We have been further developing and refining the design of the classroom, especially keeping in mind the structure, cost and rain water harvesting elements.
We are not experts in tensile structure (earth technologies and community participation is more our field), so we have being guided by Kiritbhai Patel of CEPT University, Ahmedadbad, (Centre for Environment Planning and Technologies) who has a depth of experience designing and constructing tensile structures.
Whilst for the competition submission we concentrated on a specific site, Cohesion runs classrooms like this in 30 salt pan communities on the Kutch coast and Little Rann desert. Other organisations also run similar schools in other salt pan communities, and there are of course many salt-pan communities that require facilities like this classroom but do not have them. We are determinded to see decent classrooms in all of these communities, and for these to be the spark for the overall upliftment of the salt pan worker communities. It is therefore vital that our design is locally affordable and replicable.
Our discussions with Kiritbhai, revealed that, while it was possible to construct the tensile structure as in our original design, the cost of this would be around Rs20 – 25lakh (this includes the excavation, rain water harvesting and furniture, though the major cost is the tensile structure). To be replicable, a more affordable budget would be around Rs.5 - 7 lakh.
It is possible to reduce the cost of the tensile structure through both the design and the choice of materials. We are exploring these options at the moment, namely:
i) Smaller independent structures.
The original design was basically a huge circus tent. The difficulty with having a single membrane structure was that any forces acting on one particular area of structure effected the whole structure – ie the whole structure would wobble and shake in the wind. We are now looking at breaking the structure up into a number of smaller structures. Also smaller structures help reduce the span, which makes the structure much simpler and lighter.
The existing area covered by the tensile structure is relatively large large area compared to the actual floor area of the classroom. To reduce this we are exploring reducing the stepping in the walls of the classrooms, and also increasing the gradient of the walls. We are also seeing if the common area can be semi or only partially covered, thereby reducing the amount of tensile fabric needed.
ii) Cable net structure
An option we are exploring is a cable net structure rather than a single membrane structure. Basically a ‘net’ of cables is constructed, this forms the main shape. Material is then attached between the holes of the net. This will mean we can use smaller pieces of fabric rather then one large piece, this increases the possiblities of getting this manufactured locally, and also will make maintenance easier (if there is a tear, for example, only a small piece has to be replaced).
iii) Rain water harvesting
In the original design we suggested that the roof could be ‘inverted’ during the monsoon season and used to catch rain water. However, it seems that mechanized movements in tensile structures are expensive – as they require specialist engineering and manufacture. Also a complicated mechanized procedure probably wouldn’t be a good idea in the salt pan environment, as it maybe be prone to breaking down. If a simple and robust mechanism can be designed this is still an option.
Another option is to leave the tensile structure in place during the monsoon and dig a small lined trench around the perimeter of the school to collect the rainwater as it sweeps off the roof, then channel this to an underground tank.
A third option is to remove the tensile fabric during the monsoon season but leave the columns intact. A secondary rain water harvesting could then be built using the existing columns.
Next steps
i) Hunnarshala and Cohesion are part of Abhiyan – a network of 36 organisations working for the development of the Kutch district. SETU is also part of this network. SETU has been working closely with the salt pan communities on various aspects for some time now. Through the SETU’s we have a close relationship with many of the different salt-pan communities.
However for our competition entry, we have concentrated our efforts with a single community. Whilst there are many similarities between the different salt pan communities and sites, there are also many features that are unique to each community and site. We are planning to visit the other communities as well to get their ideas about classrooms in their salt pans. At the moment the monsoon is in full swing, so we will visit the communities in their home villages first.
ii) We are also planning to build full scale samples of parts of the tensile structure, to better understand the practicalities and form of them. This will also be an opportunity for the communities to see first hand what the schools may look like, and help them take an informed decisions about the design. These communities have been living in this context for many generations, and so have a very detailed knowledge/experience about what will work and not work in these areas.
