Grenhouse Construction Manual en 2009

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SOLARGREENHOUSESFORTHE TRANS-HIMALAYAS

ICIMODThe International Centre for Integrated Mountain Development (ICIMOD) is an independent

Mountain Learning and Knowledge Centre serving the eight countries of the Hindu Kush-Hi-malayas Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal and Pakistan andthe global mountain community. Founded in 983, ICIMOD is based in Kathmandu, Nepal, andbrings together a partnership of regional member countries, partner institutions, and donorswith a commitment for development action to secure the future of the Hindu Kush-Himalayas.The primary objective of the Centre is to promote the development of economically and en-vironmentally sound mountain ecosystems and to improve the living standards of mountainpopulations.

ICIMOD can be contacted at

4/80 Jawalakhel, GPO Box 3226, Kathmandu, NepalTel: +977 552533Fax: + 977 5524509 / 5536747E-mail: [email protected]: http://icimod.org

GERESThe Renewable Energy and Environment Group (GERES) is a French NGO created in 976.GERES works in a dozen countries in Asia and Africa promoting renewable energy resourcesand energy efciency through a development process controlled by the local people. GERESencourages the use of local resources with the aim of respecting the environment and provid-ing well-balanced development schemes.

GERES has been working for 20 years for the benet of local development in the Hindu Kush-

Himalayas (HKH), with a focus on promoting well-adapted and eco-friendly technologies.The main eld activities are concerned with energy saving (passive solar buildings, improvedstoves) and income generation (solar greenhouses, solar poultry farming, ecotourism, foodprocessing, processing wool).

GERES rst project in the HKH was set up in 1982 in Ladakh (India). At present, GERES sup-ports local NGOs in India, Nepal, China, and Afghanistan in a variety of activities.Our strategy is based on privileged partnerships with various government and non-govern-ment organisations and the participation of the local population. Our projects aim at enablinglocal communities to earn additional income to access modern services while preserving thefragile environment of the Hindu Kush-Himalayan region.

GERES can be contacted at2, cours Foch, 3400 Aubagne, France

Tel: +33 442 8 55 88Fax: +33 442 03 0 56E-mail: [email protected]: http://geres.free.fr/

About the organisations


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SOLARGREENHOUSESFORTHE TRANS-HIMALAYAS2


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SOLARGREENHOUSESFORTHE TRANS-HIMALAYAS 3

Vincent Stauffer

with

Tashi TokhmatDorge RaftanGulam Razul (LEHO)Christophe ViltardLaetitia Rivagorda

Philippe RynikiewiczBenoit GiraudClaude TournellecRodolphe CastelaniThomas MansouriAlain Guinebault (GERES)

SolarGreenhouSeSforthetranS-himalayaS

A Construction Manual

ICIMODInternational Centre for IntegratedMountain Development

ARIDAgriculture and Rural Income DiversicationKathmandu, Nepal

GERES

Renewable Energy and Environment GroupAubagne, FranceApril 2004


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Copyright 2004International Centre for Integrated Mountain DevelopmentGERES (Renewable Energy and Environment Group)All rights reserved

Photo creditsAll the photographs credited to GERES, except N4 credited to ATA

Published byInternational Centre for Integrated Mountain DevelopmentG.P.O. Box 3226Kathmandu, Nepalwith

GERES (Renewable Energy and Environment Group)2, cours Foch, 3400 Aubagne, France

ISBN 92 9115 832 1

Editorial TeamA.Beatrice Murray (Editor)Dharma R. Maharjan (Technical Support and Layout Design)

Printed byQuality Printers Pvt. Ltd., Kathmandu, Nepal

The views and interpretations in this paper are those of the contributor(s). They are not attrib-utable to the International Centre for Integrated Mountain Development (ICIMOD) or GERES

and do not imply the expression of any opinion concerning the legal status of any country, ter-ritory, city or area of its authorities, or concerning the delimitation of its frontiers or boundar-ies, or the endorsement of any product.


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foreword

Food security remains the major preoccupation of mountain communities in many parts of

Asia, especially in the higher altitude and more remote parts of the Hindu Kush-Himalayanregion. The climate in this region of the trans-Himalayas is very harsh: winter temperaturescan fall below -30C, and precipitation is low. The natural resources are limited, and farmersrely on sheep, goats, cattle and yak as their main source of survival, with limited subsistenceagriculture on very small landholdings focused mainly on cereals. In the winter, snowfall blocksthe high passes and roads are closed, and the population must rely almost entirely on its ownresources for survival.

Mountain communities have survived for cen-turies in this environment, but population in-creases, environmental pressure, and politi-cal changes and limitations to movement areincreasing the challenge. At the same time,expectations and demands are increasing, ascontact with the outside world and more wide-spread education raise peoples awareness ofthe possibilities and potential benets else-where. The result is increased out-migration,especially of the young and strong; reducedcapacity of those left behind to use the land;loss of community, culture, and the indig-enous knowledge of how to survive in theseharsh conditions; and an inux of people tourban areas to join the growing ranks of thepoor and rootless.

The Renewable Energy and EnvironmentGroup GERES, supported by its partners indevelopment (European Commission, FrenchMinistry of Foreign Affairs, and others) workswith mountain communities to help them es-tablish tools and processes that strengthenand develop local potentials, improve liveli-hoods, and provide people with better optionsfor remaining in their home areas. Many inno-vative tools have been developed, improved,and adapted for local use. GERES, workingwith Indian, Chinese, Nepalese, and AfghanNGOs, has focused on technologies for savingenergy (passive solar buildings and improved

stoves to reduce consumption of wood andother fuels), and generating income (solargreenhouses, solar poultry farming, process-ing of food and wool).

One of the major challenges is to help com-munities use the inactive winter period to in-crease food security and generate additionalincome. Fortunately, one resource that thetrans-Himalayan area has in abundance issunshine, especially in winter. Solar radia-tion can be used to improve the quality oflife in many ways. Potential benets includewarming houses, schools, dispensaries and

handicraft centres, and developing off-sea-son agricultural activities such as composting,greenhouse production, and poultry farming.

This manual focuses on the construction ofpassive solar greenhouses that enable veg-etables to be grown during winter in the highaltitude areas of the trans-Himalayas.

The International Centre for Integrated Moun-tain Development (ICIMOD) works to improvethe livelihoods and security of the mountaincommunities of the Hindu Kush-Himalayas(HKH). Improving the productivity and sus-tainability of mountain agriculture, reducingfuel consumption, and reducing environmen-tal damage are central to its activities. As apart of its programme, ICIMOD has had a ma-

jor focus on rural technologies and alterna-tive energy approaches, including hosting aseries of national workshops on passive solarbuilding technologies in four of the countries

of the HKH. The new Integrated Programmeon Agriculture and Rural Income Diversica-tion (ARID) focuses on high value products,rural enterprises, and renewable energy op-tions, among others. Thus ICIMOD is delight-ed to have had this opportunity to supportGERES in the development of this manual onsolar greenhouse technology, and to be ableto make this information available to a widercommunity.

GERES and ICIMOD both hope that this man-ual will prove useful to the many NGOs andother technical organisations who are work-

ing with communities and farmers in the HKHregion to improve living standards and condi-tions, and ultimately that increased access towinter vegetables and exotic summer producewill improve the quality of life and incomegeneration opportunities of many of the smallfarmers in some of the most marginalised ar-eas of the Hindu Kush-Himalayas.

Alain GuinebaultDirectorGERES

J. Gabriel CampbellDirector GeneralICIMOD


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The greenhouse design proposed in this handbook is the result of improvements made by

NGOs and by farmers themselves of a design initially proposed by GERES. The main contribu-tors to this design evolution were marginal farmers of the trans-Himalayan areas, who sug-gested practical improvements that reduce the investment cost and construction requirementsand ensure that the design is appropriate for the resources available in these high mountainareas.

LEHO (Ladakh Health and Environment Organisation) was the rst non-government organisa-tion (NGO) to experiment with the model; this NGO did a tremendous amount of work to im-prove the design and to train carpenters and masons to build greenhouses in remote areas.

The following NGOs contributed greatly to adapting the initial design to suit specic local con-texts.

