The Thermal Spring, Taff’s Well Park, is Wales’s only thermal spring and is the smallest in the world. It's over 5,000 years old.
The event will take place in Taff’s Well Park, which has been a Green Flag Park for over four years.
Gareth Farr, who has written a book about the Thermal Spring, will be there to talk about the Thermal Spring and about recovering heat from buildings.
Directions - There's a bus service and train service to Taff's Well, and there are car parking places with an overspill car park. There are also disabled car parking spaces available.