Electricity generation generally consumes water, meaning energy efficiency reduces water consumption. Evaporative cooling offers substantial energy efficiency gains but consumes water on site, and the impact of evaporative cooling is largest in arid regions which are susceptible to droughts. Net water consumption for evaporative cooling depends on the regional generation mix, water quality, weather conditions, and the water-use efficiency for particular evaporative equipment. This presentation explores total water-use scenarios including a detailed analysis of a theoretical worst-case scenario where all water for evaporative cooling uses energy-intensive desalination, the results of which suggest that evaporative cooling is energy and cost effective.

Proposed ASHRAE Standard 212 is a Method of Test for determining the energy and peak electricity demand savings associated with adding evaporative pre-coolers to packaged HVAC equipment. The standard measures the evaporative effectiveness of a pre-cooler as a function of face velocity and weather conditions, as well as the water consumption required to produce that effectiveness. This presentation will discuss the current content of the standard, as well as the rationale for how and why different parameters are measured within the standard. It will also include preliminary test results for different pre-cooler technologies.

Several manufacturers have recently introduced hybrid vapor-compression/evaporative cooling solutions that incorporate the advantages of multiple cooling components into variable speed, multi-mode equipment. These technologies may utilize indirect evaporative cooling, exhaust air heat recovery, desiccant dehumidification (or other components) in combination with vapor compression. This presentation summarizes findings from several laboratory tests, and more than 30 monitored installations of different hybrid air conditioning solutions. It focuses on practical issues in design and commissioning that help ensure performance in operation. In most cases these strategies can reduce full-load cooling demand by more than 40%. Some systems deliver annual savings of 65% or more.

With an increasing focus on use of refrigerants with a low GWP (Global Warming Potential), one such refrigerant muscling its way back onto the scene is R-718, better known to most by its chemical formula, H₂O. This presentation focuses on two distinct uses of evaporative cooling technologies. The first case investigates DEC for a commercial office building. The second case investigates Indirect Evaporative Cooling for a laboratory building with stringent humidity control requirements. The results indicated combined chiller and fan energy savings greater than 60%. The IEC improved overall energy and water efficiency while providing significant first cost savings.