DESIGN DISSERTATION

BUILDING SKIN AND HUMAN COMFORT

IN COMPOSITE CLIMATE

BY

PRASAD PATILM. Arch. Sustainable

UNDER THE GUIDENCE OF

AR. MUKTA LATKAR

B.V.U. COLLEGE OF ARCHITECTURE,PUNE.

A C K N O W L E D G E M E N T

I hereby wish to convey my sincere gratitude towards my guide Ar. Mukta Latkar for his most valuable suggestions and time that have been the key to the satisfactory completion of my dissertation.

I thank Ar. Prof. S.L. Kolahatkar as regards to his co-operation and patience as the Head of department; M.Arch. Sustainable, Principal Ar. Mr S.D. CHAVAN; Bharti Vidhyapeeth College of Architecture, Pune and the college staff who were always there for my guidance in every regards.

I would also like to thank the authorities of Salarpuria; Bangalore and I.MAX.; Hyderabad for granting us permission to study their buildings.

Lastly I thank all my friends and those individuals who directly or indirectly extended their support and valuable advices at every step for the betterment of my project.Thank you.

P R A S A D P A T I L

M. Arch. Sustainable; B.V.U., Pune

I N T R O D U C T I O N

The skin of the building plays a very major role in creating a comfortable indoors.

It is the boundary which defines the built and the unbuilt environment. The

building skin is the first element to react with the outdoor changes creating

comfort indoors which might or might not be desirable .Conversely it is the last

element which experiences the net effect of the activities indoor and create an

impact on the immediate surroundings of the envelop . Thus a detailed study of all

the techniques of construction and the various material used will help to derive a

intelligent system which will be best suited to the local climate and at the same

time will respond to various aspects responsible for human comfort and needs.

E X E C U T I V E S U M M A R Y

Aim –

To identify various forces that are responsible for an intelligent envelop design To minimize solar gain create comfort condition To get enough daylight to minimize use of artificial lighting What U-Values are good for composite climate Opening size for natural ventilation and access

Objectives – a. To study the microenvironment which exists around the building envelop in

relation to the microclimate, and human comfort.b. To study the different elements of building envelop.c. To study the response of different material on microenvironment.d. To study adaptive technology for selected material.e. To study performance of building skin with various combinations of different

materials.

Relevance of the study – As the vocabulary of building facades are changing tremendously, today there exists a monotony of the materials used leading to a character of buildings which is repetitive. The borrowed materials from the west are a mere attempt of blind imitation of the materials without actually studying its applicability and compatibility to the local context. The study aims at providing design solutions which will be climatically responsive and which will be best suited so as to achieve human comfort with the maximum efficiency of the material used.

Scope – The study will be limited to certain materials used in non residential buildings skin for composite climate.The impact will be evaluated within a small range of microenvironment that exists next to the envelope.

Case study – a. The study will focus at behavior of particular material and technology used

for a specific building use.b. The study wills also focus on the intensive study of the materials that have

been used in the near past, present and the various possibilities that might happen in the future.

CONTENT OF STUDY

Introduction to composite climate

AREA NEAR 23ºN AND 23ºS LAHORE, MANDALE, KANO, NEW DELHI, ISLAMABAD, KANPUR.

2/3 OF THE YR 2 SEASONS HOT AND COLD AND 1/3 OF THE YR WARM AND HUMID.

HOT AND DRY WARM-HUMID COLD-DRYDAYTIME 32-43 27-32 27NIGHT TIME 21-27 24-27 4-10DIURNAL 11-22 3-6 11-22

HUMIDITYDRY PERIOD -20 TO 50%VAPOUR PRESSURE-1300 TO 1600N/M2

WET PERIODVAPOUR PRESSURE-2000 TO 2500N/M2

PRECIPITATION-PROLONGE MONSOON PERIOD FROM JUNE TO SEPTEMBERANNUAL RAINFALL 500 TO 1400MM WITH 200 TO 300MM IN WETEST MONTH

