Modern requirements for the environmental friendliness of residential buildings, the strengthening of the role of corporate reporting in terms of reflecting "green" investments, as well as the need to increase transparency in management decisions make it relevant to use methods that take into account environmental and economic parameters at the same time. The theoretical basis of the study is the methods of life cycle assessment – LCA (Life Cycle Assessment) and LCC (Life Cycle Lost), which determine, respectively, the cumulative environmental impact and the total costs of the object's life cycle. Based on the analysis of their capabilities and limitations, the integral life cycle coefficient LCA-LCC Index is proposed, which is an author's methodological tool that combines environmental and economic indicators into a single assessment system. The developed coefficient takes into account the total costs of construction, operation and disposal of the building, as well as environmental effects in the form of cumulative greenhouse gas emissions over the entire life cycle. The calculation methodology provides for the normalization of indicators, the establishment of weighting coefficients and the possibility of adaptation to various types of residential projects. The practical approbation was carried out using the example of a typical apartment building, which made it possible to demonstrate the applicability of the index for a comparative assessment of alternative "green" solutions. The results show that the use of the LCA-LCC Index increases the objectivity and validity of the choice of energy-efficient and environmentally oriented measures. The proposed approach has a scientific novelty, as it systematically combines environmental and economic components through a single integral indicator. The practical significance lies in the possibility of using the developed index in corporate reporting of developers, in planning and monitoring "green" investments, as well as in shaping a sustainable development strategy at the level of construction companies.