HeatRise
Electrical enclosure thermal calculator
24-hour thermal profile
Sydney, New South Wales, Australia · 2026-08-26 · modelled clear-sky
Peak internal at 14:00. Sol-air is the equivalent outdoor temperature including solar on the shell.
Heat balance (last 24 h)
- Internal load
- 6,000 Wh
- Solar on shell
- 1,493 Wh
- Through glazing
- 0 Wh
- Adjacent heat
- 0 Wh
- Through walls
- 5,775 Wh
- Ventilation
- 225 Wh
- Effective UA
- 6.6 W/K
- Effective fan flow
- 0 m³/h
To hold 40 °C
Clean filter-fan flow of about 733 m³/h, or a closed-loop cooler of about 348 W.
Outdoor dusty sites often need a cooler, not open filter fans.
- Above 40 °C most VFDs and power supplies start derating. Set a drive type to see current remaining.
Direct sun · sealed / natural
How this is calculated
Two-day lumped transient for a 1-day study (the settle day is discarded so thermal mass has come to periodic state). 3- and 7-day runs keep repeating the selected day’s weather after one settle day — add a heatwave overlay to lift every dry-bulb hour. Walls use a U-value from inside film, conduction through the stated thickness, and outside film plus radiation. Effective area follows IEC 60890 exposure factors.
Opaque solar is a sol-air temperature on each exposed face. Door glazing is an internal source (SHGC × front irradiance × area). Filter fans remove heat as ρ·cp·V̇·ΔT on outdoor dry-bulb, with clean / in-service / dirty flow derate. Mixing fans only raise the inside film coefficient. Adjacent heat is a constant internal wattage.
Connected load is dissipated heat, not nameplate kW. Drive derating uses typical catalogue slopes (ATV600, generic VFD, PSU, PLC). The design note is a verification aid under IEC 60890 / IEC 61439-1 / AS/NZS 61439.1 — not a type test.