After the 24^th international conference Interklima 2017, this is the second consecutive special issue of the JSDEWES bringing together the selected papers presented at the 25^th conference Interklima 2019, held in Zagreb on April 11-12, 2019. The organizers were the Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia, SDEWES Centre, Zagreb, Croatia and Faculty of Energy Technology, University of Maribor, Slovenia.

Held since 1969, Interklima is the oldest conference of its kind in this part of Europe. Over years it has grown into an international venue for meetings of scientists and experts in the field of heating, refrigeration, air conditioning, and, generally, energy conversion in buildings and industry.

Co-organized by two Universities and supported by the relevant international scientific organizations and journals, Interklima 2019 brought many new and actual topics:

• Nearly zero energy buildings;

• Smart building technologies;

• Advances in EU regulation (EPBD, EED, RES, F-Gas, ErP);

• Low GWP refrigerants;

• Cooling from renewable sources;

• Energy from waste biomass;

• Phase change materials in buildings;

• Smart meters/cities.

Interklima 2019 was composed of two sections:

• Energy efficient buildings and renewable energy sources;

• Fran Bošnjaković Day.

The papers published in this special issue were carefully selected among the presented papers at the section ‘Fran Bošnjaković Day’ and thoroughly revised before they were accepted for publication.

Prof. Damir Dović

Faculty of Mechanical Engineering and Naval Architecture

University of Zagreb, Croatia