2. FUTURE HOUSE
INTRODUCTIONNumber of Towns and Villages electrified in India by IIFL, it can be seen that even after
65 years of independence 17.7 percent of India is still in dark during nights. All of the
5161 towns in India are electrified, i.e. cent percent in the case of towns. However, in
India villages are more than towns and development of India is only possible by the
development of those villages. Out of 593732 villages in India only 488439 villages are
electrified, i.e. 105293 villages are un-electrified. Andhra Pradesh, Goa, Kerala, Punjab,
Tamil Nadu, Haryana, and Delhi are the few of the states that are 100% electrified.
Arunachal Pradesh, Bihar, Jharkhand, Orissa, Meghalaya,and Tripura are the states where
less than 60% of the villages are electrified. The worst situation is in Jharkhand
where only 31.1 %villages are electrified. The consumption of electricity in the country is
increasing at the rate of 10% per year. The energy usage has been increasing through
years, but there has been no sufficient increase in the production. In the case of
electricity, this leads to load shedding and increase in prices.
Dept of EE, DTU
2
4. FUTURE HOUSE
PHOTVOLTAIC SYSTEM DESIGN AND INSTALLATION
Photovoltaic (pv) power systems convert sunlight directly into electricity. A residential
pv power system enables a homeowner to generate some or all of their daily electrical
energy demand on their own roof, exchanging daytime excess power for future energy
needs (i.e. Nighttime usage). The house remains connected to the electric utility at all
times, so any power needed above what the solar system can produce is simply drawn
from the utility. Pv systems can also include battery backup or uninterruptible power
supply (ups) capability to operate selected circuits in the residence for hours or days
during a utility outage.
BASIC PRINCIPLES TO FOLLOW WHEN DESIGNING A
QUALITY PV SYSTEM
1. Select a packaged system that meets the owner's needs. Customer criteria for a system
may include reduction in monthly electricity bill, environmental benefits, desire for
backup power, initial budget constraints, etc. Size and orient the pv array to provide the
expected electrical power and energy.
2. Ensure the roof area or other installation site is capable of handling the desired system
size.
3. Specify sunlight and weather resistant materials for all outdoor equipment.
4. Locate the array to minimize shading from foliage, vent pipes, and adjacent structures.
5. Design the system in compliance with all applicable building and electrical codes.
6. Design the system with a minimum of electrical losses due to wiring, fuses, switches,
and inverters.
7. Properly house and manage the battery system, should batteries be required.
8. Ensure the design meets local utility interconnection requirements.
TYPICAL SYSTEM DESIGNS AND OPTIONS
Pv Electrical System Types
There are two general types of electrical designs for pv power systems for homes
ďˇ Systems that interact with the utility power grid and have no battery backup capability.
ďˇ Systems that interact and include battery backup as well.
Grid-Interactive Only (No Battery Backup)
This type of system only operates when the utility is available. Since utility outages are
rare, this system will normally provide the greatest amount of bill savings to the customer
per dollar of investment. However, in the event of an outage, the system is designed to
shut down until utility power is restored.
TYPICAL SYSTEM COMPONENTS:
Pv array: A pv array is made up of pv modules, which are environmentally-sealed
collections of pv cellsâthe devices that convert sunlight to electricity. The most common
pv module that is 5-to-25 square feet in size and weighs about 3-4 lbs./ft2. Often sets of
four or more smaller modules are framed or attached together by struts in what is called a
panel. This panel is typically around 20-35 square feet in area for ease of handling on a
roof. This allows some assembly and wiring functions to be done on the ground if called
for by the installation instructions.
Dept of EE, DTU
4
5. FUTURE HOUSE
Balance Of System Equipment (Bos): BOS includes mounting systems and wiring
systems used to integrate the solar modules into the structural and electrical systems of
the home. The wiring systems include disconnects for the dc and ac sides of the inverter,
ground-fault protection, and overcurrent protection for the solar modules. Most systems
include a combiner board of some kind since most modules require fusing for each
module source circuit. Some inverters include this fusing and combining function within
the inverter enclosure.
Dc-Ac Inverter: This is the device that takes the dc power from the pv array and
converts it into standard ac power used by the house appliances. Metering: this includes
meters to provide indication of system performance. Some meters can indicate home
energy usage.
Other Components: utility switch (depending on local utility)
FIG2: Grid Interactive Pv System Without Battery Backup
MOUNTING OPTIONS
There are several ways to install a pv array at a residence. Most pv systems produce 5-to10 watts per square foot of array area. This is based on a variety of different technologies
and the varying efficiency of different pv products. A typical 2-kw pv system will need
200-400 square feet of unobstructed area to site the system. Consideration should also be
given for access to the system. This access space can add up to 20% of needed area to the
mounting area required.
