HVAC Load Calculation Example To calculate the estimated HVAC load for a house with 2,500 square feet, 12 windows, and 3 exterior doors occupied by 4 people, simply plug it into this formula: 2,500 x 25 = 62,500 base BTU. 4 people x 400 = 1,600. 12 windows x 1,000 = 12,000.

Heat load is a term used to define the amount of temperature that can be added or removed from the system to maintain the temperature at an acceptable range. The heat load formula is represented by Q = m ¡¿ Cp ¡¿¥ÄT. Where Q represents the heat load, m represents the mass flow rate and Cp represents the specific heat.

Calculate the HVAC load (House surface in square feet) x (height of the ceiling) (Number of occupants) x 100 BTU. (Number of exterior doors) x 1,000 BTU. (Number of windows) x 1,000 BTU.

The ASHRAE Heat Balance Method was first defined as the preferred method for Load Calculations in the 2001 ASHRAE Handbook—Fundamentals, and it is now the most widely adopted non-residential load calculation method by practicing design engineers.