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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

https://firstgreenconsulting.files.wordpress.com/2012/04/dni-dhi-ghi.jpg



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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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https://www.intersolarsystems.com/heat-pumps-in-leh-ladakh



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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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e-issn: 2582-5208 international research journal of

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