Roof Mount
Often the most convenient and appropriate place to put the pv array is on the roof of the
building. The pv array may be mounted above and parallel to the roof surface with a
standoff of several inches for cooling purposes. Sometimes, such as with flat roofs, a
separate structure with a more optimal tilt angle is mounted on the roof. Proper roof
mounting can be labor intensive. Particular attention must be paid to the roof structure
and the weather sealing of roof penetrations. It is typical to have one support bracket for
every 100 watts of pv modules. For new construction, support brackets are usually
mounted after the roof decking is applied and before the roofing materials is installed.
The crew in charge of laying out the array mounting system normally installs the
brackets. The roofing contractor can then flash around the brackets as they install the
roof. A simple installation detail and a sample of the support bracket is often all that is
Dept of EE, DTU
5
6. FUTURE HOUSE
needed for a roofing contractor to estimate the flashing cost. Masonry roofs are often
structurally designed near the limit of their weight-bearing capacity. In this case, the roof
structure must either be enhanced to handle the additional weight of the pv system or the
masonry roof transitioned to composition shingles in the area where the pv array is to be
mounted. By transitioning to a lighter roofing product, there is no need to reinforce the
roof structure since the combined weight of composite shingles and pv array is usually
less than the displaced masonry product.
Shade Structure
An alternative to roof mounting is to mount the system as a shade structure. A shade
structure may be a patio cover or deck shade trellis where the pv array becomes the
shade. These shade systems can support small to large pv systems. The construction cost
with a pv system is a little different
Than for a standard patio cover, especially if the pv array is acts as part or the entire
shade roof. If the pv array is mounted at a steeper angle than a typical shade structure,
additional structural enhancements may be necessary to handle the a dditional wind
loads. The weight of the pv array is 3-to-5 lbs./ft2, which is well within structural limits
of most shade support structures. The avoided cost of installing roof brackets and the
associated labor could be counted toward the cost of a fully constructed patio cover. The
overall cost of this option will likely be higher than roof mounting, but the value of the
shade often offsets the additional costs.
Other issues to consider include :
⢠Simplified array access for maintenance
⢠Module wiring, if visible from underneath, must be carefully concealed to keep the
installation aesthetically pleasing.
⢠Cannot grow vines, or must be diligent about keeping it trimmed back from modules
and wiring.
ESTIMATING SYSTEM OUTPUT
Pv systems produce power in proportion to the intensity of sunlight striking the solar
array surface. The intensity of light on a surface varies throughout a day, as well as day to
day, so the actual output of a solar power system can vary substantial. There are other
factors that affect the output of a solar power system. These factors need to be understood
so that the customer has realistic expectations of overall system output and economic
benefits under variable weather conditions over time.
FACTORS AFFECTING OUTPUT
STANDARD TEST CONDITIONS
Solar modules produce dc electricity. The dc output of solar modules is rated by
manufacturers under standard test conditions (stc). These conditions are easily recreated
in a factory, and allow for consistent comparisons of products, but need to be modified to
estimate output under common outdoor operating conditions. Stc conditions are: solar
cell temperature = 25 oC; solar irradiance (intensity) = 1000 w/m2(often referred to as
peak sunlight intensity, comparable to clear summer noon time intensity); and solar
spectrum as filtered by passing through 1.5 thickness of atmosphere (astm standard
spectrum). A manufacturer may rate a particular solar module output at 100 watts of
power under stc, and call the product a â100-watt solar module.â This module will often
have a production tolerance of +/-5% of the rating, which means that the module can
produce 95 watts and still be called a â100-watt module.â To be conservative, it is best to
Dept of EE, DTU
6
7. FUTURE HOUSE
use the low end of the power output spectrum as a starting point (95 watts for a 100-watt
module).
TEMPERATURE
Module output power reduces as module temperature increases. When operating on a
roof, a solar module will heat up substantially, reaching inner temperatures of 50-75 oC.
For crystalline modules, a typical temperature reduction factor is 89% or 0.89. So the
â100-wattâ module will typically operate at about 85 watts (95 watts x 0.89 = 85 watts) in
the middle of a spring or fall day, under full sunlight conditions.
DIRT AND DUST
Dirt and dust can accumulate on the solar module surface, blocking some of the sunlight
and reducing output. Much of california has a rainy season and a dry season. Although
typical dirt and dust is cleaned off during every rainy season, it is more realistic to
estimate system output taking into account the reduction due to dust buildup in the dry
season. A typical annual dust reduction factor to use is 93% or 0.93. So the â100-Watt
module,â operating with some accumulated dust may operate on average at about 79
watts (85 watts x 0.93 = 79 watts).
