The end of June '03 marks the second anniversary for the "Weather Report," and I would like to thank all of you who have volunteered your $.02 along the way. The feedback has been very helpful in our effort to achieve our dual goal of becoming a dependable weather data resource as well as a good source for useful and practical "hands on" HVAC systems design and operational information. So keep those e-mails coming. Also, note that the monthly data table (Figure 1) has been modified to reflect only cooling related data since we are now well into summer, and it just didn't make sense to waste space by reporting a bunch of zeroes. Heating related values will be reinstalled when fall comes around again.
We never got around to taking a look back at the totals for 2002, so now is as good a time as any, and I thought it would be a good idea to start with ASHRAE design conditions. To recap, the ASHRAE design outdoor air conditions are published in the 1997 ASHRAE Fundamentals Handbook for 1,459 locations around the world. These values are used to determine required heating and cooling equipment capacities for HVAC systems and other energy related processes. The 0.4%, 1.0%, and 2.0% design values for outside air dry bulb and wet bulb temperatures represent the temperatures that are exceeded 0.4%, 1.0% and 2.0% of the year on average, or 35, 88, and 175 hours per year respectively. Similarly, the outside air dry bulb temperature is less than the heating 99.6% and 99% design values 35 and 88 hours per year respectively.