Question 1

What goes into a cooling load calculation?

Accepted Answer

Cooling load = fabric (conduction through walls/roof/glass) + outside-air ventilation (sensible + latent) + people (sensible + latent) + equipment (laptops, PCs, servers) + lighting + solar gain through glazing. The biggest mistake is under-counting people and equipment in densely occupied offices.

Question 2

How much heat does one office worker generate?

Accepted Answer

ASHRAE values for sedentary office work: 75 W sensible heat plus 55 W latent heat per person — about 130 W total. A laptop with monitor typically adds another 100–150 W. So a 50-person office has roughly 13 kW of cooling load from people and equipment alone, before fabric or solar.

Question 3

What is the difference between sensible and latent cooling load?

Accepted Answer

Sensible load is heat that raises temperature — fabric conduction, lighting, equipment, and the dry component of people and ventilation. Latent load is heat tied to moisture removal (dehumidification) — exhaled water vapour from people and humid outside air. In tropical climates latent can be 30–50% of total cooling. Heat pumps must be sized for total (sensible + latent).

Question 4

How much outside air does an office need?

Accepted Answer

ASHRAE 62.1 recommends 7.5 L/s per person plus 0.3 L/s per square metre for general office space. In hot/humid climates this ventilation can be the single largest cooling load — every litre of outside air must be cooled and dehumidified to indoor conditions.

Office Cooling Load Calculator

1. Climate & Building

2. People & Equipment

3. Cooling Load Result

Load Breakdown

Karnot Reversible Heat Pump Selection

Calculation Method