NATURAL VENTILATION SUBMMITTED BY :- KIRAN MAI DAS B.ARCH IX SEMESTER DCA , ANJORA, DURG
NATURAL VENTILATION
SUBMMITTED BY :- KIRAN MAI DAS B.ARCH IX SEMESTERDCA , ANJORA, DURG
AIM-• TO STUDY THE APPLICATION OF NATURAL VENTILATION AND
TECHNIQUES USED TO MINIMIZE EXTERNAL ENERGY AND ENHANCE THE QUALITY OF BUILDING.
OBJECTIVE– • TO STUDY HOW TO OPTIMIZE NATURAL VENTILATION IN
BUILDINGS AND TO MINIMIZE MECHANICAL SYSTEMS FOR VENTILATION
• TO STUDY THE SPECIFIC APPROACH AND DESIGN OF NATURAL VENTILATION SYSTEMS WHICH VARIES AND BASED ON BUILDING TYPE AND LOCAL CLIMATE .
• TO STUDY THE DIFFERENT TYPES OF FUNCTIONS AND TECHNIQUES USED FOR NATURAL VENTILATION .
NATURAL VENTILATION TYPES
WIND
BUOYANCY
WIND BLOWS THROUGH INLET ON WINDWARD SIDEAND COMES OUT FROM LEEWARD SIDE FROM OPENINGS AND ROOF.AN EXPRESSION FOR THE VOLUME OF AIRFLOW INDUCED BY WIND IS:-QWIND = K X A X V, WHEREQWIND = VOLUME OF AIRFLOW (M³/H)A = AREA OF SMALLER OPENING (M²)V = OUTDOOR WIND SPEED (M/H)K = COEFFICIENT OF EFFECTIVENESS
WIND
BUOYANCY:-• BUOYANCY OCCURS WHEN DIFFERENCE IN
TEMPERATURE OF OUTDOOR AND INDOOR AIR
• IT CAN BE TEMPERATURE INDUCED :- EG. STACK VENTILATION
• OR IT CAN BE HUMIDITY INDUCED :- EG. COOL TOWER
TEMPERATURE DIFFERENCES BETWEEN WARM AIR INSIDE AND COOL AIR OUTSIDE CAN CAUSE THE AIR IN THE ROOM TO RISE AND EXIT AT THE CEILING OR RIDGE, AND ENTER VIA LOWER OPENINGS IN THE WALL.
TEMPERATURE DIFFERENCE :-
HUMIDITY INDUCED:-• THE COOL AIR IS HEAVY DUE TO ITS HUMDITY
CONTENT AND DROPS DOWN TO THE INDOOR AREA .
• IT CAN BE ACHIEVED PROPERLY WITH A COOL TOWER OR WIND CATCHER OR MALQAF AND BADGIR
• COOL TOWER VENTILATION IS ONLY EFFECTIVE WHERE OUTDOOR HUMIDITY IS VERY LOW
• NATURAL VENTILATION IS THE PROCESS OF SUPPLYING AND REMOVING AIR THROUGH A SPACE BY NATURAL MEANS IT CAN BE ACHIEVED WITH OPENABLE WINDOWS OR TRICKLE VENTS.
WHAT IS NATURAL VENTILATION ?
• NATURAL VENTILATION AND AIR MOVEMENT CAN BE SIMPLY ACHEVIED BY ‘STRUCTURAL CONTROLS’ AS IT DOES NOT DEPENDS ON ANY FORM OF EXTERNAL ENERGY SUPPLY OR MECHANICAL INSTALLATION.
SECTION SHOWING AIR FLOW
WHY NATURAL VENTILATION ?• NATURAL VENTLILATION STARTED FROM HISTORY
ACCORDING TO THE DIFFERENT CLIMATES
TYPICAL SECTION THROUGH SHAHAJAHANABAD HOUSE. TO FACILITATE THE MOMENT OF COOL AIR INTO THE HOUSE, PARAPETS ARE NOT BUIL TOWARDS THE COURTYARD
VARIOUS TECHNQUES USED IN OLD TIMES :-
DOUBLE APERTURES USED FOR ENSURING VENTILATIONIN SHAHJAHANABAD HOUSES
WINDOW FOR VIEW AND JALI VENTILATION USED ATAMBER FORT
COLUMN COURTYARD COOLING SYSTEM-DIWAN E-KHAS, RED FORT, DELHI
•
MULTI-DIRECTIONAL WINDCATCHER
WHY NATURAL VENTILATION• THEN PEOPLE STARTED
USING EXTERNAL ENERGY FOR THERMAL COMFORT.
• TIME PASSES AND IT GROWNED UP IN MORE SOPHISTICATED WAY.
