Underfloor Electric Heating Systems

Underfloor Heating Systems, sometimes referred to as the acronym UFH (underfloor heating), are systems or methods used to produce a heat source for either whole buildings or localized floors. This form of central heating and cooling is unique to other methods in its practicality, aesthetic potential, and functionality. Underfloor heating systems achieve indoor thermal control through the primary processes of conduction, radiation, and convection.  This thermal control is generally obtained in modern times by either an electrical (“dry”) or hydroponic (“wet”) system. Electrical systems utilize electrical resistance elements to heat the flooring of a building whereas hydroponic systems involve the flowing of warm water through a piping system for the heating of the designated flooring.

As we see modern implications and improvements of underfloor heating systems, it is important to note that similar methods have been used throughout history to provide thermal control for living spaces. The Korean method of underfloor heating systems, known as either “Ondor” or “Gudeul”, is proposed as the earliest archaeological evidence of such indoor thermal control systems. An archaeological find discovered in UnggiHamgyeonbuk-do in present day North Korea that dates to around the Bronze Age, or roughly 1000 B.C., suggests evidence of the existence of gudeul in an excavated ancient building. 

More evidence provided by excavated prehistoric artifacts dating to around the Iron Age, or the 2nd century, as well as wall paintings found at Goguryeo, solidify footprints in history of Korea’s use of floor heating methods spanning across thousands of years. Initially, these ondor systems heated only parts of individual rooms. Later developments in the methodology used brought about the first systems to heat an entire room, originating in the mid thirteenth century during the Goryeo dynasty. Widespread usage of these systems throughout the Korean peninsula was seen during the early Joseon Dynasty, during the fifteenth and sixteenth centuries.

In ancient ondol systems, a critical component was the “gorae”, or the area under the floor that allowed the passage of smoke from the heated stones. Above the gorae were wide, flat stones called gudeul, which literally translates to “baked stones”. On top of this layer of gudeul was a layer of red mud clay. This layer of red mud clay served to prevent seepage or spillage of the smoke beneath the heated stone. The whole process can be described as the following: a fire was lit in the fireplace, and from this fireplace the fire and hot smoke traveled through the gorae located under the rooms, raising the temperature of the floor and in return the room itself, before exiting at a chimney near the end of the system. The traveling heated smoke provided conduction through the heated stones, or gideul, and from there radiated heat into the room through the convection of air. The traditional heat source in these Korean ondol systems was a fireplace, usually located either in the kitchen or the outside wall of the living room. If located in the kitchen, the fire used for cooking could be utilized for heating the floor as well. In this setup, the kitchen would be built two or three feet lower than the surrounding adjacent rooms, allowing for easier travelling of the heated smoke. Essentially, this method would kill two birds with one stone.

The ancient Romans were also known to use a similar method of central heating and cooling. This method was named hypocaust (hypo meaning “under”, caust meaning “burnt”), and was used for heating bathing water, houses, and other public or private buildings. The floor of these Roman buildings was raised above the ground by pillars, called “pilae stacks”. Above the pilae stacks was a layer of tile, then concrete, and finally a second layer of tile on top. Spaces were left inside the walls to allow hot air and smoke from the furnace to pass through. From the spaces in the walls, the heated air would then travel towards the roof where it would exit through flues, or ducts constructed specifically for smoke produced by a fire. Also in the walls were ceramic box tiles, serving the purpose of providing a medium to transfer heat into the room as well as aiding in the disposal of smoke. This Roman method of indoor climate control was not as efficient as the Korean ondol system, and has even been referred to as “labour intensive”; the hypocaust would need to constantly be monitored to tend to the needs of the fire.

Roman architect Vitruvius explains the design and construction of hypocausts in his work De Architectura, a piece originating at about 15 BCE. In his book, Vitruvius explained an idea in which the Korean ondol method already utilized; increased efficiency in heat and fuel consumption could be achieved by placing the heated rooms adjacent to each other. Vitruvius is also cited as suggesting a temperature control system by using a bronze ventilation device at the top of the domed ceiling in the hypocaust structures.

The invention of the hypocaust was primarily used in Roman culture for public bathhouses. Placing a pool of water near the heat source, providing both warm air for the building and steam for cleaning, brought about public sauna rooms for the Romans. However, with the decline of the Roman Empire the hypocaust faded into disuse.

In the early 1900s, American architect Frank Lloyd Wright was constructing the Imperial Hotel in Japan when a Japanese nobleman invited Wright to visit his house. Once there, Wright found a room that differed from the other rooms in this man’s house; Wright had stumbled upon a Korean ondol room. The Japanese man had once visited Korea, where he experienced first hand the comforts of ondol and decided to have a similar system implemented into his own house. Impressed by the comfort of being heated from below, Wright decided that underfloor heating systems were the ideal method of indoor climate control. This led him to the creation of radiant floor heating, the method of running hot water through pipes rather than hot air through flues. Wright began implementing these systems into his own buildings, and the rest is history.

