Each form of electric radiant panel has found application in a wide variety of buildings.
Some applications are more common for each form of electric radiant panel.
For example, discrete-metal or framed-fiberglass modules are common for T-bar
grid ceiling heating, whereas heating cables, mats, and tubing are used as floor
heaters and floor warmers. Gypsum panels with embedded or surface-affixed resistance
wire were introduced in residential, all-electric homes in the 1940s.Where concentrated
heat output is needed, high-temperature heating elements are required.
Glass, quartz, ceramic, carbon-rod, and filament heaters are used.

Electric radiant heating panels utilize a power source readily available in all buildings.
They are commercially available in the configurations required to provide heating
for all building types and a broad range of special heating needs. Features characteristic
of all radiant heating systems are present in electrically powered radiant heating systems.
The distinguishing feature of all radiant systems is the dominance of radiant
energy in providing human thermal comfort.The capacity, sizing, and energy consumption
implications are system design– and equipment selection–dependent.Yet, comfort
is attainable under conditions of lower ambient air temperature than normally required
with convection heating systems.

Key features of radiant electric heating systems include lack of dust, noise, odor,
maintenance, and impact on relative humidity. The elimination of convection heat
air distribution of airborne particles, pollen, and bacteria is a compelling characteristic
of radiant heat transfer to the chemically sensitive and allergic members of the
population.

The design characteristics, components, and nonmechanical nature of electric
radiant heat panels eliminate the possibility of noise and odor, while virtually eliminating
maintenance. Relative humidity is virtually unaffected by radiant heat panels
due to the benign impact on building infiltration and exfiltration.

Electric resistance radiant systems exhibit the control flexibility characteristic of
electricity, including virtual occupancy control of very fast-acting systems. Linevoltage
mechanical or electronic air or operative sensing thermostats frequently control
the dry electric radiant systems. Low-voltage centrally or locally programmed
controls are also used. Programmable thermostats of each type are also appropriate
for radiant panel control. Various designs are employed to monitor floor temperature,
including bulb and capillary thermostats. The control of hydronic and electric
radiant systems is more complex than simple convection systems. The reader is
referred to Sec. 6 for comprehensive information.

An important characteristic of discrete electric panels distinguishing them from
central heating system hydronic panels is their complete performance and control
independence from the other heated areas.The entire designed capacity of the electric
radiant panel may be controlled by a single thermostat or linked with other panels.
Central hydronic systems may be designed and controlled discretely, but there is
usually an efficiency penalty that diminishes the energy benefits of zoning.

The same efficiency penalties from fractional output due to zoning apply to
forced-air systems. However, the penalties are usually greater than simulation programs
project. At least two factors are often overlooked in the program and assumptions.
The first is interior duct leaks, which result in diversion of heat away from the
zoned space, but are not incorporated as duct loss or wasted heat.The second is the
impact on system balance during zonal operation.The cost of equipment to balance
on demand makes its inclusion in convection systems rare. In addition, doors are
often closed as a means of zoning, which may actually increase energy usage. Finally,
even if zoning were economic and technically practicable, the impact on building
pressure balance and air infiltration could create building condensation problems.

In-space electric radiant panels have distinguishing zonal advantages over zoned
baseboard or wall convection heaters as well as over central systems. The normal
process of heating air to transfer heat creates an air temperature gradient that significantly
increases the airflow from the heated zone, unless the space is enclosed. In-space radiant
panels raise the mean radiant temperature (MRT), while the drybulb air temperature
gradually increases, without creating large air gradients that result in significant airflow.
Radiant panel heat within the heated area is transferred out by means of conventional heat
loss and natural convection from the radiantly heated surfaces. Although it is impractical
with convection systems, zoning is practical for open floor plans with electric panel systems.

Electric radiant thermal mass heat storage options encompass a broad range of
comfort and energy use options.The objective may be to accommodate electric utility
rate structures or simply to manage building mass temperatures in the overall
comfort design. Electric cables and mats, including hydronic thermal storage tubing,
are buried under or placed in the thermal mass, in order to charge the earth or mass
with heat during periods when electricity rates are lower. Hydronic systems may use
a variety of mechanical, evaporative, or conductive methods to cool a fluid for radiant
cooling, thereby eliminating or reducing the mechanical cooling load.

There are opportunities for mass heat storage with alternative energy systems in
combination with radiant electric systems. For example, passive solar heating
strategies often require maintenance of mass temperatures during certain seasons
or time periods in order to even out the natural solar cycle. Successful application
of radiant thermal storage requires a comprehensive, overall system design including
an occupancy-responsive temperature and/or comfort control program. See Sec.
7 in this Handbook for comprehensive information on combination system design
and task heating.

Although most energy design and simulation programs have not incorporated
MRT or human thermal comfort factors, nor have they been dynamic programs,
those programs that do incorporate thermal comfort parameters have not refined
the calculation to a high level.When computer programs incorporate these factors,
they will capture performance characteristics that are unique to electric radiant
heating panels.These characteristics include reduced electrical load, human thermal
comfort at lowered ambient air temperatures, and reduced energy consumption.

Neither common nor individual radiant system characteristics are recognized
when all-electric, resistance heating systems are treated the same and are identical in
the model. The advent of computer programs that more closely link occupant
lifestyle and building use, weather conditions, internal load contribution, indoor air
quality requirements, and human thermal comfort provides engineers with better
information for system selection, which would be much more likely to be radiant.

Characteristics of radiant panels are shown in Table 2.1. Of note, studies at the
University of Illinois and Kansas State University have demonstrated that electric
ceiling panel radiant output may exceed 0.9 to 0.95 under common conditions in the
built environment (see Chap. 5 in this section of the Handbook for ASHRAE RP

876, and also RP 657).There is a discussion relative to the design and thermal comfort
impacts of draft in both Secs. 3 and 8 of this Handbook.

Evaluation of all radiant heating options is important to ensure selection of the
system that best suits the overall design and performance objectives. This chapter
empowers the reader to assemble the appropriate panel information for analysis of
electric radiant heat in comparison with any heating system.The reader is equipped
to perform comprehensive system evaluation and equipment selection.

Each form of electric radiant panel has found application in a wide variety of buildings.
Some applications are more common for each form of electric radiant panel.
For example, discrete-metal or framed-fiberglass modules are common for T-bar
grid ceiling heating, whereas heating cables, mats, and tubing are used as floor
heaters and floor warmers. Gypsum panels with embedded or surface-affixed resistance
wire were introduced in residential, all-electric homes in the 1940s.Where concentrated
heat output is needed, high-temperature heating elements are required.
Glass, quartz, ceramic, carbon-rod, and filament heaters are used.

Electric radiant heating panels utilize a power source readily available in all buildings.
They are commercially available in the configurations required to provide heating
for all building types and a broad range of special heating needs. Features characteristic
of all radiant heating systems are present in electrically powered radiant heating systems.
The distinguishing feature of all radiant systems is the dominance of radiant
energy in providing human thermal comfort.The capacity, sizing, and energy consumption
implications are system design– and equipment selection–dependent.Yet, comfort