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Application of Passive SolarSystem in Building
Dr.(Er.) Bharat R. Pahari [B.E.(Civil), M.Sc.engg (Energy Efficiency), Ph.D.(Eng.Edu.)]
Associate ProfessorDepartment of Civil Engineering,
Institute of Engineering/TU, Pulchowk.
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Basic Concept
Passive design is the process of efficient use ofenergy.
This can be achieved by the economic use ofresources in harmony with environment.
A substantial part of world energy consumption isfrom the buildings.
Passive design takes maximum advantages of solarenergy in buildings.
The example of energy conservation are built withthick walls, built in cluster, roof with mud & sun-dried tiles, open water surfaces, vegetation growthetc.
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Basic Concept
The use of this natural sun-energy direct or indirectin the building is the concept of passive design.
Passive solar design can never negate the impactof climate, but it can only minimise.
The word " passive" emphasises on the control ofthe flow of thermal energy by natural means. Itassumes the building as a natural collector.
"Active" system in the other hand is a system
where external energy (Electrical or mechanical) isused to run the system in order to transfer theheat from one place to other.
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Heating & Cooling in Building
Passive systems provide heating and coolingby using natural energy sources and sinks.
The basic heat gains: Solar radiation
Outside air when warmer than 270C (averageambient temp.)
Internal gains, conventional domestic heatingand lighting
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Heating & Cooling in Building
The main sinks:
The sky and outer space,
Outside air when cooler than 270C(average ambient temperature)
Wet surfaces and vegetation
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The Heat Gains and Losses
Sun
Air
Temp>270C
Day
Hot surface
Sources of Heat gains
Air
Temp
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Basic Assumptions of Passive Design
The purpose of the natural heating andcooling methods is to provide a comfortableinternal environment.
For this, the external building envelope canbe considered as a membrane that protectsthe indoor space from undesirable climaticinfluences.
It is focused on the energy saving taking into consideration the climatic factors and inharmony with the environment.
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Basic Assumptions of Passive Design
The external envelope will filter-out theworst climatic element in one side and inother side also interacts with out-door
environment to let-in as much radiation aspossible for the natural heating or removeseven internally generated heat for naturalcooling of the building.
The sun and the climate are the centrepoint of passive design and concerns withthe thorough study of the climatic factors.
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Mode of Passive Heating & Cooling
Direct gain A large expansion of vertical south facing
glass window usually double glazed admitsthe sun's rays, alloying them to strike themasonry floor and /or wall, which acts asthermal storage.
The thermal energy stored in theseelements is distributed to the living spaceby radiation, by convection of room airover the warm surfaces and by conduction.
A correctly designed mass can containinternal temperature swings to 100 C.
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Mode of Passive Heating & Cooling
Direct gain
Solar Radiation
Sunshade to
obstruct solar
radiation during
summer
Curtain to
obstruct during
summer & to
provide access
during winter the
solar radiation
inside buildingHeat conserving
Materials
Glass
window in
south facing
House
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Mode of Passive Heating & Cooling
Thermal storage wall This heating mode blocks and collects solar radiation outside
the living space by creating a thermally massive wall betweenit and the sun.
Heat is stored in this thermal mass and distributed to the
living space by re-radiation through the back of the wall,and/or by convection of cool room air passing the warm faceof the mass by natural thermo-siphoning.
This thermo-siphoning effect is created on the sunny face ofthe wall by placing a glazed screen about 50 mm away fromthe wall face, punching holes in the top and bottom of the
wall, and letting room air naturally thermo-siphon and becomewarm. Honeycomb masonry walls are Trombe walls. Horizontally stacked drums of water are Drum wall, Vertical tubes of water are water wall.
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Mode of Passive Heating & Cooling
Horizontal drums of waterAbsorbing solar heat
Vertical masonry wallabsorbing solar heat
Vertical Tubes ofwater absorbing solarheat
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Mode of Passive Heating & Cooling
Glass window in
front of Trombe
wall
House
SolarRadiation
Sunshade to
obstruct solar
radiation during
summer
Glass window in
front of Trombe
wall
Trombe wall
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Mode of Passive Heating & Cooling
Solar green house
This heating mode is the further development of Trombewall, but the space between the glass and the wall hasbeen widened to form a green house.
The greenhouse provides not only a means of heatingbut also a usable living space and the opportunity togrow food and flowers.
Solar green house may be made with; Glazed wall between green house and living space
Massive wall between green house and living space Small green house used as entry porch
Green house cover on the stair
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Mode of Passive Heating & Cooling
Glazed wall betweengreenhouse & living space
Massive wall betweengreenhouse & living space
Small greenhouse used asentry porch
Solar green house
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Mode of Passive Heating & CoolingSolar green house
Solar
Radiation
Glass roof in
front of trombe
wall
Trombe
wall
Glazed window
and Glass roof
on South facing
house
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Mode of Passive Heating & Cooling
Roof pond
This heating mode transfers thethermal storage to the roof.
