Water-cooled chillers have for years been the most energy efficient and cost effective means of addressing large cooling loads as is recognized by ASHRAE 90.1. However, as the price of water has increased and the performance of air-cooled chillers have improved those lines have begun to blur. It is no longer clear that the lowest total cost ownership for cooling applications over 300 tons resides with water cooled chillers. This session explores all the factors related to comparing chiller plants including: performance curves, climate, altitude, water quality, first cost and operating cost (water, energy, maintenance, and treatment).

This presentation explores evaporative cooling technologies that can vastly reduce onsite energy use of building systems. Systems explored include direct and indirect airside systems, as well as evaporative pre-filters at condensers. These new systems are compared on an energy and cost basis to conventional air-cooled systems or hydronic systems with a conventional plant and cooling tower. A case study compares the benefits of different systems in climates across the United States to examine the benefits available in different regions.

As water scarcity and utility prices increase, building water consumption is an increasingly important aspect of sustainability and efficiency. For buildings where water-efficient fixtures and cooling system upgrades have already been made, the final step toward ‘net zero’ water consumption is capture, treatment, and re-use of onsite and auxiliary water sources. This presentation provides an overview of onsite auxiliary water sources, treatment systems and other equipment required for various uses, and the site energy implications of net zero water buildings