11 passive cooling - iek.uni-stuttgart.de passive cooling.pdf · iek university of stuttgart...
TRANSCRIPT
![Page 1: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/1.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
11 PASSIVE COOLING
![Page 2: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/2.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
1. FUNDAMENTALS
11 Passive Cooling
1. � fundamentals
![Page 3: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/3.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
PASSIVE COOLING11 Passive Cooling
1. � fundamentals
• heat flows from high temperature areas to low temperature areas
• reverse flow can only be induced by feeding additional energy into the thermal system
• passive cooling seeks to use natural heat flows whenever possible
• strategies:
� reduce heat gains (internal and � external)
� open a high-to-low temperature heat � flow path to divert the excess heat � (heat removal into a suitable heat sink)
higher
temperature
lower
temperature
lower
temperature
higher
temperature
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iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
PASSIVE COOLING
• available natural heat sinks:
� ambient air (ventilation)
� evaporative cooling (adiabatic)
� radiative cooling (deep night sky)
• although limited in their capacity:
• important first steps towards reducing cooling loads
• hence: passive cooling
11 Passive Cooling
1. � fundamentals
![Page 5: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/5.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
2. SPECIFICS OF COOLING
11 Passive Cooling
1. � fundamentals2.� specifics of cooling
![Page 6: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/6.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
SPECIFICS OF COOLING11 Passive Cooling
1. � fundamentals2.� specifics of cooling
• crucial to passive heating: access to solar energy during winter
• crucial to passive cooling: availability of heat sinks for heat rejection and redirection
• important limiting factor: humidity
� high humidity limits evaporative � cooling to high temperatures
� haze blocks radiative cooling to the � night sky
![Page 7: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/7.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
SPECIFICS OF COOLING11 Passive Cooling
1. � fundamentals2.� specifics of cooling
• crucial to passive heating: reducing heat losses by means of
� thermal insulation
� low infiltrations
• crucial to passive cooling: blocking heat gains by
� solar radiation (windows!)
� internal heat sources
� latent sources (humidity)
� ... AND USING HEAT SINKS
• temperature differential beween indoor and outdoor air is smaller for cooling purposes
� hence: smaller impact of conduction and � infiltration
![Page 8: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/8.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
3. COOLING MECHANISMS
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms
![Page 9: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/9.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
COOLING MECHANISMS11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms
• relative humidity: measure of concentration of water vapour
• expressed as a percentage of the water vapour air can hold at a particular temperature
• sensible heat: associated with change in air temperature
• latent heat: associated with change in the moisture content of air
• dewpoint temperature: temperature at which water vapour begins to condensate (relative humidity 100%)
![Page 10: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/10.jpg)
INSTITUTE OF DESIGN AND CONSTRUCTION • UNIVERSITY OF STUTTGART Prof. José Luis Moroiekpsychrometric chart
![Page 11: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/11.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
COOLING MECHANISMS11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms
• average residential building:
� 60 to 80% sensible heat gains
� 40 to 20% latent heat gains
• cooling strategies need to deal with both types of loads
![Page 12: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/12.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
4. THERMAL COMFORT IN HOT CLIMATES
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates
![Page 13: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/13.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
THERMAL COMFORT11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates
• human thermal comfort:
� when heat flows in the human thermal � system are balanced
� when the internal body temperature is � near 37° C
• permanent internal heat production of 100 W
• feeling hot: when heat is absorbed and produced faster than it is lost
• in that case, bodily responses set in like:
� perspiration (evaporative cooling)
� additional blood flow to skin surface
� lethargic feeling to reduce activity
![Page 14: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/14.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
THERMAL COMFORT
• environmental determinants of comfort:
� air temperature
� relative humidity
� air motion
� mean radiant temperature (MRT)
• any combinations of these are liable to produce the required comfort
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates
![Page 15: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/15.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
5. REDUCTION OF COOLING LOADS
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads
![Page 16: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/16.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
REDUCTION OF COOLING LOADS11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads
• main heat flows in a building:
� conduction through the building envelope
� ventilation
� unintended infiltration
� solar heat gains through windows
� internal heat generation
![Page 17: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/17.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
REDUCTION OF COOLING LOADS
CONDUCTION
• thermal conduction: sensible loads dependent on differential between indoor and outdoor air temperatures
• conduction cooling loads thus increased by solar gains on the outside surface of the envelope (increased temperature differential)
• influencing factors:
