Cooling Load Calculator
Estimate HVAC cooling load for an industrial or commercial space.
Calculator
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Estimated cooling load: 42.3 kW
AC capacity needed: 12.0 TR (Ton of Refrigeration)
Indicative only — use ISHRAE handbook for final sizing
Formula
Cooling load (kW) = Sensible heat gain + Latent heat gain. Sensible = Wall/roof transmission + Solar + Occupants + Equipment + Lighting + Infiltration. 1 Ton of Refrigeration (TR) = 3.517 kW.
Example calculation
Room 10 m × 8 m × 3 m, 20 occupants, 2 kW lighting, 3 kW equipment, Indian climate. Rough estimate: (Area × 500 W/m²) / 3517 ≈ (80 × 500) / 3517 ≈ 11.4 TR. Detailed load analysis required for final sizing.
Engineering notes
The 500 W/m² rule of thumb is only for preliminary estimates in hot Indian climates. For final AC sizing, use ISHRAE handbook methods or HAP/Carrier software to calculate actual CLTD, CLF, SCL, and latent loads. Oversizing AC by 20–30% is common but wastes energy and causes humidity problems.
When to use this calculator
- New construction — size air conditioning system before selecting and specifying HVAC equipment
- Renovation — determine if existing AC capacity is adequate when repurposing a space
- Data centre/server room — estimate cooling load from IT equipment heat dissipation
- Industrial control room — size precision AC for control room with electronics and operators
- Energy budgeting — estimate annual AC electricity cost from calculated cooling load and operating hours
Frequently asked questions
- What is a Ton of Refrigeration (TR) and how does it relate to kW?
- 1 TR (Ton of Refrigeration) = 3.517 kW = 12,000 BTU/hr of cooling capacity. It originates from the cooling effect of melting 1 ton of ice in 24 hours. Air conditioners in India are rated in TR (split ACs) or kW (commercial chillers). When comparing, 1 TR of cooling requires approximately 1.2–1.5 kW of electrical input for a typical split AC (EER 2.3–3.0), or 0.55–0.75 kW for a high-efficiency chiller (COP 4.5–6.0).
- What factors have the biggest impact on cooling load?
- In Indian conditions: (1) Solar heat gain through glass — use external shading, reflective glass, or internal blinds to reduce by 40–60%. (2) Wall and roof transmission — insulate to reduce by 20–40%. (3) Ventilation/infiltration — control fresh air intake to the minimum required by occupancy codes. (4) Internal heat from equipment — computers, servers, and industrial equipment can dominate the load. (5) Occupancy — each person adds 75–100 W sensible heat plus latent heat from respiration.
- Why does the AC feel inadequate even though it's properly sized?
- Common causes: (1) Dirty filters restricting airflow — clean or replace monthly in dusty industrial environments. (2) Refrigerant undercharge due to leak — causes reduced capacity and higher running temperature. (3) Condenser coil fouled or insufficient ventilation — outdoor unit needs 0.6 m clearance all around. (4) Undersized ducting — poor air distribution means some zones are not cooled. (5) Changed room use — more equipment, people, or glass area than the original design assumed.
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