National Electric MFGTemporary power • HVAC load tools
Methodology

Electrical calculator · ventilation / heat loss / warehouse

Ventilation Heat Loss Calculator

Estimate extra heat needed when extract fans, open doors or air changes are dragging warm air out of a workspace.

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For warehouses, workshops, drying rooms and spaces with high air movement.

Field notes

Field notes for Ventilation heat loss

Practical checks to run before this calculator result turns into a site decision.

Site check

Do not treat a 13A socket as a heater busbar

A 2–3kW heater can be a heavy continuous load. Check what else shares the circuit, avoid stacked adaptors and be cautious with long or coiled reels.

Site check

Separate comfort heat from drying duty

Drying and site heating have different run times. Long-duty heaters need more margin than a short warm-up calculation suggests.

Site check

Check cable heat as well as breaker size

If the tool points to reel or lead stress, the fix is usually to fully unwind, shorten the run, use a larger connector class or split the heaters.

FAQ

Ventilation heat loss FAQ

Short answers written for UK temporary electrical and HVAC planning work.

What is the Ventilation heat loss used for?

Estimate extra heat needed when extract fans, open doors or air changes are dragging warm air out of a workspace. It is mainly for temporary HVAC, drying, cooling and site-power planning, especially where a quick pre-check is needed before selecting equipment or changing a temporary setup.

Can this replace BS 7671 design, inspection or testing?

No. It is a competent-person planning aid only. Final decisions still need current BS 7671 requirements, manufacturer data, inspection, testing, risk assessment and the actual site conditions.

What should I verify before acting on the result?

Check heater nameplate kW, plug or commando rating, lead length, whether reels are fully unwound, circuit sharing and the installation environment. If any assumption is uncertain, use the result as a prompt to investigate rather than as permission to energise.

What does an amber or red result usually mean?

It normally means the margin is weak, an assumption is missing, or the load should be split, staged, moved closer to the supply, reduced or reviewed by a competent electrician before use.

Next tools in this workflow

See super flows