Ladakh (Jammu and Kashmir, India) LEHO (Ladakh Health and Environment Organisation) LEDeG (Ladakh Ecological and Development Group) LNP (Leh Nutrition Project) CRO (Chief Representative Organisation)

Lahaul and Spiti (Himachal Pradesh, India) Himachal Pradesh Government through the Watershed Project Pragya Dawa Development

Qinghai (China) ATA (Appropriate Technology for Asia)

Badakshan, Hazara Jat, Lowgar, and Parwan (Afghanistan) Ministry of Animal Husbandry and Agriculture AKDN (Agha Khan Development Network) AFRANE Developpement (Amiti franco-afghane) SOLIDARITES

Mustang (Nepal) ATA (Appropriate Technology for Asia)

acknowledGementS

UNITS AND GEOMETRY ft = foot= 0.3048 m inch = 2.54 cm cm centimetre

m metre = 00 cmC Degree Celsius diameter

The experimentation, implementation, and publi-cation of the manual, would not have been pos-sible without the nancial support of the EuropeanCommission, French Ministry of Foreign Affairs,SOLIDARITES, Frres de nos Frres, and ATA. In

particular we would like to acknowledge the Euro-pean Commission which has been supporting eldprojects in Ladakh, Lahaul & Spiti, Mustang, andQinghai since 988. We thank ICIMOD for their sup-port and encouragement to publish the manual forwider distribution, in particular Greta Rana Divi-sion Head, IMCO for recognising the potential valueof the manual; Kamal Rijal former Energy Spe-cialist for his support and valuable comments; A.Beatrice Murray for her editorial support; DharmaR. Maharjan for layout and design; and all the othermembers of the publications unit.

Finally, it is important to mention that the green-house design and the manual itself were devel-oped in partnership with contributions from many

individuals, in particular, from GERES, ChristopheViltard and Laetitia Rivagorda, who did the agricul-tural experimentation; Philippe Rynikiewicz, Benoit

Giraud, and Claude Tounellec, who thought of manypractical improvements; Rodolphe Castelani, whodid the drawings; Thomas Mansouri, who set upthe manual; and Alain Guinebault, who initiated theproject; from LEHO Tashi Tokhmat, Dorge Raftan,

and Gulam Razul, who carried out the rst trials,and suggested major improvements; Sjoerd Nien-huys of SNV who made some useful suggestions ina review of different types of greenhouses in Mus-tang; and all the farmers and construction workersat the different project sites whose enthusiasm, in-terest, and hard work helped to improve the designand ensured the project was successful.


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introductionBackground ........................................................................................................ 3What is a Greenhouse? ........................................................................................ 4Solar Greenhouses for the Trans-Himalayas ............................................................4

Part a: theoryof PaSSive SolarGreenhouSeSforcold areaS

The Passive Solar Greenhouse Concept.................................................................9Collection and Storage of Radiation .......................................................................9Storage, Release and Containment of Heat: the Thermal Properties of Materials ........ 0

Principles of Solar Greenhouse Design................................................................ Collection of Solar Radiation ............................................................................... 2Thermal Storage and Insulation .......................................................................... 2Ventilation ........................................................................................................ 4

Principles of Site Selection ................................................................................. 4

Characteristics of a Suitable Location ................................................................... 4Site Characteristics that Affect the Design ............................................................ 5Selecting the Best Site ....................................................................................... 6

Selecting the Most Appropriate Design .............................................................. 7

Bibliography....................................................................................................... 8

Part B: technical GuidelineSforBuildinGa GreenhouSe

Building a Greenhouse........................................................................................ 2

Basic Designs ..................................................................................................... 2Design .......................................................................................................... 2Design 2 .......................................................................................................... 25Design 3 .......................................................................................................... 29Design 4 .......................................................................................................... 33

The Construction Schedule ................................................................................. 35Before Construction ........................................................................................... 35The Construction ............................................................................................... 35

Technical Datasheet 1: Constructing the Foundation ............................................... 37Principle ........................................................................................................... 37Methods for Orientation ..................................................................................... 37

Preparing and Marking the Ground ...................................................................... 39Constructing the Foundation ............................................................................... 40Preparing the Floor of the Greenhouse ................................................................. 40

contentS


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Technical Datasheet 2: Building the Walls .............................................................. 4Principle ........................................................................................................... 4Outlining the Shape / Setting the Angles of the Walls ............................................. 4Constructing the Wall ........................................................................................ 42Filling the Insulating Layer ................................................................................. 43Finishing the Walls ............................................................................................ 43Alternatives ...................................................................................................... 44

Technical Datasheet 3: Building the Partition Walls ................................................ 45Principle ........................................................................................................... 45Procedure ........................................................................................................ 45

Technical Datasheet 4: Making and Installing the Access Door ................................ 47Principle ........................................................................................................... 47Carpentry ........................................................................................................ 47Masonry Installing the Door ............................................................................. 48

Technical Datasheet 5: Making and Installing the Wall Ventilator .............................. 49Principle ........................................................................................................... 49Carpentry ........................................................................................................ 49Masonry ........................................................................................................... 50

Technical Datasheet 6: Constructing the Roof ........................................................ 5Masonry and Roof Supports ................................................................................ 5Constructing the Roof ........................................................................................ 53

Technical Datasheet 7: Making and Installing the Roof Ventilator .............................. 55

Principle .......................................................................................................... 55Carpentry ........................................................................................................ 56Installation ....................................................................................................... 57

Technical Datasheet 8: Installing the Polythene Sheet ............................................ 59Principle ........................................................................................................... 59Constructing the Support Structure ..................................................................... 59Attaching the Polythene Sheet ............................................................................ 6

Technical Datasheet 9: Installing Night Insulation .................................................. 63Principle .......................................................................................................... 63


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introduction


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SOLARGREENHOUSESFORTHE TRANS-HIMALAYAS

BackGround

The northern parts of the Hindu Kush and Himalayan ranges are mostly cold desert lying be-tween 2500 and 5000 metres above sea level. This area, often called the trans-Himalayas,

stretches from Tajikistan in the west to Bhutan in the east, with the Tibetan Plateau in thecentre. The environment is very harsh: the winter temperatures frequently fall below -30Cand precipitation both rain and snowfall is low (less than 300 mm per year). The naturalresources are very limited and the lack of trees and forests results in a very low populationdensity. Even so, some of the highest villages in the world can be found here.

During the short summer season, communi-ties devote their energy to stocking up for thewinter. Women spend two months a year onaverage collecting cow dung from the pasturesfor cooking and winter heating. The whole wayof life is geared towards surviving the longharsh winter. Subsistence farming is limited in

most of the area to one crop per year and isfocused on barley and wheat with some peas,potatoes, and occasionally other vegetables.The average agricultural landholding is small,less than 0.5 ha per household. The inhabit-ants of the high altitude plateau depend al-most entirely on cattle rearing. Poor transpor-tation infrastructure limits the supply of freshfood in all parts of the region. In winter, snow-fall blocks the high passes and the roads aremostly closed; foodstuffs are own in to themajor cities at high cost; in rural areas theyare simply not available. At the same time it

Figure : Winter view of a high valley in Zangskar, Ladakh

is very sunny, especially in winter. The solarradiation offers great potential for improvingpeoples lives. It can be used not only to warmthe interiors of houses, schools, dispensaries,and handicraft centres, it can also be used asa basis for developing off-season agriculturalactivities such as composting, production in

greenhouses and trench greenhouses, andpoultry farming.

In the following, we focus on the design andconstruction of greenhouses for the Trans-Hi-malayan region.

What is a Greenhouse?

A greenhouse is designed to provide an en-vironment suitable for growing fruit, vegeta-bles, owers, or others, at a time when the


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outside conditions are not favourable for thespecic purpose. In the trans-Himalayas, theemphasis is on vegetables. Vegetable growingdepends on two main factors: solar radiation

and climate. Vegetables need solar radiationfor photosynthesis, and the interior environ-ment (temperature and humidity) must matchthe vegetable requirements.

Solar Greenhouses for the Trans-Himalayas

A passive solar greenhouse, or solar green-house for short, is a greenhouse heated en-tirely by sunlight, with no additional fuel-based heating. In the trans-Himalayas, thetemperature inside these greenhouses can bekept high enough to grow vegetables through-

out the year, even in winter, if the greenhouseis built efciently. Thus greenhouses can be ofgreat use, particularly in those areas wherethere are continuing concerns about food se-curity and economic development. The mainbenets of solar greenhouses are

vegetable production in winter; fullment of basic subsistence needs inremote areas; and income generation in peri-urban areas.

