solar passive designs in architecture
TRANSCRIPT
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SUSTAINABLE ARCHITECTURE-SEM IX
SUBMITTED BY:
TEJASI GADKARI
30/08
ASSIGNMENT-2
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Q1. Explain the various solar passive design concepts in architecture.
Passive solar design integrates a combination of building features to reduce or even
eliminate the need for mechanical cooling and heating and daytime artificial lighting.
In passive solar building architecture, windows, walls, and floors are made to collect,
store, and distribute solar energy in the form of heat in the winter and reject solar
heat in the summer. This is called passive solar design or climatic design because,
unlike active solar heating systems, it doesn't involve the use of mechanical and
electrical devices.
The key to designing a passive solar building is to best take advantage of the local
climate. Elements to be considered include window placement and glazing type,
thermal insulation, thermal mass, and shading. Passive solar design techniques can
be applied most easily to new buildings, but existing buildings can be adapted or
"retrofitted".
PASSIVE SOLAR ENERGY
Direct gain is solar radiation that directly penetrates and is stored in the living space.
Indirect gain collects, stores, and distributes solar radiation using some thermal storage
material (e.g., Tromb wall). Conduction, radiation, or convection then
transfers the energy indoors.
Isolated gain systems (e.g., sunspace) collect solar radiation in an area that can be selectively
closed off or opened to the rest of the house.
DIRECT GAIN INDIRECT GAIN ISOLATED GAIN
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The scientific basis for passive solar building design has been developed from a
combination of:
Climatology
Thermodynamics (particularly heat transfer),
Human thermal comfort (for buildings to be inhabited by humans and animals).
Site and location of the dwelling
Prevailing level of rain
Design and construction Solar orientation
Placement of walls
Incorporation of biomass.
Various climatic factors that affect the solar passive design are: wind velocity, ambient
temperature, relative humidity and solar radiation. For a particular climate suitable
combination of solar passive techniques are required to be selected to obtain the
highest possible comfort at the lowest possible expenditure for material and energy.
KEY PASSIVE SOLAR CONCEPTS DIRECT SOLAR GAIN
INDIRECT SOLAR GAIN
ISOLATED SOLAR GAIN
HEAT STORAGE
INSULATION AND GLAZING
PASSIVE COOLING
1.DIRECT GAIN:
Direct gain attempts to control the amount of direct solar radiation reaching theliving space. This direct solar gain is a critical part of passive solar house design as
it imparts to a direct gain.
2.INDIRECT GAIN attempts to control solar
radiation reaching an area adjacent but not part
of the living space.
Heat enters the building through windows and is
captured and stored in thermal mass (e.g. water
tank, masonry wall) and slowly transmitted
indirectly to the building through conduction and
convection.
Efficiency can suffer from slow response (thermal
lag) and heat losses at night. Other issues include
the cost of insulated glazing and developing
effective systems to redistribute heat throughout
the living area.
DAY NIGHT
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3.ISOLATED SOLAR GAIN:
Isolated gain involves utilizing solar energy to
passively move heat from or to the living space
using a fluid, such as water or air by natural
convection or forced convection.
Heat gain can occur through a sunspace,
solarium or solar closet. These areas may
also be employed usefully as a greenhouse ordrying cabinet. Glass placement and
overhangs prevent solar gain during the
summer. Earth cooling tubes or other passive
cooling techniques can keep a solarium cool in
the summer.
Measures should be taken to reduce heat loss at
night by providing window coverings or movable
window insulation.
4.HEAT STORAGE
The sun does not shine all the time. Heat storage, or thermal mass keeps the building
warm when the sun cannot heat it.
In buildings in warm regions, the storage is designed for one or a few days. The usual
method is a custom-constructed thermal mass. These include a Trombe wall, a
ventilated concrete floor, a cistern, water wall or roof pond.
In subarctic areas, or areas that have long terms without solar gain (e.g. weeks of
freezing fog), the ground is used as thermal mass large enough for annualised heat
storage by running an isolated thermosiphon under the building.
5.INSULATION AND GLAZING
a.Special glazing systems and window coverings
The effectiveness of direct solar gain systems is significantly enhanced by
insulative (e.g. double glazing), spectrally selective glazing (low-e), or movablewindow insulation (window quilts, interior insulation shutters, shades, etc.).
Generally, Equator-facing windows should not employ glazing coatings that
inhibit solar gain.
b.Equator facing glass
The requirement for vertical equator-facing glass is different from the other
three sides of a building. Reflective window coatings and multiple panes of
glass can reduce useful solar gain.
