|
Despite humans'
narrow thermal comfort range, most traditional heating systems have
simple controls. A wall thermostat compares actual ambient
temperature to desired temperature and turns the heat supply on or
off to maintain desired temperature plus or minus a degree or two.
Because ambient temperature has "inertia" and does not change
rapidly this "binary" control meets our thermal comfort needs.
Lighting systems
often have more sophisticated controls. Individual fixtures or
banks of fixtures may be turned on or off or dimmed depending on
personal preference, amount of sunlight entering the room, presence
or absence of an occupant, etc. Unlike ambient temperature, light
has no "inertia" and the light intensity changes immediately with
light output. Too much light is immediately wasted and the energy
saved by turning the lights down or off when not needed justifies
the investment in controls.
Radiant heat is
somewhere between conventional heating and lighting. The ambient
temperature increase resulting for infrared absorption and
re-radiation has "inertia" but the thermal comfort effect of direct
infrared radiation, which is significant, changes immediately with
infrared output. As with lighting, the energy saved by turning the
HotZone™ heaters down or off when not needed justifies the
investment in controls.
High intensity
gas heaters are not very "dimmable" and tend to be on or off.
Thermal comfort can be achieved by overlapping the heaters' beam
patterns and turning on or off a percentage of the heaters,
depending on need. High energy efficiency is achieved by turning
off heaters when they are not required for thermal comfort.
High intensity
electric heaters are dimmable and while they are often used in an
on/off mode, can be more finely adjusted to optimize thermal
comfort. High energy efficiency is achieved by turning the heaters
down or off when they are not required.
|