Heat-retention cooking is an age-old method that can be used to conserve energy not only during times of crisis, but anytime. Depending on the food item and amount cooked, the use of a haybox or insulated cooker saves between 20% and 80% of the energy normally needed to cook a food. The longer an item usually takes to cook mormally, the more fuel is saved. For example, with a haybox, five pots of long-cooking dry beans will use the same amount of fuel to cook to completion as just one pot cooked without a haybox.