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We have been further developing and refining the design of the classroom, especially keeping in mind the structure, cost and rain water harvesting elements.
We are not experts in tensile structure (earth technologies and community participation is more our field), so we have being guided by Kiritbhai Patel of CEPT University, Ahmedadbad, (Centre for Environment Planning and Technologies) who has a depth of experience designing and constructing tensile structures.
Whilst for the competition submission we concentrated on a specific site, Cohesion runs classrooms like this in 30 salt pan communities on the Kutch coast and Little Rann desert. Other organisations also run similar schools in other salt pan communities, and there are of course many salt-pan communities that require facilities like this classroom but do not have them. We are determinded to see decent classrooms in all of these communities, and for these to be the spark for the overall upliftment of the salt pan worker communities. It is therefore vital that our design is locally affordable and replicable.
Our discussions with Kiritbhai, revealed that, while it was possible to construct the tensile structure as in our original design, the cost of this would be around Rs20 – 25lakh (this includes the excavation, rain water harvesting and furniture, though the major cost is the tensile structure). To be replicable, a more affordable budget would be around Rs.5 - 7 lakh.
It is possible to reduce the cost of the tensile structure through both the design and the choice of materials. We are exploring these options at the moment, namely:
i) Smaller independent structures.
The original design was basically a huge circus tent. The difficulty with having a single membrane structure was that any forces acting on one particular area of structure effected the whole structure – ie the whole structure would wobble and shake in the wind. We are now looking at breaking the structure up into a number of smaller structures. Also smaller structures help reduce the span, which makes the structure much simpler and lighter.
The existing area covered by the tensile structure is relatively large large area compared to the actual floor area of the classroom. To reduce this we are exploring reducing the stepping in the walls of the classrooms, and also increasing the gradient of the walls. We are also seeing if the common area can be semi or only partially covered, thereby reducing the amount of tensile fabric needed.
ii) Cable net structure
An option we are exploring is a cable net structure rather than a single membrane structure. Basically a ‘net’ of cables is constructed, this forms the main shape. Material is then attached between the holes of the net. This will mean we can use smaller pieces of fabric rather then one large piece, this increases the possiblities of getting this manufactured locally, and also will make maintenance easier (if there is a tear, for example, only a small piece has to be replaced).
iii) Rain water harvesting
In the original design we suggested that the roof could be ‘inverted’ during the monsoon season and used to catch rain water. However, it seems that mechanized movements in tensile structures are expensive – as they require specialist engineering and manufacture. Also a complicated mechanized procedure probably wouldn’t be a good idea in the salt pan environment, as it maybe be prone to breaking down. If a simple and robust mechanism can be designed this is still an option.
Another option is to leave the tensile structure in place during the monsoon and dig a small lined trench around the perimeter of the school to collect the rainwater as it sweeps off the roof, then channel this to an underground tank.
A third option is to remove the tensile fabric during the monsoon season but leave the columns intact. A secondary rain water harvesting could then be built using the existing columns.
Next steps
i) Hunnarshala and Cohesion are part of Abhiyan – a network of 36 organisations working for the development of the Kutch district. SETU is also part of this network. SETU has been working closely with the salt pan communities on various aspects for some time now. Through the SETU’s we have a close relationship with many of the different salt-pan communities.
However for our competition entry, we have concentrated our efforts with a single community. Whilst there are many similarities between the different salt pan communities and sites, there are also many features that are unique to each community and site. We are planning to visit the other communities as well to get their ideas about classrooms in their salt pans. At the moment the monsoon is in full swing, so we will visit the communities in their home villages first.
ii) We are also planning to build full scale samples of parts of the tensile structure, to better understand the practicalities and form of them. This will also be an opportunity for the communities to see first hand what the schools may look like, and help them take an informed decisions about the design. These communities have been living in this context for many generations, and so have a very detailed knowledge/experience about what will work and not work in these areas.