The model proposed in this manual is an ef-cient greenhouse constructed almost entirely

with local materials (apart from the polytheneand some minor parts like nails and hinges).The initial model was tested, developed, andimproved by farmers in Ladakh, India, workingtogether with the non-government organisa-tion (NGO) LEHO (Ladakh Health and Environ-ment Organisation) to reduce the investmentcost, facilitate construction, and increase thelife span. The improved version was furtherdeveloped and adapted to the specic localconditions by farmers and NGOs in Lahaul &Spiti and Ladakh in India; Qinghai province in

taBle 1: GreenhouSecroPSindifferentSeaSonS

SeasonCold

(min. >-0C in winter)Very cold

(min. -0C to -5C)Extremely cold(min.


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Figure 2: Constructing a greenhouse in Afghanistan

it can be constructed by local builders; the cost can be recouped in less thanthree years if the production is well-man-aged and the products sold.

Solar greenhouses can contribute to humandevelopment in a number of ways includingempowering women, since they are oftenin charge of the production and the selling;helping overcome nutritional deciencies byenabling more diversied food production allyear round; and providing a means of incomegeneration.

However, a greenhouse is only efcient if it isconstructed in the right place and used prop-erly.

Past experience has shown the importance ofplanning the dissemination method to ensurethat the maximum benet is gained. Points toconsider include the following

q Stakeholder selection focus on communities with poor families innovative and dynamic farmers

q Site selection consider availability of water (river, wells, canals,snow) availability of direct and abundant sun-shine

need to adjust dimensions and materialsaccording to the site minimising waste of land at the back ofthe greenhouse

q Setting up of facilities plan for training builders training farmers in greenhouse cultivationmethods developing networks for the supply ofseeds, tools, and polythene, and for veg-etable marketing

This manual focuses on the guidelines for de-sign and construction of an efcient green-house. The economic feasibility, dissemina-tion methodology, and agricultural use will becovered in other booklets (in preparation).

The manual is divided into two parts: a de-scription of the theoretical principles, whichprovides the basis for understand the conceptof using passive solar greenhouses in cold ar-eas and knowing how to select a suitable siteand design; and a description of the practicalelements of construction with detailed instruc-tions on each step and the points to consider

to ensure that the greenhouse is efcient.

Figure 3: Solar greenhouse built in Leh, Ladakh, India


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Part a

theoryof PaSSive SolarGreenhouSeSforcold areaS


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thePaSSiveSolarGreenhouSeconcePt

The amount of solar radiation that reaches any particular point on the earths surface during an

average day depends on a number of factors including the length of the day, the height of thesun in the sky, the amount of cloud, the elevation of the site, the angle of the site with respectto the sun, and the presence of objects (like hills, trees, or buildings) that cast shadow.

A solar greenhouse aims to trap and inten-sify the heating effect of solar radiation andthus enable plants to be grown that cannotbe grown under the normal (outside) ambientconditions. Thus solar greenhouses are par-ticularly useful in areas like the trans-Himala-yas where there is a lot of sunshine in winter,but the air is too cold for growing crops.

There are four main factors that work togeth-er to make a solar greenhouse (or any otherbuilding) an efcient user of the available en-ergy (Figure 4).

Collection of the maximum amount of so-lar radiation during the day ()

Efcient storage of the heat collected fromthe sun radiation during the day (2)

Release of this heat to the interior of thebuilding during the night (3)

Reduction of heat losses by insulation ofthe whole greenhouse (4)

Collection and Storage of Radiation

One of the major factors affecting the amountof solar radiation entering a greenhouse isthe position of the sun in sky. The sun movesacross the sky from east to west, it rises in themorning to the east, reaches its highest posi-

tion at midday to the south, and sets in theevening to the west; and it rises higher in thesky in the summer than in winter (Figure 5).

Figure 4: Passive solar concept in a greenhouse

In the trans-Himalayas, passive solar green-houses are of most use during winter whengrowing vegetables is impossible outside;thus they are designed to absorb the maxi-mum amount of solar radiation possible atthis time. The sides of a greenhouse exposedto the sun gain heat during the day, while theother sides, in the shade, lose heat. In thesummer, when the sun is high in the sky, mostof the solar radiation enters the greenhousethrough the roof or any other horizontal part,but in the winter, when the sun is low, themaximum radiation enters from the southside: the sun warms the east face during the

morning, the south face at midday, and thewest face in the afternoon and evening. Thenorth face is always in the shade. Thus an

Figure 5: Seasonal variation of solar radiation

Figure 6: Conguration and orientation of a greenhouse


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efcient passive solar greenhouse should bedesigned along an east-west axis (Figure 6),with the length of the south face increasedand angled to present the largest possible

surface area to the sun, the size of the eastand west facing walls reduced to minimiseheat loss and shade inside the greenhouse,and the north wall heavily insulated.

Storage, Release and Containment ofHeat: Thermal Properties of Materials

Different materials are selected for differentparts of the greenhouse construction accord-ing to their primary function: transmissionof radiation, heat storage and release, insu-lation, and building support. These different

properties are summarised below.

O p a q u e m a t e r ia l s

These materials block solar radiation but theycan allow transfer of energy by heat conduc-tion. There are two main types.

Dense materials (brick, stone, cement) canconduct and store heat. Except for metals,heavier materials generally store more energyand absorb it faster. In a greenhouse, densematerials are used to provide thermal massand as load-bearing materials to form the wallsupporting the polythene frame and roof.

Low density materials (light materials likestraw, sawdust, wood shavings, dry leaves,and dry grass) are poor conductors and storersof heat and are thus good insulators: they helpretain the heat inside the greenhouse. Thesematerials are lled into the cavity between theloadbearing wall and the thermal mass wall.

T r a n s p a r e n t m a t e r i a ls

Materials like glass and transparent polytheneallow radiation to pass through and are used totransmit radiation from the surface to the innerspace of the greenhouse. Transmittance is highwhen the sun is perpendicular to the surfaceand up to an angle of about 30, but decreasesstrongly at angles above 50. Transmission ishigher through glass (maximum 90%) thanthrough polythene (maximum 80%).

An important characteristic of transparentmaterials is the greenhouse effect (Figure 7),which results from the fact that the transpar-ency depends on the radiation wavelength.Materials can be transparent to solar radiationbut not to heat radiation, whose wavelength isinfra-red. The majority of incident solar radia-

tion is transmitted through the material; thisradiation heats the inside surfaces; these re-lease radiative heat which is reected back into

the greenhouse by the transparent material.In other words, the radiation that enters thegreenhouse is trapped inside, and heat losses

only take place by conduction. The greenhouseeffect is strong for glass, but 50% less efcientwith polythene. However, it is much cheaperto cover a greenhouse with polythene. If poly-thene is used, additional insulation can beadded at night to reduce heat loss.

Figure 7: The greenhouse effect

taBle 2: advantaGeSanddiSadvantaGeSofGlaSSandPolythene

Glass Polythene

Advantages highertransmission less heat loss

cheap easy to carry easy to repair

Disadvantages expensive replacementif breakage difcult to

carry

less efcient short life(in windy area) notbiodegradeable

W a l l c o l o u r

The amount of solar energy absorbed bya material is linked to its colour (Figure 8).White surfaces reect most of the suns radia-tion, whereas black surfaces absorb most ofthe radiation. The proportion of the suns ra-diation absorbed by a specic colour is calledthe absorptance.

Colour Absorptance

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

Figure 8: Absorptance related to the colour


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PrinciPleSofSolarGreenhouSedeSiGn

A passive solar greenhouse is designed to trap enough solar radiation for the photosynthesisprocess and to provide the interior climatic conditions required for growing vegetables all year

round. When the outside conditions are very cold, heat is stored during the day in the groundand walls of the greenhouse and released during the night to keep the greenhouse air warm.During winter, the greenhouse traps enough energy during the day to ensure that the veg-etables do not freeze at night.

The temperature variation between day andnight should be minimised to reduce thermalstress to the plants. Overheating during theday can be prevented using natural ventila-tion for cooling, regulated by manually oper-ated shutters. Ventilation also regulates thehumidity and thus helps to limit diseases and

pests.

A passive solar greenhousev picks up solar radiationv stores the radiation as heat in the

mass of the walls and the groundduring the day

v releases this heat during the night towarm the interior space

v is insulated to retain this heatv can be ventilated to avoid overheating

The passive solar greenhouse for cold areas

described in this manual has three main com-ponents, which together ensure that these re-quirements are met.

Walls on the east, west, and north sideswhere the amount of incident solar energy islimited. These walls are either buried into ahillside or insulated to limit heat loss and in-crease thermal storage (Figure 0).

