7/30/2019 Renewable Energy Systems in buildings pdf.doc
1/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSCHAPTER 1
INTRODUCTION
More than 90 per cent of our time is spent in buildings i.e. either in the office or at home.
Energy used in buildings (residential and commercial) accounts for a significant percentage of a
countrys total energy consumption. This percentage depends greatly on the degree of
electrification, the level of urbanization, the amount of building area per capita, the prevailing
climate, as well as national and local policies to promote. Recent studies have shown that in
India, the buildings sector accounts for nearly 30-35% of total energy consumption. This
includes the residential and commercial sector.The building sector encompasses a diverse set of
end use activities, which have different energy use implications. Space heating, space cooling
and lighting, which together account for a majority of building energy use in industrialized
countries, depend not only on the energy efficiency of temperature control and lighting systems,
but also on the efficiency of the buildings in which they operate. Building designs and materials
have a significant effect on the energy consumed for a selected set of end uses In terms of
Potential in savings, the residential sector offers a saving potential of almost 30% while
commercial sector offers a saving potential of almost 40%.The most common method of
harnessing renewable energy in buildings is with the use of technologies which rely on naturally
occurring renewable resources such as water, wind, sun etc. These primarily include Solar Photo
Voltaic (PV) cells and Solar Water Heaters (SWH). Solar PVs help convert suns energy into
electricity. Solar PV panels can be used can be used to provide a certain percentage of energy
requirements in a buildings, thereby reducing the pressure on grid electricity. Solar PVs can be
installed on rooftops, porches etc. Or can be integrated into the various glazing systems on
buildings facades or rooftops. Solar PVs can be used to directly supply electricity to a building or
can be clubbed with a battery bank to store excess electricity generated for later use. Solar Water
Heater can be placed on rooftops and used to heat water and store it for later use. Using
renewable energy systems helps in reduction of Green House Gas (GHG) emissions. Since thesystems use suns energy or wind energy, they act as a clean source of energy which is available
1
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
2/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSfree of cost. It is important to develop, promote and adopt these technologies in order to help
avert/ mitigate dangers due to climate change.
1.1 ENERGY EFFICIENCY
The ratio of energy input to the calculated or estimated amounts of energy required to
cover the various requirements relating to the standardized use of a building serves as the
measure of energy efficiency. According to EU Directive "Energy Performance of Building
Directive" (EPBD), the following thermal and electrical forms of energy are considered when
determining the energy efficiency of a building:
Heating
DHW (domestic hot water)
Cooling
Ventilation
1.2 WHAT IS ENERGY EFFICIENCY OF A BUILDING?
The energy efficiency of a building is the extent to which the energy consumption
Per square meter of floor area of the building measures up to established energy consumptionbenchmarks for that particular type of building under defined climatic conditions. Building
energy consumption benchmarks are representative values for common building types against
which a buildings actual performance can be compared. The benchmarks are derived by
analyzing data on different building types within a given country. The typical benchmark is the
median level of performance of all the buildings in a given category and good practice represents
the top quartile performance. Comparisons with simple benchmarks of annual energy use per
Square meter of floor area or treated floor area (kWh/m2/annum) allow the standard Of energy
efficiency to be assessed and priority areas for action to be identified. Benchmarks are applied
mainly to heating, cooling, air-conditioning, ventilation, Lighting, fans, pumps and controls,
office or other electrical equipment, and electricity consumption for external lighting. The
2
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
3/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSbenchmarks used vary with the country and type of building. The measure of heat loss through a
material, referred to as the U-Value, is also used as a way of describing the energy performance
of a building. The U-value refers to how well an element conducts heat from one side to the
other by rating how much the heat the component allows to pass through it. They are the
standard used in building codes for specifying the minimum energy efficiency values for
windows, doors, walls and other exterior building components. U-values also rate the energy
efficiency of the combined materials in a building component or section. A low U-value
indicates good energy efficiency. Windows, doors, walls and skylights can gain or lose heat,
thereby increasing the energy required for cooling or heating. For this reason most building
codes have set minimum standards for the energy efficiency of these components.