MISMATCH AND WIRING LOSSES
The maximum power output of the total pv array is always less than the sum of the
maximum output of the Individual modules. This difference is a result of slight
inconsistencies in performance from one module to the next and is called module
mismatch and amounts to at least a 2% loss in system power. Power is also lost to
resistance in the system wiring. These losses should be kept to a minimum but it is
difficult to keep These losses below 3% for the system. A reasonable reduction factor for
these losses is 95% or 0.95.
DC TO AC CONVERSION LOSSES
The dc power generated by the solar module must be converted into common household
ac power using an inverter. Some power is lost in the conversion process, and there are
additional losses in the wires from the rooftop array down to the inverter and out to the
house panel. Modern inverters commonly used in residential pv power systems have peak
efficiencies of 92-94% indicated by their manufacturers, but these again are measured
under well-controlled factory conditions. Actual field conditions usually result in overall
dc-to-ac conversion efficiencies of about 88-92%, with 90% or 0.90 a reasonable
compromise. So the â100-watt moduleâ output, reduced by production tolerance, heat,
dust, wiring, ac conversion, and other losses will translate into about 68 Watts of AC
power delivered to the house panel during the middle of a clear day (100 Watts x 0.95 x
0.89 x 0.93 x 0.95 x 0.90 = 67 Watts).
INSTALLATION LABOR EFFORT
Installation effort is very sensitive to specific house layouts and roofing type. An
experienced crew can install a 2 kW non-battery PV system in two-to-four person-days.
Systems with large solar arrays are relatively less effort per watt of power and kWh of
energy than smaller systems because the installation of the inverter and other hardware
required by all PV systems is spread over more solar modules. Systems with battery
backup are more labor intensive than non-battery systems because of the additional
wiring required for wiring the critical load subpanel. A battery system can add 50-100%
to the time required for the installation.
Dept of EE, DTU
7
8. FUTURE HOUSE
PROPOSED INCLINATION OF ROOFS
Based on various calculations, we found that roofâs inclination should be kept at 20
degrees, for efficient utilisation of light. Based on that, the following model is proposed.
Isometric Projection of room
FIG 3 : ISOMETRIC PROJECTION OF ROOM
Side view of room
FIG 4 : SIDE VIEW OF ROOM
Dept of EE, DTU
8
9. FUTURE HOUSE
LIGHTING SYSTEMS
1.
Solar Tube Lighting
These devices channel sunlight from your rooftop through your attic space into an
overhead light that resembles a conventional light, can be used with the push of a
button, and requires no energy to run. A softening lens and high-quality reflective
materials allow for even lighting on sunny and cloudy days. Many solar tube
lights come equipped with a conventional back-up light for night time use.
Figure 5: Diagram of a Solar Tube [1]
Reference : []
2.
Solar Tube with Mechanical Tracker
Another specialized system consists of a receiver which tracks the sun
mechanically and directs the sun light through cables for indoor lighting
purposes.[2]
Dept of EE, DTU
9
10. FUTURE HOUSE
FIG 6: SOLAR TUBE WITH MECHANICAL TRACKING
3.
LED Lighting
The next generation of efficient lighting brings LEDs or Light Emitting Diodes into the
picture. While the cost of production has kept the purchasing cost significantly high, the
benefits outweigh the pricing issues.
The standard unit for comparison is lumens which is the SI derived unit of luminous flux
which is the total amount of visible light emitted by source.
Benefits of LED Bulbs :
1. Long lasting: LED bulbs last up to 10 times as long as compact fluorescents, and
far longer than typical incandescent bulbs.
2. Durable: LEDs do not have a filament; they are not damaged under
circumstances when a regular incandescent bulb would be broken. Because they
are solid, LED bulbs hold up well to jarring and bumping.
3. Mercury Free: no mercury is used in the manufacturing of LEDs.
4. Cost effective: although LEDs are initially expensive, the cost is recouped over
time and in battery savings. LED bulb use was first adopted commercially, where
maintenance and replacement costs are expensive. But, the cost of new LED
bulbs has gone down considerably in the last few years and is continuing to go
down.
Dept of EE, DTU
10
11. FUTURE HOUSE
The Following Table Depicts The Comparison In Lumens And Watts For Various
Lighting Sources:
LUMENS
POWER RATING OF
LED (in Watts)
450
800
1100
1600
4-5
6-8
9-13
16-20
POWER RATING OF
INCANDASCENT BULB(in
Watts)
40
60
75
100
POWER RATING
OF CFL (in Watts)
9-13
13-15
18-25
23-30
Table: Comparison of Lumen to Watt values for various lighting sources [3]
While incandescent bulbs provide diffused light that spreads in all directions, LED
lighting is used more as directional lighting. These can be powered from the energy
stored from the PV array during the day.
