Withindia Building Solutions has signed a technology deal with the Dutch company RC Panels late 2013. This deal was designed to transfer production technology for sandwich panels and machinery to its Withindia Facilities in Ahmedabad, Gujarat (India).
Thereafter Withindia has set up its production site in Ahmedabad, received the necessary Factory License, installed the production line and joined ‘Make in India’ as of February 2016. Today we produce SINH Panels for the Indian market.
Now you could think: so what?
Well, using sandwich panels in building, will help Farmers and their communities to earn more money. How?
The Indian Government has developed several programmes to support Farmers and Rural communities. An example: in Gujarat a new Initiative has been launched to support every village to build a small cold storage warehouse or cold room. This room is the first step in the logistics chain from harvest to market. In it the temperature is kept between 6C and 12C to protect the crop from rotting.
Currently 30-40% of the harvest is lost, mainly in between the time of harvest and the delivery at the market. Sometimes logistics fail, sometimes the sun does its work or animals ate part of the harvest.
When you know there are 18.500 villages only in Gujarat, then you could see the magnitude of such an Initiative.
Our company completed a study to see how we could support the Initiative of Indian Government. In this article I want to share our findings about basic steps to make cold rooms.
The main building element to realize a cold storage room is a sandwich panel. One of the sandwich panels available in India is SINH™ Panel. This sandwich panel consists of two layers Magnesium Oxide Boards and in between the boards an insulation material (see figure below). The panel can be designed for walling, flooring or roofing.
Using Magnesium Oxide Boards into these panels, gives you benefits of light weight, fast construction, dry construction (saving water) and ease-to-work with.
1. Insulation material
Most common insulation materials currently used in the Gujarat market are Cellular Glass (CG), Expanded Polystyrene (EPS), Extruded Polystyrene (XPS), Mineral Wool (MW), Polyisocyanurate (PIR), Polyurethane (PUR) and Kooltherm (bouw, 2015) (Association, 2007)
In the table below you find these insulation materials displayed and compared with each other based on their Lambda value (thermal conductivity value). Notice: the lower the lambda value, the better the material insulates and the less material is needed to realize the same amount of the R-value (Thermal resistance value).
cg= cellular glass, EPS= Expanded Polystyrene, XPS= Extruded Polystyrene, MW=-Mineral Wool, PUR= Polyurethane
It can be concluded that Kooltherm is the best material with the lowest thermal conductivity and thus the best R-value. PIR and PUR insulation can be considered as the same. PIR is only a better version of PUR in certain aspects. PIR has a slightly better insulation value and is more fire resistant. The same goes for EPS and XPS looking at its insulation value. Mineral Wool is too soft to apply into the SINH-Panels.
2. Thickness of the panel
Material thickness also contributes to Thermal Resistance. Thermal Resistance is a measurement of how the Panel resists Heat Flow. Thermal resistance is measured by the R-value. You could use the Cold Storage Calculator from the company Alfa Laval to make calculations of the cooling (http://cold-room-calculator.soft112.com/)The calculator takes the following main parameters into account: room temperature inside, outside temperature, dimensions of the cold storage room, amount of storage and entering temperature of the crops.
Below a table is shown with the required capacities for de cool system that should be implemented. Also insulation capacity losses are shown between different wall thicknesses. Using this information could give you an approach of the material thickness you should consider.
The table above shows that EPS has a lambda value of 0.036 W/mK. Therefore, the wall thickness, using EPS insulation should be 150mm for the wall (external use), 150mm for the ceiling/roof and 125mm for the floor.
Using PUR, the thickness should be considered 100mm thickness for the wall (external use), 100mm ceiling/roof and 100 for the floor.
The recommended thicknesses mentioned above are based on a cold storage temperature in the range of -4 to 2 degrees inside. All other major parameters that were used in the previously mentioned calculator are not taken into account in this table above.