1.3. ENERGY EFFICIENCY MEASURES FOR BUILDINGS
Energy efficiency measures for buildings are approaches through which the energy
consumption of a building can be reduced while maintaining or improving the level of comfort in
the building. They can typically be categorized into:
Reducing heating demand
Reducing cooling demand
Reducing the energy requirements for ventilation
Reducing energy use for lighting
Reducing energy used for heating water
Reducing electricity consumption of office equipment and appliances
Good housekeeping and people solutions.
1.3.1 REDUCING HEATING DEMAND
3
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
4/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSHeating demand can be reduced by:
Limiting the exposed surface area of the building
Improving the insulation of the buildings fabric
Reducing ventilation losses
By selecting efficient heating systems with effective controls
1.3.2 REDUCING COOLING DEMAND
Energy use in typical air-conditioned office buildings is approximately double that of
naturally ventilated office buildings. The need for air-conditioning or the size of the systems
installed can be reduced by:
Controlling solar gains through glazing
Reducing internal heat gains
Making use of thermal mass and night ventilation to reduce peak temperatures
Providing effective natural ventilation
Reducing lighting loads and installing effective lighting controls.
1.3.3 REDUCING ENERGY REQUIREMENTS FOR VENTILATION
When the cooling demand is sufficiently reduced by implementing the above measures, it
may be possible to reduce heat gains so that air-conditioning is unnecessary and comfort
conditions can be maintained through the use of natural ventilation. The energy required for
ventilation can be minimized by:
A building design that maximizes natural ventilation
Effective window design
Use of mixed mode ventilation
4
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
5/25
RENEWABLE ENERGYSYSTEMS INBUILDINGS Using efficient mechanical ventilation systems.
1.3.4 REDUCING ENERGY USED FOR LIGHTING
This can be accomplished through:
Making maximum use of daylight while avoiding excessive solar heat gain
Using task lighting to avoid excessive background luminance levels
Installing energy-efficient luminaries with a high light output to energy ratio
Selecting lamps with a high luminous efficiency
Providing effective controls that prevent lights being left on unnecessarily.
1.3.5 REDUCING ENERGY USED FOR HEATING WATER
This can be achieved by:
Installing time controls, and setting them to correctly reflect the hours of hot water
requirement
Setting sanitary hot water thermostats to the appropriate temperature no more than 60C
for normal requirements (but ensure the water does not drop below 56C)
Switching off electric heating elements (immersion) when hot water from the boiler is
available
Switching off any associated pumps when hot water is not required
Replacing any damaged or missing insulation from all hot water pipe work and cylinders,
except where the pipes are providing useful heat into the space
Identifying a suitable hot water system.
The most significant reduction in energy use for hot water can be achieved by providing
solar water heating.
5
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
6/25
RENEWABLE ENERGYSYSTEMS INBUILDINGS1.3.6 REDUCING CONSUMPTION OF OFFICE EQUIPMENT AND APPLIANCES
Most businesses rely on a range of office equipment in order to function. From the basic
essentials such as computers, monitors, printers, fax machines and photocopiers to projectors,
scanners and teleconference facilities, it is widely recognized that these items have become
integral to daily activity. Office equipment is the fastest growing energy user in the business
world, consuming 15 per cent of the total electricity is used in offices. This is expected to rise to
30 per cent by 2020. There are also associated costs that are often overlooked, specifically those
of increasing cooling requirements to overcome the additional heat this equipment produces. As
ventilation and air conditioning are major energy consumers themselves, it makes good business
sense to ensure they are only used when absolutely necessary. Typical measures to reduce
consumption which also apply to household appliances
are:
Switching off switching off or enabling power down mode reduces the energy
consumption and heat produced by equipment, which in turn lowers cooling costs
Upgrading existing equipment some energy efficient appliances may cost more to buy
but will recoup savings over the lifetime of the equipment
Matching the equipment to the task bearing in mind current and predicted requirements
and purchase equipment that meet these
Taking advantage of energy labeling schemes some well know energy labeling
schemes are Energy Star, European Ecolabel Scheme, Energy Saving Recommended and
the Market Transformation Program.
