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The material to follow is taken from "Ecological Steps Towards a Sustainable Future: The Ladakh Project, 21 Victoria Square , Clifton Bristol BS8, 4BS, England, 198.

The information presents successful examples of appropriate technology that was introduced in Ladakh over the past decade or so. As Ladakh is a geographical extenuation of Western Tibet, having roughly the same high altitude and climate that accompanies it, it is clear that successful use of appropriate technology there would also be suitable and benefit much of the province of U-Tang in Tibet.

The role of technology in Ladakh's development has been, and will continue to be critical. Since the areas was first opened up to the outside world, there has been a growing trend towards a dependence on modern technologies of various kinds, and as a consequence reliance ? with all its implication? on the importation of fossil fuels. This of course, is the standard pattern through the 'developing world'.

This new trend is a matter of very great concern, particularly because it has proved the undoing of so m any other societies in the past. For ten years now, we have been developing and demonstrating more "appropriate" technologies, which seek to maximizes the use of renewable sources of energy  and local materials while minimizing the impact of these technologies on the traditional culture and the region's fragile environment.

We are very keen to ensure that our technical work does not operate, as it were, in a vacuum. However appealing a technology may seem when viewed in isolation, it is only a value if it is appropriate to the context of a particular place and its people. A technical programme which ignores this fact can very easily do more harm than good even if the technologies themselves might appear at first glance to provide undeniable benefits.

The 'appropriateness' of appropriate technology involves a recognition of natural and cultural diversity. While there clearly is some common ground between one environment and the next and between one culture and the next, there are also very significant differences. We are not, therefore, concerned with developing the 'universal' plough, which would serve farmers the world over, no matter what the soil might be, no matter what animals are used. We are not concerned with producing a stove that will equally help the people of Ladakh as the people of Peru. That kind of approach can lead to consequences which are positively inappropriate and unecological. Our emphasis by contrast, is on the local. In fact, even with Ladakh itself, we seek to match the technologies which we develop to the particular needs of different situations.

Ladakh is fortunate to have been blessed with and abundance of renewable sources of energy. The sun shines for 325 days a year, and strong winds blow along the valleys, streams or rivers run through the heart of every village. In purely physical terms, the case of re-encouraging the use of solar, wind and water power could hardly be better. Moreover, the scattered nature of settlements and the extremely rugged terrain make the provision of energy from a central source particularly unattractive. Small scale, localized energy production, on the other hand, makes very good sense. For centuries, Ladakhi villagers have been almost completely self-sufficient, dependent on the outside only for a few 'luxuries', like salt and tea. If the production of energy can remain as far as possible on a village level, the villages themselves will be strengthened, and the people's capacity to make a living from the land given much-needed support. At the same time, a strategy of decentralization will greatly reduce the extent to which people become dependent on the vagaries of the international money economy, and thus help to avert some of the problems which such dependence inevitably brings.

An emphasis on renewable sources of energy in no way represents a 'secondbest' option, as is sometimes believed. On the contrary, if offers the surest prospect of sustainable and equitable improvements in material standards of living. Events around the world in the last two decades have been shown that a dependence on imported energy and large-scale centralization systems can cause not only untold ecological damage but economic instability, inflation and massive debt. Cities are favoured over the countryside, leading to frighteningly high rates of urbanization; and the rich are favoured over the poor, with the effect that the gap between the two, both within countries and internationally, is growing.

In most industrialized countries, there is now a growing awareness of the need to use finite resources more wisely, and to develop technologies which are more conducive to environmental and social harmony. Ladakh is in a very good position to adopt such a far-sighted strategy before it is too late, and could even become something of an inspiration for other societies around the world.

It should be noted that much of the work describe in the following pages had been undertaken in close collaboration with personnel from the Ladakh Ecological Development Group.

Solar Space Heating

One of the major problems of life in Ladakh is the bitter cold of winter. More than half the year, temperatures stay below or close to freezing, dropping at times to as low as minus forty degrees the point at which fahrenheit and centigrade meet. Traditionally, the only source of heat was the kitchen stove, which was (an still is it is only very slowly being replaced) fueled by animal dung and scrub vegetation. These stoves give our relatively little heat. Moreover, the fuels which they burn are in short supply, and have to be used sparingly.

In recent years, people in and around the capital Leh, have begun using metal braziers, or 'bokaris', to provide additional heat. These serve to increase comfort levels considerably, but they are far from efficient, and require large quantities of wood or coke, which have to be  brought in over the Himalayas.

