How to Perform Heat Load Calculations Step by Step

Here’s a concise step-by-step guide for performing heat load calculations:

1. Define the Space:
   Measure room dimensions (length, width, height) and note the building layout.

2. Gather Data:
   Collect information on building materials, insulation levels, window sizes, and orientations.

3. Determine External Gains:
   Calculate solar heat gains through windows and walls (using factors like Solar Heat Gain Coefficient and surface area).
   Calculate conduction losses/gains through exterior surfaces with the formula:
   $Q = U \times A \times \Delta T$Q=U×A×ΔT.

4. Assess Internal Loads:
   Estimate heat generated by occupants, lighting, equipment, and appliances based on standard values.

5. Include Ventilation/Infiltration Loads:
   Calculate additional heat load from fresh air entering the space using:
   $Q_{vent} = \dot{m} \times c_p \times (T_{out} - T_{in})$Qvent​=m˙×cp​×(Tout​−Tin​).

6. Separate Sensible and Latent Loads:
   Determine the sensible load (temperature increase) and latent load (moisture removal) if dehumidification is needed.

7. Sum the Loads:
   Add all the calculated values together for the total cooling (or heating) load.

8. Apply a Safety Factor:
   Incorporate a contingency (typically 10–20%) to account for uncertainties or future changes.

Fri Apr 11, 2025