M
Mass density (kg/m³)
The mass of a material or fluid per volume.
Mean radiant temperature
(°C)
The area-weighted mean temperature of the surfaces surrounding a space.
Mean whole-house temperature
(°C)
A volume-weighted average of room temperatures in a dwelling over a stated period
(during heating only, or over the 24-hour daily cycle).
Murocaust
Similar to a hypocaust, except
that a massive wall with air channels is used and the air flow is vertical instead
of horizontal.