ARCHITECTURE AND ENERGY

Solar System and Earth

Renewable Sources of Energy
Global Climates and Architecture in Historic
Perspective - Contemporary Trends
Sustainability and Architecture

By Ar. B. K. Prabu

Solar System and Earth

Solar energy reaches everywhere, it costs

nothing and it is renewable . However, it is
very diluted in space and it is not continuous it varies with the alternating of day and night,
the different seasons and various weather
conditions.

The amount of energy that reaches

earthsupper atmosphere is about 1,350
W/m2 the solar constant. The atmosphere
reflects, scatters and absorbs some of the
energy

All the energy radiated by the Sun reaches the surface of the
Earth: some of it is reflected back into space, some is dispersed
and diffused in all directions by air molecules and dust
particles in the atmosphere, and some is absorbed by water
vapour, by carbon dioxide and by the ozone in the atmosphere

Solar System and Earth

Solar Heat
Collector

Solar Cell (or)

Photovoltaic Cell
(or) PV Cell
Solar Water Heating
Solar Collector and
Storage Tank

Solar Cooking

Solar Furnace

Solar Power Plant

SOLAR HEAT COLLECTOR

These can be passive or active in nature.

Passive solar heat collectors are natural materials
like stones, bricks etc. or material like glass which
absorb heat during the day time and release it
slowly at night.
Active solar collectors pump a heat absorbing
medium (air or water) through a small collector
which is normally placed on the top of the building.

SOLAR CELL (OR) PHOTOVOLTAIC CELL

SOLAR CELL (OR) PHOTOVOLTAIC CELL

Solar cells are made of thin wafers of semi

conductor materials like silicon and gallium.
When solar radiations fall on them, a
potential difference is produced which
causes flow of electrons and produces
electricity.
Silicon can be obtained from silica or sand,
which is abundantly available and
inexpensive.
By using gallium arsenide, cadmium
sulphide or boron, efficiency of the PV
cells can be improved.
The potential difference produced by a
single PV cell of 4 cm2 size is about 0.40.5 volts and produces a current of 60
milli amperes.

SOLAR CELL (OR) PHOTOVOLTAIC CELL

A group of solar cells joined together in a definite pattern form a

solar panel which can harness a large amount of solar energy and
can produce electricity enough to run street-light, irrigation water
pump etc.
Solar cells are widely used in calculators, electronic watches, street
lighting, traffic signals, water pumps etc. They are also used in
artificial satellites for electricity generation.
Solar cells are used for running radio and television also. They are
more in use in remote areas where conventional electricity supply is
a problem

SOLAR WATER HEATING

SOLAR WATER HEATING

Solar heating systems are generally composed of solar thermal collectors, a fluid
system to move the heat from the collector to its point of usage. The system may
use electricity for pumping the fluid, and have a reservoir or tank for heat storage
and subsequent use. The systems may be used to heat water for a wide variety
of uses, including home, business and industrial uses.
Solar water heaters save electricity and thus money; electricity is becoming
more and more expensive; they could even turnout to be more reliable than
electric power supply (at least in many parts of our country); they are clean and
green and thus reflect one's commitment for preservation of environment; they
are safer than electric geysers as they are located on the roof; and, if well
designed, may even look good on the house top.

Components of solar water heaters:

A typical domestic solar water heater consists of a hot water storage tank and one or more flat plate
collectors.
The collectors are glazed on the sun facing side to allow solar radiation to come in.
A black absorbing surface (absorber) inside the flat plate collectors absorbs solar radiation and transfers
the energy to water flowing through it. Heated water is collected in the tank which is insulated to prevent
heat loss.
Circulation of water from the tank through the collectors and back to the tank continues automatically due
to density difference between hot and cold water

SOLAR COOKERS

Solar cookers make use of solar heat by reflecting the solar radiations using
a mirror directly on to a glass sheet which covers the black insulated box
within which the raw food is kept.
A new design of solar cooker is now available which involves a spherical
reflector (concave or parabolic reflector) instead of plane mirror that has
more heating effect and hence greater efficiency.
The food cooked in solar cookers is more nutritious due to slow heating.

However it has the limitation

that it cannot be used at night
or on cloudy days.
Moreover, the direction of the
cooker has to be adjusted
according to the direction of
the sun rays.

SOLAR FURNACE

Thousands of small plane mirrors are arranged in

concave reflectors, all of which collect the solar heat
and produce as high a temperature as 3000C.

SOLAR POWER PLANT

Solar energy is harnessed on a large scale by using

concave reflectors which cause boiling of water to
produce steam.
The steam turbine drives a generator to produce
electricity.
A solar power plant (50 K Watt capacity) has been
installed at Gurgaon, Haryana.

