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e-ISSN: 2582-5208 International Research Journal of Modernization in Engineering Technology and Science Volume:02/Issue:12/December -2020 Impact Factor- 5.354 www.irjmets.com
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SOLAR SPACE HEATING IN LADAKH AND HIMACHAL PRADESH
Khushboo *1, Sai Spandana*2, J.P. Kesari*3
*1,2B.Tech Student (3rd Year), Department of Applied Physics, Delhi Technological University,
New Delhi-110042, India.
*3Associate Professor, Department of Mechanical Engineering, Delhi Technological University,
New Delhi –110042, India.
ABSTRACT
Since generations we have witnessed only coal being a major source of electricity generation. In the year
2017-18, the power sector in India was the major consumer of coal it had a share of 64% in the total coal
reserves supplied. This was followed by the Steel and washery industry which had a meager share of
around 7% of the total coal consumption. We are clearly still years and years away from seeing a
complete dominance of renewable energy resources over non-renewable sources. It is a pity that still
around 72% of the electricity generation in India is done by coal. Niti Aayog, which replaced the Planning
Commission, in a 2017 report estimated the share of coal in the energy mix in 2040 to be at least 44%.
Our project covers an important part of renewable energy, namely solar energy. We have studied solar
space heating systems in detail and we intend to cover all the major design aspects of this including, a
case of study of such systems in high altitude areas. Whether we witness a paradigm shift towards
renewable energy systems still remains to be seen.
Keywords: Renewable Energy, Active Solar Space Heating, Passive Solar Space Heating, Radiant Flooring,
Corn Glycol, Glazing.
I. INTRODUCTION
Solar energy is a form of renewable energy which makes use of the sun’s radiation and uses it to generate
heat and for the generation of electricity. With the advancement of technology, humans have devised
ways to harness power from the solar radiation. It is extremely valuable due to no emission of
greenhouse gases and it is abundantly available which is why we should not let it go waste Solar energy
has a high initial investment whereas coal is extremely cheap. In a nation as populous as ours, coal is
preferred due to this factor. The only major problem is that coal has myriad disadvantages apart from
being limited in nature. It is responsible for 40% of carbon dioxide emissions from fossil fuels. Mining
coal wreaks havoc on the environment and on the people who live there. Besides CO2, burning coal
produces pollutants like mercury, sulphur dioxide, which is the main cause of acid rain, and particulate
matter, which causes respiratory illnesses. That is why there is immense need to look for alternatives. In
order to tackle climate change effectively we need to move towards wind, solar, hydro, geothermal
sources of energy. India wants to increase renewable energy capacity from 78 GW to 175 GW till March
2022, 175/100 GW is supposed to be solar power. It also going to double the share of renewable power
capacity to 40% till 2030.
II. CLASSIFICATION
It is essential to first understand what exactly is a solar space heating system and how is it classified. They
can broadly be classified into two.
2.1 ACTIVE SOLAR HEATING SYSTEM
It includes pumps, boiler, solar collector, controller to control the supply of the water.
2.1.1 Advantages
No need to worry about deriving power from sources other than the sun, this is because it utilizes the
power of your external devices.
2.1.2 Disadvantages
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Demand expensive external equipment along with a high maintenance cost. The fluids which store the
heat most efficiently cause the air pollution and release toxic chemicals.
Figure-1: Active Solar Heating System
(https://www.daviddarling.info/encyclopedia/A/AE_active_solar_energy_system.html)
2.2 PASSIVE SOLAR HEATING SYSTEM
It includes orienting a building to the Sun, absorbing materials, thermal mass, insulation, glass which
absorb the solar radiation.
2.2.1 Advantages
No external equipment needed, hence cheaper than active systems. It can bring down your energy
expenditures by nearly 14 percent. It also help in improvement of health.
2.2.2 Disadvantages
Its effectiveness depends on the weather. This is not suitable with place having high temperature and
warmer climate. High temperature can damage the glass and other construction materials.
