Heat load Calculation Step by Step as per ISHRAE/ASHRAE Standard

Step by Step Heat load Calculation by using excel sheet as per ISHRAE/ASHRAE standard

The heat load calculation is a very important role in the HVAC industry to calculate Tonnage of Refrigeration (TR)

NORMAL DESIGN CONDITIONS – SUMMER

Normal design conditions are recommended for use with comfort and industrial cooling applications where it is occasionally permissible to exceed the design room conditions. These outdoor design conditions are the simultaneously occurring dry-bulb and wet-bulb temperatures and moisture content, which can be expected to be exceeded a few times a year for short periods. The dry-bulb is exceeded more frequently than the wet-bulb temperature. And usually when the wet-bulb is lower than design. When cooling and dehumidification (dehydration) is performed separately with these types of applications, use the normal design dry-bulb temperature for selecting the sensible cooling apparatus; use a moisture content corresponding to the normal design wet-bulb temperature and 80 % RH for selecting the dehumidifier (dehydrator) The daily range is the average difference between the high and low dry-bulb temperatures for a 24-hr period on a design day. This range varies with local climate conditions.

MAXIMUM DESIGN CONDITIONS-SUMMER

Maximum summer design conditions are recommended for laboratories and industrial applications where exceeding the room design conditions for even short periods of time can be detrimental to a product or process. The maximum design dry-bulb and wet-bulb temperatures are simultaneous peaks (not individual peaks). The moisture content is an individual peak and is listed only for use in the selection of separate cooling and dehumidifying systems for closely controlled spaces. Each of these conditions can be expected to be exceeded no more than 3 hours in a normal summer.

NORMAL DESIGN CONDITIONS – WINTER

Normal winter design conditions are recommended for use with all comfort and industrial heating applications. The outdoor dry-bulb temperature can be expected to go below the listed temperatures a few times a year, normally during the early morning hours. The annual degree days listed are the sum of all the days in the year on which the daily mean temperature falls below 65 F DB, times the number of degrees between 65 F DB and the daily mean temperature.

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