Solar Energy Buildings

Solar Energy for Buildings presents basic information on solar

building design, which includes passive solar heating,
ventilation air heating, solar domestic water heating and
shading.
to incorporate solar design into multi-unit residential buildings,
and provides calculations
early design decisions can increase the useable solar energy.
Solar buildings work on three principles: collection, storage
and distribution of the suns energy.
A passive solar building makes the greatest use possible of
solar gains to reduce energy use for heating and, possibly,
cooling. By using natural energy flows through air and
materialsradiation, conduction, absorptance and natural
convection.

SOLAR BUILDING DESIGN

Buildings can be designed to meet the occupants need for

thermal and visual comfort at reduced levels of energy and
resources consumption. Energy resource efficiency in new
constructions can be effected by adopting an integrated
approach to building design.
The primary steps in this approach are listed below.
Incorporate solar passive techniques in a building design to
minimize load on conventional systems (heating, cooling, ventilation,
and lighting)
Design energy-efficient lighting and HVAC (heating, ventilation, and
air-conditioning) systems
Use renewable energy systems (solar photovoltaic systems / solar
water heating systems) to meet a part of building load
Use low energy materials and methods of construction and reduce
transportation energy

SOLAR BUILDING DESIGN

Careful solar design can:

Maximize possible solar transmission and absorption in winter to minimize or reduce to zero the heating
energy consumption, while preventing overheating.
Use received solar gains for instantaneous heating load and store the remainder in embodied thermal
mass or specially built storage devices.
Reduce heat losses using insulation and windows with high solar heat gain factors.
Employ shading control devices or strategically planted deciduous trees to exclude summer solar gains
that create additional cooling load.
Employ natural ventilation to transfer heat from hot zones to cool zones in winter and for natural cooling in
the summer; use ground-source cooling and heating to transfer heat to and from the underground, which is
more or less at a constant temperature, and utilize evaporative cooling.
Integrate building envelope devices such as windows, which include photovoltaic panels as shading
devices, or roofs with photovoltaic shingles; their dual role in producing electricity and excluding thermal
gain increases their cost-effectiveness.
Use solar radiation for daylighting,which requires effective distribution into rooms or onto work planes,
while avoiding glare.
Integrate passive solar systems with active heatingcooling/air-conditioning systems in both design and
operation.

PASSIVE SOLAR DESIGN

Depending on climate and building function, certain

heating/cooling systems are more compatible with
passive systems.
For example, the thermal mass in a floor may store
passive solar gains and act as a floor-heating
system.
This is a control challenge that must be carefully
planned if it is to achieve acceptable thermal
comfort for the occupants.

PASSIVE SOLAR DESIGN

The key aspects of passive solar design are interlinked, dependent design parameters:

Location and orientation of a building;

Fenestration area, orientation and type;
Thermal massing and envelope characteristics;
Amount of insulation;
Shading devicestype, location and area;
Effective thermal storage insulated from the exterior environment, as well as amount and
type;
sensiblesuch as concrete in the building envelope with exterior insulation, or latent such
as phase-change materials.

The ultimate objective of design integration is to minimize energy costs while

maintaining interior comfort. A larger thermal mass within a building can
delay its response to heat sources such as solar gainsthe thermal lag effect.
This thermal lag can avoid comfort problems if taken into account in selecting
the thermal mass, choosing appropriate control strategies and sizing the
heatingcooling system.

RENEWABLE SOURCES OF ENERGY

Natural Resources Renewable sources and
Non Renewable Sources
Solar Energy
Wind Energy
Hydropower
Geothermal Energy
Biofuel
Tidal Energy
Ocean Thermal Energy
Biomass Energy
Biogas

RENEWABLE AND NON-RENEWABLE

ENERGY SOURCES
RENEWABLE AND NON-RENEWABLE ENERGY SOURCES
A source of energy is one that can provide adequate amount of
energy in a usable form over a long period of time. These
sources can be of two types:
(1) Renewable Resources which can be generated
continuously in nature and are inexhaustible e.g. wood, solar
energy, wind energy, tidal energy, hydropower, biomass
energy, bio-fuels, geo-thermal energy and hydrogen. They
are also known as non-conventional sources of energy and
they can be used again and again in an endless manner.
(2) Non-renewable Resources which have accumulated in
nature over a long span of time and cannot be quickly
replenished when exhausted e.g. coal, petroleum, natural gas
and nuclear fuels like uranium and thorium.

WIND ENERGY

The high speed winds have a lot of energy in them as kinetic energy due to their motion. The
driving force of the winds is the sun.

