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Cooling load calculator for cold rooms & freezer rooms
Calculate the refrigeration capacity (kW) your cold room or freezer room needs – free of charge, using the ASHRAE method, in about 60 seconds. You then get matching refrigeration units, cold room kits and accessories straight from our range.
- Takes about 60 seconds
- Free, no sign-up
- Method: ASHRAE / EN 378
Questions about sizing or selection?
Our technical support team will help you personally – by phone, call-back or in writing.
A service of H + H Kältetechnik GmbH, Laer, Germany – specialist wholesaler for refrigeration and air conditioning since 2008.
How the cooling load calculation works
- Choose the application: medium temperature (0 to +5 °C), low temperature (−18 to −22 °C) or special ranges — together with the stored product (food, beverages, frozen goods…).
- Enter the room dimensions: internal dimensions in metres; insulation thickness and U-value are suggested to suit the temperature range.
- Specify the usage: daily product intake, door openings and runtime — or take the shortcut with the quick result using default values.
From this, the calculator determines the transmission, infiltration and product loads in accordance with the ASHRAE Handbook – Refrigeration (chapter 24) and recommends the evaporator and condensing unit capacity, including the refrigerant (F-gas compliant), power supply and defrost type. Matching cold room kits, condensing units and evaporators are filtered live from our range. For the room enclosure there is the cold room configurator with a panel parts list.
The most common mistakes in cold room calculations
From our support team's day-to-day advisory work — these mistakes most often lead to incorrectly sized systems:
- Underestimating door openings: Every door opening lets warm, humid air into the room. In frequently used rooms (catering, order picking), infiltration can exceed the transmission load — so state the door usage honestly in the calculator.
- Forgetting the daily product intake: Newly stored product first has to be cooled down to room temperature. If you only calculate the ‘empty room’, you get a system that is overwhelmed with every delivery.
- Confusing watts and kilowatts, or the rating temperature: Manufacturer figures such as ‘refrigeration capacity at To −10 °C’ apply only to exactly that evaporating temperature. A unit with 2 kW at To 0 °C delivers considerably less at −30 °C — always compare the rating that matches the temperature range.
- Choosing too thin an insulation: 80 mm in the low-temperature range saves money during construction but costs electricity for decades. Usual today: 100 mm for medium temperature, 120–150 mm for low temperature.
- Confusing refrigeration capacity and heat rejection: The evaporator and the condensing unit are both selected on the basis of the required refrigeration capacity and their manufacturer's rated capacity at the relevant operating point — not on how much heat has to be rejected at the condenser. A complete condensing unit is not the same component as a separate condenser.
- No reserve planned: A system running at 100 % load has no capacity left for heatwaves, peak door-opening times or ice on the evaporator. That is why the calculator includes a safety margin.
- Ignoring the ambient temperature: A unit in a 35 °C attic or in the sun delivers less than stated in the catalogue. Installation location and ambient temperature belong in every design.
Frequently asked questions about cooling load calculation
How do I calculate the refrigeration capacity for a cold room?
The refrigeration capacity results from the heat gain through walls/ceiling/floor (transmission), the air exchange when the door is opened (infiltration), cooling down newly stored product (product load) and internal loads such as lighting and fans. Our calculator determines all components automatically from the room dimensions, temperature range and usage — you do not need to know any formulas.
How accurate is the online calculation?
It is a recognised rule-of-thumb design with a typical accuracy of ±20 % (method: ASHRAE Handbook – Refrigeration, chapter 24; Breidenbach vol. 2). Before buying, check the capacity against the data sheet — or use our free check by competent persons in accordance with EN 378.
How much refrigeration capacity does a cold room need per cubic metre?
As a rough guide, small medium-temperature cold rooms (up to approx. 10 m³) often need 0.5–1.2 kW, freezer rooms considerably more. The actual demand depends heavily on insulation, door usage and daily product intake — that is why our tool calculates with your specific values instead of flat rates.
Refrigeration capacity of the condensing unit vs. heat rejection at the condenser?
The evaporator and the condensing unit are both selected on the basis of the required refrigeration capacity and their manufacturer's rated capacity at the relevant operating point. A complete condensing unit (compressor + condenser) is not the same component as a separate condenser: its condenser heat exchanger has to reject the compressor work as heat in addition to the refrigeration capacity absorbed. The calculator shows this estimated heat rejection separately — it is only relevant for sizing a stand-alone condenser, not for selecting the condensing unit.
Which refrigerant is recommended for cold rooms?
For new systems, natural refrigerants such as R290 (propane, GWP 3) or R744 (CO₂, GWP 1) are recommended — future-proof under the F-gas Regulation. R404A (GWP 3,922) is no longer recommended for new systems. Depending on capacity and temperature range, the calculator suggests a suitable refrigerant with alternatives.
Do I need 230 V or 400 V for my refrigeration unit?
Up to around 3 kW refrigeration capacity (low temperature: approx. 2 kW), a 230 V supply is usually sufficient. Above that, a three-phase supply (400 V) is required — in that case, plan for a qualified electrician. The calculator shows the recommended supply automatically.
What are the most common mistakes in cold room calculations?
Most common: underestimating door openings and daily product intake, comparing capacity figures at the wrong rating temperature (To), choosing too thin an insulation and planning no capacity reserve. The list above explains all seven mistakes in detail — the calculator asks for the critical points automatically.