Figure 9: Inside views of a greenhouse in Ladakh

Figure 0: Greenhouse walls and structure


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A polythene sheet on the south side, whichpicks up the largest amount of solar energy.The polythene transmits the majority of inci-dent solar radiation into the greenhouse. This

warms the interior space and is absorbed bythe vegetables, the ground, and the walls.The sheet can be covered with a moveablelayer of insulation like a curtain, cloth, or matafter sunset to reduce night time heat loss.The polythene sheet is set at an angle andsupported by a wooden frame (Figure ).

A (solid) roof on the north side to limit heatloss. The roof is tilted to avoid shading in winterand reduce the interior volume (Figure 2).

Figure : Greenhouse covered with polythene

Collection of Solar Radiation

Solar radiation is taken up through a transpar-ent polythene sheet covering the south faceof the greenhouse. The angle of the polythene

is calculated so that the maximum amount ofsolar radiation is transmitted into the interior.The angle of the lower section of the polythene

Figure 2: View of the roof from inside the greenhouse

is 50 or more (measured from the horizontal) the best angle to transmit solar radiation inthe early morning or late afternoon when thesun is low in the sky. The angle of the up-

per section is 25 or more (measured fromthe horizontal) the best angle to transmitthe mid-day solar radiation and allow smallamounts of snow to slide off.

Moveable insulation (parachute, cloth) is usedas a curtain below the polythene after sun-set to reduce heat loss; it is removed aftersunrise. Moveable insulation can increase theground and interior temperature at night byup to 5C. At high altitudes, a double poly-thene layer can be used to reduce heat loss;it can also increase the interior temperatureby up to 4C at night.

Thermal Storage and Insulation

Several components are used in the designto increase thermal storage and reduce heatloss.

D o u b l e w a l l

The walls are composed of three layers: anouter load-bearing wall built with mud brick,rammed earth, or stone; an inner wall usedto store heat during the day and release itat night, also built with mud brick, rammed

earth, or stone; and an insulating layer ofmaterials like straw, sawdust, wood shavings,dry leaves, dry grass, or wild bush cuttingspressed between the two.

Co l o u r

The inner side of the west wall is paintedwhite (whitewash) to reect the morning so-lar radiation after the coldness of the night;the inner side of the east wall is painted blackto absorb and store the afternoon solar radia-tion, which is then released at night to heatthe interior space; and the bottom two feetof the inner side of the north wall are white-washed and the upper part painted black forsimilar reasons.

Roo f

The xed roof is sloped (to the north) at anangle of 35. In winter, when the sun has alow elevation angle, this angle optimises thesolar radiation absorption on the inside sur-face. During summer, when the sun is highin the sky, the roof partly shades the green-house and reduces the risk of overheating.The roof is covered with a layer of insulation(straw, or similar); a piece of white cloth or

parachute material can be added below it toimprove the insulation and reect solar radia-tion onto the vegetables. The shape of the


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roof reduces the interior volume compared totraditional greenhouses, thus increasing theinterior temperature.

G r o u n d The greenhouse oor is dug out so that it lies6 (5 cm) below the outside surface level.This improves plant growth as the dip acts asa trap for carbon dioxide, as well as providingadditional thermal insulation. In extremelycold climates, a 2 layer of dung should belaid four inches below the surface to insulatethe ground and increase the thermal mass ef-ciency. Horse or donkey dung are the mostsuitable as they contain straw, but yak or cowdung can also be used.

D o o r

The door is located on the wall opposite tothe side from which the prevailing wind blows(the lee side) to reduce inltration of cold air.

V e n t i l a t i o n

On sunny days, the air in the greenhouse canbecome very warm. Overheating (over 30C)can damage the vegetables and encouragediseases and pests. Manually operated open-ings (ventilators) are provided in the lowerpart of both sides (door, wall shutter) and inthe roof. The warm air rises and leaves thegreenhouse through the roof ventilator, draw-ing in the cooler ambient outer air through

the lower ventilators (Figures 4 & 5).

Figure 3: Greenhouse under construction (view of the double walls and thestructure of the roof)

Figure 4: Air circulation in a greenhouse

Figure 5: Opening the roof ventilator

PrinciPleSofSiteSelection

Characteristics of a Suitable Location

W a t e r su p p l y

Vegetables require water to grow. During thecold winter period, the greenhouse requiresless ventilation, evaporation is lower, andmore moisture is retained inside, thus onlya small amount of water is required. But inspring and summer, the greenhouse is ven-tilated during daytime to avoid overheating,evaporation is higher, and moisture is lost withthe ventilated air, so that a larger amount ofwater must be given.

During winter and spring, many streamsand springs are frozen; it is necessary toensure that there is a source of running wa-

ter located close enough to the greenhousethat transportation is not so difcult as todiscourage the farmer from operating thegreenhouse.

The crucial period is spring, when more wateris required than in winter but static sourcesmay still be frozen. The distance to the near-est running water has to be acceptable duringthis period.

The maximum distance that a farmer can beexpected to carry water without it becoming

a disincentive is about 600 feet (200 m) inwinter and 300 feet (100 m) in spring andsummer.


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So l a r r a d i a t i o n

Solar radiation is required both for photosyn-thesis and to heat the greenhouse. If the sun-

rise is too late or the sunset too early, thegreenhouse remains cold longer and vegeta-ble production is reduced. Nearby obstaclescan also shade the greenhouse.

Sunrise must be before 9:30 am and sunsetlater than 3:00 pm.

S lo p e a n d t y p e o f l a n d

The slope of the land inuences the amount ofsolar radiation collected, the ground tempera-ture, and the heat loss through the walls.

A site is suitable if the land is at and dry the land is on a south-facing slope: theamount of solar radiation is increased bythe ground reection, at the same time,the greenhouse is partly underground, theground is warmer than the ambient air, andheat loss through the walls is reduced the land backs on to a south-facing ter-race (the drop down from one terrace tothe next forms the back of the site): theterrace wall can be used as the back wall ofthe greenhouse and may support the roof;

the benets are a lower investment cost,warmer ground, and a larger thermal massif the step is built up using stone masonry

A site is rejected if the land is on a north-facing slope theamount of solar radiation is decreased the land is against a north-facing terrace:the greenhouse has to be oriented towardsthe north and the benets will be limited the land is marshy: the ground freezeseasily in winter and the vegetables mayalso freeze the site is not on agricultural land (stone,sand, or similar)

Site characteristics that affect the design

W i n d

If the door of the greenhouse is exposed to

wind, inltration of cold ambient air will lowerthe inner temperature of the greenhouse.

The door must always be located on the op-posite side from the prevailing wind.

Cl i m a t e (Altitude)Temperature decreases with altitude, thus asimilar greenhouse will be more efcient atlower altitudes than on the high plateau. Thedesign can be adapted to colder climates byincreasing the thermal mass and ground insu-lation and reducing the width, among others.

The greenhouse design should take into ac-count the normal lowest winter temperaturesat the site.

Snow

Heavy snowfall can damage the polythene laidover the greenhouse if a considerable weightof snow remains on it. In snowy areas, thepolythene needs to slope more steeply so thatthe snow slips off.

The polythene sheet must slope more steeplyin areas with high snowfall.

Selecting the Best Site

A site is suitable for a greenhouse project if allthe criteria shown in Table 3 are fullled.We have developed a simple selection toolthat weights these different factors and pro-vides an easy way of comparing the advan-tages and disadvantages of different possiblesites using the criteria listed above. The dif-ferent site characteristics are allotted marksaccording to the list shown in Table 4, and thenumber of marks lled out in the form shownas Table 5. The total number of marks is cal-culated; the site with the highest number isthe most suitable based on these criteria.Similar sites can then be further differentiatedon the basis of other criteria of more specicinterest like accessibility, security, distance toworkforce, and so on.


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taBle 4: criteriamarkinGSyStem

Characteristic Points Characteristic Points

Distance to running water in winter Sunrise in January

less than 50 feet 5 Before 7:30 am 8

less than 00 feet 4 8:00 am 6


less than 300 feet 9:00 am 2


Distance to running water in spring Sunset in January

less than 50 feet 6 After 5:00 pm 6

less than 00 feet 5 4:30 pm 5



Slope

Site adjacent to a south-facing terrace(terrace wall between .5 and 4 feet high)

5

South-facing slope 3

Flat 2

taBle 3: SuitaBilityofaSitefortheimPlementationofaGreenhouSeProject

Feature Factor Condition Site survey

Shade sunrise (January ) before 09.30 am

sunset (January) after 03:00 pm

shade from distant object (hill/moun-tain) between 9:30 am and 03:00 pm

none

shade from nearby object (trees/hous-es) between 9:30 am and 03:00 pm

none

Waterdistance to water

December to March


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SelectinGthemoStaPProPriatedeSiGn

The design of a greenhouse for a specic location is inuenced by the site characteristics, theclimate , and the expected amount of snowfall. Ten different basic designs have been devel-

oped: one for each of the three main types of land in each of three different climates, and atenth for at land in snowy areas. Details are provided in Section B.