In 1979, we started to explore the possibility of using the heat of the sun for the purpose of space heating, and introduced the Trombe wall system to Ladakh. In the years since, we have been developing not only the Tombe but other simple solar techniques. The results have been very encouraging. Technically, we have proved that solar energy is a very viable alternative to the use of fossil fuels; and perhaps more importantly, we have succeeded to a great extent in convincing the Ladakhi people at large that is the more sensible and sustainable option in the long term.

The space heating systems which we have been working on are all 'passive' systems. They require no other source of energy and involve no moving parts. All the materials require are readily available in Leh, while design and construction techniques are well within the reach of local craftsmen. Maintenance of the various systems is next to nil.

The principles involve are extremely straightforward. The sun's rays pass through an area of vertical glass, and fall on an area of thermal mass which stores heat for night-time use. The 'greenhouse effect' prevents the heat from passing back through the glass, while insulation ensures that it does not radiate out of the living space through walls or ceiling. For optimum performance, solar systems should be located on the south-facing wall of a building, and the room or rooms to be heated should be longer on the east-west axis. The south-facing orientation maximizes the absorption of solar radiation during the cold winter months. During the summer when the sun is at a higher altitude in the sky, the sun's rays fall more obliquely on the vertical glass, and the system absorbs less energy. Solar space heating systems thus work in perfect harmony with the cycle of nature. As winter approaches, and the need for heating increases, so the system produces more heat. In the summer, when no heating at all is required, the system automatically 'closes down'.

New building s in Ladakh can usually be designed so as to face due south. However, the system which we have developed can also be 'retrofitted' to existing buildings. Orientation as much as 30 degrees off south has proved to be quite satisfactory.

The Trombe Wall

The Trombe wall is an 'indirect gain' system. A double layer of glass is attached to the outside of a south-facing masonry wall, which is painted black for maximum solar absorption. Vents are  built in the wall, at the top and bottom, so as to connect the living space inside with the air gap (appro., 10cm) between wall and glass. The room itself is heavily insulated. During the day, the room is kept warm by a process of natural convection, which circulates air through the vents, while after the sun has gone down, the wall radiates the heat which it has been storing throughout the day. (We have also experimented with 'ventless' Trombes)

The thickness of the wall and the material of which it is made determine the length of the 'time lag' between the moment when the sun strikes the wall and the time at which the heat is transferred to the room. The primary need for space-heating in Ladakh is during the evening; reasonable fluctuations in the temperature during the night are acceptable. The wall is, therefore, constructed to allow maximum transfer of heat to the living space shortly after the sun has gone down. From our experience, it seems that the optimum thickness of the thermal wall is about 20cm (15cm brick, plus plaster inside and out).

The Trombe wall can be designed so as to blend well with the beautiful architecture of the Tibetan plateau. Moreover, the building materials traditionally used in Ladakh are very appropriate. Sun-dried mud bricks and stone are excellent materials for the thermal wall itself, while straw serves as a very good insulation for walls.


We have undertaken extensive monitoring of the various solar-heated rooms which we have constructed over the years. Some sample results are given below. It would be unwise to place too much emphasis on the relative performance on any individual installations, since for a number of reasons no two buildings are truly comparable. Standards of construction (perhaps the greatest variable of all) vary from house to house, while experience has shown that even within a single village there can be significant differences in the composition of the mud used for sun-dried bricks. More over no two installations are exactly the same in terms of location of the room within the house, dimensions and orientation.

Nonetheless, it is quite clear that solar space heating can be tremendously effective. Both the Trombe wall and the half Trombe show a very marked improvement over unheated rooms. While initial observation of the improved 'glass room' indicate that the necessary modifications, our results show that vented Trombe are indeed more effective than unvented ones when day-time heating is required, although the 'user participation' required in manually closing vents when automatic baffles are not fitted or where they have deteriorated, has to be borne in mind.

It is important to note that the Ladakis' comfort threshold are very different from those of Westerners. Consequently, the thermometer readings, which are by any standards impressive enough, will tend if anything to understate the true nature of the improvement which solar heating provides. Subjective assessments of the rooms by the people who actually use them can at times be more revealing. In a recent review which we carried out, one householder explained that he now requires only one blanket to sleep under during the winter, whereas previously he required four or more. At another site, neighboring children used the solar room to do their homework in the winter evenings, sometimes staying overnight.

It is quite common for the well constructed Trombes to maintain comfortable temperatures throughout the night without the additional use of stoves or heaters? a fact that serves to underline the importance of insulation. Where no solar installation is possible, we try to encourage householders to insulate doors and windows with thick curtains and, if possible to install double glazing. Ceiling insulation (coconut fibre has been found to work well, below the traditional willow roofing) is also recommended.

Trombe Room and Outside Temperature






































































Heat and Window Orientations

Trombe Wall Design

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