ℹ️ About This Calculator
A cold room's refrigeration plant must remove heat from four sources: conduction through the insulated envelope, the product being cooled, air infiltration through doors, and internal gains from lights, fans and people. This calculator estimates the total load in kW and TR from the room size, temperatures and product data, following ASHRAE Refrigeration practice.
The four components rarely peak together, so a diversity and a safety factor (usually 10-20%) are applied to the total. Product load - cooling the goods and, for freezing, removing the latent heat of fusion - often dominates in a high-throughput store, while infiltration dominates where doors open frequently. Running the plant 16-18 hours a day, not 24, sets the design capacity.
📐 Cold Room Load Components
ASHRAE Refrigeration
Q_total = Q_trans + Q_product + Q_infil + Q_internal Q_trans = U × A × ΔT (envelope conduction) Q_product = m × Cp × ΔT (+ latent for freezing) Q_infil = air changes × volume × enthalpy diff Q_internal = lights + fans + people + motors Design capacity = Q_total × safety ÷ run hours/24
🧮 Worked Example
Example: A 5 × 4 × 3 m chill room at 2 °C in a 35 °C ambient, storing 2 tonnes of produce cooled 20 °C per day: transmission through 100 mm PUF is a few hundred watts, product load ≈ 2000 × 3.6 × 20 / (24×3600) ≈ 1.7 kW, plus infiltration and fan/light gains. Totalling and applying a 1.15 factor over an 18-hour run gives roughly 4-5 kW (about 1.3 TR).
📊 Cold Room Design Reference (ASHRAE)
Design temperatures and insulation drive the transmission load:
| Store type | Room temp | Typical PUF insulation |
|---|---|---|
| Chiller (produce, dairy) | 0 to 4 °C | 80 – 100 mm |
| Cold store (meat) | −2 to 2 °C | 100 mm |
| Freezer | −18 to −25 °C | 125 – 150 mm |
| Blast freezer | −30 to −40 °C | 150 – 200 mm |
Load Components
Transmission grows with the temperature difference and thinner insulation; product load with throughput and (for freezers) the latent heat of freezing; infiltration with door openings and room volume. Add a 10-20% safety factor and size the plant on a 16-18 hour run so it can recover after defrost and door activity.
Indicative values - confirm against the ASHRAE Refrigeration Handbook and product cooling data.
❓ Frequently Asked Questions
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