There are many benefits to installing underfloor heating systems in your building or home. In regards to hydroponic systems, the underfloor heating component can easily be combined with the heat pumps that produce your warm water for showering and bathing. This is an efficient way to save energy and provide constant, controlled heat. With electric underfloor heating systems there is no required maintenance. If installed correctly, little can go wrong, proving heating that is highly reliable and predictable. Furthermore, underfloor heating systems can arguably provide more comfort for your rooms. The idea is that, unlike conventional heat sources such as radiators, underfloor heating systems provide more radiant heat as opposed to convective. Instead of warm air being localized in a room, it will be rising at a constant temperature throughout the whole surface of the floor. This also means that your feet will be warm and your head cool, ideal for comfort. This explains the Korean culture of sitting, eating, and sleeping on the floor. The implementation of underfloor heating systems also means that you have an interrupted space when designing your rooms; no radiator is present to consume wall space and restrict your furniture layout. With modern technology, it is also possible to provide a customized indoor thermal control experience. Instead of the conventional single thermostat used in traditional central heating systems, it is possible to have programmable thermostats in every room to allow individual control of each space. Underfloor heating systems also provide a safer environment for small children and others by removing the possibility of being burnt. It is also worth noting that these systems can aid in the quality of life by producing less airborne dust and debris; a feature that greatly protects sufferers of asthma and allergies.

Focusing on electric underfloor heating, it is important to note that this method can only heat. If you require both heating and cooling, a hydronic fluid based system must be used. Electric underfloor heating is achieved through the usage of non-corrosive and flexible heating elements. These come as cables, sometimes pre-spaced on mesh mats or carbon films. Electric UFH systems are typically installed under floor finishes such as ceramic, porcelain and stone tiles, engineered wood, and laminate floors. These systems can also utilize time-of-use electricity metering to ensure peak operating efficiency. Installation is generally easier than hydronic systems, proving to be a better solution during house renovation through easier installation and a lower price.

Click HERE  to view the electric underfloor heating range from Total Tiles.

Do-it-yourself kits are very popular amongst the electric underfloor heating product line, as most of the work can be carried out by a competent DIY person with only the thermostat connections needing to be completed by a qualified electrician. One of the most popular products in this area is the “underfloor heating mat”, an electrical heating element pre-installed on a self-adhesive mat that is simply rolled out for easy installation. To install such a system, you should first consider the power source in which the electric system will be connected to. Areas of up to 20m2 of 150W/m2 heating and 16m2 of 200W/m2 heating can be supplied by a single fused spur taken from a ring main. Larger areas should either be split into separate zones, each with its own thermostat or a dedicated circuit installed with a contactor switch which converts the thermostat into a secondary switching device. All electric floor heating systems must be protected with a 30mA RCD. The next step is to calculate what size heat mat to buy. The area of any furniture should be subtracted from the room size along with a further 10% deduction for the space around the edge. Note that you can safely cut the mesh mat, but never the wiring itself. Some mats are completely self-adhesive whereas some are secured to the floor with strips of double-sided tape. To install, the mat is rolled out from the thermostat point along or across the room. When the opposite wall or obstacle is reached, the mesh of the mat is cut (taking care not to cut the wire) the mat turned round either90ºor 180º and then rolled back the other way. This is then repeated until the whole room is covered. The mat can even be cut into single strips of wire so any shaped room can be covered. Don’t forget to install the floor temperature sensor which normally comes with the thermostat and always follow the specific instructions that come with the UFH kit.

Underfloor heating systems have been, and still remain to be steadily growing in their usage, especially throughout the UK and other European countries. AMA research published its seventh edition of a report titled, “Underfloor Heating Market Report – UK 2014-2018 Analysis.” In this around 50 companies were surveyed to gather information about the current market. In 2013, underfloor heating systems accounted for about 6 percent of the total heating market, and were valued at roughly £97 million at manufacturers selling prices. The research predicts that by 2018, this heating niche will grow in value to about £120 million at MSP. This increase would be about 25 percent through a 5-year span, proving the growth of the underfloor heating market. The main findings of the research done by AMA prove to be positive and in favor in regards to market trends. Higher quality and increased amounts of insulation, influenced by tighter restrictions and requirements, is contributing toward the effectiveness of underfloor heating systems. This new practicality and usefulness may be reflected through future market growth. Also, an increase in renewable energy efforts to reach UK government energy targets and carbon savings show promise for the market as well. Furthermore, an increase in the availability of quality DIY installation kits has been an effective boost to the sales of underfloor heating systems. The research report also suggests that with the modern use of tiles in non-traditional locations such as living areas spreading to the UK from our European neighbours, underfloor heating systems will prove to be great energy savers for consumers as this is their ideal setup. It is worth noting that the report also suggests that imports still contribute a significant portion to the underfloor heating systems sold throughout the UK. This may lead to high price competition and inhibit value growth in the long run.

Underfloor heating systems, whether electric or hydronic, have been tested and developed methods of achieving indoor climate control for thousands of years. Modern innovation and technology has provided great growth amongst the usage of these methods. These implemented systems provide great benefits to those who utilize them, such as greater comfort, more space, less airborne dust and debris, greater temperature customization, and consistent radiant heat throughout whole houses or individual floors. Underfloor heating systems have a lot to offer, and should be seriously considered when deciding which heating system to use in your home or building.