As an introduction to the current approaches to building's greening and sustainability this paper outlines the intrinsic harmony of the traditional village houses encompassing efficiency and balanced use of renewable materials and energy sources. Further paper reviews technical advances in integrating energy efficiency, solar and other renewable energy sources in new and existing buildings, to approach sustainable net Zero Energy Buildings, villages and cities. Paper stresses importance of the BPS (Building Performance Simulation) and Co-simulation in developing reliable method/engineering procedures for RES co-utilization and interwoven “energy mix” scenarios optimization, including existing buildings RES integrated refurbishment. Finally, presented are study results on the technical feasibility of efficient/cost-effective use of relatively low temperature geothermal waters for co- and tri-generation of electricity and heat for heating and/or cooling by absorption refrigeration for building integration. As a result of global warming a need for air-conditioning is in extreme growth in Central and Southeastern Europe, as well as in many other regions in the world rich in low temperature geothermal waters <100°C (<212°F), and there is a growing interest to utilize these waters in an efficient and cost effective way. It is well known that Kalina thermodynamic cycle can convert relatively low temperature energy, at relatively low temperature difference towards environment, to mechanical power and further to electricity using as a working fluid mixture comprised of at least two different components (water and ammonia). However, its co-generation efficiency at the heat source temperatures below and about 100°C is too low. That was the reason to explore technical possibilities to expand the low-temperature Kalina cycle's geo-water utilization for co- and tri-generation based on the co-utilization - hybridization of geothermal with solar or other renewable energy sources (RES).