How to use this calculator
- Enter or choose inside length.
- Enter or choose inside width.
- Enter or choose inside height.
- Enter or choose panel U-value.
- Enter or choose design outside temperature.
- The refrigeration load updates as you type. Use Copy result or Share to keep it.
Method
Q_walls = U × A × (T_out − T_in); Q_product = m × c × (T_product − T_in) ÷ t; Q = (Q_walls + Q_product + Q_internal) × (1 + Air%) × (1 + Safety%); TR = kW ÷ 3.5169
- A
- 2 × (L·W + L·H + W·H), all six inside faces
- m, c
- product mass and specific heat
- t
- pull-down time in seconds
- 1 TR
- 12,000 BTU/h = 3.5169 kW
Worked example
- Area = 2 × (24 + 18 + 12) = 108 m²; walls = 0.25 × 108 × 33 = 891 W.
- Product = 2,000 × 3.6 × 23 = 165,600 kJ over 43,200 s = 3,833 W.
- Subtotal = 891 + 3,833 + 500 = 5,224 W; +15% = 6,008 W; +10% = 6,609 W.
- 6.61 kW ÷ 3.5169 = 1.88 TR.
The 6 × 4 × 3 m chiller needs about 6.6 kW (1.9 TR) of refrigeration.
What the result means
Use this as a first sizing check. Product pull-down usually dominates for rooms receiving warm product; transmission dominates for long-term storage of pre-cooled goods.
Assumptions and limits
- Product is cooled but not frozen (sensible heat only).
- Floor heat gain uses the same U-value and outside temperature as the walls.
- Latent heat of freezing, product respiration, defrost heat, solar gain and humidity are not included.
- Final equipment sizing should be done by a refrigeration engineer using the full load method.
Questions
Can I use this for a freezer?
Only for the part above freezing. Freezing product releases latent heat that this tool does not model, so the load would be badly underestimated.
Why a safety factor?
It covers uncertainty in the inputs and lets the system recover after door openings. Typical allowances are set by your engineer.
Please note: Quantities are estimates. Confirm requirements with your engineer or supplier before ordering materials.