Essentially there are three shapes of green-house designed to t the three different typesof site.

Shape A for a at and dry site Shape B for a south-facing slope Shape C for a site adjacent to a south-facingterrace wall

The designs for different climates focus on

reducing heat loss at the colder sites. Threedesigns are proposed, for cold, very cold, andextremely cold (winter) climates. The altituderange at which these designs are appropriatewill differ in different areas depending on thelatitude and longitude. As a guide, the climateat any given altitude will be colder in Afghani-stan and Central Asia than in Ladakh, andcolder in Ladakh than in Sikkim (for example,the temperatures at 2800m in Afghanistanare similar to those at 3500m in Ladakh).

Design 1For sites with a cold climate: lowest tempera-ture above -0C.Examples: Nubra (Ladakh, India), Lahaul (Hi-machal Pradesh, India), and Kabul (Afghani-stan)

Design 2For sites with a very cold climate: lowest tem-perature -0C to -5C.Examples: Leh (Ladakh, India), Bamyan (Af-ghanistan), Qinghai (China)

Roof insulation layer is increased to 2

Design 3For sites with an extremely cold climate: low-est temperature below -5C.Examples: Chang Tang (Ladakh, India),Wakham (Afghanistan)

An inner partition is added to increasethermal mass A double layer of polythene is used The ground is insulated Only one roof ventilator is required

Design 4For snowy areas.

The slope of both roof and polythene in-crease to 40 so that snow can slide off onboth sides A double layer of polythene is used Only one roof ventilator is required

Table 6 shows a grid for selecting the appro-priate design for a particular site. In all thedesigns the door must be constructed on thewall opposite to the prevailing wind to limitinltration of cold air. Details of the designs

and how to construct the greenhouses areprovided in Part B.

taBle 6: SelecttheaPProPriatedeSiGn

Climate

Site Coldmin > -0C

Very coldmin -0C to -5C

Extremely coldmin


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Passive solar techniques

Balcomb, D. (983) Heat Storage and Distri-bution inside Passive Solar Buildings. LosAlamos (USA): Los Alamos National Labo-ratory

Bansal, N.K.; Rijal, K. (2000) Proting fromSunshine: Passive Solar Building in theMountains. Kathmandu: ICIMOD

Guinebault, A.; Rozis, J.F. (997) Passive SolarHeating in Cold Areas. Aubagne (France):GERES

Levy, M.E. (983) The Passive Solar Con-

struction Handbook: Featuring Hundreds ofConstruction Details and Notes, MaterialsSpecications and Design Rules of Thumb.Emmaus (USA): Rodale Press

Mazria, E. (979) The Passive Solar EnergyBook. Emmaus (USA): Rodale Press

Prakash, S. (99) Solar Architecture andEarth Construction in the North West Hima-laya. New Delhi: Development Alternatives

Shapiro, A. (985) The Homeowners Com-plete Handbook for Add-On Solar Green-houses and Sunspaces. Emmaus (USA):

Rodale PressStauffer, V.; Hooper, D. (2000) A Training

Manual on Passive Solar. Aubagne (France):GERES

Greenhouse construction

Aldrich, R.A.; John, W.B. Jr. (989) Green-house Engineering, NRAES-33. Ithaca:Cornell University

Alward, R.; Andy, S. (98) Low-Cost PassiveSolar Greenhouses. Butte (USA): National

Center for Appropriate TechnologyAnon (980) A Solar Adapted Greenhouse

Manual and Design. Charlottetown (Cana-da): Miller-Solsearch

Anon (984) Building and Using the SolarGreenhouse. Huntsville (USA): AlabamaSolar Energy Center

Bartok, J.W.; Susan, M. (982) Solar Green-houses for the Home. Ithaca: Cornell Uni-versity, Northeast Regional Agricultural En-gineering Service

Fisher, R.; Bill, Y. (976) The Food and HeatProducing Solar Greenhouse: Design, Con-struction, Operation. Santa Fe: John MuirPublications

Freeman, M. (997) Building Your Own Green-house. Mechanicsburg (USA): StackpoleBooks

Fuller, R.J. (992) Solar Greenhouses forthe Home Gardener. Melbourne: VictorianDept. of Food and Agriculture

Geery, D. (982) Solar Greenhouses: Under-ground. Blue Ridge Summit (USA): TABBooks

Kramer, J. (980) Your Homemade Green-house. New York: Cornerstone

McCullagh, J.C. (ed) (978) The Solar Green-house Book. Emmaus (USA): Rodale Press

Nienhuys, S. (2003) Mission Report Green-house Applications - Jomsom, Internal re-port prepared for KMNTC and WWF-Nepal.Kathmandu: SNV-Nepal

Nienhuys, S. (2003) Construction Designs forGreenhouses in High Altitude Areas, Inter-nal report. Kathmandu: SNV-Nepal

Parsons, R.A., et al. (979) Energy Conser-vation and Solar Heating for Greenhouses.Ithaca: Cornell University, Northeast Re-gional Agricultural Engineering Services

Running a Greenhouse

Kemble, K.; Todd, P. (985) Managing YourSolar Greenhouse. Helena (USA): MontanaDept. of Natural Resources and Conserva-tion

Murray, I. (993) Practical Greenhouse Gar-dening. Ramsbury (UK): Crowood Press

Williams, T.; Jeff, S.L.; Larry, H. (99) Green-houses. San Ramon (USA): Ortho Books

Viltard, C. (2003) A Manual of Solar Green-house Running In the Trans Himalayas.Aubagne (France): GERES

BiBlioGraPhy


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Part B

technical GuidelineSforBuildinGa GreenhouSe


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Figure 16: Design 1A - Greenhouse for cold climate, at land


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Figure 7: Design B - Greenhouse for cold climate, south-facing slope


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Figure 8: Design C - Greenhouse for cold climate, site adjacent to a south-facing terrace wall


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BaSiccharacteriSticSof deSiGn 2

Characteristic Description

Structure Orientation South

External dimensions 32 x 4 0

Internal dimensions 28 4 x 2

Door position Opposite to prevailing wind

Inner partition No

Roof slope 30

Depth of soil surface below outside level 6

Insulation Wall insulation 4

Roof insulation 2

Ground insulation No

Ventilation Wall ventilation Yes

Roof Ventilation 2 roof ventilators

Polythene Single / Double Single

Manually operated night insulation Yes

Choose Design 2A for a at site (Figure 19), 2B for a site on a south-facing slope (Figure 20),and 2C for a site adjacent to a south-facing terrace wall (Figure 2).

Design 2Very cold climate: lowest temperature between -0C and -5C


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Figure 20: Design 2B - Greenhouse for very cold climate, south-facing slope


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Figure 2: Design 2C - Greenhouse for very cold climate, site adjacent to a south-facing terrace


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Internal dimensions 28 4 x 2


Inner partition Yes

Roof slope 30



Roof insulation 2

Ground insulation Yes


Roof Ventilation roof ventilator

Polythene Single / Double Double


Design 3Extremely cold climate: lowest temperature below -5C

Choose Design 3A for a at site (Figure 22), 3B for a site on a south-facing slope (Figure 23),and 3C for a site adjacent to a south-facing terrace wall (Figure 24).


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Figure 22: Design 3A - Greenhouse for extremely cold climate, at land


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Figure 24: Design 3C - Greenhouse for extremely cold climate, site adjacent to a south-facing terrace


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Internal dimensions 28 4 x


Inner partition No

Roof slope 40



Roof insulation 2

Ground insulation No


Roof Ventilation roof ventilator

Polythene Single / Double Double


Design 4Snowy areas

The design for a at plot is shown in Figure 25.


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Figure 25: Design 4 - Greenhouse for snowy areas (at land)


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theconStructionSchedule

Before Construction

Select the best site and the most suitable design as described in Part A.Study the design and list the materials needed, use the table in Technical Datasheet 0 as aguide.Collect all the materials together and store them on site.