The wind energy is harnessed by making use of wind mills.

The blades of the wind mill keep on rotating continuously due to the force of the striking wind.

The rotational motion of the blades drives a number of machines like water pumps, flour mills and
electric generators.
A large number of wind mills are installed in clusters called wind farms, which feed power to the
utility grid and produce a large amount of electricity.

These farms are ideally located in coastal regions, open grasslands or hilly regions, particularly
mountain passes and ridges where the winds are strong and steady.
The minimum wind speed required for satisfactory working of a wind generator is 15 km/hr.
The wind power potential of our country is estimated to be about 20,000 MW, while at present we
are generating about 1020 MW.
The largest wind farm of our country is near Kanyakumari in Tamil Nadu generating 380 MW
electricity.

Wind energy is very useful as it does not cause any air pollution.

After the initial installation cost, the wind energy is very cheap.

HYDROPOWER

The water flowing in a river is collected by constructing a big dam where

the water is stored and allowed to fall from a height.
The blades of the turbine located at the bottom of the dam move with
the fast moving water which in turn rotate the generator and produces
electricity.
Construct mini or micro hydel power plants on the rivers in hilly regions
for harnessing the hydro energy on a small scale, but the minimum height
of the water falls should be 10 metres.
The hydropower potential of India is estimated to be about 4 1011KWhours.
We have utilized only a little more than 11% of this potential.
Hydropower does not cause any pollution, it is renewable and normally
the hydro power projects are multi-purpose projects helping in controlling
floods, used for irrigation, navigation etc.

TIDAL ENERGY

Ocean tides produced by gravitational forces of

sun and moon contain enormous amounts of
energy.
The high tide and low tide refer to the rise and
fall of water in the oceans.
A difference of several meters is required
between the height of high and low tide to spin
the turbines.
The tidal energy can be harnessed by constructing
a tidal barrage.
During high tide, the sea-water flows into the
reservoir of the barrage and turns the turbine,
which in turn produces electricity by rotating the
generators.
During low tide, when the sea-level is low, the sea
water stored in the barrage reservoir flows out
into the sea and again turns the turbines.

OCEAN THERMAL ENERGY

The energy available due to the difference in temperature of water at the surface
of the tropical oceans and at deeper levels is called Ocean Thermal Energy.
A difference of 20C or more is required between surface water and deeper water
of ocean for operating OTEC (Ocean Thermal Energy Conversion) power plants.
The warm surface water of ocean is used to boil a liquid like ammonia.
The high pressure vapours of the liquid formed by boiling are then used to turn the
turbine of a generator and produce electricity.
The colder water from the deeper oceans is pumped to cool and condense the
vapours into liquid.
Thus the process keeps on going continuously for 24 hours a day.

GEOTHERMAL ENERGY

The energy harnessed from the hot rocks present inside the earth is called
geothermal energy.
High temperature, high pressure steam fields exist below the earths
surface in many places.
This heat comes from the fission of radioactive material naturally
present in the rocks.

In some places, the steam or the hot water comes out of the ground
naturally through cracks in the form of natural geysers as in Manikaran,
Kullu and Sohana, Haryana.
Sometimes the steam or boiling water underneath the earth do not find
any place to come out.
We can artificially drill a hole up to the hot rocks and by putting a pipe in
it make the steam or hot water gush out through the pipe at high pressure
which turns the turbine of a generator to produce electricity

BIOGAS

Biogas is a mixture of methane, carbon dioxide, hydrogen and hydrogen sulphide, the major constituent
being methane.
Biogas is produced by anaerobic degradation of animal wastes (sometimes plant wastes) in the
presence of water.
Anaerobic degradation means break down of organic matter by bacteria in the absence of oxygen.
Biogas is a non-polluting, clean and low cost fuel which is very useful for rural areas where a lot of
animal waste and agricultural waste are available.
India has the largest cattle population in the world (240 million) and has tremendous potential for
biogas production.

From cattle dung alone, we can produce biogas of a magnitude of 22,500 Mm3 annually.

A sixty cubic feet biobar gas plant can serve the needs of one average family.

Biogas has the following main advantages : It is clean, nonpolluting and cheap. There is direct supply
of gas from the plant and there is no storage problem.
The sludge left over is a rich fertilizer containing bacterial biomass with most of the nutrients
preserved as such.
Air-tight digestion/degradation of the animal wastes is safe as it eliminates health hazards which
normally occur in case of direct use of dung due to direct exposure to faecal pathogens and parasites.