Table : Cost Comparison Of Various Lighting Sources
Table : Cost Comparison of various lighting sources. [4]
Dept of EE, DTU
11
12. FUTURE HOUSE
The typical lighting setup is shown below:
Here the bold dots marked on the floor plan show the proposed location of the lighting
sources (solar tube + LED) combined:
FIG 7:THE TYPICAL LIGHTING SETUP
Lighting will be controlled intelligently. Sensors located on doorways will detect
movement of people in and out of the room. For instance, if the individual steps out of
the bedroom and into the kitchen, the lights of the bedroom will dim automatically and
shift to Power Saving Mode while lighting in the Kitchen will switch to Normal Mode.
Manual override switches shall be provided on the walls too.
During the day, lighting shall be provided using solar tubes which have adjustable covers
to control the intensity of light. As the day progresses, timed sensors shall track the
intensity of light falling in the solar tubes and hence control the artificial lighting
provided within with increasing darkness in the evening and night (or during cloudy
days).
Dept of EE, DTU
12
13. FUTURE HOUSE
Figure 8: Control Algorithm for system controlling automatic lighting systems for
day and night
Dept of EE, DTU
13
14. FUTURE HOUSE
INTRODUCTION-:
PEDAL-POWER
World is a storehouse of energy. We all know that energy can neither be created nor
destroyed but can be transformed from one form to another. But we are wasting resources
that can produce energy as if they are limitless. If we can renew and reuse the energy we
waste, it would help in some way to the problem of scarcity of energy, which is the major
threat of present world. Humans are able to generate approximately 150W of power while
riding bicycle. However, this power goes waste without any use. If we can make use of
this energy, we would be able to power many electronic devices. A dynamo or an
alternator can be used for harvesting the energy generated by a cycle rider while riding.
We can charge mobile phones or a small lighting device with this power. Not only in
bicycles but also in alternator bikes, cars, and exercise bikes we can use this principle.
In India, many of the villages are still without electricity and most of them use bicycle as
their medium of transportation. In such places, our system will be of great help. Charging
of the battery can be done by a layman by just connecting the circuit to the output of the
dynamo/alternator which is connected to the bicycle. This would charge the NiMH
batteries.
As long as we are pedalling and the system is working fine, we can get the power
whenever needed. Power generation using bicycle is very cheap and eco-friendly. Even
though people have been using pedal power for various day-to-day chores, generating
electricity from pedalling was not in vogue until few decades back. Today dynamo
equipped bicycles are common which power the incandescent headlights during night.
The rotational energy that is generated when the tire rotates because of the application of
force on the pedals can be used in two ways. This energy can also be used in
dynamo/alternator, which is then converted to electrical energy. Rotational energy of the
tire can be used to pump water out from the well, to drive a washing machine, to operate
blender/grinder etc.
DYNAMO:
Bicycle Dynamos are alternators equipped with permanent magnets, which produce ac
current.
Two types of dynamos available are :-
ďˇ The hub dynamo
o Hub dynamo is built into the hub of a bicycle wheel. Here generation of
electricity is done by using
the rotation of the bicycle wheel.
Dept of EE, DTU
14
15. FUTURE HOUSE
FIG 9: HUB DYNAMO
ďˇ The Bottle Dynamo:o It is also a small electric generator like hub dynamo.It is generally
placed to the rear wheel of bicycle.
FIG 10: BOTTLE DYNAMO
ALTERNATOR:The output energy from the dynamo is very low. Only three 1.2V NiMH batteries can be
charged using this power, which can be used for low power applications like small led
lights. Also, it takes a lot of time in charging these batteries. It is definite that the dynamo
output will be insufficient for high power applications and an alternative is needed.
A dynamo can be replaced with an alternator since it is capable of producing more power
in less time. Alternator has both pros and cons over dynamo, but alternator generates
more power than dynamo with lesser time and effort.
One way to connect an alternator with the bicycle is to place it behind the seat by
removing the carrier. The shaft of the alternator should be connected to the tire with a
belt that rolls over shaft on one end and other end rolls over a cylindrical structure
attached to its rear tireâs hub. In this way when the bicycle moves, the structure rotates
and thereby facilitates rotation of alternatorâs shaft.
The other way to connect the alternator with the bicycle is by making the shaft directly
roll over the tire. A rubber cap placed on the shaft is used to provide grip and to facilitate
roll without slipping.
Among the two ways, the first way will be more power efficient but the bicycle is needed
to be pedalled in stationary mode.
Dept of EE, DTU
15
16. FUTURE HOUSE
As alternator would produce more power, a rechargeable battery of high voltage rating is
required. The rectifier (conventional bridge rectifier) and filter will not undergo any
alterations. However, in the regulator part, a regulated voltage of 15v has to be
maintained using a regulator IC 7815.