1.3.7 GOOD HOUSEKEEPING AND PEOPLE SOLUTIONS
The level of achievable energy savings from office equipment is down to the everyday
management by staff. A simple energy conservation program for an organization
would consider:
Setting up an energy policy for the organization
Appointing an energy champion
6
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
7/25
RENEWABLE ENERGYSYSTEMS INBUILDINGS Involving staff
Setting targets
Using notices and reminders
Conducting walk-rounds
Taking meter readings
CHAPTER 2
BUILDING AUTOMATION SYSTEM
7
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
8/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSBuilding automation describes the advanced functionality provided by the control system
of a building. A building automation system (BAS) is an example of a distributed control system.
The control system is a computerized, intelligent network of electronic devices designed to
monitor and control the mechanical, electronics, and lighting systems in a building.
BAS core functionality keeps the building climate within a specified range, provides lighting
based on an occupancy schedule, and monitors system performance and device failures and
provides email and/or text notifications to building engineering/maintenance staff. The BAS
functionality reduces building energy and maintenance costs when compared to a non-controlled
building. A building controlled by a BAS is often referred to as an intelligent building or a smart
home.
Most building automation networks consist of a primary and secondary bus which
connect high-level controllers with lower-level controllers, input/output devices and a user
interface. The primary and secondary bus can be BAC net, optical fiber, ethernet, ARCNET, RS-
232, RS-485 or a wireless network. Most controllers are proprietary. Each company has its own
controllers for specific applications. Some are designed with limited controls. Inputs and outputs
are either analog or digital. Analog inputs are used to read a variable measurement. Examples are
temperature, humidity and pressure sensor which could be thermistor, 4-20 mA, 0-10 volt or
platinum resistance thermometer (resistance temperature detector), or wireless sensors. A digital
input indicates if a device is turned on or not. Some examples of a digital input would be a
24VDC/AC signal, an air flow switch, or a Volta-free relay contact (Dry Contact).Analog
outputs control the speed or position of a device, such as a variable frequency drive, a I-P
(current to pneumatics) transducer, or a valve or damper actuator. An example is a hot water
valve opening up 25% to maintain a set point. Digital outputs are used to open and close relays
and switches. An example would be to turn on the parking lot lights when a photocell indicates it
is dark outside. The Fig 3.1 shows a BMS system.
8
NCERC
http://en.wikipedia.org/wiki/Computer_networkinghttp://en.wikipedia.org/wiki/Computer_networkinghttp://en.wikipedia.org/wiki/Smart_homehttp://en.wikipedia.org/wiki/Smart_homehttp://en.wikipedia.org/wiki/Computer_networkinghttp://en.wikipedia.org/wiki/Smart_homehttp://en.wikipedia.org/wiki/Smart_home7/30/2019 Renewable Energy Systems in buildings pdf.doc
9/25
RENEWABLE ENERGYSYSTEMS INBUILDINGS
Fig 2.1: Building Automation System
2.1 CONTROLLER
Controllers are essentially small, purpose-built computers with input and output
capabilities. These controllers come in a range of sizes and capabilities to control devices
commonly found in buildings, and to control sub-networks of controllers. Inputs allow a
controller to read temperatures, humidity, pressure, current flow, air flow, and other essential
factors. The outputs allow the controller to send command and control signals to slave devices,
and to other parts of the system. Inputs and outputs can be either digital or analog. Digital
outputs are also sometimes called discrete depending on manufacturer. Controllers used forbuilding automation can be grouped in 3 categories. Programmable Logic Controllers (PLCs),
System/Network controllers, and Terminal Unit controllers. However an additional device can
also exist in order to integrate 3rd party systems (i.e. a stand-alone AC system) into a central
Building automation system).PLC's provide the most responsiveness and processing power, but
at a unit cost typically 2 to 3 times that of a System/Network controller intended for BAS
applications. Terminal Unit controllers are usually the least expensive and least powerful. PLC's
may be used to automate high-end applications such as clean rooms or hospitals where the cost
of the controllers is less of a concern. In office buildings, supermarkets, malls, and other
common automated buildings the systems will use System/Network controllers rather than
9
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
10/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSPLC's. Most System controllers provide general purpose feedback loops, as well as digital
circuits, but lack the millisecond response time that PLC's provide. System/Network controllers
may be applied to control one or more mechanical systems such as an Air Handler Unit (AHU),
boiler, chiller, etc., or they may supervise a sub-network of controllers. In the diagram above,
System/Network controllers are often used in place of PLCs. Terminal Unit controllers usually
are suited for control of lighting and/or simpler devices such as a package rooftop unit, heat
pump, VAV box, or fan coil, etc. The installer typically selects 1 of the available pre-
programmed personalities best suited to the device to be controlled, and does not have to create
new controllogic.
