4.5. SR 04-20-1998 - Laserfiche WebLink

Home Browse Search

ELK RIVER ARENA ELK RIVER, MINNESOTA APRIL 8, 1998 FEASABILITY STUDY ESTIMATE OF THE EXISTING BUILDING HUMIDITY LOAD: The moisture problems that occur in the arena are directly related to the amount of moisture in the air and the temperature of the building surfaces in the arena. The ice sheet acts as a giant refrigerator that cools the building structure during even the warmest summer days. Common structural beam temperatures in arenas range from 50°F to 55°F. Condensation will form on the surface of the structure anytime the dew point temperature of the air is above the temperature of the structure. This is the same principle that causes water to condense on the outside of a cold glass of water on a humid summer day. When the dewpoint temperature of the air is higher than the surface temperature of the glass of water or structural beam, water condenses on the surface. There are several major sources of moisture that need to be evaluated during the design of an ice arena: (1) the moisture load from outside air used for ventilation purposes; (2) the moisture load from outside air due to infiltration; and (3) the moisture load from the building occupants. The moisture load from the outside air is by far the largest source of moisture into the building. We have summarized the moisture load on the new arena in the following paragraphs. The amount of moisture being added or removed from a building is commonly estimated in pounds of moisture per hour, (lbs/hr). 1. Three 12,000 ft3/min exhaust fans are located above the ice sheet. All three of the fans are used during the ice resurfacing operation. This amounts to a total of 36,000 ft3/min of outside air used during the resurfacing operation. The make-up air drawn into the building by the exhaust fans adds approximately 2,000 lbs/hr of moisture to the building during a humid design day. The fans typically are run for 15 minutes per hour. The average moisture load due to the ventilation fans is therefore 500 lbs/hr on a summer design day. 2. When the air outside the arena contains more moisture than the air in the arena, moisture will infiltrate into the building. This infiltration occurs through cracks in the building construction, through doors and windows, through louvers and directly through the building structure. We have estimated that the moisture load due to infiltration for the arena is approximately 130 lbs/hr. 3. The spectators that are in the arena add moisture to the air. We have been informed that the arena was designed for 500 spectators during a summer event and 1500 spectators during a winter event. The spectators for a summer event add an estimated 50 lbs/hr of moisture load to the arena. 4. An additional 20 people are typically actively involved with the hockey game or skating competition on the ice. The people actively skating in the arena add an estimated 20 lbs/hr of moisture to the arena. 5. The total moisture load that the facility will experience will fluctuate with the amount of people in the arena and the conditions of the outdoor air. Ifa large event were held on a humid day, with 500 people watching the event, the total moisture load being added to the arena would be approximately 700 lbs/hour of water vapor. 6. A more typical moisture load for a practice with twenty skaters and one 15 minute ventilation period per hour would be 650 lbs/hr. The dehumidifiers installed in the arena have a total moisture removal capacity of 34 lbs/hr. The large difference between the amount of moisture being added to the arena and the amount being removed by the dehumidifiers accounts for the humidity problems being experienced at the facility. NELSON-RUDIE & ASSOCIATES, INC. Page 3