AlfaTech Big Book: Data Centers

E N G I N E E R I N G S E R V I C E S

High Dry Bulb Occurrences

WEATHER ANALYSIS

AlfaTech provides weather analysis to review historical weather data to influence site selection, for HVAC equipment sizing, and for other critical building arrangement decisions. American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) publish BIN, or analyzed “average” weather data, which is typically issued for airports and major metropolitan areas. ASHRAE also posts analyzed data for these sites such as extreme weather conditions that can be expected over a five-year period, a ten-year period, and on up to a fifty-year period. ASHRAE also publishes an Extreme Max Wet Bulb temperature which is important for design of any evaporative process such as cooling towers or evaporative cooling systems. The challenge with published data is that extreme weather conditions published by ASHRAE do not cover all cities and possible mission critical facility locations. Also, the extreme weather data represents the single worst-case conditions to be expected, but provides no information on how long that condition may last, or how often and how long weather conditions exist just below these extreme conditions. Through downloaded hour-by-hour weather data information, AlfaTech is able to provide additional insight into weather patterns, how long hot spells and cold spells tend to last, and the magnitude of these weather anomalies. We also use this information to confirm system sizing differences between sites due to weather conditions.

tower selection for the western site location would require a cooling tower fan motor increase from 3 horsepower to 7.5 horsepower to meet the same indoor design conditions. These comparisons can provide insight into optimal site locations with respect to impacts as a result of weather. These analyses can review weather trends going back as far as recorded data can be sourced, in most cases up to 50 years in the past. This trend data can identify weather pattern changes that can occur due to urbanization such as converting open field to commercial developments and industrial usage. It can also provide information related to climate change which is affecting peak weather conditions. Through detailed review of this data, additional information can be provided to influence decisions on what worst case design condition should be included in the design. The design conditions published by ASHRAE and other resources provide single points of peak weather while the additional data collected and analyzed by AlfaTech can identify trends that can result in a more cost-effective design.

Duration

As an example, through evaluating two sites less than 35 miles apart in the Portland, Oregon area of the US, it was determined that a cooling