Figure-2: Passive Solar Heating System
(http://www.iklimnet.com/save/passive_solar_heating.html)
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2.3 ELEMENTS OF PASSIVE SOLAR DESIGN
2.3.1 Aperture/Collector
It is the large glass area through which sunlight enters the building. The aperture(s) should face within 30
degrees of true south and should not be shaded by other buildings or trees.
2.3.2 Absorber
It is the hard darkened surface of the storage element. It is used to absorb the solar radiation and store it
for longer period of time.
2.3.3 Thermal Mass
Materials which retain or store the heat produced by sunlight. While the absorber is an exposed surface,
the thermal mass is the material below and behind this surface.
2.3.4 Distribution
It is the method by which solar radiation circulates from the collection points and distribute to different
areas of the house. Conduction, convection and radiation natural phenomenon are used to distribute the
heat in the house. Fans, ducts and blowers can also be used to distribute the heat in the house.
2.3.5 Controlling
Overhang roofs is used to shade the aperture area during summer months. Other controlling elements are
under and/or overheating include like electronic sensing devices to control the overheating, thermostat is
used to control the rotation of the fans, operable vents and dampers are used to restrict the flow of heat.
Figure-3: Passive Solar design
(https://ases.org/passive-solar-heating/)
III. SOLAR RADIATION AT HIGH ALTITUDE AREAS
Since our project focuses on solar space heating at high altitude areas, we have covered the case of
Himachal Pradesh and Ladakh, using satellite based global horizontal insolation (GHI) datasets it is very
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clear that the state receives an annual average GHI above 4.5 kWh/m2/day or total of 99530395 million
kWh. The lower altitude zones of the state experiences a tropical to wet temperature climate throughout
the year. The higher altitude zones of the state experiences a dry-temperate climate. In the entire world
approximately about 1.36kW/m2 of solar radiation falls on the surface and this is called the solar
constant. This solar radiation which falls is encountered by clouds, aerosols, dust etc. and it gets
attenuated due to absorption and scattering, which is called insolation and 0.3 fraction of the incident
solar radiation is reflected back into space, which is called albedo. The remaining solar energy is in the
form of direct and diffuse insolation and it reaches the surface of the earth where it is used for various
purposes like heating, illuminating, photosynthesis and it is known as Global Horizontal insolation (GHI).
The information mentioned below is extremely important as solar PV Modules, Solar water heaters, Solar
cookers require correct and adequate information about the GHI and location of the place.
Global Horizontal (GHI) = Direct Normal (DNI) X Cos (θ) + Diffuse Horizontal (DHI)
Figure-4: Difference between DNI, DHI AND GHI
Photovoltaic cells are also temperature sensitive. With a surge in the temperature the internal energy of
the electrons also increases and this reduces the band gap. This causes more electrons to move into the
conduction band and it increases the current but decreases the voltage. Hence this decrease in voltage
affects the open circuit voltage, Voc and this affects the maximum power point and the overall power is
reduced. Generally till 250C the curve between the Voltage and temperature is linear. At higher
temperatures the voltage starts falling rapidly. On mountains or hilly areas the ambient temperatures
decreases with increase in altitudes due to low temperature there is lesser effect on the solar power.
Figure-5: Effect of the high altitude on the PV modules
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IV. CASE STUDIES
4.1 SOLAR IRRADIANCE IN HIMACHAL PRADESH
Sunshine duration is a climatological indicator, measuring duration of sunshine in given period (usually, a
day or a year) for a given location on Earth, typically expressed as an averaged value over several years.
Measurement is performed by instruments called sunshine recorders. When the intensity exceeds a pre-
determined threshold, the tape burns. In 1924, Angstrom proposed a basic model. He stated that,
sunshine duration can be used to calculate the monthly average global solar radiation on the surface.