2.2 OCCUPANCY
Occupancy is one of two or more operating modes for a building automation system.
Unoccupied, Morning Warm-up, and Night-time Setback are other common modes. Occupancy
is usually based on time of day schedules. In Occupancy mode, the BAS aims to provides a
comfortable climate and adequate lighting, often with zone-based control so that users on one
side of a building have a different thermostat (or a different system, or sub system) than users on
the opposite side. A temperature sensor in the zone provides feedback to the controller, so it can
deliver heating or cooling as needed. If enabled, Morning Warm-up (MWU) mode occurs prior
to Occupancy. During Morning Warm-up the BAS tries to bring the building to set point just in
time for Occupancy. The BAS often factors in outdoor conditions and historical experience to
optimize MWU. This is also referred to as Optimized Start. An override is a manually initiated
command to the BAS. For example, many wall-mounted temperature sensors will have a push-
button that forces the system into Occupancy mode for a set number of minutes. Where present,
web interfaces allow users to remotely initiate an override on the BAS. Some buildings rely on
occupancy sensors to activate lighting and/or climate conditioning. Given the potential for long
lead times before a space becomes sufficiently cool or warm, climate conditioning is not often
initiated directly by an occupancy sensor.
2.3 LIGHTING
10
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
11/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSLighting can be turned on, off, or dimmed with a building automation or lighting control
system based on time of day, or on occupancy sensor, photo sensors and timers. One typical
example is to turn the lights in a space on for a half hour since the last motion was sensed. A
photocell placed outside a building can sense darkness, and the time of day, and modulate lights
in outer offices and the parking lot. Lighting is also a good candidate for Demand response, with
many control systems providing the ability to dim (or turn off) lights to take advantage of DR
incentives and savings.
2.4 AIR HANDLERS
Most air handlers mix return and outside air so less temperature change is needed. This
can save money by using less chilled or heated water (not all AHUs use chilled/hot water
circuits). Some external air is needed to keep the building's air healthy. Analog or digital
temperature sensors may be placed in the space or room, the return and supply air ducts, and
sometimes the external air. Actuators are placed on the hot and chilled water valves, the outside
air and return air dampers. The supply fan (and return if applicable) is started and stopped based
on either time of day, temperatures, building pressures or a combination.
2.5 CENTRAL PLANT
A central plant is needed to supply the air-handling units with water. It may supply a
chilled water system, hot water system and acondenser water system, as well as transformers
and auxiliary power unit for emergency power. If well managed, these can often help each other.
2.5.1 CHILLED WATER SYSTEM
Chilled water is often used to cool a building's air and equipment. The chilled water
system will have chiller and pumps. Analog temperature sensors measure the chilled water
supply and return lines. The chiller are sequenced on and off to chill the chilled water supply. A
chiller is a refrigeration unit designed to produce cool (chilled) water for space cooling purposes.
The chilled water is then circulated to one or more cooling coils located in air handling units,
11
NCERC
http://en.wikipedia.org/wiki/Lighting_control_consolehttp://en.wikipedia.org/wiki/Demand_responsehttp://en.wikipedia.org/wiki/Air_ducthttp://en.wikipedia.org/wiki/Air_ducthttp://en.wikipedia.org/w/index.php?title=Chilled_water_system&action=edit&redlink=1http://en.wikipedia.org/wiki/Hot_water_systemhttp://en.wikipedia.org/w/index.php?title=Condenser_water_system&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Condenser_water_system&action=edit&redlink=1http://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Auxiliary_power_unithttp://en.wikipedia.org/wiki/Chillerhttp://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/w/index.php?title=Return_line&action=edit&redlink=1http://en.wikipedia.org/wiki/Lighting_control_consolehttp://en.wikipedia.org/wiki/Demand_responsehttp://en.wikipedia.org/wiki/Air_ducthttp://en.wikipedia.org/w/index.php?title=Chilled_water_system&action=edit&redlink=1http://en.wikipedia.org/wiki/Hot_water_systemhttp://en.wikipedia.org/w/index.php?title=Condenser_water_system&action=edit&redlink=1http://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Auxiliary_power_unithttp://en.wikipedia.org/wiki/Chillerhttp://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/w/index.php?title=Return_line&action=edit&redlink=17/30/2019 Renewable Energy Systems in buildings pdf.doc
12/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSfan-coils, or induction units. Chilled water distribution is not constrained by the 100 foot
separation limit that applies to DX systems, thus chilled water-based cooling systems are
typically used in larger buildings. Capacity control in a chilled water system is usually achieved
through modulation of water flow through the coils thus, multiple coils may be served from a
single chiller without compromising control of any individual unit. Chillers may operate on
either the vapor compression principle or the absorption principle. Vapor compression chillers
may utilize reciprocating, centrifugal, screw, or rotary compressor configurations. Reciprocating
chillers are commonly used for capacities below 200 tons centrifugal chillers are normally used
to provide higher capacities rotary and screw chillers are less commonly used, but are not rare.