The Construction

The construction itself can be divided into ten basic steps, each is described in detail in theTechnical Datasheets provided in the following. The steps are as follow:

v Constructing the foundationTechnical Datasheet

v Building the wallsTechnical Datasheet 2

v Building the partition wallsTechnical Datasheet 3

v Making and installing the doorTechnical Datasheet 4

v Making and installing the wall ventilatorTechnical Datasheet 5

Figure 26: A team constructing a greenhouse in Qingha

v Constructing the roofTechnical Datasheet 6

v Making and installing the roof ventilator(s)Technical Datasheet 7

v Finishing the wallsTechnical Datasheet 2

v Installing the polythene sheetTechnical Datasheet 8

v Installing night insulationTechnical Datasheet 9

v A list of materials is provided inTechnical Datasheet 0


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technicaldataSheet 1: conStructinGthefoundation

Principle

Foundations are the basis of every structure. The orientation and outline of the wall positionsmust be exactly as given in the design to ensure maximum efciency of the greenhouse. Theoutline of the walls is rst drawn on the ground and the foundations are then dug and lled.

Methods for Orientation

Orientation: nding southThe greenhouse must face south for maximumefciency. The orientation may vary by up to0 from due south towards east or west ifthis is an advantage in terms of the site con-guration, and to save agricultural land.

The rst step is to draw a line on the groundshowing the orientation of the south-facingmain wall (an east-west axis). There are twoways to do this.

Use a compassIn the Hindu Kush-Himalayas, magnetic northis very close to geographic north (+ 5) andyou can use the direction shown on a compassto nd south. Lay a rope on the ground par-allel to the east-west axis given by the com-pass. Draw a line parallel to the rope to markthe orientation of the south facing wall.

Use the plumb-line methodFirst you must know the exact time of truemidday, when the sun is at its highest point inthe sky. In Ladakh, for example, this is at 20minutes past 2 (2:20 pm).

If you dont know the exact time of midday,place a stick rmly in the ground and markthe position of the tip of its shadow every 0minutes from about .30 to 2.30 or later.Note the time of the position when the shad-ow is shortest. This is midday.

Then hang a stone from a rope and hold therope in your hand. Draw a line on the groundalong the line of the shadow of the rope at ex-act midday: this line is the north-south axis.Now draw the four cardinal points north, east,south, and west on the ground as shown inFigure 27. Make a line for the position of thesouth face of the greenhouse by drawing aline along the east-west axis using a rope.

Now draw a line to mark the position of thefull length of the outer wall of the south faceof the greenhouse.

Constructing a right angle

One of the most important parts of wall con-struction is making sure that the walls areperpendicular to each other, in other wordsforming a right angle between adjacent walls.There are two ways to do this: the 3,4,5method and the bisecting lines method.These methods are used when marking theposition of the foundation as well as laterwhen building the walls.

The 3,4,5 methodFix a thin rope to a thin post at one end of the

line marking the position of the south face. Fixthe other end of the rope to a second post ex-actly 3 along the south face line. Unwind ex-actly 9 of a measuring tape and x or hold thetwo ends of the tape to the two marker posts.Hold the tape at a point exactly 4 from thepost marking the end of the southern face ofthe greenhouse. This point is 5 from the sec-ond post. Pull the tape towards the north untilit is taut. It will form a triangle with sides of 3along the south side, 4 along the north-southsidewall, and 5 along the diagonal betweenthem. The tape will form an exact right angle(Figure 28). Mark the position of the side-wall

by drawing a line along the tape. Repeat forall four corners and mark the position of theoutside of all the walls.Figure 27: Finding south with a plumb line 38


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The bisecting lines methodStarting at the point marking one end of theline showing the position of the south face,draw two lines of the same length a in op-posite directions, one along the line and one

along its extension (Figure 29). Draw an arcof a circle of radius b from the end of eachof the lines such that they intersect. Draw a

Figure 28: Drawing a right angle using the 3,4,5 method

Figure 29: Bisecting lines method to draw a right angle

line between the point where the arcs inter-sect and the point marking the end of the wallalong the south face: this line marks the posi-tion of the side-wall, and is perpendicular to

the south face.

Note: Similar methods are used to determinethe position of the inner partition in Design 3,see Datasheet 5.

Preparing and Marking the Ground

Excavating the slopeIf the plot is on a slope, the rst step is toexcavate the land to provide a at area. Thedug out area at the back protects the backwall (Figure 30).

Figure 30: Excavating a slope

Marking the wall positionMark the position of the foundations of thegreenhouse with stakes and string, and achalked line on the ground, as described above(Figure 3). The foundations of the back andside-walls are 2 wide (or 22 as in the plans).The south wall foundation is wide, in a linestretching from the southern edges of theeast and west walls, as shown in the plan. ForDesign 3, also mark the position of the inter-nal partition walls. No foundation is necessaryalong the north wall in Design C.

Note that the scale plans show a foundation 22 wide, i.e., 4 wider than the walls and ex-tending 2 beyond the wall on each side. This


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may be marginally stronger but experienceshows that a 2 wide foundation, extending beyond the walls on either side, is sufcient.

If the walls have to be built with rammedearth or stone (see Technical Datasheet 2),then the foundation trench must be madewider accordingly.

Figure 3: Marking the position of the walls

Constructing the Foundation

Digging the trenchDig a trench 6 deep within the markings.

Mark the position of the door frame 3 fromthe interior of the north wall on either the eastor west side, whichever is opposite to the pre-vailing wind, as shown in the plan.

Filling the foundationFill the trench with mediumsized loose stonesand dry/mud mortar, according to the usualpractice in the area. In rainy areas, the foun-dations can be strengthened by concretemortar, but the price will be higher. A 2 thicklayer of concrete can be laid on the top ofthe foundations to strengthen the structure ofthe greenhouse and reduce the risk of damp

(Figure 32).

Preparing the Floor of the Greenhouse

In Designs , 2 and 4, when the foundationis complete, dig out the greenhouse oor toa depth of 6 so that the level of the oor islower than that of the outside ground.In Design 3, dig out the oor to a depth of2 after wall construction is complete butbefore installing the plastic cover. Cover thesurface with a 2 layer of dung, and replacehalf the soil in a 6 layer to give a nal oorlevel inside the greenhouse that is 6 below

the level of the outside ground.

Figure 32: Covering the top of the foundation with a layer of concrete


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technicaldataSheet 2: BuildinGthewallS

Principle

The walls are built on the foundations, leaving of the (2 wide) foundation clear on either sideof the wall. The walls must be shaped in the precise way shown in the designs so that the roofangle is correct. The back wall is a simple vertical wall whose top is parallel to the bottom.

If the greenhouse is built in a extremely coldclimate area (Design 3), two partition wallsmust also be built, as described in TechnicalDatasheet 3.

If the site is adjacent to a south-facing terracewall, then this wall can be used as the northwall of the greenhouse. The stones shownin designs C, 2C, 3C represent the terracewall, although in general the wall will be solidearth. If necessary, the wall can be strength-ened with additional stones, especially thetop, which supports the roof.

Care must be taken to ensure that water isdrained away from the back of the greenhouse inDesigns B (on sloping land) and C (built againsta terrace). Construct a drainage channel behindthe greenhouse as shown in the plans.

Outlining the Shape /Setting the Angles of the Walls

Outline the shape of the top of the nishedeast and west walls in the air using the ropeand stakes method as follows. Hammerthree long stakes into the ground along theouter edge of the side wall, one at the posi-tion of the outer edge of the north wall, one46 from the inside edge of the north wall(64 from the rst stake), and one 26 fromthe outer edge of the south foundation. Tiea piece of string around the rst stake at apoint 4 above the foundations (the height ofthe north wall), then tie it around the sec-ond stake at a point 76 above the foundation

(36 above the level of the north wall), andaround the third stake at a point 4 above thefoundation, and nally x it to the ground atthe outer edge of the south foundation. Theline of the string marks the edge of the roof ata 30 angle to the top of the north wall, andthe top of the side-wall (Figures 33, 34).

Repeat for the other side-wall. The wall is thenconstructed up to the level of the rope (Figure34). A piece of string tied between the pointsmarked on the middle stakes marks the posi-tion of the central beam and the top edge ofthe roof.

Use a plumb line (stone hanging from a pieceof string) to ensure that the walls are vertical.

Constructing the Wall

Planning the wallGenerally, the wall should be built of threevertical layers (Figure 35):

an external load-bearing wall, 2 wide, built

with mud bricks, rammed earth, or stone a layer of insulation, 4 thick an internal thermal storage wall, 6 wide,built with mud bricks

The mud bricks are cut fresh (not sun-dried)and should measure about 2 x 6 x 6. Thewall thicknesses given are a minimum (2 forthe load-bearing wall and 6 for the internalthermal storage wall). It is advisable not toreduce these sizes when using the mud bricktechnique, although they can be increased.

