Glossary

Heat Load

Heat load is the heat that is generated and released by a piece of electronic equipment. It is measured in British Thermal Units.

Any piece of electronic equipment that is powered on generates heat, whether it is idle or doing work. The heat that is generated and released can be measured in British Thermal Units (BTU).

One BTU equals about 1055 joules.
One watt per hour is equal to 3.4 BTU.

It is important to calculate how much heat is produced by all electronic equipment within an AV rack that is powered on during normal operation.

An AV designer will typically calculate the total BTU in a system and provide that information to the HVAC engineer. Designers can then design in appropriate cooling to counteract the effects of the equipment to prevent equipment from failing and to balance HVAC systems so people can be comfortable while they are using the space. Usually you can find the watts that a piece of equipment in the audiovisual rack uses in the owner's manual or on the device itself.

The formula for calculating heat load is:

Total Btu = W_E * 3.4

Where:

W_E = Total watts of all equipment used in the room
3.4 = Conversion factor, where 1 watt of power generates 3.4 Btu of heat per hour

This formula does not account for the heat load generated by amplifiers.

Watch the Video: Calculating Heat Load

View video lecture (2 mins) for more information about calculating heat load.

Quick Tip: Going Digital

As our AV gear continues to process more signals in the digital realm, they are more and more “computer like.” Meaning that the digital devices tend to draw more current and generate more heat than their analog counterparts due to the A/D and D/A conversions and digital processing.

Managing heat dissipation in racks, credenzas, lecterns, etc. (any enclosures that house AV gear) becomes increasingly important.