However, direct-gain systems are more dependent on double or triple glazing
to reduce heat loss. Indirect-gain and isolated-gain configurations may still be
able to function effectively with only single-pane glazing. Nevertheless, the
optimal cost-effective solution is both location and system dependent.
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c.Roof-angle glass / Skylights
Skylights admit sunlight either horizontally (a flat roof) or pitched at the same
angle as the roof slope. In most cases, horizontal skylights are used with
reflectors to increase the intensity of solar radiation depending on the angle
of incidence.
Large skylights should be provided with shading devices to prevent heat loss
at night and heat gain during the summer months.
d.Angle of incident radiationThe amount of solar gain transmitted through glass is also affected by the
angle of the incident solar radiation.
Sunlight striking glass within 20 degrees of perpendicular is mostly transmitted
through the glass, whereas sunlight at more than 35 degrees from
perpendicular is mostly reflected.
e. Operable shading and insulation devices
A design with too much equator-facing glass can result in excessive winter,
spring, or fall day heating, uncomfortably bright living spaces at certain times ofthe year, and excessive heat transfer on winter nights and summer days.
Variable cloud cover influences solar gain potential. This means that besides
latitudespecific fixed window overhangs, other seasonal solar gain control
solutions are required.
Control mechanisms (such as manual-or-motorized interior insulated drapes,
shutters, exterior roll-down shade screens, or retractable awnings) can
compensate for differences caused by thermal lag or cloud cover, and help
control daily / hourly solar gain requirement variations.
PASSIVE COOLINGa.Exterior colours reflecting - absorbing
Materials and colours can be chosen to reflect or
absorb solar thermal energy.
The thermal radiation properties of reflection or
absorption of a colour can assist the choices of
cool colours.
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WORKING
During summer the vent A at the top of the south-facing wall is kept closed while the
vents B, C and D are opened. The hot air between the glazing and the wall then flows
out through the vent C and the air from room flows in to fill this space. Simultaneously,
the air is pulled into the room through the vent D which is located in the shaded cool
area.
The construction of the building is such that the overhanging roof prevents direct
sun rays to heat the glazing during summer
Generally, thickness of storage wall is between 200 mm to 450 mm, the air gap
between the wall and glazing is 50-150 mm, and the total area of each row of vent is
about one percent of the storage wall area.
The Trombe wall should be adequately shaded for reducing summer gains.
B.WATER WALL
Water walls are based on the same
principle as that for Trombe walls, except
that they employ water as the thermal
storage material. A water wall is a thermal
storage wall made up of drums of water
stacked up behind glazing. It is usually
painted black to increase heat absorption.
It is more effective in reducing temperatureswings but the time lag is less.
Heat transfer through water walls is much
faster than that for Trombe walls.
Therefore, the distribution of heat needs to
be controlled if it is not immediately
required for heating the building. Buildings
that work during daytime, such as schools
and offices, benefit from the heat transferin the water wall. Overheating during
summer may be prevented by using
suitable shading devices.
Direct gain interior - A direct gain designwith an interior water wall for heat storage.
Heat stored in the water wall is radiated
into the living space at night.
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C. ROOF-BASED AIR HEATING SYSTEM
In this technique, incident solar radiation is trapped by the roof and is used for
heating interior spaces. In the northern hemisphere, the system usually consists of
an inclined south-facing glazing and a north-sloping insulated surface on the roof.
Between the roof and the insulation , an air pocket is formed , which is heated by
solar radiation.
A moveable insulation can be used to reduce heat loss through glazed panes duringnights. There could be variations in detailing of roof air heating systems.
D.SOLARIUM
A sunspace or solarium is the combination of direct and indirect gain systems. Solar
radiation heats up the sunspace directly, which, in turn, heats up the living space
(separated from the sunspace by a mass wall) by convection and conduction through
the mass wall.
The basic requirements ofbuildings heated by sunspace
are:
(1) a glazed-south facing
collector space attached yet
separated from the building
(2) living space separated
from the sunspace by a
thermal storage wall.Sunspaces may be used as
winter gardens adjacent to
the building space.
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E. SOLAR CHIMNEY
Solar chimney is an air-heating solar collector attached to the south wall of the building.
As the air in the solar collector is heated, it expands rises and enters the house. Cooler
house air is drawn into the collector to take its place.
Solar chimneys avoid many of the problems of direct gain systems, such as glare and
heat loss. But the disadvantage is that like direct gain, too large a system may result in
higher than normal temperature within the rooms. Careful construction is required to
ensure proper efficiency and durability.
ADVANCED PASSIVE COOLING TECHNIQUES
Passive cooling systems rely on natural heat-sinks to remove heat from the building.
