SF Environmental


Promoting low-impact cooking to improve people’s

lives and protect the environment


SF Environmental - sponsored by SF Innovations Ltd

9, The Pastures, York, YO24 2JE, UK

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Short video clip of 2019 Solar & Haybox Cooking promotion in Killinochchi


DIY off-grid Slow Cooker




A well constructed haybox can keep food temperatures well above 65 deg C after 3 hours. There are a number of factors that determine the effectiveness of a haybox.


Insulation: The thickness of the insulation is very important to the working of the haybox cooker. If kapok, polystyrene or cork is used, this must be at least 5 cm (2 inches) thick all round the pot. If straw, newspaper, cotton or chaff is used as insulation then it is good to aim for a thickness of around 10 cm (4 inches).


Thickness of pot: A thicker walled pot works better than a thinner one as it retains more heat. This will then slowly release heat while in the haybox and help cook the food and keep it hot for longer.


Lid: It’s important to have a tight fitting lid on the pot to reduce evaporation and heat loss. One can also wrap the pot in a towel before putting it into the haybox – this will help keep the lid on tight. When heating the ingredients up before putting it in the haybox make sure the lid is on the pot. This way the lid heats up to the same temperature as the pot. Putting a cold lid on a heated pot will lower the overall temperature.


Amount of food in pot: The pot needs to be at least 3/4 full of food to ensure that the food temperature remains above 70 deg C after 3 hours. If the pot is only a 1/4 full then after 3 hours the temperature could be as low as 55 deg C and the food will need to be heated up before eating.


Checking on the food: Fight the temptation to keep checking the food. Every time the lid is opened heat will escape from the pot thus slowing down the cooking process. Just trust the cooking process and leave things to cook in the retained heat.