Whenever winter is around the corner, seasonal illnesses follow right behind.However, most Korean families have no such worries. This typical apartment in Korea has something that lets the entire family relax without wearing any socks. How can their feet be warm in cold weather[Interview : Kim Jun-yeong, Local resident] "The heating system in a typical Korean residence evenly distributes heat through the floor in every room, therefore eliminating the need for a separate heating device."It's none other than the ondol [온돌], or Korean traditional heating system! Ondol works by heating the floor of a residence, and it is found in most apartments and houses in Korea. The modern ondol system works by funneling hot water through pipes which heats the floor.Ondol has a 2000-year-long history. The traditional system involves lighting a fire in a furnace, and funneling the smoke underneath the floor.[Interview : Kim June-bong, ChairmanInternational Society of Ondol] "Since the floor is warm, the rooms are pleasant to be in despite low indoor temperatures, saving energy. Moreover, ondol offers health benefits by keeping the feet warm and head cool."Today, ondol is no longer only incorporated into floors.This family gathers together on a special type of sofa on cold days. What kind of sofa is this[Interview : ] "It's as warm as the floor."[Interview : Lee Jeong-rye, Local resident] "This is an ondol sofa. It's as warm as a traditional ondol floor."This ondol sofa may look like your everyday sofa, but it can warm up to 50 degrees Celsius, warming up anyone who sits on it.Besides sofas, the ondol system has been incorporated into other pieces of furniture. This company produces ondol beds, and the combination of a Western-style bed with Korean traditional heating elements is a major hit.[Interview : Park Eun-gyeong, Customer] "Ondol is great in the winter. Women like to keep warm, and we especially like to frequent a jjimjilbang, or dry sauna. So, I'm here to take a look at some ondol beds."The ondol sofa and bed work by artificially heating natural rocks contained in the furniture.The warming properties of the ondol furniture are popular not only in Korea, but also China, Japan, the United States and other countries.[Interview : Choi Chang-hwan, CEOOndol bed manufacturer] "Ondol beds are now being exported to many countries, and they are particularly popular in China. We also have branches in Finland and the United States, and we are enjoying excellent sales there."This company in Pyeongtaek, Gyeonggi Province introduces ondol in a softer presentation, suitable for those who aren’t accustomed to the original form of ondol which comes in hard floors.[Interview : Baek Gyeong-hui, Department headOndol bed manufacturer] "Our products were used during the G20 Seoul Summit, and they are also being used in Cheong Wa Dae."This form of soft ondol is popular among foreigners. In fact, it proved to be immensely popular with the first ladies of the G20 member states.[Interview : Baek Gyeong-hui, Department headOndol bed manufacturer] "Traditional ondol features lumps of coal underneath flat stones.These coal lumps emit plenty of far-infrared radiation which stimulates blood circulation. We are developing a type of mat that adapts the far-infrared radiation-emitting properties of coal into carbon heaters, so that there are no emissions of electromagnetic waves."While modern ondol differs from traditional ondol, research to maintain the properties and features of the latter is ongoing.As the effects of ondol becomes more well-known around the world, other countries are showing interest and adopting it. Some of the newest buildings in European countries like Germany or Switzerland are incorporating ondol-style heating.[Interview : Thomas Schretter, Ondol userGermany] "You could say this heating system more efficiently uses energy and preserves the environment. Since it limits carbon dioxide emissions, it should be much better for our kids in the future. It may be a while before I have grandchildren, but I am sure they'll be pleased that we took these measures to preserve the environment for them."Ondol is becoming an integral heating system around the world.Currently, a Korean research team is leading efforts to create a global standard for ondol, and Korean companies are creating a variety of products that incorporate ondol.[Interview : Kang Jae-sik, ResearcherKorea Institute of Construction Technology] "We are very familiar with ondol, use it conveniently, and find it everywhere. Based on its level of distribution and potential for technological advancement, I believe it's a technology that can be pushed to the front of the Korean construction field as a national brand."Ondol is a traditional heating system that has maintained a 2000-year-long history.2011 marks the year ondol becomes integral in more than just household heating.Ondol is now part of a global culture.[STUDIO]This is one feature that many expats simply love about Korea.It's so comforting and inviting when the ondol is on.And I'm sure it's no surprise that other countries are adopting this system as well and are also going to enjoy a warm winter this year thanks to the ondol.