The authors of the paper present a methodological approach for combining environmental and energy life cycle assessments of building energy refurbishments towards a nearly zero-energy building. The authors applied the proposed approach to a case study and examined several energy class renovation scenarios. Specific life cycle indicators and paybacks were calculated for all scenarios. The paper analyses the efficiency of insulation of the external envelope of a building (the external wall, floor on the ground and the roof) in terms of 2E efficiency criteria (energy - non-renewable primary energy consumption and ecology - CO2 gas emissions), focusing on different thermal insulation materials. The life cycle assessment method was applied to analyse the environmental performance of building envelope insulation. Primary energy consumption and CO2 gas emissions when insulating the envelopes to change their energy efficiency class from F to B and from B to A++ were determined. The paper also presents a graphical interpretation of primary energy savings and CO2 gas emissions over a period of 60 years as well as identifies thermal insulation materials that are the most reasonable for building insulation in terms of energy and ecology. (C) 2018 Elsevier B.V. All rights reserved.