Assessing the extent of evidence available relating to the impact of solar energy for households (HHs) in developing countries, surveys are reviewed focusing on the impact of pico‐photovoltaic (e.g., solar lanterns) or solar home systems (SHS) on rural HHs and directly related economic activities of their occupiers. Ninety‐eight documents have been analyzed. Areas of enquiry have included the impact of small individual solar photovoltaic systems on different facets of the life of HHs' occupiers: their education, health, finance, livelihoods, and social relations.

Around the world, engineers, architects and policymakers have been exploring ways to deliver highly efficient buildings whose reduced energy demand is satisfied by clean, renewable energy. Building off of the broader concept of a green or sustainable building, the concept of the “net zero building” focuses on the energy dynamics and performance of the building. And as policymakers and leaders align toward the net zero concept, the focus on achieving deep energy efficiency has centered on integrated technologies as well as ways to connect buildings to the natural environment.

This study presents three cost-optimal calculations. The overall aim is to provide a deeper analysis and to provide additional guidance on how to properly implement the cost-optimality methodology in Member States. Without proper guidance and lessons from exemplary case studies using realistic input data (reflecting the likely future development), there is a risk that the cost-optimal methodology may be implemented at suboptimal levels.