Dewpoint Evaporative Comfort Cooling
EW-200821
Objective
Air conditioning is the single largest contributor to peak demand on electric grids and is the primary cause of grid failure resulting in blackouts. Power generators and electric air conditioners are least efficient at high ambient temperatures when cooling demand is highest, straining regional water resources and leading to increased pollution, excessive investment in standby generation capacity, and poor utilization of peaking assets. Evaporative air conditioners can help meet Department of Defense energy policy goals by eliminating energy waste and reducing electric demand. However, common experience is that evaporative coolers do not supply air cold enough to provide comfort. New dewpoint evaporative cooler configurations offer colder temperatures and more comfortable indoor conditions. The objective of this project is to demonstrate the capabilities of new high-performance indirect evaporative cooling technology to enhance energy efficiency and comfort in dry climates while substantially reducing peak demand on the power grid. The project will quantify energy and water consumption, cost savings relative to air conditioners, and improved comfort relative to conventional evaporative coolers. Water conservation techniques including advanced controls and greywater utilization will be used to minimize regional and site water impacts.
Technology Description
Innovative, high-performance evaporative coolers have been developed that surpass evaporative cooling paradigms for comfort-cooling applications. Specifically, an internally manifolded design by Coolerado of Arvada, Colorado, has made dewpoint temperature rather than wetbulb, the new low temperature limit for evaporative cooling. Department of Energy (DOE) laboratory testing has proven its ability to supply air at or below ambient wetbulb temperature (100% wetbulb effectiveness), surpassing state-of the-art indirect coolers (approximately 75% effective) and even swamp coolers (approximately 90% effective) without adding any humidity to the supply air. This approach is two to four times as energy efficient as conventional air conditioning and significantly enhances both occupant comfort and the climate range for evaporative cooling. Comfort is achieved in climates with design wetbulbs below 70°F, which includes most of the western United States. The only electrical input to the system runs a single fan resulting in cooling energy efficiency ratios (EER) consistently over 20 and exceeding 60 at part-load. EER is the cooling provided (Btu/hour) divided by the electrical power consumed (kW). The current DOE standard for seasonal EER is 13, and its long-term goal is 20.
Benefits
Peak power demand reductions in excess of 20% are possible with proportionate reductions in demand charges. This is expected to reduce strain on the grid, increase electric delivery reliability, and reduce projected service expansion costs. Electricity costs for air conditioning are expected to drop by 50-75% relative to packaged rooftop units. By allowing higher ventilation rates that flush buildings of volatile organic compound (VOC) contaminants and by maintaining lower indoor humidity than swamp coolers, high-performance dewpoint evaporative coolers will create more comfortable and healthy indoor spaces. (Anticipated Project Completion - 2011)
Points of Contact
Principal Investigator
Mr. Jesse Dean
National Renewable Energy Laboratory (NREL)
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.