Heat rejection from a chiller may be by way of an air-cooled condenser or a cooling tower (both
discussed below). Vapor compression chillers may be bundled with an air-cooled condenser to
provide a packaged chiller, which would be installed outside of the building envelope. Vapor
compression chillers may also be designed to be installed separate from the condensing unit
normally such a chiller would be installed in an enclosed central plant space. Absorption chillers
are designed to be installed separate from the condensing unit.
2.5.2 CONDENSER WATER SYSTEM
Cooling towers and pumps are used to supply cool condenser water to the chillers.
Because the condenser water supply to the chillers has to be constant, variable speed drives arecommonly used on the cooling tower fans to control temperature. Proper cooling tower
temperature assures the proper refrigerant head pressure in the chiller. The cooling tower set
point used depends upon the refrigerant being used. Analog temperature sensors measure the
condenser water supply and return lines.
2.5.3 HOT WATER SYSTEM
The hot water system supplies heat to the building's air-handling unit or VAV box
heating coils, along with the domestic hot water heating coils (Calorifier). The hot water system
will have aboiler(s) and pumps. Analog temperature sensors are placed in the hot water supply
12
NCERC
http://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/wiki/Condenser_(heat_transfer)http://en.wikipedia.org/wiki/Chillerhttp://en.wikipedia.org/w/index.php?title=VAV_box&action=edit&redlink=1http://en.wikipedia.org/wiki/Calorifierhttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/wiki/Condenser_(heat_transfer)http://en.wikipedia.org/wiki/Chillerhttp://en.wikipedia.org/w/index.php?title=VAV_box&action=edit&redlink=1http://en.wikipedia.org/wiki/Calorifierhttp://en.wikipedia.org/wiki/Boiler7/30/2019 Renewable Energy Systems in buildings pdf.doc
13/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSand return lines. Some type of mixing valve is usually used to control the heating water loop
temperature. The boiler(s) and pumps are sequenced on and off to maintain supply.
2.6 ALARMS AND SECURITY
Many building automation systems have alarm capabilities. If an alarm is detected, it can
be programmed to notify someone. Notification can be through a computer,pager, cellular phone
or audible alarm.
CHAPTER 3
RENEWABLE TECHNOLOGIES AND ENERGY EFFICIENCY IN BUILDINGS
13
NCERC
http://en.wikipedia.org/wiki/Pagerhttp://en.wikipedia.org/wiki/Pager7/30/2019 Renewable Energy Systems in buildings pdf.doc
14/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSThere is an extremely important connect between renewable energy technologies and
energy efficiency. Technologies like solar PVs are extremely expensive to install, especially
when used along with a battery bank. If a conventional building is to be run using solar PVs the
cost of installation and size of the entire system increases substantially.
This is so because the energy demands of a conventional building are high as compared
to an energy efficient building. Once a building and its systems are optimized for high energy
efficiency its overall energy requirements reduce by up to 50 %. This helps in downsizing the
solar PV system there by reducing the installation costs of the panels as well as the size of the
battery banks. In case of grid connection, excess electricity generated from the solar panels in a
building can be sold to the grid. Excess electricity production can be achieved only once the
building is designed to be energy efficient.
