This Excel spreadsheet calculator will estimate the average internal air temperature and external wall temperature of a ventilated or sealed cuboid enclosure typically used to house electrical or electronic equipment.
Empirical heat transfer correlations and a thermal resistance network are used to calculate the results.
If a sealed enclosure results in too high of a temperature rise the influence of ventilation openings on the temperature rise within the enclosure can be investigated by varying the size and location of the openings.
The negative influence of high altitudes on the cooling of the enclosure is also calculated. The calculator assumes that the enclosure is cooled via natural convection and radiation only.
Visit the blog articles How to calculate the temperature rise in a sealed enclosure and How to calculate the temperature in a ventilated enclosure for a detailed explanation of the calculation methodology.