Evaporative Cooling and Other Low-Energy Cooling Strategies in Large Commercial Buildings
J. Huang, A. Palombo
Figure. Section drawing of standard lot detached housing.
Since 1993, we have been participating in the International Energy Agency's (IEA) Annex 28 on Low-Energy Cooling. "Low-energy cooling" refers to techniques to cool buildings with minimum reliance on air conditioning by using naturally available cooling sources (outdoor air, ground, or water), non-compressive techniques (such as desiccants), and efficient delivery systems (such as radiant cooling combined with displacement ventilation). These strategies are not only energy efficient, but many are also environmentally beneficial because they do not use chlorofluorocarbons.
Nine IEA member nations participate in Annex 28. The Table shows the lead country for each low-energy cooling technology under study. Most effort is devoted to developing detailed algorithms, simplified design tools, and case studies of innovative buildings. As lead researcher for evaporative cooling, we have improved the capability of the DOE-2 building energy analysis computer program to model evaporative cooling systems. DOE-2 evaluates the benefits and limitations of evaporative cooling in U.S. and European buildings and climates and documents successful applications in commercial buildings.
Figure. Diagrammatic sketch of cooling system for One Utah Center.
Evaporative cooling is extremely effective in arid and semi-arid climates. In large commercial buildings, evaporative cooling cannot meet the cooling load during all hours, but combined with air conditioning, it can meet the entire load during milder cooling periods as well as reduce the compressor load under peak conditions. One Utah Center, a 22-story office building recently built in Salt Lake City, has a three-stage cooling system designed for 100% outside air, with indirect evaporative, cooling coil, and then direct evaporative cooling (see Figure). Under design dry-bulb conditions, the two evaporative cooling stages displace 78% of the total cooling load; while under design wet-bulb conditions, they displace less than one-half. Compared to a survey of typical office buildings in Salt Lake City, the One Utah Center used 28% less energy for heating and cooling in 1993.
| Technology | Lead Country |
| Evaporative Cooling | US |
| Night Cooling and Natural Ventilation | UK |
| Residential Night Cooling and Evaporative Cooling | France |
| Ground Cooling | Switzerland |
| Slab Cooling with Air | Finland |
| Slab Cooling with Water | Portugal |
| Chilled Ceiling and Displacement Ventilation | Germany |
| Desiccant Cooling | Canada |
Table. Annex 28 low-energy cooling technologies.
References
Huang YJ. Modeling Evaporative Cooling Systems Using the DOE-2 Program (Draft). Lawrence Berkeley National Laboratory, 1995.
Huang YJ. The "Solar Energy Research Facility." National Renewable Energy Laboratory, Golden, CO, evaporative cooling case study for IEA Annex 28 (Draft). Lawrence Berkeley National Laboratory, 1995.
Huang YJ. The "One Utah Center Building." Salt Lake City, UT, evaporative cooling case study for IEA Annex 28 (Draft). Lawrence Berkeley National Laboratory, 1995.
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