CIRCUIT FOR POWER GENERATION
FIG 11:CIRCUIT FOR POWER GENERATION
COMPONENTS REQUIRED
A Bicycle
Type of bike:
Road bikes are most suitable type of bike for generating electricity because they have
slick tires. Slick tyres help keep friction and noise to a minimum level. Road bikes are
designed to be efficient on smooth roads. You will generally get more watts from a road
bike than a town (designed for comfort) or a mountain bike (designed for bumps and
bashes).
Gears:
ďˇ Geared bikes have the advantage that cyclists of different abilities can use them.
ďˇ Single speed bikes have the advantage that the cyclist cannot change gear and
make life easier for him/herself. Therefore you can almost guarantee the same
power out from each person.
Dept of EE, DTU
16
17. FUTURE HOUSE
FIG 12: GROUP OF PEDAL GENERATORS
Batteries/Super capacitors
Rechargeable battery is used to store the energy produced by pedaling. Rechargeable
batteries are made up of one or more electrochemical cell used to store energy in the form
of electrical energy. The only reason why batteries are preferred over capacitor is its easy
usage i.e. the batteries after recharging can be easily removed from the charging case and
can be used for desired purpose like for lighting up torch, etc.
A battery for use with a pedal power set up should not be too large. Industrial pocket
plate nickel cadmium batteries are ideal for this application because they have a relatively
flat discharge curve and don't mind being deeply discharged and operated in a partial
state of charge. This applies only to the pocket plate type of NiCad cell which has no
memory characteristic. Unless several people are contributing regularly to the charging
process, 20-40 ampere hours of capacity is very adequate. Larger capacities will work of
course, or you can simply pipe the current generated into the larger battery bank of a
complete home
power system.
Voltage Regulator
The alternative to using a battery is to use a voltage regulator to buffer the variable
output from the generator down to a constant 12.6 volts. With this arrangement, the
lights and other appliances are on while you crank but go off when you quit. This offers
a real education in the amount of power we drain from the system. Cranking a color TV
and VCR is hard work while powering a reading light or two is so easy of a load that you
hardly feel it. The advantage of having a regulator available is that you can get full use
from the system even if your battery is flat dead. It also doesn't take up the space
required by the batteries and it provides some discipline in the use of certain
appliances. Some folks, for example, connect the TV set to their bike generator with a
regulator and require the kids to carry their own weight when watching television.
Dept of EE, DTU
17
18. FUTURE HOUSE
Belts and Stands
The motor needs to be attached to your stand somehow and then tensioned up to the back
wheel of your bike. The location of the motor is critical and you may need to make a
number of mounting points suitable for different bicycles.
FIG 13: CYCLE STAND
FIG 14: BELT
An Inverter
If you are wishing to use AC mains powered appliances you will need to purchase an
inverter. There are 2 types of inverters. A pure sine wave inverter creates a smooth AC
output. A quasi sine makes a square wave. Some devices may not work with a quasi sine.
Inverters are designed to work with batteries so they usually work with voltages between
9 and 14volts.
APPLICATIONS OF PEDAL POWER
Charging Mobile Phones
For this we need a mobile charging circuit which would give the appropriate voltage and
current required for charging the mobile. Here, the difference will be the input to
charging circuit. In normal chargers, the input is from ac main 230V.However,in our case
the voltage will be of lower value.
Correspondingly, some changes are required to be made in the mobile charging circuit.
Here two types of chargers are possible:
ďˇ The first, in which the mobile phone battery is charged by connecting the
charger output to mobile phone directly.
ďˇ The second in which battery of the mobile phone is charged separately.
Pedal Powered Laptops
Dept of EE, DTU
18
19. FUTURE HOUSE
Laptops powered using solar energy is available, but not everyone can afford to buy it. A
simpler way will be to pedal and charge it. This already exists in Afghanistan and they
claim that even a third grader will be able to use it without any difficulty. Here the pedal
is fitted to the laptop table so that while using the laptop one could charge it.
FIG 15: LAPTOP CHARGING
Pedal Powered Washing Machine
Pedal power can be used to operate washing machine. It agitates, cleans and rinses the
clothes. Already existing models uses pedal power in two different ways. In one of the
model, plastic barrel filled with water, soap powder and clothes are put and lid is closed.
This plastic barrel itself is rotated by pedalling. In the other model also plastic barrel is
used. But one person can sit on that barrel and pedal the foot pedal provided at the bottom
of the plastic barrel.
Blenders
Drive coupling of the blender is connected to the bicycle tire, which would rotate the
blades of the blender. Electric blenders are high-powered devices, which work at about
500watts power. If blenders can be operated mechanically it would save electricity as
well as money.
FIG 16: BLENDER PEDAL POWER GENERATOR
ENERGY LOSSES
Dept of EE, DTU
19
20. FUTURE HOUSE
Energy loss cannot be avoided and is present in each stage, from production to storage.