MONSOON OVER CAST & DULL

DRY CLEAR &DARK BLUEIN THE END IT BECOMES DRK BLUE

WINDSIN DRY SEASON – HOT & DUSTY

WARM & HUMID – DIRECTIONAL CHANGEMONSOON - STRONG & UNIDIRECTIONAL

SPECIAL CHARACTERISTICS—

HUMIDITY CAUSE WAKINING OF BUIDING MATERIALSIN DRY SEASON DUST AND SAND STROM MAY OCCURTERMITES ARE COMMONOCCASIONAL CONDENSATION PROBLEM

RESPONSE TO THE CLIMATE

PHYSIOLOGICAL OBJECTIVE

OBJECTIVE ARE SET FOR TWO EXTRAM CONDITION BUT PROBLEM ARE CREATED BY THIRD SEASON

DESIGN CRITERIA THERMAL DESIGN CRITERIA ARE APPLICABLE TO BOTH HOT DRY AND

COLD SEASON EXCEPT FOR MINOR DETAIL FOR MONSOON BUILDING SHOULD BE DESIGNED ACCORDING TO THE CRITERIA OF WARM AND HUMID CLIMATE

DISCOMFORT INDEX

FORM AND PLANNING COMPACT PLANNING WILL HELP MOST OF THE YEAR

ADVANTAGE OF WIND IN MONSOON & IN SOME DRY HOT PERIOD

MUTUAL SHADING OF EXTERNAL WALL PROTECTION FROM WIND IN COLD SEASON

SHELTER FROM SUN & EDUCTION OF EXPOSED SURFACE TO SUN

ROOF WITH LOW TRANSMITANCE VALUE AND GOOD THERMAL CAPACITY

ROOF AND WALL

RETAINTION OF HEAT TRANSMISSION VALUE AND GOOD THERMAL CAPACITY IS PROVIDED IN FLOOR AND ROOF PERMITTING

THE OUTER WALL TO BE USED FOR MORE FREELY FOR LARGE OPENING

SURFACE TREATMENT

PREVENTION OF HEAT THRO OUTER SURFACE IS FUNDAMENTAL RULE

SURFACE SHOULD BE LIGHT COLOURED OR SHINEY POLISH METAL

IN COLD SEASON HEAT SUN IS IMPORTANT THEREFORE

PRINCIPLES OF DESIGN AND CHOICE OF MATERIALS TO ADAPT BUILDING TO CLIMATE

COLOURWHITE –ABSORBS ONLY 15% OF INCIDENT RADIATIONLIGHT COLOURS LIKE LIGHT GRAY, CREAM –ABSORBS 40%-45%OF INCIDENT RADIATIONMEDIUM DARK SHADES ABSORBS 60%-65%BLACK AND DARK SURFACES ABSORBS 80%-90%

SOLAR RADIATION PENETRATION THRO WINDOWDEPENDS ON COMPOSITION OF GLASS AND SHADIND COMPONENT

WITH DARK EXT SHADING IS 10% OF INCEDENT RADIATION.

USING INTERNAL SHADE 40 TO 70% ENTERS

WITHOUT SAHDING PROPORTION, IT IS ABOUT 90%.

PLAN FORMPrime parameters : Radiation Air movementClimatic ImplicationThe perimeter to area ration of the building is an important indicator of heat loss and gain.

A large perimeter to area (P/A) ratio means that a small area is being bounded by a large perimeter. A small P/A ratio means that the same area would be bound by a much smaller perimeter.

In hot climates the P/A ratio should be kept to a minimum.In cold climates too the P/A ratio be minimal. This ensures minimum heat loss.In warm-humid climates the prime concern is a plan form for maximizing air movement. Here too, minimizing the P/A ration is useful as it minimizes heat gain.

BUILDING ORIENTATIONPrime Parameter Radiation Air Movement

North faces receive minimum direct radiation and south faces receive the maximum. This however is not entirely true. For instance; at 28⁰ N on June 22nd the sun is mostly in the northern hemisphere.