They derive cooling directly from evaporation, convection, and radiation without using
any intermediate electrical devices. All passive cooling strategies rely on daily
changes in temperature and relative humidity.
1. VENTILATION
Outdoor breezes create air movement
through the house interior by the push-
pull effect of positive air pressure on the
windward side and negative pressure
(suction) on the leeward side.
Good natural ventilation requires
locating openings in opposite pressure
zones. Also, designers often choose to
enhance natural ventilation using tallspaces called stacks in buildings.
With openings near the top of stacks,
warm air can escape whereas cooler air
enters the building from openings near
the ground.
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2. WIND TOWER
In a wind tower, the hot air enters the tower through the openings in the tower, gets
cooled, and thus becomes heavier and sinks down. The inlet and outlet of rooms induce
cool air movement.
In the presence of wind,air is cooled more effectively and flows faster down the tower and
into the living area.
After the whole day of air exchanges, the tower becomes warm in the evenings.During the
night, cooled ambient air comes in contact with the bottom of the tower through the rooms.
The tower walls absorb heat during day time and release it at night, warming the cool night
air in the tower. Warm air moves up , creating an upward draft , and draws cool night air
through the doors and windows into the building. The system works effectively in hot and
dry climates where diurnal variations are high.
A wind tower works
well for individual units
but not for multi-
storeyed apartments.
In dense urban areas,
the wind tower has to be
long enough to be ableto catch enough air.
3.COURTYARD EFFECT
Due to incident solar radiation in a courtyard, the
air gets warmer and rises. Cool air from the ground
level flows through the louvered openings of
rooms surrounding a courtyard, thus producing air
flow.
At night, the warm roof surfaces get cooled by
convection and radiation. If this heat exchange
reduces roof surface temperature to wet bulb
temperature of air, condensation of atmospheric
moisture occurs on the roof and the gain due to
condensation limits further cooling.
If the roof surfaces are sloped towards the internal
courtyard, the cooled air sinks into the court andenters the living space through low-level
openings. However, care should be taken that the
courtyard does not receive intense solar radiation,
which would lead to conduction and radiation heat
gains into the building. Intensive solar radiation in
the courtyard also produces immense glare.
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4 .EARTH AIR TUNNELS
Daily and annual temperature fluctuations decrease with the increase in depth below the
ground surface. At a depth of about 4m below ground, the temperature inside the earth
remains nearly constant round the year and is nearly equal to the annual average temperature
of the place.
A tunnel in the form of a pipe or otherwise embedded at a depth of about 4 m below the
ground will acquire the same temperature as the surrounding earth at its surface and,therefore, the ambient air ventilated though this tunnel will get cooled in summer and
warmed in winter and this air can be used for cooling in summer and heating in winter.
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5.EVAPORATIVE COOLING
Evaporative cooling lowers indoor air temperature by evaporating water. It is effective in
hot and dry climate where the atmospheric humidity is low.
In evaporating cooling,the sensible heat of air is used to evaporate water, thereby cooling the
air, which,in turn, cools the living space of the building. Increase in contact between water
and air increases the rate of evaporation.
The presence of a water body such as a pond, lake and a sea near the building or a fountain
in a courtyard can provide a cooling effect.
The most commonly used system is a desert cooler, which comprises water, evaporative
pads, a fan, and pump.
6.PASSIVE DOWNDRAUGHT COOLING
Evaporative cooling has been used for many centuries in parts of the Middle East, notably
Iran and Turkey.
In this system, wind catchers guide outside air over waterfilled pots, inducing
evaporation and causing a significant drop in temperature before
the air enters the interior.
Such wind catchers become primary elements of the
architectural form also. Passive downdraught evaporative cooling is particularly
effective in hot and dry climates.
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7. EARTH BERMING
Since the ground is nearly always cooler than the air, in the month when cooling is required,
the more a house is in contact with the ground, the cooler it will be.
8. ROOF PONDS
Roof ponds can be used both for heating during the winter months and for cooling during
the summer months. The roof ponds of contained water are the heating (and cooling)
unit.
The movable insulation above the ponds is the weather protection, winter time heating is
comprised of daytime opening the insulating roof layer to allow solar radiation to heat the
water bed; water bed warming heats the supporting structure which is also the ceiling for
spaces below; heated support structure radiates heat to the space.
At night the insulated roof panels close to contain heat gathered by the ponds to continue
heating the spaces below. Cooling strategies are the opposite operation.
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Q2.What is the role of sustainable architecture in conserving natural resources?
Buildings produce half of all greenhouse gases and account for one-sixth of the
world's freshwater withdrawals, one-quarter of its wood harvest and two fifths of its
material and energy flows.
