Radiant Heat Is More Comfortable

Underfloor heating and cooling is a form of central heating and cooling which achieves indoor climate control for thermal comfort using conduction, radiation and convection. The terms radiant heating and radiant cooling are commonly used to describe this approach because radiation is responsible for a significant portion of the resulting thermal comfort.

Radiant heat is similar to the sun's heat. It travels through the air until it finds an object to warm up. Typical heating systems rely on convection. A convection heater is a type of heater that uses air convection currents to generate and spread heating. These currents circulate throughout the body of the appliance and across its heating element. Hot air rises, cool air falls.

Underfloor heating has a long history dating back to the Neoglacial and Neolithic periods. Archeological digs in Asia and the Aleutian islands of Alaska reveal how the inhabitants drafted smoke from fires through stone covered trenches which were excavated in the floors of their subterranean dwellings. The hot smoke heated the floor stones and the heat then radiated into the living spaces. These early forms have evolved into modern systems using fluid filled pipes or electrical cables and mats.

Modern underfloor heating systems use either electrical resistance elements ("electric systems") or fluid flowing in pipes ("hydronic systems") to heat the floor. Either type can be installed as the primary, whole-building heating system or as localized floor heating for thermal comfort. Some systems allow for single rooms to be heated when they are a part of a larger multi-room system, avoiding any wasted heat. Electrical resistance can only be used for heating; when space cooling is also required, hydronic systems must be used. Other applications for which either electric or hydronic systems are suited include snow/ice melting for walks, driveways and landing pads, turf conditioning of football and soccer fields and frost prevention in freezers and skating rinks. A range of underfloor heating systems and designs are available to suit different types of flooring.

Thermal comfort and quality

Underfloor heating influences the radiant exchange by warming the interior surfaces. The heating of the surfaces suppresses body heat loss resulting in a perception of heating comfort. This general sensation of comfort is further enhanced through conduction (feet on floor) and through convection by the surface's influence on air density. Underfloor cooling works by absorbing both short wave and long wave radiation resulting in cool interior surfaces. These cool surfaces encourage the loss of body heat resulting in a perception of cooling comfort.

Indoor air quality

Underfloor heating can have a positive effect on the quality of indoor air by facilitating the choice of otherwise perceived cold flooring materials such as tile, slate, terrazzo and concrete. These masonry surfaces typically have very low VOC emissions (volatile organic compounds) in comparison to other flooring options. In conjunction with moisture control, floor heating also establishes temperature conditions that are less favorable in supporting mold, bacteria, viruses and dust mites. By removing the sensible heating load from the total HVAC (Heating, Ventilating, and Air Conditioning) load, ventilation, filtration and de-humidification of incoming air can be accomplished with dedicated outdoor air systems having less volumetric turnover to mitigate distribution of airborne contaminates. There is recognition from the medical community relating to the benefits of floor heating especially as it relates to allergens.

Energy costs

Under floor radiant systems are evaluated for sustainability through the principles of efficiency, entropy, exergy (available energy) and efficacy. When combined with high performance buildings, under floor systems operate with low temperatures in heating and high temperatures in cooling in the ranges found typically in geothermal and solar thermal systems. When coupled with these non combustible, renewable energy sources the sustainability benefits include reduction or elimination of combustion and greenhouse gases produced by boilers and power generation for heat pumps and chillers, as well as reduced demands for non renewables and greater inventories for future generations.

In short, underfloor heating and cooling systems are more comfortable and more efficient.