The sizing of supply equipment to meet a time varying demand is an important engineering problem. Optimal sizing of various supply equipment can reduce the overall cost of the supply system significantly. In this paper, the screening curve methodology, originally proposed for planning electrical power system, is extended to address various process system related problems: cost optimal sizing of various pumps to satisfy time varying water demand, ideal mix of various lighting options for a given lighting load, etc. These examples illustrate that the proposed methodology is a simple, versatile, and powerful tool for appropriately sizing various equipment to satisfy time varying demands during grassroots design. During debottlenecking, supply system is expanded; new supply equipment are installed along with appropriate utilisation of existing supply equipment. A methodology is proposed to address expansion planning of various supply equipment during debottlenecking and demonstrated using an example of debottlenecking an air conditioning system. (C) 2015 Elsevier Ltd. All rights reserved.