Thesis devoted to the development of the approaches to estimate the energy efficiency of the national economy. The bibliometric and trends analysis allowed identifying and explain the interest's change in the issues of energy efficiency of the national economy, the main evolution stages of the energy efficiency theory, clustering of international scientific alliances and directions of interdisciplinary energy efficiency research in the context of national economy transition to carbon-neutral model.
The government energy policy should base on the targets of carbon-neutral development of the national economy. Energy efficiency is a balance between indicators of the energy sector development at which availability, reliability, economy, and ecological friendliness of energy resources were provided to reach stable rates of the national economic growth and increase competitiveness and satisfaction of society's needs.
The economic, environmental, and energy parameters of the national economy's energy efficiency, which were based on targets and indicators of the carbon-neutral model of economic development, were directly and indirectly affected by institutional, social information, regulatory, investment, and innovation determinants. Their synergetic impact should be taken into account under determining the principles, mechanisms and tools for implementing the state policy of energy efficiency increasing. The principles of government regulation for enhancing energy efficiency was extended by the principles of: dissemination and diffusion; consistency and synchronicity; convergence. These principles should be considered under development of government instrument enhancing energy efficiency (mechanism for assessing, forecasting and monitoring the energy efficiency, its convergent and divergent components, determining the asynchrony of Ukraine's state policy with the European on enhancing energy efficiency).
The approaches for energy efficiency estimation proposed to classify depending on the core criteria that explain the energy sector development conditions. It allowed identifying: dynamic-comparative, statistical-interval, and integral-additive approaches. The methodological tools for identifying the asynchrony and speed of response of Ukrainian energy policy to exogenous and endogenous changes in the national economy was developed. It was based on the σ- and β-convergences considering the trend component of energy, environmental and economic parameters. It allowed justifying the divergent and convergent factors of energy efficiency, taking into account the level of economic development, openness, and globalization process.
Under the estimation of the energy efficiency index, the fluctuation of stimulators/disincentives of energy efficiency, the dynamics of the energy sector development, convergent and divergent determinants should be considered. The findings showed that in 2008 the integrated energy efficiency index was 0.628 points (corresponds to the average level), and in 2016 – 0.594 points (the lowest level). It was provoked by military and political instability in the country, the transformation of the world model development from export-raw materials to resource-innovation, and changing the structure of the energy balance to increase the share of green energy.
The balance between the convergent and divergent sub-indices of energy efficiency allowed ensuring the energy efficiency index growth. It was empirically substantiated that the government's priority actions should increase the divergent parameters of the energy efficiency index. The results of the forecasting of the level of divergent parameters of the energy efficiency index until 2030 (using the Braun model) confirmed that under the optimistic scenario, its growth to the level of the convergent component in 2020 takes more than ten years.
The findings proved the among the governance efficiency indicators, the following indicators had the most impact on the divergent parameters of energy efficiency for Ukraine: the rule of law, the government's ability to implement policies and regulatory measures openly, and control corruption.
The findings of the mutual influence of statistically significant indicators (the rule of law, government's ability to openly implement policies and regulatory measures, corruption control), green investment and innovation in the energy sector on the divergent parameters of energy efficiency for EU and Ukrainian panel data during 2000–2020 showed that effective state regulation in the EU countries led to increasing in energy efficiency by an average of 15 % and increasing of 1 % in green investment and innovation in the energy sector by 2 % and 4 %, respectively. The inefficiency of the green investment market in Ukraine restrict the multiplier effect of the diffusion of green innovations and investments in the energy sector.
