What Information is Required to have a Heating and Cooling Calculation Generated?

There are many factors in how much cooling or heating a building will require to maintain a set temperature.  Many times, building owners and architects are not aware of the information required to get the mechanical calculations started.  Most seasoned architects have a good idea of what they need to provide to the mechanical engineer, while less experienced architects may expect a building load to be generated using only a building layout.  Below are 5 common areas that will need to be addressed prior to generating a heating and cooling calculation. The more accurate the information provided the more accurate the load calculation.

  1. Location – Physical address or closest town.  This information is vital to defining design temperatures for both summer and winter, along with solar orientation, elevation and number of heating and cooling hours.
  2. Envelope – Details of the walls, floors, roofs, windows, skylights and doors to be utilized and their respective R-values and U-values.  Windows, skylights and doors play and important role in load calculations.  They are major points of heat gain and loss due to their low R-values (U=1/R) compared to walls.  They can also significantly contribute to the solar heat gain. R-values for wall, roof and floor will also play an important role in heat gain and loss for a building.
  3. Type of Occupancy – Occupancy activity levels play an important role in performing load calculations.  Greater occupancy requires more outside air, which results in greater need for conditioning.  An active occupancy like a gym will require more cooling than an office due to occupant output.  The occupant output can range from 330 BTUh (theater) to 2000 BTUh (gymnasium) per person.
  4. Building Orientation – This is important for both heating and cooling.  South facing exposures in Northern hemisphere will be warmer than a North facing exposure due to exposure to the sun’s radiant energy.
  5. Equipment – Equipment heat gain differs room to room and can play a major role in the amount of cooling required.  For instance a server room will require substantially more cooling than an office.

If these 5 items are addressed at the time a building layout is presented to your mechanical engineer, you will save both the engineer and yourself time and money.  See below for a sample format of the information above.

sample table heat cool calculation


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