By several estimates, we will double the size of the built environment over the next
twenty to forty years. For these reasons there is a critical and immediate need to shift
thinking on how the built environment is designed.
Building principles have to be changed
To reduce environmental impact,
To protect public health
To improve environmental equity and Justice
OBEJECTIVES OF SUSTAINABLE DEVELOPMENT
Preserving, protecting and improving the quality of the environment.
Rational utilization of natural resources.
Protecting human health.
Promoting measures at international level to deal with environmental problems.
Sustainable architecture should be seen and perceives as a process and a vehicle
towards achieving sustainable development. This process is governed by set of
principles and patterns, which form a more comprehensive design matrix for architects
and planners.
PRINCIPLES OF SUSTAINABLE ARCHITECTURE
Design for low environmental impact (locally, regionally and globally). Continuous learning from vernacular and primitive architecture
The use of local materials and indigenous building sources.
Regulation of energy efficient design principals.
The use oflabor-intensive rather than energy-intensive construction techniques.
Standards that would discourage construction in ecologically inappropriate areas.
Exploration of methods to encourage and facilitate the recycling and reuse of building
materials, especially those requiring intensive energy consumption in their
manufacture.
The use of clean technologies.
The use of appropriate building technologies (ABT).
Use of environment-friendly materials and processes which seek to have the
minimum impact upon the environment throughout their life-cycle (manufacture, use,
disposal).
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BENEFITS OF SUSTAINABLE ARCHITECTURE
1.STRONGER SOCIAL NETWORKS
Development of sustainable buildings restores the nations
resources, revitalizing the towns and states. Local
transportation of materials reduces air emissions and
petroleum consumption, therefore reducing ones
dependence on foreign oil.
Besides, locally produced and purchased materials result
in decreased transportation costs and yield financial as
well as environmental benefits.
2.HIGH PERFORMANCE BUILDINGS REDUCE
OPERATING AND MAINTENANCE COST
High efficiency water fixtures dramatically cut water
consumption levels. Additionally, gray water systems
filter and reuse water (in toilets and for landscaping).
Fewer light fixtures and the use of motion sensors and
timing devices decreases energy consumption.
Also, installing compact fluorescent light bulbs is
useful as they last longer and they do not need regular
bulb changes. Increased use of daylight improves
employee morale and reduces energy operating costs.
3.REDUCE THE IMPACT ON THE NATURAL ENVIRONMENT:-
Reuse of land for an infill development project reduces the impact of additional roads and
sewers on the environment and promotes walking and transit use.
Conscientious construction methods divert tons of waste materials from landfills and minimize
site disturbance. Informed choice of building materials reduces the demand on natural resources
and can improve the quality of the building.
Storm water reuse reduces the demand for potable water and municipal groundwaterwithdrawals. Smart growth helps protect green and open spaces as well as reduce sprawl which
results in occupants not commuting as far, in turn reducing vehicle emissions. The use of
renewable wood and recycled content materials is encouraged. Reduced energy consumption
means fewer power plant emissions.
Land infill
development in
North Camden
,New Jersey
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SUSTAINABLE ARCHITECTURE-TECHNIQUES
SITE: The layout and design of a building and grounds has an impact on energy and water
consumption. A well-planned site will preserve much of the natural vegetation, increase the
energy efficiency of the building, and reduce the amount of storm water leaving the site.
EXCAVATION: In addition the amount of excavation required can be reduced, thus reducing
construction costs and environmental impacts of the construction process. A comprehensive
site design can save money and increase the appeal of a property.
CARBON EMISSION: By implementing efficient technologies that save water and energy,
developers, homeowners, and businesses can protect the environment while saving money.
Every kilowatt (kW) of power that is not consumed reduces energy bills and decreases the
amount of carbon dioxide and other pollutants released into the environment during the
generation process.
WATER CONSERVATION: Because toilets represent a homes largest water consuming device,
installing water-efficient toilets (about 1.6 gallons per flush) can yield significant economic
savings. Significant quantities of water can be saved by using recycling n waste watertreaments like gray water recycling.
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GREEN BUILDING: refers to a structure and using process that is environmentally responsible
and resource-efficient throughout a building's life-cycle: from siting to design, construction,
operation, maintenance, renovation, and demolition.
This requires close cooperation of the design team, the architects, the engineers, and the
client at all project stages.[The Green Building practice expands and complements the
classical building design concerns of economy, utility, durability, and comfort.
