If a cold room is to be held at a given temperature, as much heat must be rejected as enters the room by every route. This total is the "heat load", and it is the figure the cooling capacity is chosen from. It is calculated as a daily total in kWh and divided by the compressor’s daily running hours to find the kW required.
The items of the load are: heat conducted through the panels and floor (panel thickness, outside temperature), the heat that must be removed to bring incoming product down to room temperature (product quantity, entry temperature, latent heat if freezing), the respiration heat of fresh fruit and vegetables, warm humid air entering with door openings, people in the room, lighting, vehicles such as forklifts, evaporator fan motors and defrost heaters.
In a typical 0 °C storage room, conduction and product load make up two thirds of the total; in a blast freezer the product load alone reaches 80%; in a distribution warehouse with frequent door openings air infiltration can be the biggest item. So there is no general ratio of "so many m² of room, so many kW"; two rooms of the same size can need twice as much capacity as each other depending on product and use.
Sonkar’s cold room cooling load calculator works out these items one by one, shows the breakdown and finds the matching evaporator and condensing unit in the catalog. For the final selection our technical team reviews the project conditions.