� temperature difference across the envelope‘s section � (delta T)
� insulating characteristics of the section
� thermal capacitance of internal masses
• control of conduction heat gains through:
� adding insulation
� reducing the surface area (A/V-ratio)
� reducing the temperature of the exteriour surface
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction
![Page 18: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/18.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
REDUCTION OF COOLING LOADS
INFILTRATION, VENTILATION
• infiltration, ventilation cooling load are the result of the flow of warmer and more humid air into the building (both sensible and latent heat components)
• when internal heat and solar gains drive the indoor temperature above the outdoor temperature, infiltration and ventilation may reduce cooling loads
• since infiltration is hardly controllable it should be curtailed (infiltration barrier)
• however, ventilation (natural or forced) needs be controllable to allow for minimum hygienic air exchange and for necessary cooling
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation
![Page 19: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/19.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
REDUCTION OF COOLING LOADS
SOLAR LOADS
• solar loads affect both opaque and glazed surfaces
• however, gains through glazed surfaces significantly exceed those through opaque walls
• hence, orientation and size of transparent or translucent surfaces are to be carefully designed
• since solar gains through windows are desirable in winter, glazed surfaces should be adaptive (solar protection)
• horizontal, east and west oriented glass produces the largest cooling loads, south oriented the least
• external shading is the most efficient method to reduce solar loads
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads
![Page 20: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/20.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
REDUCTION OF COOLING LOADS
INTERNAL HEAT GAINS
• internal heat gains are due to:
� presence of people
� mechanical and electrical equipment
• sensible gains: e. g. light bulb
• latent gains: e. g. human respiration, bathing, gas combustion (water vapour)
• excess lighting due to solar shading increases cooling loads significantly (paradox)
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains
![Page 21: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/21.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
6. VENTILATION FOR COOLING PURPOSES
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes
![Page 22: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/22.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
VENTILATION FOR COOLING PURPOSES11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes• ventilation provides cooling by carrying away
heat by means of moving air (natural or forced movement)
• may involve either the building (open sys-tem) or the human body (closed system)
• prerequisite: outdoor air temperature must be below indoor air temperature (building cooling)
• atmosphere is a heat sink with virtually unlimited capacity
• buildings can be ventilated at night when the ambient air is cool to take advantage of the storing effect of thermal masses (heat sink)
![Page 23: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/23.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
VENTILATION FOR COOLING PURPOSES
• main ventilation mechanisms available:
� wind-driven ventilation
� stack-effect ventilation
� forced ventilation (electric fans)
� solar chimneys
� ceiling and space fans
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes
![Page 24: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/24.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
VENTILATION FOR COOLING PURPOSES
WIND-INDUCED VENTILATION
• air movement is induced by air pressure differential between windward and leeward sides of the building
• amount of wind-induced flow is proportional to window area
• fully-opening windows (casement, awning windows) are convenient
• architectural features like wind towers (e. g. malqaf, badgir) may benefit the cooling effect
+-
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes6.1� wind-induced ventilation
![Page 25: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/25.jpg)
INSTITUTE OF DESIGN AND CONSTRUCTION • UNIVERSITY OF STUTTGART Prof. José Luis Moroiek
traditional type of malqaf ventilation
![Page 26: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/26.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
VENTILATION FOR COOLING PURPOSES
STACK-EFFECT VENTILATION
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventilation
• warmer air lis lighter and thus more buoyant than cooler air
• the temperature differential (stacking) induces a forced upward flow
• comparatively weak form of ventilation with small flow volumes
• especially adequate for large hall-like spaces
warm
cool
![Page 27: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/27.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
VENTILATION FOR COOLING PURPOSES
FORCED VENTILATION
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventilation6.3� forced ventilation
• most consistently effective means of providing ventilation
• relatively small amount of energy required for operation
interiour fans provide air circulation inside:
� remove heat from the occupants
� without changing the indoor air temperature
• potential problems: excess air speed and noise
![Page 28: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/28.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
VENTILATION FOR COOLING PURPOSES
INTERIOUR THERMAL MASS COOLING
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventilation6.3� forced ventilation6.4� interiour thermal mass cooling
• extensively used to:
� store excess heat during the day
� release it at night
• however: lack of large temperature differential
• driving force: day-to night variation in ambient temperature (benefits the cooling effect)
• hence: increased air circulation during nighttime required (nocturnal ventilation)
• thermal masses increase nighttime indoor temperatures (as compared to lightweight construction)
• exposed thermal mass surfaces required
