Cost optimality and net-zero energy in the renovation of Portuguese residential building stock – Rainha Dona Leonor neighbourhood case study

Cost optimality and nearly-zero energy buildings are two fundamental concepts within the current European Union policy related to the energy performance of buildings and consequently related to climate change mitigation and non-renewable resources consumption. While cost optimality is mainly focused on costs, nearly-zero energy buildings are focused on low energy consumption levels and on-site renewables harvesting.Using a residential building from a social housing neighbourhood, this study investigates the most cost-effective packages of renovation measures to achieve a zero energy balance building and compares these packages with those resulting from the calculation of cost-optimal levels. The investigation on the trade-offs between both approaches is relevant to achieve a smooth transition from cost-optimal levels to nearly-zero energy buildings.The results show that the measures that lead to the cost-optimal levels are very similar to the ones needed to achieve the zero energy balance and the results ...