increase in solar gain with no shading and also no natural ventilation is used resulted in increase of cooling demand . the annual source energy consumption for building with masonry wall facade is 66.5KWh/m2 for composite climate and 36.1KWh/m2 for warm and humid climate , whereas for building with curtain wall facade it was 106.8KWh/m2 and68.5KWH/m2 respectively .

4.3.2 CASE 2 When internal heat gain is taken into account and basic lighting ,shading and ventilation system is used. South facing building is considered with two occupant load . Installed lighting power density is 12W/m2 for building with masonry wall facade and 9W/m2 for building with curtain wall .Interior roller shades are used for windows . Curtain wall uses reflective shade of 77% reflectance, while 37% for the building with masonry wall facade.

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4.3.2.1

COMPARISON

The curtain wall results in high heating and cooling demand than the masonry wall but lower lighting demand , which also affects the cooling energy use . Heating gains also increased as occupant load was also considered.Use of lighting system in building with curtain wall facade benefits the daylighting level which helps in total source energy consumption.

Masonry wall facade

curtain wall facade

Composite climate

masonry wall facade

curtain wall facade

Warm and humid climate

The total energy consumption of building with curtain wall is 12% lower than the masonry wall building in composite climate , whereas it is 15% lower in Warm and humid . Using basic lighting and shading systems resulted in reduction in energy consumption .

4.3.3 CASE 3 Earlier study was based on basic lighting ,shading and ventilation devices , in this section advanced system is used to make the facade intelligent .

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4.3.3.1

Shading control strategies considered and analyzed

For masonry wall building open/closed controls are used during working hours , which remains shut during night time . In curtain wall building various shading controls are used :   

Open/closed control 1 (set point: 300 W/m2 incident radiation) and closed during the night (same as for the punched windows for direct comparison) Open/closed control 2 (set point: 150 W/m2 incident radiation) and closed during the night Advanced shading control with intermediate shading positions

When first two options are considered the conservative control of 150W/m2 results in increase the energy use up to 16%in composite climate and 40% in Warm and humid climate. This is due to increase in lighting energy use due to insufficient lighting .

Daylight glare probability value is calculated for the open/closed control and the advanced shading control, for the same reference point at the center of the modern office, for a seated person (1.1 m from the floor) facing towards the window . The simple open/closed control results in several hours with glare probability exceeding 35 % for both cases, but those can be eliminated with the advanced control, which has 2000 lx as a good set point for work plane illuminance.

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Composite climate

Warm and humid climate 4.3.3.2

COMPARISON

The curtain wall building results in lower overall source energy use considering all the climates than the masonry wall facade building . Intelligent facade includes advanced solar shading devices which reduces heat gains and optimizes day lighting ,and natural ventilation leading to less load on cooling system. The energy consumption varies in different climates , for composite the energy use is comparatively more than warm and humid for both curtain wall as well as masonry wall building since the heating and cooling requirements are more in warm and humid climate .

Composite climate

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Warm and humid climate

4.4 CONCLUSION This study compares the energy performance of two buildings, one made up of brick wall, and other with curtain wall construction integrated with intelligent facade. Faรงade design is considered a perimeter zone design, and the aim is to balance the need for day lighting , view, the need of controlling of solar gains and maintaining human comfort, while reducing the energy demand for air-conditioning and lighting. Result shown that the building consumes less energy if equipped with intelligent skin . This study on intelligent skins shows that intelligent faรงades not only provide more natural light and ventilation but also, if properly controlled and integrated with perimeter zones systems, they may result in lower energy use and operational cost compared to traditional faรงade.

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5 BIBLIOGRAPHY 2002. (Betancourt, L., 2002.

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(Bell, V. & Rand, P., 2006). (http://gaia.lbl.gov/hpbf/techno_d.html ). (http://gaia.lbl.gov/hpbf/techno_d.html). (http://www.dyerenvironmental.co.uk/natu ral_vent_systems.html). (http://www.dyerenvironmental.co.uk/ natural_vent_systems.html). (http://www.dyerenvironmental.co.uk/natural_ vent_systems.html). http://www.neuralpower.com/technology.htm.

Lomholt, I. august 27, 2011. http://www.rawnarch.com/.

McCown, James. december 09, 2009. http://www.e-architect.co.uk/poland/thespianwroclaw. wigginton, M.& Harris, michael. "intelligent skins." By jude harris. 2002.

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