Energy loss happens in the battery, in the alternator/dynamo, in the converter (which
converts ac to dc), in the voltage regulator. This means that the total energy loss in a
pedal powered generator will be about 50-70 %. Losses can be minimized by reducing
the number of electrical connections and use mechanical connections wherever possible.
Considering the cost factor, components of maximum efficiency must be used.
COST
SINGLE BIKE GENERATOR
S.NO
1
2
3
4
5
6
COMPONENTS
GEARED CYCLE
STAND
BELT
GENERATOR (300 W)
LEAD ACID BATTERY
INVERTER
TOTAL
QUANTITY
1
1
1
1
1
1
PRICE in INR
15000
2000
1000
5000
10000
7000
40000
ADVANTAGES
ďˇ Pedal power vehicles are becoming popular day by day. Pollution in the
environment is causing serious health issue and doctors are emphasizing the use
of bicycle as an exercise to be healthy. On this line Chinese are replacing their
vehicles with pedal power vehicles.
ďˇ At a time when there is energy crisis casting its shadow all over the world, one
has to look into alternate renewable energy resources. One such alternate way
to generate power is presented in this paper. The rotational energy of the tires in
the bicycle, generated by pedalling can be used to operate small powered
devices. Both dynamo and alternator can be used and various options and
situations where a dynamo or alternator can be used are provided.
Dept of EE, DTU
20
21. FUTURE HOUSE
PIEZOELECTRICITY:
Piezoelectricity is the electric charge that accumulates in certain solid materials (notably
crystals, certain ceramics, and biological matter such as bone, DNA and various proteins)
in response to applied mechanical stress. The word piezoelectricity means electricity
resulting from pressure. It is derived from the Greek word âpiezoâ, which means to
squeeze or press, and electric or electron, which stands for amber, an ancient source of
electric charge. Piezoelectricity was discovered in 1880 by French physicists Jacques and
Pierre Curie. They found that when certain types of crystals such as quartz, tourmaline,
and Rochelle salt, are compressed along certain axes, the resulting mechanical
deformation produces a voltage on the surface of the crystal. When pressure is applied to
an object, a negative charge is produced on the expanded side and a positive charge on
the compressed side. Once the pressure is relieved, electrical current flows across .This
effect is known as piezoelectric effect. The converse effect is also possible i.e. when the
emf applied along certain electrical axes in the crystal ,this crystal produces mechanical
vibrations .This effect is used in some variety of practical devices such as buzzers, ultra
sonic filters and sonar for the production of Ultrasonic waves.
FIG 17: ELECTROMECHANICAL CONVERSION VIA PIEZOELECTRICITY
Dept of EE, DTU
21
24. FUTURE HOUSE
Advantages of Piezoelectricity:
The rise of piezoelectric technology is directly related to a set of inherent advantages.
The high modulus of elasticity of many piezoelectric materials is comparable to that of
many metals and goes up to 106 N/m². Even though piezoelectric sensors are
electromechanical systems that react to compression, the sensing elements show almost
zero deflection. This is the reason why piezoelectric sensors are so rugged, have an
extremely high natural frequency and an excellent linearity over a wide amplitude range.
Additionally, piezoelectric technology is insensitive to electromagnetic fields and
radiation, enabling measurements under harsh conditions. Some materials used
(especially gallium phosphate or tourmaline) have an extreme stability even at high
temperature, enabling sensors to have a working range of up to 1000 °C. Tourmaline
shows pyroelectricity in addition to the piezoelectric effect; this is the ability to generate
an electrical signal when the temperature of the crystal changes.
APPLICATIONS:
It has been found that piezoelectric crystals that have been embedded in the sole of a shoe
can yield a small amount of energy with each step. This could be applied in a way that
the power for instruments such as torches, cell phones or other entertainment devices can
be sourced from the movement of the operator.
Dept of EE, DTU
24
25. FUTURE HOUSE
Block Diagram of Footstep Power Generation:
FIG 19: BLOCK DIAGRAM OF FOOT STEP PEWER GENERATION
Dept of EE, DTU
25
26. FUTURE HOUSE
FIG 20: PIEZOSHOES
FIG 21: GRAPH OF PIEZOELECTRICITY PRODUCED
Dept of EE, DTU
26
27. FUTURE HOUSE
Piezoelectric Generators:
Piezoelectric generator is nothing but a piezoelectric crystal sandwiched between two
metallic electrodes. So when the mechanical pressure/stress is applied on the crystal, emf
is generated.
FIGURE 22: PIEZO GENERATOR
Dept of EE, DTU
27
28. FUTURE HOUSE
WINDOWS
The use of heat reflecting glass in place of ordinary glass increases energy efficiency of
the house by a considerable amount. Heat-reflecting windows are usually sealed, doubleglazed unitsâones with two panes of glass separated by a noble (non-reactive) gas such
as argon that improves insulation (stops heat from escaping in air drafts). The inner
surface of one of the panes of glass is coated with a very thin layer of metal or metallic
oxide (typical coatings include titanium dioxide, bronze, silver, or stainless steel). Heat
reflecting glass lets visible light pass through it virtually unimpeded, but the metallic
coating reflects short wavelength ultraviolet light very effectively, much like a mirror.
