Starting from Climate and Comfort, the article takes an overview and analyzes concepts and detailed design of EC Systems. Topics covered include, Importance of Wet Bulb and Wet Bulb Depression, Revision of Concepts of Comfort, Plant Sizing, Room Air Movement, Use of Local Air Moving Devices like personal fans, Year-round Plant Performance, Energy Consumption Calculations, Comparative Studies Between Direct Evaporative Cooling, Indirect Evaporative Cooling and Air Conditioning - all with a fresh approach. The focus on energy saving is sharp throughout. The role that Evaporative Cooling can play in creating Energy Efficient Buildings and Green Buildings is emphasized. HVAC engineers have challenges and also opportunities to fashion EC in a fresh garb, using today’s concepts, technology and tools for design and calculations.