Utilizing low flow fixtures in the building reduces the amount of water required by the
building occupants by almost 40 %. Thus the sizes of solar water heater panels and storage tanks,
required for meeting the hot water requirements of the building, can be effectively reduced as
water consumption levels are brought down. This brings down the capital investment required
for solar water heater as well.
3.1. PASSIVE INTERVENTIONS
Passive interventions refer to measures in building design which respond to sun path,
Solar access and local wind movement. Solar and Wind energy can be harnessed by adopting
various passive features which determine the design of the building. These can further be
supplemented by various active systems. There are various ways in which a building can be
designed to harness the solar energy available at a given location. Building orientation plays an
important role in reducing the energy consumption. Since almost 90 % of the regions in India
face extensive heat, buildings should be designed keeping the longer facades facing north and
south. It is extremely simple to cut off direct solar radiation on the northern and southern
facades. The area of glazing on the facades also determines the heat gain in a building. The
greater the glass surface area on the facades ,the higher is the heat gain. This principle can be
14
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
15/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSused in cold climates in order to capitalize on solar radiation to reduce artificial heating demands.
In colder regions, glazing are should be increased to allow for natural heat gain. In warm areas,
the glass area need to be reduced and shaded to avoid excessive heat gains. Buildings can be
designed to allow for maximum penetration of daylight while simultaneously cutting off direct
solar radiation and glare. Natural light can prevent use of artificial lights during the day in
buildings. Different spaces in a building can be designed to benefit from suns energy. In cold
regions, additional spaces called Solariums are added next to main living/ working areas of a
building. Solariums capture the suns heat and heat up the air is then circulated in the living /
working areas to avoid the use of electric heaters,
Building envelopes can be constructed using material compositions which have high
thermal mass. All building surfaces absorb the heat of the sun during the day which permeates
inside the building thereby heating the indoor spaces during the day which leads to
uncomfortable ambient conditions. Buildings where building surfaces are constructed using
materials with high thermal mass have much more comfortable indoor conditions as these
materials prevent the heat absorbed from reaching the interior spaces during the day. During
night when the outdoor temperatures drop, this stored heat in such materials is released into the
living areas making them comfortable.
Natural wind movement can also be harnessed in building design. Natural ventilation
provides fresh air to building occupants removes internal heat gains and makes the spaces
comfortable. Opening on facades can be designed keeping in mind the natural wind flow patterns
for the given area. Besides these, natural wind movement can be harnessed by the use of wind
towers which can be used to channel wind inside the building into various areas. Commonly in
such wind towers, the air is passed over/ mixed with water droplet which reduces the
temperatures of the air and cools it there by eliminating the need of air-conditioning systems.
These are called Passive Down-draft Evaporative Cooling Systems.
3.2. SOLAR PHOTO VOLTAIC SYSTEMS
15
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
16/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSSolar PVs systems allow for building users to generate a certain portion of their daily
electricity requirements which can be stored for later use as well. Solar PV systems can be grid
interactive in which case they supply the excess electricity generated back to the grid. Solar PVs
can be used to generate electricity for day-use only or for night-use as well in which case the
excess electricity generated during the day is stored in battery banks for use at night. Solar PV
systems can be of two types:
Building Mounted
Building Integrated
Building mounted solar PV refers to solar panels which are mounted on different building
components like roof, porches etc. Mounting the solar panels on rooftops is the most commonstrategy adopted as it allows for maximum solar access, efficiency and output. In India, Solar
panels should be mounted facing south at an angle which is equal to the latitude of the place for
maximum efficiency and solar access. Grid interactive systems consist of the solar panels, DC-
AC converter, various structural and electrical components and meters. Systems with battery
backup include an additional battery storage system, charge controllers and sub panel besides the
other components. The Fig 3.1 shows a Building mounted solar PV
Fig 3.1 :Building mounted solar PV
Building Integrated PV systems refer to use of glazing systems with solar PVs
incorporated in them. Building Integrated PV can be used in roof skylights as well as faade
glazing systems. In India Building Integrated PV can be used on southern facades and skylights
facing south for maximum output and efficiency. If you are doing new construction or a
16
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
17/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSreroofing job, it is possible to make the roof itself a solar PV collector. This saves the cost of the
roof itself, and offers a more aesthetic design. The new roof can be shingled or look like metal
roofing. An example is shown below in Fig 3.2
Fig 3.2 Building Integrated solar PV
3.3. SOLAR WATER HEATERS
There is a huge potential for Solar Water Heaters in India. They should be placed on
rooftops in a completely shadow free area. There are two types of SWH available:
