Solar Passive Designs in Architecture

8/13/2019 Solar Passive Designs in Architecture

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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

Solar Passive Designs in Architecture

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