Figure-6: GHI maps of Himachal Pradesh based on NASA SSE data
Himachal Pradesh is located from 30.38° to 33.21° North latitudes and 75.77° to 79.07° East longitudes in
the western Himalayas, covering a geographical area of 55673 km2. The state is divided into 12 districts
surrounded by Jammu & Kashmir in the North, Tibet in the Northeast, Uttarakhand in East/Southeast,
Haryana in South, and Punjab in Southwest/West, with an abundance of snow-fed perennial rivers and
rivulets. HP is the first state in India to take such a policy decision for promoting energy efficiency in
buildings. In June 2009, solar passive heating technology features were incorporated in the building by
laws and it has been made mandatory in the government/semi government and commercial sectors.
Figure-7: District wise annual availability of solar energy in Himachal Pradesh
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In Himachal Pradesh 92% population lives in the villages and they are largely dependent on fuel wood
and coal. Wood, charcoal, coal, kerosene, LPG and electricity are main source of cooking and space heating
during winters. In the tribal areas of the state, fuel wood, coal, and kerosene are supplied on subsidy to
the public, resulting in serious burden on government exchequer. As the winters are extremely cold in
Himachal Pradesh, government buildings, offices, hospitals etc. require efficient heating systems in order
to keep indoor surroundings warm. Installing and setting up such systems would lead to a huge cost
hence it is better to incorporate solar passive heating systems. Apart from these two reasons, Himachal
experiences around 250-300 days of sunshine throughout the year, which facilitates the setting up of
solar passive heating systems. There are approximately 7-8 hours of sunshine per day which would make
utilization of solar energy efficient.
4.1.1 COST OF THE PROJECTS
By installing such systems there is of course a marginal increase in the costs which depends on the
features of the solar passive system which is adopted. This ranges around an increase anywhere between
(10-60)%. However, this increase can be cut down if the material selection, site selection, planning and
designing are done properly. Solar space heating system help in saving fuel and electricity which is used
for space heating/cooling in buildings, the additional cost can be easily recovered in 2–3 years. This solar
building incorporates a heat-collecting wall and a roof-top solar air heater with an electric heating
backup, sunspaces and double-glazed windows. Under the Passive Solar Building Program, more than 100
buildings have been constructed in the high altitude region of the Indian State of Himachal Pradesh. A
policy decision has been taken by the State that all government/semi-government buildings are to be
designed and constructed as per passive solar housing technology.
4.1.2 FUNDING OF THE PROJECT
The programme in Himachal Pradesh pertaining to solar space heating has been funded by the
government of Himachal Pradesh and MNRE (Ministry of New and Renewable Energy), Government of
India. The funds covered only- fabrication of solar heating systems, training and capacity building. The
housing agencies and the house owners provided the amount for construction. All the data related to the
technology used was shared with other states like Arunachal Pradesh, Sikkim, Nagaland etc. which also
experience severe winter.
4.1.3 NOTABALE EXAMPLES
In the rooftop of this college USS (Ultimate Sun System), MNRE Channel Partner Company had installed a
300kW grid tied solar PV system in this college at Solan, Himachal Pradesh. The benefit of this move is
that this installation is expected to generate 369,000 kWh of electricity every year and significantly bring
down the institute’s carbon footprint. The biggest solar power plant of HP has been established in
Rampur with a capacity of 4 lakh units in one year. It was on 14th October, 2005 that the state government
of Himachal Pradesh took a decision that all government/semi-government institutions will in-corporate
solar passive heating and cooling features along with earthquake resistant and rain-harvesting structure.
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4.2 LADAKH
Due to its high altitude, Ladakh is always freezing cold and dry for most of the year. The air is so thin that
you can feel the sun's heat intensely which is why installation of solar systems would be beneficial here.
In summers, the temperature during the day is just above zero degrees and the night temperature is much
below -30°C.
