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During the 1980’s, Trond Dahlsveen was active in the energy efficiency market in Norway. In addition to manage development and implementation of several energy efficiency projects in the building sector, he was involved in developing Norwegian building codes, standards, norms, methods and tools, and performed a number of training programmes.

In the position as president of the Norwegian HVAC Association he met colleagues from a number of countries, and learned about the situation in building sector in Central and Eastern Europe. Although high theoretical skills, they were lacking knowledge and experience in how to develop and implement energy efficiency projects. Then the idea of offering capacity building programmes based on Norwegian methods, tools and experience were born.

The first project on “Energy Auditing of Buildings” was financed by the Norwegian Ministry of the Environment in 1991, and successfully implemented together with the Technical University in Bratislava.

There was a great interest in the Norwegian methods, tools and know-how, and in 1992 Trond Dahlsveen established ENSI - Energy Saving International. Since then, ENSI has conducted projects in 35 different countries, most of them in Central and Eastern Europe and the CIS.

During the first years of operation, the main focus was on energy auditing and management in the building sector. In 1996, the first “Financial Engineering” programme was implemented in Hungary, together with UN Economic Commission for Europe. Later ENSI started to implement capacity building programmes on “Energy Efficiency and Cleaner Production in Industry” and “Municipal Energy Efficiency Planning”.

In several countries ENSI has supported establishing and development of local Energy Efficiency Centres, and supported them in order to become self financed through offering professional services in their local market. In the recent years, ENSI also has provided guidance and support to authorities in developing new sub laws, regulations and standards related to energy efficiency in the building sector, incl. EU harmonization.

During the first 15 years, all projects were implemented in Central and Eastern Europe and the CIS. In 2007 the first project was launched in China, Vietnam in 2012, and countries in yet new continents will be added to the list of references in the near future.


In 2015, ENSI became part of the NIRAS Group.