Are magnesium oxide boards suitable for the Indian building market? Design Point Architects gives an answer to this question, take a look at the video interview.
This article is about farming in Gujarat (India) and how Farmers could benefit from using cold storage rooms.
Talking Farming Numbers (Gujarat)
Gujarat is one of the 29 states of India and has a population of more than 65 million people and a surface of 196.024 km². (Population Gujarat, 2015) Ahmedabad is its central city. Gujarat is divided 26 districts with each their own typical crops. The total yearly production of fruit is more than 8 million Tons and the production of vegetables is more than 11 million Tons a year. (Pandya, 2014) Next to fruits & vegetables flowers and spices are also cultivated.
Current Value Chain for Fruits & Vegetables (Gujarat)
As shown above, there is a complicated value chain for fruits and vegetables in India. Sometimes the crops will be traded more than 6 times before it reaches the end-consumer. The multiply factor between the selling price for the farmers and the end-consumer price can be more 10!
The current supply chain for national trade does not require cold storages. All trading of fruits and vegetables is done within a maximum of three days. Most of the harvesting will be finished during the mornings. Directly after harvesting the crops will be graded and sorted. The best quality products will go to the APMC’s and will be traded to wholesalers. The lower quality products will be traded directly at local markets. The APMC’s and wholesalers trade the harvests on the same day they are harvested. Dependent on the buyer, the harvest load will be transported by night in unrefrigerated trucks. The transport happens always at night because of lower temperatures.
The APMC act is established to ensure that intermediaries do not compel farmers to sell their products at the farm gate against extremely low prices. All food products should first be brought to the market yard and then be sold through auction. (Wikipedia, sd)
‘’ A State is geographically divided and Markets (Mandis) are established at different places within the states. Farmers have to sell their products through the auction in Mandi. To operate in Mandi, a trader has to get a license. Wholesale, retail traders (e.g. shopping mall owners) or food processing companies cannot buy farm output directly from the farmer. They have to buy through the Mandi.’’ (Wikipedia, sd)
Do cold storage rooms have value in the Value Chain?
1. Let’s start with Definitions of Cold storage, cold room and pre-cooling
A cold storage is a space in a building where crops can be stored for a longer time. The main purpose of a cold storage is to store crops for a longer time to fulfill the different demands during the year and to get a better price for the crops. To optimize the performance of cold storage machines that can control the ideal humidity are essential. Because every crop has a different ideal cooling temperature and humidity, cold storages are used for only on crop at the same time.
A cold room is a storage space that is used to keep products cool between trading. Products stay in general for a maximum of three days in the cold rooms. Cold rooms are in general not equipped with humidity control. Cold rooms are used to cool different types of fruits and vegetables at the same time.
Pre-cooling is a technique were the crops within 4 hours after harvesting gets cooled. Several studies showed that when pre-cooling is applied on crops the shelf life will extend significantly.
2. Current cold storage presence Gujarat
Nowadays there are around 450 cold storages present in Gujarat. Mr. Ashish Guru, president of the Gujarat Cold Storage Association explained there are around 216 cold storages for potatoes and another 25 are coming up.
Gujarat is the only state that offers power subsidy for cold storages. (Agriexchange, sd) Potato can be preserved for more than 10 months in a cold storage. The existing cold storages in Gujarat have an average stock capacity of 2000 MT. (business-standard, sd)
3. Potatoes, Onions and Egg-plant (Brinjal)
As explained above, there is already a lot of cold storage present in Gujarat for potato. Onions need to be dried for at least 5 weeks and by that time they will be traded in the market. Brinjal has a too short shelf life in a cold storage with a maximum of 14 days under optimal conditions.
4. How to select other fruits & vegetables for cold rooms?
There are five requirements for the selection of a crop that is suitable for cold rooms:
– The shelf life of the crop will be significantly extended when they will be cooled
– The production volume of the concerning crop
– The average price must be above a certain price per kg per volume If the crop has a low volume/price ratio a cold storage is not economical because of the high power costs.
