Consider the type of application. Low-intensity radiant heaters are typically used where total heating of a large area is required. High-intensity radiant heaters can be used both for spot or localized heating and for heating large areas. Small retail and office buildings can be successfully heated with low-intensity radiant ceiling panels or gas-fired tube heaters. Retrofitting steam heat systems to low-intensity tube heating has been shown to be an effective way to reduce energy use in older commercial buildings.
Conventional heaters are often ineffective in large areas such as warehouses and loading docks, where maintaining air temperatures of 60° to 70°F is costly and inefficient. In such situations, if reflector-focused gas or electric radiant heaters are mounted above the areas where workers need warmth, the air temperature of the building as a whole can often be reduced to as low as 40° to 50°F.
Think about maintenance requirements. Maintenance and associated costs are virtually nonexistent with electric radiant heating panels. These units have no pumps, blowers, compressors, or burners to fail, and there are no filters to change. They operate with hardly any attention throughout their useful life. And if a panel does fail, it can quickly and easily be replaced, often with an interruption of an hour or less.
Account for eliminating or reducing the size of ducts. In new, heating-dominated commercial buildings, radiant heating may eliminate the need for air ducts or allow ducts to be downsized, which, in turn, may make it possible to reduce floor-to-floor height. Where building heights are restricted by code, the use of this technology may even make room for an additional floor—and more rentable space—as compared with traditional construction and other types of HVAC systems.
Remember the limitations. The effectiveness of radiant heating decreases in the presence of substantial winds or drafts. To minimize discomfort from the movement of cold air, pressurize the building or take steps to block winds. Radiant systems also require a direct line between the heater and the person or object being heated. Care must be taken not to place furniture where it might interfere with the heater’s ability to warm the room’s occupants. Also, note that radiant systems can’t be controlled by conventional thermostats, because comfort doesn’t correspond to air temperature alone; thermostats that sense both temperature and radiation should be used.
If you answer yes to any of the following questions, radiant heating could be beneficial in the application you have in mind:
Are occupants uncomfortable on the coldest days? As outdoor temperatures drop, the radiant temperature of walls and windows also decreases, which adds to the sensation of being cold even when the thermostat is set at what would normally be a comfortable temperature. Radiant heating panels can increase the temperature of inside surfaces of the building envelope, making occupants feel more comfortable at lower thermostat settings.
Is the area frequently unoccupied? Radiant heaters are particularly effective in areas that are frequently unoccupied—because there is little delay in providing heat, there’s no reason to keep the heat on in unoccupied rooms. They also work best in areas with open architecture, without lots of doors or other obstructions.
Is the primary heat source for the building electric baseboard heating? Baseboard heaters warm the air, which then warms occupants and furnishings, whereas radiant technologies directly warm occupants and furnishings, which then reradiate heat to the surrounding air. With resistance heating, higher space temperatures are required to achieve the same level of comfort that can be achieved at lower temperatures with radiant technologies. When used as a supplement to, or replacement for, electric resistance heaters, radiant heating allows for lower thermostat settings that translate directly into reduced peak demand for a given building.