Figure-10: Heat Pumps in Leh Ladakh
(https://www.intersolarsystems.com/heat-pumps-in-leh-ladakh)
4.2.1 NEED FOR SOLAR PASSIVE HEATING INSTALLATION IN LADAKH
Since the Ladakh is not connected to the national electricity grid. Therefore only few areas of Ladakh are
connected to the local hydropower plants. The place also has a lot of sunshine in the day even if the
temperature falls drastically during night in winter.
Figure-11: Annual Direct Normal Irradiance in Jammu & Kashmir
4.2.2 SOLAR PASSIVE BUILDINGS IN LADAKH
The Indian Army has taken up a project for the forthcoming financial year starting in April to tap the ever-
shining sun both directly and indirectly for keeping people warm through an effective design using local
and low-cost materials for passive solar heating for residential buildings. Sonam Wangchuk, an innovator-
entrepreneur from Ladakh, has developed this passive heating housing concept. Wangchuk has won the
prestigious Global Award for Sustainable Architecture 2017.
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4.2.3 WANGCHUK’S INNOVATION
Wangchuk is one of the founders of the Students’ Educational and Cultural Movement of Ladakh The
SECMOL Alternative School was started in 1988 with an aim to reform the educational system of Ladakh,
is an eco-friendly campus near Leh town.
“Solar passive structures are not new. However, these are movable, prefabricated, and can be assembled
on the spot and give solutions to meet the Army’s shelter requirements. The cost of heating will be zero.
Even if the temperature outside is minus 20 degrees Celsius, it will be 20 degrees Celsius inside the hut,
without any heating.” Available sunshine for almost 300 days a year with high radiation is one of the best
alternatives to offset the burning of fossil fuel adding to India’s overall emissions. After the US and China,
India is the third largest pollution emitter therefore, we need to reduce the emissions. The schools of Mr.
Wangchuk are extremely warm even in the extremely cold climatic conditions of Ladakh. This has been
achieved without the use of any fuel, wood or fire. The main building is in the Phey village near Leh and
remains comfortably warm.
Figure-12: Sonam Wangchuk Figure-13: Orientation of the buildings
4.2.4 ARCHITECTURE EMPLOYED
The buildings are made south facing in order to maximize the solar radiation. It is completely covered
with windows so that the radiation can directly fall on its glazing. The top openings of the buildings are
made from glass to keep the building illuminated and trap the heat. Double-layered and south-facing
windows made of plastic sheet and glass or both glass are used. It helps in trapping heating. The other
sidewalls are made of thick mud with insulation in between. The insulation is at times air and at times a
mixture of waste paper and dried grass.
4.2.5 MATERIALS USED FOR CONSTRUCTION
Opaque materials allow only the transfer of energy through them via conduction. The conductivity of
these materials increases as their density increases. These materials are further classified as dense
materials and low density materials. The dense materials are also the load-bearing materials in
construction they can support the load (weight) of roofs and walls. Dense materials can be used to
support more load. Denser materials are also a better conductors of heat. For example, stone is denser
than mud-brick and mud-brick buildings are warmer than stone buildings, the heat is conducted more
rapidly through stone due to which the heat get radiated outside the environment more rapidly. Heat
energy transfer takes some certain amount of time to transmit from one side of a wall to the other side of
the wall in house and the time elapsed is called the lag time. Heat energy takes 12 hours to transfer 35 cm
thick mud-brick wall. Therefore lag time is 12 hours.
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Figure-14: Temperature Vs. hours graph
4.2.6 ABSORPTION MATERIALS
The amount of sunlight which a material absorbes depends on its colour. Black is known to absorb the
maximum amount of hear radiation wheras white absorbs the least amount of heat. Absorbivity is the
amount of radiation absorb by the material. Different colours have different absorbivity black colour has
maximum absorbivity.