– The price fluctuation during the year
– The harvest season of the crop. This in combination with the shelf life is an important parameter.
– The cooling temperature.
Selection of vegetables
In the image below the 6 most cultivated vegetables of Gujarat are displayed. The little squares in the left beneath corner show the maximum shelf life when the crop is stored in a cold storage. In the thermometer the best cooling temperature is displayed for each crop. In the beams on the right of every vegetable, the total annual production in metric TON (1000kg) of Gujarat is indicated.
The Shelf life, temperature and production
- Onion – 2. Potato – Cabbage – 4. Tomato – 5. Brinjal (eggplant)- 6. Okra
The most cultivated crop in Gujarat is Potato with more than 2294 Tons in 2014. Onion has the longest extendable shelf life and Brinjal requires the highest cooling temperature.
These can deliver better revenues for Farmers. Cabbage has a really long shelf life so it is appropriate for cold storage. The shelf life of tomato can be extended with a month during cold storage. Cabbage is a second possibility.
Selection of fruits
For the selection we focused on the 11 most cultivated fruits in Gujarat. Cashew nut is also mentioned in the statistics notwithstanding it is not considerate as a fruit.
- Datepalm – 2. Coconut – 3. Custard apple – 4. Pomegranate – 5. Guava – 6. Papaya – 7. Mango – 8. Lemon – 9 lime – 10. Banana – 11. Chiku – 12. Aonla(indian gooseberry) – 13. Cashew nut
Maximizing Farmer revenue show citrus and pomegranate are most suitable to be used for cold storage. Compared to the other fruits they also have higher shelf life.
Conclusion do Cold Storage rooms add Value?
1. Reduce Fruit en vegetable losses in India
Gujarat, belonging to the top 10 horticulture producing states in India, loses almost Rs 11,400 crore worth of fruits and vegetables after harvest every year due to lack of proper storage facilities. That is more than 1,7 billon euros. (Newsservice, 2013).
The losses experienced by for example Tomato Farmers are caused by damages, sorting, pests and diseases. In the field study our company has conducted, it turned out that only 1-2% of the losses at the farmer’s site are caused by over-ripening.
Farmers bring their crops sometimes directly to the collection centers, bigger farmers bring it for them or they sell it directly to supermarkets or CPC in big cities. Trucks are used to transport the crops. The trucks are not refrigerated and have in general an open trunk. This trunk will be covered with jute to protect the crates or boxes filled with fruits or vegetables.
Losses caused by bad handling during sorting are evident. To reduce these losses cold storages and cold transport should be added to the value chain.
2. Add cold storage capacity and start with Tomato, Pomegranate and Citrus
3. Get better prices for farmers
On an average basis the farmer is only able to receive 1/4th to 1/3rd of the final retail prices. During low season, when end-consumer prices are high, the farmers do not get higher returns on their products.
Farmers can start influencing daily market prices into their benefit when they influence timing of selling and quantities of selling.
Cold storage units are essential for this!
In the previous article, insights were give about material use and insulation capabilities to build adequate cold storage rooms.
In the concept of cold storage pre-cooling is essential. Pre-cooling helps to maximize results for both earning capabilities of Farmers and costs. In the current article I want to share some ideas about how to furnish the cold storage room itself. Furnishing well will influence the extension of the ripening period of a crop positively. The most important suggestions to take into account are listed below:
Use of crates
For the storage of the crops it is recommended to use well ventilated pallets, crates, boxes or bins.
Movement of air through the Cold Room
Why? It is important that the cold moving air can easily go through to remove the heat coming from the products. For best result the crates should be stacked so that the moving air can contact all the container surfaces for adequate and rapid cooling. Ventilated crates can be used as they speed-up the cooling rate. The cool air should be divided equally over all crates that are placed.
