This morning I attended a session on Economizers. This technology is really interesting and I was anxious to learn more about it. Besides - the session was presented by someone with access to a lot of data (Dave Picket from Equinix). Here are a couple of interesting items I learned in this session.
A Psychometric chart is an excellent tool for analyzing data on air properties (enthalpy)
Research the temperature BINs for the particular region you are in. This facilitates the calculation of potential operating hours on economizer systems.
Water-side economizers: easy in climates with cool fall and spring seasons, and cold winter weather, such as Chicago, NY, and Washington D.C. It is with medium difficulty in climates with moderate weather year-round, such as San Francisco. It simply does not work where it is hot and humid most of the year.
There are many caveats associated with operation in freezing weather. Excessive ice build-up can damage tower components and operational errors can result in loss of cooling
Dave promoted two excellent sources of information - the EPA final report to Congress and the LNBL paper on air-side economizers and air quality.