According to the Latvian Law on State Secrets, unclassified buildings include such non-residential buildings as penal institutions, prisons and detention centres, buildings of the armed forces, police and fire services and barracks of these institutions, as well as auxiliary buildings and rooms in auxiliary premises. The buildings of the armed forces as well as police and fire services have been investigated in the Thesis. The aim of the Thesis is to develop a methodology for determining the energy efficiency of unclassified buildings, guidelines for the technical survey of unclassified buildings, the main emphasis of which is on the development of unified renovation and energy supply solutions which will ensure high quality of work and minimize the number of people involved in the renovation process of buildings in order to achieve and propose possible improvements for reducing energy consumption.