COOLING TUTORIAL INSTRUCTIONS

Open the tutorial.xls Excel Workbook which is in the Hort 4050 directory. Select the COOLING worksheet. This is a spreadsheet which allows you to enter information needed in order to calculate the summer or winter cooling specifications for a greenhouse. Keep in mind that more exact calculations would require us to measure and use the actual volume within the greenhouse rather than the "fudge factor" of 8 CFM/ft² of floor area. Think about what information is missing / would be needed in order to accurately calculate greenhouse volume and thus the CFM requirements for cooling. For each greenhouse situation described below, find the appropriate information in the tables in Chapter 4 of your textbook and enter this into the spreadsheet. Record the answers in the appropriate spaces on this instruction sheet.

Take note of:

1. the impact of shifts in greenhouse situations on the cooling requirements and
2. the speed and ease of conducting a cost analysis of cooling when you use a computer.

A. Summer Cooling

1. What are the summer cooling specifications for a greenhouse that measures 70 feet wide and 140 feet long and is located at sea level, has a maximum interior light intensity of 5,500 fc and a pad-to-fan temperature rise of 7 degrees F?

   Corrected CFM of air to exhaust. __________ Whole no. of fans __________ Fan size (CFM) __________

   Pad length __________, pad height __________, and pad area __________.

   Pump capacity __________. Sump volume __________.

    

2. If the above greenhouse was located in the mountains of North Carolina at an elevation of 3,000 feet, what differences would there be in the corrected amount of air to exhaust per minute __________ and the area of the pad? __________

    

3. If the greenhouse in example A1 was shaded heavier to a maximum of 4,000 fc for growing foliage plants, how much less air would be exhausted per minute __________ and how much smaller would the pad area be? __________

B. Winter Cooling

1. What are the winter cooling specifications for a greenhouse measuring 40 feet wide by 150 feet long located at 500 feet altitude if the maximum interior light intensity is 5,500 fc and the desired inside temperature to outside temperature difference is 15 degrees F?

   Corrected CFM of air to exhaust. __________

   Number of convection tubes. __________ Diameter of convection tubes. __________

   Minimum capacity of each pressurizing fan. __________

    

2. What are the winter cooling specifications for two greenhouses connected together into a gutter-connected configuration? Each greenhouse measures 35 feet wide by 100 feet long. They are located at 1,000 feet altitude, have a maximum interior light intensity of 5,500 fc, and a temperature difference of 15 degrees Fahrenheit from outside to inside. When determining the corrected CFM of air to exhaust treat the greenhouse as a single building 70 ft. wide by 100 ft. long. For the number of tubes and their diameter consider that you have two separate greenhouses each measuring 35 ft. wide and 100 ft. long.

   Corrected CFM of air to exhaust. __________

   Number of convection tubes. __________ Diameter of convection tubes. __________

   Minimum capacity of each pressurizing fan. __________

    

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