Figure-15: Absorption of material Figure- 16: The absorbivity for different colours
4.2.7 GLAZING MATERIALS
The windows are usually covered with these transparent materials so that the solar radiation reaches the
interiors. Glass and polythene are examples of materials which transmit the radiation. These materials
are classified by their transmittance (τ), which tells how much incident radiation is transmitted through
the material. Below is the transmittance of some material:
a) τ(glass) – 0.8
b) τ(polythene)- 0.9
The transmittance also depends on the angle at which the sun is with respect to the windows. If the sun is
perpendicular it is maximum and till 300 it is high. It decreases as the angle goes on increasing and is
small for an angle more than 500. Heat loss in buildings mainly occurs due to loss from windows. There
are few approaches to maximize direct gain, such that by double glazing is employed or on single glazing
we put polythene. In night time movable insulation like curtains and blinds are placed.
COLOUR ABSORBIVITY
White 0.25 to 0.4
Grey to dark grey 0.4 to 0.5
Green, red, brown 0.5 to 0.7
Brown to dark blue 0.7 to 0.8
Dark blue to black 0.8 to 0.9
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Figure-16: Effect of different glazing type on different temperature inside the building.
4.2.8 SLOPE OF A PLACE
The slope also plays a very important role in determining the amount of sunshine which the building will
receive. In summers horizontal surfaces receive more radiation as compared to in winters due to the
orientation of the sun and the angle which it makes with the building. If the upward slope is north facing-
A bit of the northern facing wall of the building should be made underground by digging the slope facing
north. If the upward slope is south facing- Elevate its northern side and dig the building into the southern
side. A slope which is south facing is less preferred as the heat radiations which will be received from the
southern direction will get attenuated. Hence a slope facing the north is preferred as there is no
attenuation.
4.2.9 SITE SELECTION
There are certain factors which influence the selection of the ideal site for the solar passive house
construction, which are the presence of any obstruction which blocks the solar radiation. This could
include trees or other buildings. The slope or steepness of the site. Reflectivity of nearby buildings, if
there are any. Another important factor which is looked into is the groundwater table. Groundwater
found below the surface of the land and exist in pores between sedimentary deposits like soils, sands and
gravels. It is important that the ground should be dry and the groundwater should be 8 feet below or
more in order to avoid any dampness and its foundations are taken care of. It plays a very important role
in villages near the river for e.g.- Shey in Ladakh.
Figure-18: Shey in Ladakh
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V. CONCLUSION
This paper covers all the aspects of solar space heating systems along with the case study of solar heating
systems in high altitudes in India. Solar Space Heating is a very useful application for an area with low
climate temperature and very good sun radiation. Ideal for higher altitude. It keeps the room temperature
constant in winter in cold areas. It saves fuel for heating. We did two case studies in order to understand
how solar heating systems are used in high altitude areas like Himachal Pradesh and Ladakh. We have
include how the geographical position and building orientation can help in solar heating system and how
it affect the solar irradiation. In the end we would explained how the different properties of construction
materials such as glazing, absorptivity and site location and its slope increase the absorption of solar
energy/radiation. At last we would say solar renewable energy is the best source of renewable energy to
control the environmental pollution and India is making good progressed in it.
VI. REFERENCE
[1] Design Guidelines- Solar Space Heating of Factory Buildings by Dagmar Jaehnig and Werner
Weiss.
[2] Sameer Kapur, Satyam Shandilya, Vishal Tiwari and J.P. Kesari on “Recent Advancement in Solar
Furnace Technology” published in IRJMETS volume:02/Issue:12/December-2020
[3] Rajat Malik, Raviratna Subir, Rishabh and J.P.Kesari on “Concentrated Solar Power for Mid-day
Meal Program in Delhi” published in IRJMETS volume:02/Issue:11/November -2020
[4] inhabitat.com/green-building-101-energy-atmosphere-part-1/
[5] en.wikipedia.org/wiki/Trombe_wall
[6] sciencing.com/differences-between-north-southfacing-slopes-8568075.html
[7] slideshare.net/jswindel/space-heating
[8] solar-energy-at-home.com/solar-space
heating.html#:~:text=Solar%20space%20heating%20uses%20solar,%2C%20propane%2C%20
and%20natural%20gas
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