Location of crates
The storage crates must be stacked to form air-channels which are 4 to 6 inches wide (10 to 15 cm) to help direct the air movement. There should also be space between the product and walls to allow refrigerated air to absorb the heat of conduction through the walls. In the figure below an overview is given of how the crates should be placed in the IGLOO design. A passageway is created in between the crates. This location set up will result in a better air circulation and the crates can easily be replaced or taken out when crops need to be sold. (Board, 2010)
Overview of the location of the crates
Maximize capacity in the cold room
Different concepts are used the get the most out of the crate positioning capacity. The dimensions of the crate are a given (WxHxL):360x305x542mm. Since the roof height of our SINHBUILD concept is 2440mm, the maximum amount of crates that can be stacked is seven (height of 2135mm). We favor the concept in which three lines of crates are taken into stock. In between the crates a space is created of 10cm to allow refrigerated air to absorb the heat from any direction. On the right two lines of crates are placed on their long side. On the left one line of crates is place on their short side The passage width between the lines of the crates is 668mm which gives the opportunity to move a crate easily through (a crate is 542mm on the long side). The total amount of crates that can be stored is 210.
Shape and dimension of used crates
As mentioned before it is recommended to use ventilated pallets, crates, boxes or bins. Jut or nylon bags are not recommended since these materials won’t ventilate in a proper way. Further exact dimensions are not required because the only requirement is that the storage should be ventilated well.
Storage after harvest
It is recommended to transport all harvested crops to the cold room as rapidly as possible. For fresh crops one hour time loss at the field by a temperature of 35°C between harvest and pre-cooling can reduce quality as much as 20 hours in storage under proper conditions. Delay in pre-cooling or cooling overall results in loss of moisture from the product, causes weight loss and combined with active micro-biological organisms result in deterioration of quality and value loss.
Use of Cold Room Door
The cold room door is the only connection to the outside temperature and is thereby the most important point which should be taken into account considering cold air loss. The loading rate is another factor referring to the amount of use of the door. The higher the loading rate, the more energy loss or cold air loss is created. Generally the refrigeration system capacity is based upon 4% to 5% loading rates of the total cold store capacity. The loading pattern is also a design consideration for sizing the storage chamber capacity for optimal utilization and performance. It is therefore recommended to store all crops only once a day (as little as possible). The frequency of entry is then reduced to its minimum. Additionally it is recommended to store the crops in the morning or in the evening since the outside temperatures are relatively lower at these times. In Gujarat at noon the outside temperature is at its highest point which will result in a bigger delta T (temperature difference) between inside and outside and additionally more energy loss. (Board, 2010)
- A perfect cold storage room needs a pre-cooling area. In the cooling area itself crates are used. Most important feature of crates is the support of ventilating cold air throughout the cooling unit.
- The crates should be stored in a way that supports air flow.
- The crates storage plan should allow maximization of number of crates.
- The cold room door, and the use of it, is very important as it may ruin the efficiency of your unit.
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.
Another question came in yesterday about the finishing of Magnesium Oxide Boards in case of exterior walling.
The most common exterior surface finishes are: Paint, Plaster and Tiles.
Before you start applying the finishing material:
When the MgO boards are fitted, the boards should not be exposed to the weather for a long period of time. Both heavy rains or high dryness will have their negative effects on shrinkage or expansion of the boards. These will cause cracks later when the finishing material is applied.
The MgO boards should also be clean and dry before starting finishing.
Small damages to the MgO boards should be removed or repaired.
Paint can be applied easily to the MgO boards. For exterior use, the boards should be primed with 1 or 2 coats of Plaster/Masonry Primer before coating with exterior quality paint. The primer works here as a sealant and water repellent that protects the ‘open’ structure of Magnesium Oxide Board.
Cement plaster can be applied to the surface of the MgO boards. All joints between the Boards must be meshed with Fibre Mesh (preferably 4mm x 4mm) or wire scrim prior to applying the cement plaster coat.
After plastering, a sealant primer should protect the Plaster.
Tiles may also be applied to the surface of the MgO boards. In this case it is recommended to roughen up the surface of the Board and put a suitable bonding agent (glue) on it before tiling. The amount of Glue has to be affluent.
When the tiles are applied for walls higher than 10 feet, these tiles should not be bigger than 1,3 Square Feet and thicker than 12mm.