1. Flate Plate Collector.
2. Evacuated Tube Collector
Flat Plate SWH systems comprise of a metallic box which contains the absorber sheet
with in laid water channels carrying water which gets hot by absorbing the heat from the
absorber sheet.Evacuated Tube SWH consists of dual-layered glass tubes with vacuum in
between them. The outer layer of the tubes is covered with an absorbent material which absorbs
the heat from sun rays and transfer it to the water.
17
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
18/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSEvacuated Tube Collector systems have a shorter life than Flat Plate Collector and are
relatively cheaper than Flat Plate Collector systems as well. Average life of a Flat Plate
Collector systems is usually 15-20 years. Evacuated Tube Collector systems are more reliable
for colder regions. The Fig 3.3 shows a Solar Water Heater
Fig 3.3: Solar Water Heater
3.4. PRECAUTIONS FOR SOLAR PV AND THERMAL SYSTEMS
While mounting the PVs or water heaters on rooftops, care should be taken to re-seal the
waterproofing layers of the roof.
The materials being used for the systems should be able to withstand the high
temperatures and sunlight resistant.
The PV panels should be installed in a shadow free area which has abundant direct
sunlight from 9:00 am to 4:00 pm.
Water pipes in case of Solar Water Heater should be properly insulated.
3.5. WIND MILLS
18
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
19/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSUtility of windmills exists only in places which have substantial, unobstructed wind flow
round the year. Urban areas offer a lot of disruption and resistance to wind flow. Hence, there
are very few urban areas where small scale windmills can be used for electricity generation.
There are few manufacturers which have begun to manufacture small-scale windmills for the
purpose of generation of electricity in areas which have unobstructed and plentiful wind flow all
year round. However, due to reasons mentioned above, their use in individual building units has
not been extremely beneficial yet.
CHAPTER 4
NATIONAL RATING SYSTEM
19
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
20/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSGreen Rating For Integrated Habitat Assessment (GRIHA) has been adopted by Ministry of
New and Renewable Energy (MNRE), Government of India as the National Green Rating
System for Green Buildings in India. GRIHA has been developed by TERI (The Energy and
Resources Institute) as a rating tools, which evaluates a building on 34 different criteria and
rates the greenness of a building on a scale of 1-100 points. A building has to achieve a
minimum of 50 points for it to be certified Green. The buildings are given star rating from 1-5
with 5 stars being the highest rating. GRIHA has various criteria dedicated to incorporation of
renewable energy systems in the buildings. The criteria on outdoor lightning lays stress on use
of renewable sources of energy for powering the outdoor lights on site. GRIHA has also made
mandatory that 1 % of the total connected load of internal lighting and HVAC systems should
be met by renewable sources of energy. Beyond that a building scores more points if it meets
more of its internal lighting loads through the use of renewable energy systems. In case of hot
water supply, the criterion has allotted points to a building for meeting its supply of hot water
through renewable energy systems. A minimum of 20% of annual hot water demand has to be
met through renewable energy systems to qualify for a point under this criterion.
In order to support and promote renewable technology systems in buildings, MNRE, Gol
has launched various schemes for promotion of solar PVs and Solar Water Heaters. The
Ministry has offered various incentives and financial benefits towards incorporation of Solar
PVs and Solar Water Heaters in buildings. This is expected to provide impetus and create more
awareness and acceptance of these systems within the buildings sector.
CHAPTER 5
EXAMPLES OF RENEWABLE ENERGY UTILISATION IN BUILDINGS IN INDIA
20
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
21/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSTorrent research centre Ahmadabad shown in Fig 5.1 is a complex consisting of
research laboratories which require cleanest possible indoor air conditions. The buildings uses
PDEC systems (Passive Down-draft Evaporative Cooling) to provide treated fresh air to the
indoors. In PDEC systems wind towers capture outside wind and guides it through a spray of
water which cools the air naturally through evaporation and then channels this cool air indoors
eliminating the need for mechanical air-conditioning. Filters are used to purify air. The indoor
conditions have been monitored for a couple years and result show that they are quite
comfortable for building users.
