Cooling Load
Cooling load is the computed rate at which a space gains heat — solar gain through the envelope, occupants, lighting, equipment and fresh-air conditioning — expressed in kW or TR; every honest HVAC selection starts from it.
Why it matters on an MEPF project
Load calculation is where HVAC is engineered or faked. Room-wise computation with real orientation, glass, occupancy and equipment produces a defensible plant size and duct schedule; ₹-per-sq.ft folklore produces oversized plant that short-cycles and dehumidifies badly, or undersized plant that never holds setpoint in May. Both errors are permanent.
The split matters as much as the total: sensible vs latent load drives coil selection (a Delhi monsoon room fails on latent even when sensible is covered), and the peak-vs-diversified distinction sizes central plant sanely — every room peaks, but not together.
How it's specified in practice
| Parameter | Typical / working position | Governing reference |
|---|---|---|
| Envelope & solar | Orientation, glass area/type, shading — often dominant in offices | load-calc methodology |
| Internal gains | People, lighting W/m², equipment W/m² | design assumptions (declared) |
| Fresh air | Ventilation air conditioned from ambient — heavy in Indian summers | NBC 2016 Part 8 rates |
| Sensible/latent split | Drives coil ADP selection; monsoon punishes latent shortcuts | psychrometric design |
Common mistakes
- Thumb-rule tonnage with no calculation on file.
- Ignoring fresh-air load, then wondering why capacity vanished in June.
- Sizing central plant to the sum of room peaks with zero diversity.
- No margin policy — or compounding "safety" margins at every step.
Related on this site
One of 68 working definitions in the MEPF & solar engineering glossary. The buying side of the same decisions is in the buyer's guides; the numbers are in the calculators.
Frequently asked
What information does a proper load calc need?
Drawings with orientation, glass specification, occupancy and equipment schedules, and the design ambient. With those, room-wise loads are arithmetic; without them, everything is a guess wearing software.
How much oversizing is healthy?
A declared, single margin on honest inputs — not stacked fudge factors. Oversized plant cycles, controls poorly and dehumidifies worse; "bigger to be safe" is usually less comfortable.
Standards referenced: NBC 2016 Part 8 (ventilation rates) · ECBC 2017 (envelope context)