It consists of plastic bags of waterthat are supported on a steel deckroof or RCC construction on theroof.
Control is affected by the
positioning of the movableinsulating shutters that are locatedabove the water bags or pond.
Roof pond
Pond
Pondcover
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Mode of Passive Heating & Cooling
Roof pondSolar Radiation
Pond or
water drums
condition of
closed covering
condition of
opened covering
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Mode of Passive Heating & Cooling
Convective loop In this system an angle solar
collector heats a transportfluid (that can be either air or
water) and, by a thermo-siphoning loop, allows it torise to a thermal storelocated above the collector.
After transferring its heat tothe store, the fluid continuesdown to re-enter the base ofthe collector.
Convective loop
Air space orliquid spaceheating system
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Solar Chart
Solar chart is a graphical representation of the path ofsun in the sky for various days in the year of theparticular latitude.
The hemisphere of the sky is represented by a circularplane diagram, the centre of which represents the
zenith and the outer circumference represents thehorizon line.
The various line of compass are shown alone thecircumference of the chart and the altitude angles arerepresented by concentric circles, the outermostcircumference denoting zero and the centre denoting
900 of altitude. Solar chart can establish the sun's position in the sky
hemisphere.
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Reference angles
i = Incidence angle, a =Altitude Angle, =Azimuth angle
a
i
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Solar Chart..\..\climatic design tools\drawsunpath.exe
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Solar Chart & Its use
Uses of solar charts
The basic use of the solar chart is to findthe position of sun in the sky hemisphere.
This is very important; To determine the intensity of solar radiation,
To design shading device (shape and size) in tothe building,
To define the angle of incidence of solarradiation
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Shading Devices
The devices that are used to block the solar radiationincident on the exposed surfaces of a building,consequently reducing heat gain, are called shadingdevices,
Shadings are normally done in the openings,
The shading devices may be internal or external andthey may be fixed, adjustable or retractable,
The internal devices may be venetian blinds, rollerblinds and curtains,
The external shading devices are much more effective
than the internal arrangement, It is true that more than 90% of heating effect ofsolar radiation is possible to eliminate with efficientuse of the shading devices
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Types of external devices
Vertical devices
Horizontal devices
Horizontal shadow angle
= horizontal shadow angle
= horizontal
shadow angle
= vertical shadowangle
a = solar altitudeangle
tan = tan a * sec
Vertical shadow angle
a
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Types of external devices
Egg-crate devices
Inclined devices
Normallouver
Inclinedlouver
Window
Wall
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Passive techniques in housing
Heat gain prevention techniques Orientation of building
Shading by neighboring buildings
Shading by vegetation/pergolas Shading by overhangs and louvers
Special construction of wall
Solid wall
Mud wall Cavity wall
Textured wall surface
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Orientation of building
Bad Fair Best
N
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Shading by neighboring buildings
BuildingBuilding
Building
Building
Shadow
Shadow
Shadow
Shadow
House enclosed with verandah
Building
Verandah
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Shading by vegetation
Hot air escape
Verandah
Air buffer
Moisture
Slow evaporation
Shady tree
Protection from solar radiation
Room space
Brick wall
RCC slab
Roof shading by Pergolas
Radiation ShadingPartly
RadiationEvaporation
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Shading by overhangs
shade
Roof projection
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Shading by overhangs
House enclosed with verandah
Building
Verandah
Rooms
Ve
r
a
n
dah
Courtyard
Courtyard House
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Special construction of wall
Solid wall
Brick wall
Cavity wall
CavityBrick wall
Cementplaster
Mud wall
Mud wall
Cementplaster
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Textured wall surface
Textured wall surface
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Design toolsFlow chart of the Energy efficient Building Planning
Building planning
Site planning
1. Energy conservation
3. Active spaceheating/cooling modes
2. Passive spaceheating/cooling modes
1. Energy conservation
3. Active spaceheating/cooling modes
2. Passive spaceheating/cooling modes
Energy efficient
Building Planning
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Design tools
h
8h
Spacing for wind deflection
Vegetable shading
VentilationInsulating earth berming
BERMING for added insulation and wind
Site Planning
Energyconservation
Passive spaceheating/cooling
Bad Fair Best
N
250250S
* 150 for due south obstruction* 100 for any other obstructions
N-Maximize in south-Minimize in north, east, west
Layout
Shape
OrientationSpacing
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Design tools
Building Planning
Energyconservation
Passive space
heating/cooling
InsulationVentilationTemporary zoningWindowsLightingBuilding volume
ColorDomestic hot water
GeneralDirect gainThermal storage wallSolar green houseRoof pondConvective loop
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Thank you