This issue consists of several articles. A cost-benefit analysis of concentrator photovoltaic technology use in South Africa: A case study investigates the economic efficiency of the implementation of concentrator photovoltaic (CPV) technology in the Tyefu area in the Eastern Cape, South Africa, as a means of addressing these problems. A possible design and justification for a biogas plant at Nyazura Adventist High School, Rusape, Zimbabwe was carried out to assess the biogas potential at Nyazura Adventist High School, Rusape, Zimbabwe, a co-educational school with a total enrolment of 700 boarders. The objectives of “Critical factors to be considered when planning the implementation of environmental improvements and energy saving” is to identify the critical success factors in the adoption of energy efficiency actions in Brazilian hospitals and describe their behaviour . Emissions analysis from combustion of eco-fuel briquettes for domestic applications investigates flue gas emissions from combustion of eco-fuel briquettes in a ceramic lined stove. Experimental study on natural convection greenhouse drying of papad reports on the convective heat transfer coefficients of papad for greenhouse drying under a natural convection mode. Dirt analysis on the performance of an engine cooling system looked at the effect of sand blocking the heat transfer area of the radiator and its effect on the engine coolant through the conduct of experiments. System and component modelling of a low temperature solar thermal energy conversion cycle looks at the conversion of low temperature solar thermal energy to electrical energy. Modelling influence of temperature on daily peak electricity demand in South Africa discusses the modelling of the influence of temperature on average daily electricity demand in South Africa. Performance analysis of an air humidifier integrated gas turbine with film air cooling of turbine blade investigates the effects of compressor pressure ratio, turbine inlet temperature, ambient relative humidity and ambient temperature on the performance parameters of an air cooled gas turbine cycle.