How the calculator works

  1. Transmission: U × A × ΔT, with U = 0.022 W/(m·K) ÷ panel thickness (PU/PIR core) and A = walls, ceiling and floor.
  2. Air infiltration: air changes per day ≈ 95 ÷ √volume, × door-use factor, × about 2.2 kJ per m³ per K of temperature difference (sensible + moisture).
  3. Product: mass × specific heat (3.6 kJ/kg·K above freezing, 1.9 below) plus 250 kJ/kg latent heat when product freezes. Blast-room batches are counted over 8 hours.
  4. Internal loads: +15% for evaporator fans, lights and people; then +10% safety margin.
  5. Capacity = daily heat ÷ running hours (16 h chillers, 18 h freezers, to allow for defrost and cycling).

The result is an estimate for budgeting. Our engineers confirm the final selection with your site data. See also the panel thickness guide.