SURFACE AREA TO VOLUME RATIONPrime Parameter RADIATION

CLIMATIC IMPLICATION

The surface area to volume (S/V) ration (the three dimensional extrapolation of the P/A ratio) is an important factor determining heat loss and gain.In hot dry climates S/V ration should be as low as possible as this would minimize heat fain. In cold dry cimates also S/V rations should be as low as possible to minimize heat losses.

FENESTRATION PATTERN AND CONFIGURATIONPrime Parameter RADIATION, AIR MOVEMENT, DAYLIGHT

In warm-humid climates fenestration areas should be large to facilitate ventilation. Large overhangs would be desirable in cutting off diffuse solar radiation.

In cold climates fenestration should e large, unshaded but sealed. This would enable heat gain but reduce cool breezes. The shades must cut off summer sun but permit winter heat gain.

FENETRATION ORIENTATIONPrime Parameter RADIATION RECEIVED, AIR MOVEMENTIn hot dry climates the fenestration should be oriented north. In cold climates they should be facing south.

In humid climates they should be within 45” of the perpendicular to the direction of airflow. The inlet and outlet should not be in a straight fine, in order to maximize airflow.

FENETRATION CONTROLSPrime Parameter RADIATION, AIR MOVEMENT AND DAYLIGHT

In hot cimates, if glazed windows are not shaed then they heed to shaded from the sun. light shelves would be unnecessary.In cold climates, optimum glazing is advisable. Shading of the window is undesirable. Window section should once again, be such that air velocity is reduced.In warm humid climates window shades are not so much of an issue since solar radiation is largely diffuse.

WALLSPrime Parameter: RADIATIONWall materials, like roof materials should be of low U-values in hot and in cold climates. In warm humid climates walls should have a low thermal capacity.

ROOF MATERIALSPrime Parameter RADIATION RECEIVEIn hot and cold climates the roof should have a low transmittance value. This would ensure maximum heat fain and heat loss, respectively. Using insulation would minimize the heat, stored by the floor.

In warm humid climates heat storage is undesirable. The roof should, therefore, be light, probably having high U-values and low heat capacities.

EXTERNAL COLOURS AND TEXTURESPrime Parameter RADIATIONIn hot climates surface colors should be light while textures should be rough. This will result in greater reflectivity, shading and reradiation. If rough textures are not possible then a smooth surface would be preferable.

In cold climates surface textures should be dark and flat though not smooth. This would ensure maximum absorption and minimum shading and reradiation.

In warm humid climates, again, the aim would be to minimize heat gain. Light coloured and rough surfaces therefore, are preferable.

INTERNAL TEMPERATUREDEPENDS ON EXTERNAL COLORS, MATERIALS, SIZE AND SHADING WINDOWS AND VENTILATION.

WITH WHITE EXTERIOR THICK WALLS SMALL AND CLOSE SHADED WINDOWS.

IT IS POSSIBLE TO REDUCE 10 TO 50% OF THE OUTDOOR TEMPERATURE.

WITH ADDITIONAL VENTILATION AT NIGHT, POSSIBLE DECREASE IN MAXIMUM IS 60%.

IN HOT CLIMATE, MAX MAY REACH 10 DEG C. WITH THIN LOWER RESISTANCE CAPACITY WALL EXTERNAL DARK COLOR WITH LARGE UNSHADED WINDOW INNER TEMPERATURE ARE OFTEN MORE THAN 10 DEG OUT DOOR.

BUT MINIMUM OF THOSE SURFACES MAY FALL TO 8DG BELOW TO OUTDOOR, WHERE CLIMATE IS DRY AND NIGHT STILL.

INDOOR AIR VELOCITY

WITH EFFECTIVE CROSS VENTILATION, AVERAGE INTERNAL AIR SPEED REACHES 60% AND MAX OF 120% OF THE OUTDOOR FREE WIND SPEED.