So, sunlight enters the home as normal, but the heat is reflected back again. Even when
the sun has moved around and is not shining directly, objects warmed by ultraviolet
radiation from the sun can still re-radiate infrared radiation into the home. But heat
reflecting glass will simply reflect it back.
FIG 23: WINDOW HEAT REFLECTION
During the night time (especially useful during winters, heat-reflecting glass, the metallic
coating will reflect most of the infra red radiation straight back into the room.[5]
Spacious windows using heat reflecting glass shall be provided that will maximize light
entering the house during the daytime. The house will require minimum air conditioning
as the glass will keep most of the heat out of the house. This reduces the power
consumption of the house dramatically.
SELECTION
When selecting windows for energy efficiency, it's important to first consider
their energy performance ratings in relation to your climate and your home's design. This
will help narrow your selection.
Dept of EE, DTU
28
29. FUTURE HOUSE
FIG 24 WINDOW DESIGN
A window's energy efficiency is dependent upon all of its components. Window
frames conduct heat, contributing to a window's overall energy efficiency, particularly
its U-factor. Glazing or glass technologies have become very sophisticated, and designers
often specify different types of glazing or glass for different windows, based on
orientation, climate, building design, etc.
Another important consideration is how the windows operate, because some operating
types have lower air leakage rates than others, whichwill improve your home's energy
efficiency. Traditional operating types include:
ďˇ
Awning. Hinged at the top and open outward. Because the sash closes by pressing
against the frame, they generally have lower air leakage rates than sliding windows.
Dept of EE, DTU
29
30. FUTURE HOUSE
ďˇ
Casement. Hinged at the sides. Like awning windows, they generally have lower
air leakage rates than sliding windows because the sash closes by pressing against
the frame.
ďˇ
Fixed. Fixed panes that don't open. When installed properly they're airtight, but
are not suitable in places where window ventilation is desired.
ďˇ
Hopper. Hinged at the bottom and open inward. Like both awning and casement,
they generally have lower air leakage rates because the sash closes by pressing
against the frame.
ďˇ
Single- and double-hung. Both sashes slide vertically in a double-hung window.
Only the bottom sash slides upward in a single-hung window. These sliding windows
generally have higher air leakage rates than projecting or hinged windows.
Single- and double-sliding. Both sashes slide horizontally in a double-sliding window.
Only one sash slides in a single-sliding window. Like single- and double-hung windows,
they generally have higher air leakage rates than projecting or hinged windows
Dept of EE, DTU
30
31. FUTURE HOUSE
FIGURE 25- WINDOW TYPES
INSTALLATION
Even the most energy-efficient window must be properly installed to ensure energy
efficiency. Therefore, it's best to have a professional install your windows.
Window installation varies depending on the type of window, the construction of the
house (wood, masonry, etc.), the exterior cladding (wood siding, stucco, brick, etc.), and
the type (if any) of weather-restrictive barrier.
Dept of EE, DTU
31
32. FUTURE HOUSE
Windows should be installed according to the manufacturerâs recommendations and be
properly air sealed during installation to perform correctly. To air seal the
window, caulk the frame and weatherstrip the operable components.
TYPES OF WINDOW FRAMES
Improving the thermal resistance of the frame can contribute to a window's overall
energy efficiency, particularly its U-factor. There are advantages and disadvantages to all
types of frame materials, but vinyl, wood, fiberglass, and some composite frame
materials provide greater thermal resistance than metal.
ALUMINUM OR METAL FRAMES
Although very strong, light, and almost maintenance free, metal or aluminum window
frames conduct heat very rapidly, which makes metal a very poor insulating material. To
reduce heat flow and the U-factor, metal frames should have a thermal break -- an
insulating plastic strip placed between the inside and outside of the frame and sash.
COMPOSITE FRAMES
Composite window frames consist of composite wood products, such as particleboard
and laminated strand lumber. These composites are very stable, they have the same or
better structural and thermal properties as conventional wood, and they have better
moisture and decay resistance.
FIBERGLASS FRAMES
Fiberglass window frames are dimensionally stable and have air cavities that can be filled
with insulation, giving them superior thermal performance compared to wood or
uninsulated vinyl.
VINYL FRAMES
Vinyl window frames are usually made of polyvinyl chloride (PVC) with ultraviolet light
(UV) stabilizers to keep sunlight from breaking down the material. Vinyl window frames
do not require painting and have good moisture resistance. The hollow cavities of vinyl
Dept of EE, DTU
32
33. FUTURE HOUSE
frames can be filled with insulation, which makes them thermally superior to standard
vinyl and wood frames.
