On 16th May 2017, SIST hosted the meeting of working group CEN/TC 88/WG 5 in Ljubljana. The work of this European technical group which deals with Rigid cellular polystyrene (extruded) is covered by the Slovenian national technical body SIST/TC TOP Thermal insulation. The Slovenian technical committee is chaired by Mr. Matjaž Zupan, who has been convenor of the work group CEN/TC 88/WG 5 since 2016. The meeting was attended by ten experts, representatives from Germany, Finland, France, Austria, Spain and Slovenia, who discussed the future of standards covering requirements for extruded polystyrene.