The form is shown in Figures 35 & 36. Mark the

position of the door frame and wall ventilatorand install these while constructing the wall asdescribed in Technical Datasheets 4 and 5.

Figures 33, 34: Outlining the position of the top of the wallwith thick string (in Qinghai and Ladakh)


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Building the wallWhen the walls are constructed with mudbrick, then the outer and inner walls areconstructed simultaneously (Figure 36). Thestructure can be reinforced with sticks every8 along the wall and every 2 of wall height(Figure 37). When stone or rammed earth isused, the walls are constructed one after the

other. Be careful to leave spaces for the doorand ventilator and to line the door frame withmud bricks as described in Technical DataSheets 3 and 4.

Filling the Insulating Layer

The gap between the inner and outer walls islled with insulating material.

Suitable insulating materials include straw(long stems), machine straw (short stemscut by machine), wild bushes, dried horse ordonkey dung, dry grass, sawdust, and wood

shavings. Dry leaves are not suitable as theygenerally turn to dust within four years or so,so that the insulation effect is lost.

Erect 2 mud walls 6 and 2 thick, leav-

ing a 4 gap between them.

Fill the gap with: -6 seabuckthorn + insulator mixed

straw or other insulator

cover with (plank and) a layer of mud

Figure 35: Plan of double wall construction

Figure 36: Building a double wall with mud bricks in Af-ghanistan

First chop seabuckthorn or any other thornbush into 4 to 6 long pieces and mix themwith the chosen insulating material. Fill thelower 6 of the gap with this mix. The aim isto protect the greenhouse from rats and mice.A mix of chopped water resistant grass, suchas nai in Afghanistan or yagzee in Ladakh,and chopped seabuckthorn can limit moistureproblems arising from groundwater.

Fill the remaining gap with insulating mate-rial. When the gap is full, push the material

down a little with a stick, and then completelyll again to the top with loose material. Dontpush down again.

Figure 37: View of double wall separated by insulation lay-er (sticks are added to reinforce the gap)


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expensive and the useable area smaller. Inspecial situations other modications areneeded. In Qinghai, for example, the quality ofthe soil (for mud bricks) is poor and a 4 thick

outer wall is built with baked bricks to protectthe wall from the rain and a 2 thick innerwall is constructed with rammed earth stabi-lised by 5% cement to increase the thermal

Finishing the Walls

Finish the wall by covering the insulating layerwith mud. A more durable, but more expensive,

solution is to lay strips of waste planks (3 wide)on top of the insulating layer before adding themud layer. A bank of earth can be added aroundthe lower part of the outside of the walls to re-duce heat loss through the foundations.Plaster the walls completely, outside and in-side. Traditional mud plaster is suitable for theoutside; cement wash plaster is preferable in-side. If mud plaster is used for the inside, donot add straw to it as this will rot in the hotdamp atmosphere. The walls have to be verysmooth so that they can be whitewashed orpainted.

Painting the wallsPaint black or whitewash the inside walls asfollows (Figure 38).

The inner side of the west wall is white-washed to reect the morning radiation tothe vegetables. The inner side of the east wall is paintedblack to absorb and store the afternoon so-lar radiation. The bottom two feet of the inner side ofthe north wall are whitewashed and the up-per part painted black for similar reasons.

The black paint can be made with a mixture ofoil and ashes or with powder paint.

Alternatives

Various alternatives are possible accordingto the availability of local materials. If mudbricks are not available, the walls can be built

with rammed earth or stone, but the foun-dation width (and wall width) will need to beincreased and the greenhouse will be more

Figure 38: View of whitewashed west wall and black paint-ed north wall.

Figure 39: Construction of an outer wall with baked bricksand an inner wall with stabilised rammed earth in Qinghai

mass (see Figure 39). In Spiti (India), wherethe clay content of the soil is high, skilled ma-sons are able to construct the double wall us-ing a single frame with two layers of rammedearth inside (2 x 8 thick) separated by a 4sandwich layer of straw. Another possibility isto construct a double wall out of stone with a2-3cavity between the walls packed with in-sulating material. Such a wall may need insidereinforcement in the form of a strip of knottedgalvanised wire joining the two layers.


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technicaldataSheet 3: BuildinGthePartitionwallS

Principle

Two small ( thick) internal partition walls are built at the back of the greenhouses built forextremely cold climates (Design 3) to increase the thermal mass. These walls can usually alsobe used to replace the wooden pillars that are otherwise needed to support the roof.

Figure 40: Plan view of greenhouse partition walls

Procedure

The partition walls should be built on a foun-dation for strength. Mark the position of thepartition walls when marking out the foun-dation, and dig and prepare a foundation forthem at the same time as for the other walls(Technical Datasheet ).

Erect the partition walls at the same time asthe back (north) wall (Figure 40).

The walls need to be sloped at the angle ofthe roof. Stop building when the walls have

reached a height of 4 above the outsideground and mark the shape of the wall slopein the same way as described for the east andwest walls in Technical Datasheet 2. Build upthe wall to this shape.

Figure 4: Finishing off the partition walls

Figure 42: Completed inner partition walls, greenhouse inZeback district, Afghanistan


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Build the east or west wall (as appropriate)

starting from the north and south walls asdescribed in Technical Data Sheet 2. Line theopening for the door frame with mud bricks asshown in Figure 47. Continue erecting the wall until it reachesthe top of the door frame. When the wall reaches the top of the frame,install the lintel. The best way is to balancetwo small beams (4 long, section 4x3 or di-ameter 4) across the ends of the walls (oneon the inside and one on the outside) so thatthey support one (or two narrow) horizon-tal thick, 36 long, and 0 wide plank(Figure 48). A cheaper alternative is to ll the

space between the two beams with woodensticks and to place a jute bag over the sticksand beams. Continue constructing the double wallabove the door frame according to the plan(Figure 48). When the wall is complete, x the door itselfto the hinges on the door frame. An additional half shutter covered with chick-en mesh or metal bands can be added to theoutside of the door. This can be closed to keepanimals out when the greenhouse is ventilatedby opening the main door (Figure 49).

Figure 46: Position of door

Figure 47: The masonry procedure for building the wallsupporting the doorway

Figure 48: The masonry procedure for building the wallsupporting the doorway

Figure 49: A second shutter covered by metal bands


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technicaldataSheet 6: conStructinGtheroof

Masonry and Roof Supports

The north and side-walls of the greenhouse are constructed in a shape that supports the roof.

Start erecting the north wall and side-wallsfollowing the guidelines given in TechnicalDatasheet 2. Complete to a height of 4.

When the north wall reaches a height of 4above the foundations, build a single line ofbricks of width 6 along the outside of the wallto sustain the roof material, as shown in Fig-ure 55. Stop building the north wall.

Build the east and west walls to the shapemarked out (Technical Datasheet 2).

Prepare two wooden beams 6 in diameter,each the same length as the greenhouse in-cluding the end walls (32), or four beamseach 6 long, or six beams each long.Impregnate with oil to make them moisture

resistant. Full 32 long beams are the mostsuitable.

If necessary, join two (or three) beams to-gether to achieve the length. For three beams,two posts are required as support.

Install one (or two) vertical wooden posts( 6) impregnated with oil at equal intervalsalong the line marking the top edge of the roofto support the main roof beam. A second setof posts can be added inside the rst to sup-port the second roof beam depending on thematerials used and design (as in Figure 55).

This second set is never required in Design 3.

Lay the main beam across the end walls atthe point marking the edge of the roof and xto the supporting posts using one of the twotechniques illustrated in Figures 56.

The second (inner) beam can be installedin the same way using posts, or supported bythe cross-beam to the north used to stabilise

the main beam (see next step), or support-ed by the partition walls (Figure 42). The in-ner beam supports the bottom of the shutterframe(s) (Figure 57).

The roof structure is stabilised by a cross-beam towards the north or south. Either

a) cross beam to the south. Fix a 6 di-ameter crossbeam to the centre of the topbeam (where it is supported by the post),with one end pressing against or under thebeam and the other on the foundation ofthe south wall. This is stronger, but it re-duces the freedom of movement inside the

front part of the greenhouse (Figures 0and 3). Or

Figure 55: Position of roof and supports

Figures 56: Fixing the beam to a post, Ladakh (top) andQinghai (bottom)


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b) cross beam to the north from the top ofthe roof to the top of the north wall. Fix an8 diameter beam to the centre of the topbeam (where it is supported by the post),

with one end under the beam and the otherresting on the top of the north wall (Figures5 and 38). Or

c) cross beam to the north from the top ofthe roof to the bottom of the north wall. Fixa 6 diameter beam to the centre of the topbeam (where it is supported by the post),with one end under the beam and the oth-er resting on the bottom of the north wall(Figure 58).The most durable greenhousesare constructed with solutions a) and c).

