BPI Multifamily Building Operator (MFBO) Practice Exam 2026 - Free BPI MFBO Practice Questions and Study Guide

Radiation transfers heat through electromagnetic waves and does not need any medium to travel; energy moves through space or air until it meets something that can absorb it. The thing to remember is that the radiant energy typically heats the surface it hits directly. In many situations, gases between the source and a surface absorb very little of that radiant energy, so the primary heating occurs in the first solid or liquid surface that absorbs it. That’s why the statement that radiation heats the first solid or liquid it encounters, not gases, aligns with how radiant heat transfer usually works.

A couple of quick real-world notes to reinforce the idea: some gases can absorb specific wavelengths (for example, certain greenhouse gases absorb infrared), but in general, gases are less effective at absorbing broad radiant heat compared with solid or liquid surfaces. Also, radiant heat does not need a fluid medium to propagate, and it can transfer heat across a vacuum.