WHY NATURAL VENTILATION• AND AGAIN DUE
TO ENERGY CRISES AND COMLEXITY OF INSTALLATION AND FOR THE NEW LINE OF EVOLUTION PEOPLE STARTED USING NATURAL VENTILATION
FLOW OF AIR IN KANCHANJANGA APARTMENT MUMBAI
DIFFERENT TECHNIQUES TO ACHIEVE NATURAL VENTILATION:-
• STACK EFFECT • WIND TOWER • COURTYARD EFFECT • SOLAR CHIMNEY
STACK EFFECT :-STACK EFFECT DEPENDS ON THERMAL FORCES AND DIFFERENCE IN TEMPERATURE .REASON OF STACK EFFECT :-• PRESSURE DIFFERENCE BETWEEN THE OUTSIDE AIR
AND THE AIR INSIDE THE BUILDING CAUSED BY DIFFERENCE IN TEMPERATURE
Outdoor air
Outdoor air
Section
• STACK EFFECT WORK WELL – WINTER• HIGHER THE SHAFT AND CROSS SECTION AREA GREATER THE STACK EFFECT • ‘MOTIVE FORCE’ – STACK PRESSURE• STACK PRESSURE CAN BE CALCULATED FROM:-• PS =
STACK PRESSURE IN N/M2
HEIGHT OF THE STACK IN M
TEMPERATURE DIFFERENCE IN DEG C
STACK VENTILATION SECTIONS :-
TALL ROOMS TALL ROOMS AT EDGE
STAIRS AS STACKTALL ROOMS WITHIN
WIND TOWER
• AIR ENTERS IN WIND TOWER THROUGH OPENINGS- COOLED DOWN- BECOMES HEAVIER AND SINKS DOWN ( PRESENCE OF AIR MOVEMENT)
• AFTER WHOLE DAY AIR EXCHANGE – TOWER BECOMES WARM IN THE EVENING .
• TOWER WALLS ABSORBS HEAT DURING DAYTIME AND RELASES AT NIGHT WARMING COOL NIGHT AIR AT NIGHT.
WIND TOWER
A TYPICAL WIND TOWER SECTION
EVAPORATIVE COOLING
DIFFERENT TYPES OF WIND TOWERS :-
WATER SUPPLY
MULTI DIRECTIONAL WIND CATCHER
EVAPORATIVE COOLING
EVAPORATIVE COOLING METHOD
WIND TOWER AND EVAPORATIVE TECHNIQUE USED IN INDIA :-
A VIEW OF THE WIND TOWER USED IN A HOSTEL BUILDING (JODHPUR)
VENTS CONNECTING WIND TOWER
WIND TOWER AND EVAPORATIVE TECHNIQUE USED IN INDIA :-
EVAPORATIVE COOLING SYSTEM IN TORRENT RESEARCH CENTRE, (AHMEDABAD)
SECTION OF THE BUILDING
PLAN OF THE BUILDING
COURTYARD EFFECT:-DUE TO INCIDENT SOLAR RADIATION IN A COURTYARD, AIR GETS WARMER AND RISES , COOL AIR FROM GROUND LEVEL FLOWS THROUGH THE LOWER OPENINGS
RADIATION TO SKY
LANDSCAPE OR WATER BODY
SECTION SHOWING COURTYARD EFFECT
HOW COURTYARD COURTYARD EFFECT WORK:-
IN SUCH PLACES NIGHT VENTILATION IS NOT VERY EFFECTIVE FOR COOLING AND NIGHT SKY RADIATION IS THE ONLY ANSWER.
TO FACILITATE THE MOMENT OF COOL AIR INTO THE HOUSE,PARAPETS ARE NOT BUILT TOWARDS LIVING AREA
PARAPET TOWARDS ROAD SIDE TO AVOID OUTSIDE HEAT
SECTION OF SAHAJANABAD DELHI
COURTYARD IN MODERN BUILDING :-
AMERICAN INSTITUTE OF INDIAN STUDIES (GURGAON):-
VIEW
SUNKEN COURTYARD INSIDE THE BUILDING WITH WATER BODY AND LANDSCAPE
PLAN
NATURAL VENTILATION EXTERNAL FEATURES:-
• ORIENTATION OF BUILDINGS• POSITION OF OPENINGS• CROSS VENTILATION• SIZE OF OPENINGS• OPENING TYPES
MASSING AND ORIENTATION OF BUILDING:-• AS A GENERAL RULE, THIN TALL BUILDINGS WILL
ENCOURAGE NATURAL VENTILATION AND UTILIZE PREVAILING WINDS, CROSS VENTILATION, AND STACK EFFECT.
• TALL BUILDINGS ALSO INCREASE THE EFFECTIVENESS OF NATURAL VENTILATION, BECAUSE WIND SPEEDS ARE FASTER AT GREATER HEIGHTS
Tall buildings improve natural ventilation, and in lower latitudes reduce sun exposure.
OREINTATION :-ORIENTING THE BUILDING SO THAT THE SHORTER AXIS ALIGN WITH THE PREVAILING WIND
WHILE ORIENTING IT PERPENDICULAR TO PREVAILING WINDS WILL PROVIDE THE LEAST PASSIVE VENTILATION.
OPENING SIZE:-
Pairing a large outlet with a small inlet increases incoming wind speed.
SMALL INLETLARGE
OUTLET
OPENING TYPE:-
OPENING CAN BE ANY TYPE ACCORDING TO THE BUILDING TYPE AND CLIMATIC CONDITION
CROSS VENTILATION:-
WINDOWS OR VENTS PLACED ON OPPOSITE SIDES OF THE BUILDING GIVE NATURAL BREEZES A PATHWAY THROUGH THE STRUCTURE.
SCOPE –
• TO MINIMIZE THE EXTERNAL ENERGY OR MECHANICAL SYSTEM.
• IMPLEMENTATION OF NATURAL VENTILATION SYSTEM- NATURAL DAYLIGHTING CAN BE PROVIDED.
• THERMAL COMFORT CAN BE ACQUIRED WITH LESS ECONOMICAL BUDGET
LIMITATION -
CALCULATION OF WIND THROUGH DIFFERENT TOOLS