WOOD FRAMES
Wood window frames insulate relatively well, but they also expand and contract in
response to weather conditions. Wood frames also require regular maintenance, although
aluminum or vinyl cladding reduces maintenance requirements.
TYPES OF WINDOW GLAZING OR GLASS
In addition to choosing a frame type, you will need to consider what type of glazing or
glass you should use to improve your home's energy efficiency. Based on
various window design factorssuch as window orientation, climate, building design, etc.,
you may even want to choose different types of glazing for different windows throughout
your home.
GAS FILLS
To improve the thermal performance of windows with insulated glazing, some
manufacturers fill the space between the panes with inert gas -- commonly argon or
krypton -- that has a higher resistance to heat flow than air.
HEAT-ABSORBING TINTS
Heat-absorbing window glazing contains special tints that change the color of the glass.
Tinted glass absorbs a large fraction of the incoming solar radiation through a window,
reducing the solar heat gain coefficient (SHGC), visible transmittance (VT), and glare.
Some heat, however, continues to pass through tinted windows by conduction and reradiation, so the tint doesn't lower a window's U-factor. Inner layers of clear glass or
spectrally selective coatings can be applied on insulated glazing to help reduce these
types of heat transfer.
Dept of EE, DTU
33
34. FUTURE HOUSE
The most common gray- and bronze-tinted windows are not spectrally selective, and
reduce the penetration of both light and heat. Blue- and green-tinted windows offer
greater penetration of visible light and slightly reduced heat transfer compared with other
colors of tinted glass. In hot climates, black-tinted glass should be avoided because it
absorbs more light than heat. Tinted, heat-absorbing glass reflects only a small
percentage of light, so it does not have the mirror-like appearance of reflective glass.
Note that when windows transmit less than 70% of visible light, indoor plants can die or
grow more slowly.
INSULATED
Insulated window glazing refers to windows with two or more panes of glass. To insulate
the window, the glass panes are spaced apart and hermetically sealed, leaving an
insulating air space. Insulated window glazing primarily lowers the U-factor, but it also
lowers the SHGC.
LOW-EMISSIVITY COATINGS
Low-emissivity (low-e) coatings on glazing or glass control heat transfer through
windows with insulated glazing. Windows manufactured with low-e coatings typically
cost about 10% to 15% more than regular windows, but they reduce energy loss by as
much as 30% to 50%.
A low-e coating is a microscopically thin, virtually invisible, metal or metallic oxide
layer deposited directly on the surface of one or more of the panes of glass. The low-e
coating lowers the U-factor of the window, and different types of low-e coatings have
been designed to allow for high solar gain, moderate solar gain, or low solar gain. A lowe coating can also reduce a window's VT unless you use one that's spectrally selective.
Although low-e coatings are usually applied during manufacturing, some are available for
do-it-yourselfers. These films are inexpensive
Dept of EE, DTU
34
35. FUTURE HOUSE
compared to total window replacements, last 10 to 15 years without peeling, save energy,
reduce fabric fading, and increase comfort.
REFLECTIVE COATINGS
Reflective coatings on window glazing or glass reduce the transmission of solar radiation,
blocking more light than heat. Therefore, they greatly reduce a window's VT and glare,
but they also reduce a window's SHGC. Reflective coatings usually consist of thin,
metallic layers, and come in a variety of colors, including silver, gold, and bronze.
Reflective window glazing is commonly used in hot climates to control solar heat gain.
The reduced cooling energy demands can be offset by the need for additional electrical
lighting, so reflective glass is used mostly for special applications.
SPECTRALLY SELECTIVE COATINGS
A special type of low-e coating is spectrally selective, filtering out 40% to 70% of the
heat normally transmitted through insulated window glass or glazing while allowing the
full amount of light transmission. Spectrally selective coatings are optically designed to
reflect particular wavelengths, but remain transparent to others. Such coatings are
commonly used to reflect the infrared (heat) portion of the solar spectrum while
admitting more visible light. They help create a window with a low U-factor and SHGC
but a high VT.
Spectrally selective coatings can be applied on various types of tinted glass to produce
"customized" glazing systems capable of either increasing or decreasing solar gains
according to the aesthetic and climatic effects desired. Computer simulations have shown
that advanced window glazing with spectrally selective coatings can reduce the electric
space cooling requirements of new homes in hot climates by more than 40%.
Dept of EE, DTU
35
36. FUTURE HOUSE
Figure26: Floor plan showing spacious windows located so as to maximize light
input during the day.
To maximize light entering, care must be taken to align the windows (during
construction) in a East to West direction so as to maximize light input during the day.
Dept of EE, DTU
36
