Energy technologies and energy management strategies has been gaining attention in the last decade as energy is vital for a safer and sustainable future. Dependency on energy is much higher than the past due to the industrial growth, increasing population as well as the comfort demand. However, recognising that global energy demand is rising but the world can burn only 20% its established fossil fuel reserves by 2050 if global warming is not to exceed 2°C represents a major threat to the future of all humans (Berners-Lee and Clark, 2013). The present rate of fossil consumption means that this will be achieved by ~2030. Yet domestic sector is count as the leading energy consumer as more people around the world aspire to comfort living standards which will drive the demand for air conditioning and electric power. Urgent solutions are required not only to increase share of renewable resources but also more efficient usage of fossil fuels which could be achieved with innovative power, air conditioning and refrigeration cycles utilising “Long term sustainable” (LTS) fluids, especially air, water and CO2. In the paper we provide a rational approach to the future use of working fluids based on our interpretation of the available technical evidence. We consider it self-evident that volatile fluids will continue to play major role in cooling and power generation, however new technologies will be needed that optimise energy efficiency and safety with minimum environmental impact. Concordantly we discuss the past and current situation of volatile fluids and look at four innovative technologies for future, using natural refrigerants including dew point cooling, combined heat and power generation, heat networks and heat storage systems.