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School Of Eco Responsive Architecture

PSH Buildings

All buildings at HIAL are going to be passive solar heated (PSH) – that use only sunlight as the source of heat. Currently, we are experimenting with materials and different composition of PSH techniques like an attached greenhouse, Trombe wall and direct gain. We have successfully experimented with increasing the heat storage capacity in the Trombe Wall system with our Thermal Blocks. Or insulation values of bricks through our straw clay bricks.  Further research is currently underway using earthen construction techniques of rammed earth, straw clay and adobe wall systems to test the efficiency in PSH design. Local natural materials are tested, experimented with and then used in construction such as clay from Basgo village, soil from Taru village. The innovations in this technique have been phenomenal with buildings that stay at +15 °C inside the house even when it is -15 °C outside in winters. PSH buildings expedite the process of achieving Carbon Neutrality of Ladakh, as envisioned by the Prime Minister, as space heating and cooking consumes almost 90% of all energy consumption in Ladakh in 2010. 

The images below present the PSH buildings constructed at HIAL as live labs to prototype and test the different construction techniques in real-time. 


The diagram above compares the indoor temperature of a PSH Building with a heated and a non-heated room of a non-PSH Building. The PSH building at Phyang stay at around 20-25 °C daily average temperature using only solar energy, with minimums of upto 15 °C only. While the fossil-fuel heated room in a typical building in Leh averages at around 12 °C . The non-heated room in the same building stays between -5 °C to -3 °C . The outside temperature fell to as low as -15 °C  minimum in the same time period.

Thermal blocks for Modified Trombe Walls in PSH Buildings

The south-facing wall called the Modified Trombe Wall in these PSH buildings is made of a special type of brick called the “Thermal Blocks”. A thermal block is a unique brick constructed using water-filled plastic bottles embedded inside plain-cement-concrete (PCC) block, invented at HIAL. The combination of concrete & water in the block enhances its overall thermal capacity while utilising the benefit of high thermal conductivity of concrete for efficient heat transfer in the Trombe Wall. The outer surface is black-painted to utilise black surface-absorption. These modified Trombe Walls are one of the reasons for the enhanced performance of PSH buildings in Ladakh’s cold climate. Invention of new construction materials and designs are crucial to make the construction sector in Ladakh sustainable.

Strawclay bricks

These are Fibre-reinforced earthen bricks, designed by HIAL. It has low density and hence high insulation properties. The brick uses straw that is RESCUED from Punjab and hence saves pollution twice, once in Punjab from stubble burning and second in Ladakh by offsetting the need for space-heating. The brick is Easy to work with due to its low-weight and reduces construction time in ladakh’s short construction season owing to its large size. As the brick is highly insulative, it does not need cavity wall systems for insulation, hence does not need especially trained construction workers unlike other construction techniques like cavity wall systems. The material is also cost effective.

PreFREB Construction and Net Energy Positive Building

An innovative construction technique, the Pre-Freb (prefabricated Fibre-reinforced block) wall system enables ease and allows for time-saving in conventional construction systems. The blocks are pre-cast, have high insulation and uses straw rescued from Punjab. The straw helps in making the blocks low-density as well as provide compressive strength. The blocks can also be reinforced using TMT bars, cement and sand. Pre-Freb when structurally enhanced with conventional or modern techniques like concrete, steel and timber, could be a solution for a modular multi-storey composite structure with natural materials. The blocks are lego-like structures that can fit one above the other and be constructed in a matter of weeks. The structure is modular, consisting of two leaves which can accommodate different thickness of insulation depending upon the location of the building. Thus, it is very beneficial in Ladakh where the construction season is 6 months or less at places.

The building uses passive solar technique to meet its space heating needs. And hence, the solar panels installed on the top as the roof (a special type of solar panels system that act as water proof roof system) generates enough power to electrify 3 other similar buildings at HIAL. Thus becoming a Net energ positive Building.

PSH Framed Building

So far PSH buildings have mainly been constructed using earth as the loadbearing structure, which does not fall into the building code requirements of Indian government and hence the major energy intensive government and defence buildings do not benefit from this type of construction technique. To address to thai issue, HIAL is constructing a pasive solar heated concrete column-beam structure to demonstrate PSH buildings that also meet the building codes.


HIAL suggested using insulative materials (like its straw-reinforced earthen bricks) to cover the entire framed structure, a technique we call as ex-fill. The conductive concrete structure when sunken under these insulative materials prevent any thermal bridges, unlike in-fill techniques where the beams and pillar are exposed to the environment of Ladakh, creating heat sinks (thermal bridges). Thus helping in retention of heat within the building element. To further increase the construction speed considerable, we are also exploring a confined construction technique.

These simple but innovative building techniques have the potential of revolutionising the construction sector of Ladakh.

Large Scale PSH building

To further demonstrate the possibility of Passive solar heated technique, a large scale PSH building in HIAL. The building would be multi-storey and have a footprint of around 22,000 sqft. The building is currently under preliminary construction stage and will employ the pillar-beam (framned structure) with ex-fill construction technique. It will demonstrate a size and technique that can be used for building headquarters of different governmental organisations in Ladakh. One of the first demonstration for such large scale building.

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Strawclay-arch construction for woodless roof

Ladakhi construction relies heavily on wood imported from kashmir and othr arts of India. The resource is very expensive and getting scarce with each passing year. Urther, th eimpact on climate is also heavy. To address this issue, HIAl’s team has come up with the design of construction of wood-less roof structures using low-weight,  strawclay blocks for added insulative properties. The technique will help in reducing construction time, provide alternative to use of wood as roof’s load bearing structure, provide insulation where it is needed most, reducing the construction cost considerably in the meanwhile. Being low-weight, it also keeps the center of mass for the building low, hence providing earthquake resistant properties.

Solar tent

There is a huge requirement of portable passive solar heated tents in Ladakh. The construction team of HIAL has addressed teh issue by developing a passive solar heated tent. Each component of the tent is portable and designed to weight less that 30 kgs.