Install the top ventilator frame(s) as ex-

plained in Technical Datasheet 7.

Figure 57: Roof structure with two beams and shutterframes in position in Spiti

Figure 58: Cross beam to the south

Figure 59: General view of greenhouse structure

Note: If wooden beams are cheap, a strongerroof can be constructed using a single hori-zontal top beam (6 diameter) with transver-sal joists (4 diameter) every 2 feet resting at

the bottom on the north wall and at the top onthe horizontal beam (see Figure 59).

Constructing the Roof

The basic composition of the roof is shown inFigure 60.

Place thick sticks or bamboo canes (about diameter) in a continuous layer lying acrossthe beams with their lower ends resting againstthe line of mud bricks at the edge of the northwall (Figure 6). Trim the sticks to the correctlength (7). The sticks can be nailed to the topof the beam to prevent bending.

Figure 60: Roof composition

Figure 6: The layer of sticks forming the underside of theroof

Completely cover the sticks with a layer ofcardboard or jute bags.

Cover the cardboard or jute bags with a

(Design ) or 2 (Designs 2, 3, 4) thick layerof straw.


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Apply a 3 thick layer of mud mixed withcoarse chopped straw (pushka in Ladakh)(Figure 62).

A white cloth may be added under the roofto increase the insulation and reect more so-lar radiation onto the crops (Figure 63).

Figure 62: Applying the layers of cardboard, straw, andmud

Do not use polythene lm for any of the lay-ers of the roof, as it will cause the sticks torot. The roof must be able to breathe in orderto avoid trapping moisture.

After the roof has been constructed, buildthe inner part of the north wall up to the sticksor bamboo as shown in Figure 55.

Figure 63: A white cloth added under the roof

Note: in rainy areas, a small overhang (about6 wide) made with metal sheet or smallwooden sticks can be added at the back ofthe greenhouse to protect the wall from rain

(Figure 64).

Figure 64: Small overhang at the back of a greenhousein Spiti

Figures 65 & 66: A roof structure made of timber and bam-boo (Qinghai)

In some places, such as Qinghai, timber andbamboo are cheaper than beam and sticks(Figure 65).The bamboo canes are nailed onto the wood-en joists (Figure 66).


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technicaldataSheet 7: makinGandinStallinGtheroofventilator(Shutter)

Principle

During spring and summer (April to September), the air in the greenhouse can become veryhot reaching temperatures of 45C or more. Temperatures above 30C can damage the vege-tables, so when the interior temperature rises above 28C, the greenhouse has to be cooled.

Properly designed natural ventilation offersan efcient way of cooling the greenhouse:the warm air rises and leaves the greenhousethrough openings in the roof, drawing in cool-er air from outside through openings locatedat the bottom of the greenhouse. In this de-sign, one (Designs 3 and 4) or two (Designs and 2) ventilators are installed in the roofof the greenhouse, and the door and wallshutter provide the lower openings (TechnicalDatasheets 4 and 5). The ventilation systemis shown schematically in Figure 67. When theinterior temperature rises above 28C, all theventilators are opened to cool the greenhouse

(Figure 68). When the temperature falls be-low 28C, they are closed.

Carpentry

The ventilator is composed of a xed woodenframe and an insulated articulated shutterwhich can be opened and shut manually. Theconstruction method is similar to that for thedoor and wall ventilator, but the upper side ofthe shutter is covered with a metal sheet.

The shutter frame

Use pieces of timber of cross-section 4 x 3to make a xed frame of outer dimensions 4x 3 x 4 as shown in Figure 30. Cut the inner

Figure 67: View of air circulation through roof ventilator

Figure 68: Inside view of the roof shutter propped open

edges as shown in Figure 69 in order to xthe shutter and make the shutter/frame joint

air tight. Paint the frame white or use oiled wood toprevent weathering.

Figure 69: Construction of the frame


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The shutter Make a frame with outer dimensions 29x39 using wooden battens of cross-section 2x 2.

Cut a piece of 4 mm plywood the same sizeas the frame and nail it to the internal side ofthe assembled frame. Turn the shutter over and ll the spaces withinsulating material. The best material is ma-chine straw, but ordinary straw, wood shav-ings, and horse dung are also suitable. Saw-dust and goat dung, which may leak, shouldbe avoided. Nail a metal sheet to the external side of theframe to cover the insulating material. Paint the inner side of the shutter white toreect the solar radiation to the crops. A coat-ing of waterproof paint can be added to the

outer side of the shutter to protect the metalsheet and help prevent water inltration. Take a 4 long at iron bar. Drill 5mm diam-eter holes every 4 along the lower half andattach to the inside of the shutter at centrebottom with a 2 hinge. The bar is used topush and pull the shutter open and shut, andto prop it fully or half open (Figures 38, 68).

Installation

The roof ventilator frames are installed at thesame time as the roof structure is constructed(Figure 70). In Designs and 2 two frames

are inserted each located 7 from the insidesidewall, and tted into the roof. In Designs3 and 4, a single frame is installed in the roofmidway between the two side-walls.

Place the frame lengthways so that the top isresting on the main roof beam and the bottomon the second roof beam in such a way thatthe shutter will open to the outside (Figures70 and 7). The canes or sticks that providethe base of the roof lie between the frame andthe lower beam (Figure 38).

Nail the frame to the beams and continueto construct the roof around it so that it isembedded in the layers that make up the roof(Figure 70). Fix the shutters on the top of the frame tothe outside with two hinges after the roof iscompleted. Hammer a nail into the centre of the lowerpart of the frame or the inner beam inside theshutter in such a way that it can slip into theholes in the iron rod or bar attached to theshutter and be used to prop the shutter open(Figures 38, 72). The amount of ventilation isregulated by using different holes in the barto prop the shutter partially or fully open. Place a strip of rubber along the shutter/frame joint to make it air tight when the ven-tilators are closed at night.

Note: A centre strut can be added to the frameto make it stronger (Figure 72).

Figure 70: Fixing the frame of the roof shutter

Figure 7: Open roof shutter from outside

Figure 72: Open roof shutter from inside


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technicaldataSheet 8: inStallinGthePolytheneSheet

Principle

It is very important point to ensure that the polythene sheet is stretched tight and attachedrmly to prevent it apping in the wind. If this is done properly, the sheet can last as long asseven years. If not, damage resulting from apping and rubbing can destroy the sheet in oneseason. Polythene expands with heat, so it should be xed during the warmest hour of a sunnyday when it is well-expanded so that it becomes taught as it cools. If it is xed when cold, itwill later expand and become loose, and be more susceptible to wind damage.

Constructing the Support Structure

The polythene for the front part of the roofcan be supported by a wooden structure or astructure made out of reused steel pipe. Con-struction of the wooden structure is describedbelow and shown in Figure 73 and 74. Steelpipe structures are constructed in a similarway to provide the same support shape.

Prepare 2 wooden posts (4 diameter, 56long) and 3 wooden beams (3 x 2 section, long). Round beams are also suitable. (Itis also possible to use 2 wooden beams 6long, with 3 wooden posts as support.)

Fix the 2 posts at a position 9 from eachside-wall, and 6 from the inside edge of thesouth side of the greenhouse along the linethat marks the change in wall angle. Embedthe posts into the ground (6 below theoutside ground level) so that the tops reacha line joining the walls at the point where thewall angle changes.

(If a double layer of polythene is used the

thinner inner sheet is draped in position overthe posts before the next step, see below.)

Figure 73: Wooden support structure for the polythene sheet

Fix the 3 x 2 (or round) wooden beams ona line from the top of the walls (at the posi-tion of the angle change) across the top of theposts. The beams should be embedded in thesidewall, cut to size, and nailed to the top ofthe posts.

Add wooden joists between the central sup-ports and the top beam, one above each postand/or at intervals as described below. The

joists can be 2 diameter wooden sticks, 3 x2 wooden strips, or strips of 4 bamboo splitinto quarters. The number and spacing de-

pend on the wind and snow load. More joistsprovide more support and reduce the dangerof wind damage, but they also reduce the so-lar transmission and impair plant growth.

v For low wind or snow load space joistsat about 5. No transversal iron wires arerequired.v For mediu

Documents

Grenhouse Construction Manual en 2009