OBJECTIVE
The common objective is that green buildings are designed to reduce the overall
impact of the built environment on human health and the natural environment by:
Efficiently using energy, water, and other resources
Protecting occupant health and improving employee productivity
Reducing waste, pollution and environmental degradation
Sustainability presents itself as a unique challenge in the field of Architecture Construction
projects typically consume large amounts of materials, produce tons of waste, and often
involve weighing the preservation of buildings that have historical significance against the
desire for the development of newer, more modern designs.
Sustainable construction is defined as the creation and responsible management of a
healthy built environment based on resource efficient and ecological principles.
Sustainably designed buildings aim to lessen their impact on our environment through
energy and resource efficiency.
A building cannot be sustainable unless its interior design is not in tandem with it. Solar
and Wind energy should be made use of and the orientation and placement of a site should
be looked into.
Positioning of windows should be such that they allow cross ventilation, thus creating
climate sensitive design.
Day lighting is an important factor that has considerable importance in case of any design.
Day lighting reduces the need for artificial lighting thus saving energy.
For furniture, instead of hardwoods, renewable materials like rubber wood, bamboo and
cane can be used.
Glass can be used as facade cladding with opaque insulation thus helping in keeping the
building cool. Special venetian blinds further cool the rooms.
Landscaping should be done on roofs to minimize solar gain.
Innovative construction techniques for roofing such as domes, arches and precast brick
panels should be used as they reduce energy consumption of a building.
Rainwater harvesting is an important aspect of sustainability.
METHODS TO CONSERVE NATURAL RESOURCES BY ADOPTING SUSTAINABLE ARCHITECTURE
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Sustainable design is the thoughtful integration of architecture with electrical, mechanical,
and structural engineering. In addition to concern for the traditionalism, aesthetics, massing,
proportion, scale, texture, shadow and light, the design team needs to be concerned with long
term costs: environmental, economic and human.
All in all, a sustainable design is more a practical philosophy of the building than perspective
building style.
CASE STUDY TZED HOMES,BANGALORET-ZED stands for zero energy development
LOCATION-Whitefield road,Bangalore
SITE-5 acre
CONCEPT: The total number of homes is based on the carrying capacity of the land:
To ensure the autonomy in water the amount of water harvested from the annual
rainfall is calculated and gives the feeding capacity of the land which is divided by theannual average consumption of a modern family, giving at last the maximum figures for
settlement.
The master plan consists in two parallel four-floor buildings containing a street for
pedestrian and vehicles movements along it. The south-facing buildings are segmented
into blocks in order to provide maximum natural light to the street and homes located
in the second row of buildings. These cavities called e-zone are treated as garden for
recreation.
MATERIALS:
TZed uses building technologies and materials (like stone and mud) that reduces
carbon emission through savings on resources and embodied energies.
BCIL has used filler slabs, incorporating fly ash blocks, to save the amount of steel and
cement used.
External walls are built using soil-stabilised blocks (around five lakhs have been used),
laterite blocks and finishing treated with fine waterproof coating. This ensures thatsurfaces are non-erodable, need no external paint applications and are thermally
efficient.
Sky bridges have been used to
connect two building blocks which
reduces travel distance and hence
elevator travel.
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Green roofs or sky gardens also contribute to the thermal comfort of the dwellings.
These provide a planting space for every home while serving as thermal insulation for
adjoining and lower built spaces. Each sky garden uses lightweight mulch and coir pith
instead of heavier soil, and is irrigated via a drip method.
Rubberwood, a non-forest timber, is used for door shutters and as flooring. Palm wood
has been used for external walkway decking. They have also used compressed coir door
panels for the door shutters, while bamboo composites provide roofing for part of the club
and the interior woodwork in places. These are local resources that use less energy to
produce, thus reducing carbon emissions.
Shading devices have been provided to give
shade.It protects from harsh sunlight entering the
building, reducing air conditioning
A self sufficient and secure water supply system is also
provided, using the rainwater collected from the roofs,
which is stored in shallow aquifers, through a system of
drains, percolation pits, trenches and wells.
Around 44 recharge wells are dug to help water
percolation through the ground into the shallow zone.
Four bore wells act as backup for water in extreme conditions of shortage of harvested
water, these wells are equipped with sand filters and ozonation systems.
Solar water pumps draw this water from the shallow aquifers into a transit tanks from
where it is sent for ozonizing thereby making it potable.
Then it is sent to small overhead tanks for daily storage before it reaches the homes. Hot
water is always available as solar water heaters have been installed.
WATER CONSERVATION
Filler slabs to save material, use of
laterite stone which is locallyavailable and a thermal insulator
Use of eco friendly and locally
available bamboo in the lower part ofthe structure
Through this project, an effort has been made to provide modern comfortable housing and
at the same time, minimize the environmental impact. The various technologies and design