Factory-production activity is conducted based on production plans, which will unavoidably have to be revised due to changes in the production context. These changes should be considered when drafting production plans because of the frequent occurrence of rush orders with short deadlines. Since rush orders interrupt regular orders, we may consider that increased setup times, lower production quantities, and increased specific-energy consumption will accompany their addition.We have previously supposed a management form that immediately adds rush orders to the production line, and proposed expressions for calculating the specific-energy consumption. Actual companies, looking to restrict increases in setup times, may implement management where rush orders are accumulated and added in time slots. However, in studies on formulae for calculating specific-energy consumption that consider rush orders, we see no consideration of management where the rush orders are added in time slots. Accordingly, this study presents a pre-emptive evaluation method using specific-energy consumption by formalising it for management where rush orders are added in time slots.