Cooling Load Calculation Procedure

Obtain Building Characteristics

1. Construction materials.
2. Construction material properties: U-values, R-values, shading coefficients, solar heat gain coefficients.
3. Size.
4. Color.
5. Shape.
6. Location.
7. Orientation, N, S, E, W, NE, SE, SW, NW, etc.
8. External/internal shading.
9. Occupancy type and time of day.

Select Outdoor Design Weather Conditions

See http://hvac-eng.com/weather-design-conditions-for-selected-locations/

1. Temperature.
2. Wind direction and speed.
3. Conditions in selecting outdoor design weather conditions:

• Type of structure, heavy, medium, or light.
• Is structure insulated? If the structure is heated or cooled, the structure must be insulated by code.
• Is structure exposed to high winds?
• Infiltration or ventilation load.
• Amount of glass.
• Time of building occupancy.
• Type of building occupancy.
• Length of reduced indoor temperature.
• What is daily temperature range, minimum/maximum?
• Are there significant variations from ASHRAE weather data?
• What type of heating devices will be used?
• Expected cost of fuel.

Select the indoor design temperature to be maintained in each space.

See http://hvac-eng.com/indoor-design-conditions/

• Estimate temperatures in unconditioned spaces.
• Select and/or compute U-values for walls, roof, windows, doors, partitions, etc.
• Determine the area of walls, windows, floors, doors,  partitions, etc.
• Compute the conduction heat gains for all walls, windows, floors, doors, partitions, skylights, etc.
• Compute the solar heat gains for all walls, windows, floors, doors, partitions, skylights, etc.
• Infiltration heat gains are generally ignored unless space temperature and humidity tolerance are critical.
• Compute the ventilation heat gain required.
• Compute the internal heat gains from lights, people, and equipment.
• Compute the sum of all heat gains indicated in items G, H, I, J, and K earlier in this list.
• Include morning cool-down for buildings with intermittent use and night setup.
• Take into account excess HVAC system capacity permitted for morning cool-down.
• Consider equipment and materials that will be brought into the building above the inside design temperature.
• Cooling load calculations should be conducted using industry-accepted methods to determine the actual cooling load requirements.