WITHOUT CROSS VENTILATION EVEN WHEN WINDOWS ARE OPEN THE INCREASE WILL BE 15 TO 10%.

INDOOR VAPOUR PRESSUREIN VENTILATED BUILDING, IT IS EQUAL TO OUTSIDE PRESSURE.

IN CROWDED BUILDING, WHEN WINDOWS ARE CLOSED IN WINTER PRESSURE MAY RISE TO 7MM Hg. OR MORE ABOVE OUTDOOR LEVEL.RANGE IN VARIATION IN INDOOR CLIMATE.

CLIMATIC VARIABLE RANGE OF VARIATIONSOLAR RADIATION ABSORB IN WALL 15 TO 19% OF INCEDENT RADIATIONSOLAR RADIATION PENETRATING THROUGH WINDOWS

10 TO 19% OF INCEDENT

INDOOR AIR TEMPERATURE AMPLITUDE

10 TO 15% OF OUTDOOR AMPLITUDE

INDOOR MAX AIR TEMP -10 T0 TO 10 FROM OUTDOOR MAXINDOOR MIN AIR TEMPERATURE 0 TO 7DEG.C. FROM OUTDOOR

TEMP.INDOOR SURFACE TEMPERATURE -8 TO 30DEG.C. FROM OUTDOOR

MAX AND MINAVERAGE INTERNAL AIR SPPED WINDOWS OPEN

15 TO 16% OF OUTDOOR WIND SPEED

ACTUAL AIR SPEED ANY POINT 10 TO 120% OF OUTDOOR WIND SPEED

INDOOR VAPOUR PRESSURE 0 TO 7 MM Hg ABOVE OUTDOOR LEVEL

REF. MAN, CLIMATE AND ARCHITECTURE, B. Givoni

Façade systems and building envelopCombined facade

Single-skin façade

Mullion and transom facade

Un segmented double facade

Box window facade

Corridor facade

Alternating facade

If facades were hermetically sealed, this would certainly result in the objective comfort parameters being fulfilled, but many subjective aspects of comfort would be ignored. The perception of the environment through odors, noises, and airflow, moisture and temperature fluctuations is lost The sense of the time of the year or day is greatly reduced.

FAÇADE DIVISIONTOP ZONE IS DAY LIGHT ZONE WHICH PROVIDES NATURAL LIGHTING OF THE ROOM. IN THE IDEAL SITUATION LIGHT IS DEFLECTED INTO THE DEPTH OF THE ROOM SO THAT THE DAYLIGHT FACTOR DOES NOT DROP AS SHARPLY FURTHER INTO THE ROOM.

The middle zone provides the view and natural light when no direct sunlight strikes the facade This area has shading so that during the summer months the amountof energy entering the room is reduced. In winter, when heat gain is desirable, internal shading improves visual comfort,

In the spandrel area, daylight plays a very minor role.This zone can provide outside views as required by the users. A glazed spandrel can give the user on the lowerstoreys a feeling of being continuously watched. For taller buildings, a transparent spandrel zone allows the user a view of the horizon and promotes a feeling of safety.

SINGLE SKIN FACADESSingle-skin facades Single-skin building envelopes usually have very little distance between their functional elements.

MULTISKIN FACADES

Double-skin facades have a second plane of glass positioned in front of the primary facade. The other functional elements are positioned in layers one behind the other, which means interaction of their functions cannot be avoided. The result is that the requirements of the individual functional layers are higher.

ALTERNATING FACADES

The alternating facade is a combination of single- and double-skin facades and incorporates the principles of both types into an overall system.The disadvantages of the interaction of the individual layers of a multi skin system are avoided by the bays with single-skin facade elements.

FAÇADE CONCEPTS

WINDOWED FAÇADEELEMENT FAÇADEBAFFLE PANELALERNATING FAÇADEBOX WINDOW FAÇADECORRIDOR FAÇADEUNSEGMENTED DOUBLE SKIN FAÇADECONTROLLABLE DOUBLE SKIN FAÇADE