Fig 5.1 :Torrent research centre Ahmadabad
Rabirashmi Abasam shown in Fig 5.2 is Indias First Solar Housing complex which has
come up in the New Town area of Kolkatta, West Bengal. The project is supported by the West
Bengal Renewable Energy Development Agency (WBREDA) with support from Ministry Of
New and Renewable Energy (MNRE), Government of India. Besides the various features like
sustainable site planning, energy and water efficiency etc. Renewable energy system has been
incorporated in a big way. All outdoor lights are powered by solar PVs. Each house has been
provided with Evacuated tube type Solar Water Heaters of 130 lpd (Liters per day) capacity.
The rooftop of each house has been fitted with solar PV panels which generates about 2 KW of
power. Each house has been provided with battery backup of 3 KW of power for use during the
evening. When the demand of electricity rises, the power will automatically switch over to a
21
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
22/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSconventional grid. In order to reduce loads and to run maximum appliances and fixtures on solar
PVs ,the houses have been asked to opt for LED and CFL lamps along with high efficiency
appliances. The complex uses net metering which means that excess electricity generated by the
solar PVs will be supplied back to the main power grid.
Fig 5.2 :Rabirashmi Abasam
Mangarpatta city shown in Fig 5.3 is a development coming up on the outskirts of pune.
It comprises of almost 10,000 dwelling units spread over 550 acres. Each residential dwelling in
the city has an Evacuated Tube Solar Water Heater installed for its use. This is expected to help
save almost 1.45 crore units in a year as well as 13483 tones of carbon dioxide and Rs.3.9
crores every year in savings from power .This city has won a place in the LIMCA Book of
Records for the biggest residential solar water heating system in India. Besides the SWH
systems, the city also incorporates features like rainwater harvesting systems, garbage
segregation, a Biogas plant, Vermiculture and utilization of fly ash.
22
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
23/25
RENEWABLE ENERGYSYSTEMS INBUILDINGS
Fig 5.3: Mangarpatta city
The CESE building at IIT KANPURshown in Fig 5.4 is the first 5 star TERI-GRIHA
rated building in India. It has various features like sustainable site planning incorporation of
energy efficient and waste efficient measures, waste management and health and well-being of
building users. The building has also incorporated solar PV panels in the building generated
power equivalent to the over 30% of the total internal lighting load. Outdoor lighting systems
have been powered by solar PVs as well. The SWH systems cater to more than 70% of the
buildings annual hot water requirements.
Fig 5.4 :CESE building at IIT KANPUR
23
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
24/25
RENEWABLE ENERGYSYSTEMS INBUILDINGSCONCLUSION
Building sector in the country is in the middle of tremendous growth due to massive
urban population influx into the metropolitan cities. In order to meet the requirements of these
cities while simultaneously reducing the dependence on conventional fuels, renewable sources
of energy need to be adopted at a large scale. The renewable energy systems offer clean energy,
free of GHG emissions and can be adopted at various scales in buildings. There are passive
features which can be incorporated in building design as well as active systems like Solar Photo
Voltaic panels to generate electricity. There are various examples of buildings in India where
such systems have been effectively adopted. A higher promotion of such systems by creating
more awareness about their benefits and advantages will help in increasing their adoption. This
will eventually help in contributing towards establishing a cleaner, more sustainable and
environmentally friendly habitat.
REFERENCES
24
NCERC
7/30/2019 Renewable Energy Systems in buildings pdf.doc
25/25
RENEWABLE ENERGYSYSTEMS INBUILDINGS
[1] Apoorva. Vij, Renewable Energy Systems in Buildings in India, Electrical India journal,
Page 76 , January 2010.
[2] Pranjal Dutta, Building Efficiency, Electrical India journal, Page78, November 2011.
[3] Shruthi Goel & Prem C Jain, Innovations in Building Design For Energy Conservation,
Electrical India journal , Page 52,December 2009.
[4]www.wikkipedia.com
25
NCERC
http://www.wikkipedia.com/http://www.wikkipedia.com/