![Page 29: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/29.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
VENTILATION FOR COOLING PURPOSES
SOLAR CHIMNEYS
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventilation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys
• solar chimneys are stack-effect ventilators
• driving force: passive solar heat
• also called: solar-enhanced ventilators
• inlet draws air from indoors
• outlet discharges to the outdoors
• as indoor air evacuates, (cooler) outdoor air flows into the building
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University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
7. EVAPORATIVE COOLING
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventilation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling
![Page 31: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/31.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
EVAPORATIVE COOLING11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventilation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling
• by evaporation of water the sensible heat content decreases
• heat is absorbed by the phase change of water (liquid to gaseous)
• hence, moisture content of the air rises
• dry ambient air is beneficial to this process
• limit of the cooling process: when relative humidity reaches the saturation point (100%)
• direct evaporative cooling: misting of the inlet air
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University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
8. RADIATIVE COOLING
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventilation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling8. � radiative cooling
![Page 33: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/33.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
RADIATIVE COOLING11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventilation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling8. � radiative cooling
• outer space has a constant temperature near absolute zero, i. e. -273° C
• although warmer, the sky all the same provides a suitable natural heat sink for cooling
• heat is rejected through radiation heat transfer
• a temperature differential is necessary for this effect to develop
• unobstructed direct line between radiant objects is required (to ,see‘ each other)
• clear, dry climates are beneficial
![Page 34: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/34.jpg)
iek
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
RADIATIVE COOLING
• architectural applications:
� sleeping on terraces
� roof pond cooling
� � water surface radiates heat to � � the night sky
� � open water ponds or
� � large bags of water (sprayed)
� � movable insulation panels � � during daytime
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventilation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling8. � radiative cooling
![Page 35: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/35.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads5.1� conduction5.2� infiltration, ventilation5.3� solar loads5.4� internal heat gains6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventilation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling8. � radiative cooling
closing of the umbrellas in the courtyard of the Mosque in
Madinah in the evening in order to benefit from the
nightly radiation to the cool deep sky
1
2
3
![Page 36: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/36.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
9. HEAT PUMPS
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventliation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling8. � radiative cooling9.� heat pumps
![Page 37: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/37.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
/cooling
/cooling
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventliation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling8. � radiative cooling9.� heat pumps
basic working principle of a heat pump for cooling or heating purposes
![Page 38: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/38.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventliation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling8. � radiative cooling9.� heat pumps9.1� air-source heat pumps
basic working principle of an air-source heat pump for cooling or heating purposes
![Page 39: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/39.jpg)
INSTITUTE OF DESIGN AND CONSTRUCTION • UNIVERSITY OF STUTTGART Prof. José Luis Moroiek
![Page 40: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/40.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventliation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling8. � radiative cooling9.� heat pumps9.1� air-source heat pumps9.2� water-source heat pumps
basic working principle of a water-source heat pump for cooling or heating purposes
![Page 41: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/41.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventliation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling8. � radiative cooling9.� heat pumps9.1� air-source heat pumps9.2� water-source heat pumps
![Page 42: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/42.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventliation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling8. � radiative cooling9.� heat pumps9.1� air-source heat pumps9.2� water-source heat pumps9.3� earth-coupled heat pumps
![Page 43: 11 PASSIVE COOLING - iek.uni-stuttgart.de passive cooling.pdf · iek University of Stuttgart Institute of Design and Construction Prof. J. L. Moro PASSIVE COOLING 11 Passive Cooling](https://reader030.vdocument.in/reader030/viewer/2022040701/5d61d9ae88c9933b078b5478/html5/thumbnails/43.jpg)
University of Stuttgart
Institute of Design and Construction
Prof. J. L. Moro
iek
11 Passive Cooling
1. � fundamentals2.� specifics of cooling3.� cooling mechanisms4.� thermal comfort in hot
climates5.� reduction of cooling loads6.� ventilation for cooling
purposes6.1� wind-induced ventilation6.2� stack-effect ventliation6.3� forced ventilation6.4� interiour thermal mass cooling6.5� solar chimneys7.� evaporative cooling8. � radiative cooling9.� heat pumps9.1� air-source heat pumps9.2� water-source heat pumps9.3� earth-coupled heat pumps