BIOGAS

BIOMASS

Biomass is the organic matter produced by the plants or animals which include wood,
crop residues, cattle dung, manure, sewage, agricultural wastes etc. Biomass energy
is of the following types :

(a) Energy Plantation

(b) Petro Crops

(c) Agricultural and Urban Waste biomass:

(a) Energy Plantations: Solar energy is trapped by green plants through

photosynthesis and converted into biomass energy. Fast growing trees like
cottonwood, poplar and Leucaena, non-woody herbaceous grasses, crop plants
like sugarcane, sweet sorghum and sugar beet, aquatic weeds like water
hyacinth and sea-weeds and carbohydrate rich potato, cereal etc. are some of the
important energy plantations. They may produce energy either by burning directly
or by getting converted into burnable gas or may be converted into fuels by
fermentation.

BIOMASS

(b) Petro-crops: Certain latex-containing plants like Euphorbias and oil palms are rich in
hydrocarbons and can yield an oil like substance under high temperature and pressure. This
oily material may be burned in diesel engines directly or may be refined to form gasoline.
These plants are popularly known as petro-crops.
(c) Agricultural and Urban Waste biomass: Crop residues, bagasse (sugarcane residues),
coconut shells, peanut hulls, cotton stalks etc. are some of the common agricultural wastes which
produce energy by burning. Animal dung, fishery and poultry waste and even human refuse
are examples of biomass energy. In rural India, animal dung cakes are burnt to produce heat.
About 80 % of rural heat energy requirements are met by burning agricultural wastes, wood
and animal dung cakes. In rural areas these forms of waste biomass are burned in open
furnaces called .Chulhas. which usually produce smoke and are not so efficient (efficiency is <8
%). Now improved Chulhas with tall chimney have been designed which have high efficiency
and are smokeless. The burning of plant residues or animal wastes cause air pollution and
produce a lot of ash as waste residue. The burning of dung destroys essential nutrients like N
and P. It is therefore, more useful to convert the biomass into biogas or bio fuels.

GLOBAL CLIMATES AND ARCHITECTURE

IN HISTORIC PERSPECTIVE
CONTEMPORARY TRENDS
Global Climates and Architecture in Historic
Perspective - Contemporary Trends

Dry stone Dwelling - SKARA BRAE

3000 BC Europe

Skara Brae is made up of 7 dwellings, linked together by a series of low

alleyways.
They were built into mounds of pre-existing rubbish known as "middens".
Although the midden provided the houses with a small degree of
stability, its most important purpose was to act as a layer of insulation
against Orkney's harsh winter climate.
Each house shares the same basic design- a large square room with a
central fireplace, a bed on either side and a shelved dresser on the wall
opposite the doorway.

COLOSSEUM, ROME

Cooling system:

Another innovative feature of the Colosseum was its cooling system, known as the valerium,

which consisted of a canvas-covered, net-like structure made of ropes, with a hole in the center.

This roof covered two-thirds of the arena, and sloped down towards the center to catch the wind and
provide a breeze for the audience.

Sailors, standing on special platforms, manipulated the ropes on command.

At the top brackets and sockets carry the masts from which the velarium, a canopy for shade, by
suspension

PANTHEON ROME 118 126 CE

The dome has a shallow stepped profile

The only natural light enters through an unglazed oculus at the center of the dome and through the
bronze doors to the portico.

As the sun moves, striking patterns of light illuminate the walls and floors of porphyry, granite and
yellow marbles.

The interior of the roof is intended to symbolize the heavens.

The Great Eye, 8.7m across, at the dome's apex is the source of all light and is symbolic of the sun

Its original circular bronze cornice remains in position.

The interior features sunk panels (coffers), which originally contained bronze star ornaments. This coffering
was not only decorative, however but reduced the weight of the roof, as did the elimination of the apex by
means of the Great Eye.

THERMAE OF CARACALLA 212-216 CE

ROME

Hypocaust system:
Inside the main building a complicated distribution system carried the water directly to the cold pools or to
boilers over wood fires where it was heated for the warm and hot baths.
Outlets from each basin and in the floor of each room led to the drains, which ran below the level of the
distribution pipes and took the waste water to the municipal drain in the valley.
Both distribution and drainage pipes were housed in tunnels providing easy access for inspection and
maintenance.
A third network of tunnels was used to store the enormous amounts of wood required to fuel the furnaces
(praefurnia): there were at least fifty of these, some to heat the water and others to heat the rooms by a
hot air system beneath the floor (hypocausta).
The heated rooms were on the southwestern side of the building. The hottest room of all, the calidarium,
projected beyond the line of the building to take full advantage of the sun's rays. Hollow terracotta tubes
ran inside the walls to provide insulation and channel hot air.

THERMAE OF CARACALLA 212-216 CE

ROME