Created by T H E U N S E E N, a material craft and innovation studio which started life at Somerset House, the Choropleth flag uses a chromic colour change compound developed by T H E U N S E E N, which reacts in real-time to ultraviolet (UV) radiation. The depletion of the ozone layer over London, due in large part to the capital’s congested roads and continual construction, leads to astronomical amounts of greenhouse gases being emitted into the environment. This allows excessive amounts of UV radiation to unwittingly reach people on the city’s streets.
Taking the form of the Union Jack, the flag’s iconic colours transforms in real time according to radiation exposure levels in central London, turning the invisible visible. When the red, white and blue of the Union Jack is more vivid, UV radiation exposure - caused by harmful human-made emissions - is low in the area surrounding Somerset House. However when the Union Jack becomes monochrome, the levels of exposure are higher.
Up close, the Choropleth flag also reveals a street map of London superimposed onto the Union Jack, highlighting the issue from its very source.
In 2016, Somerset House initiated a series of commissions with artists to design its iconic flag, flying over its famous courtyard, with former flag artists including Jeremy Deller and Somerset House Studios artist Larry Achiampong. This significant commission provides access to free public art for audiences from multiple vantage points across London.