Marco António Pedrosa Santos Ferreira

Comparing cost-optimal and net-zero energy targets in building retrofit

The recast of the European Unions Energy Performance of Buildings Directive introduced the concept of nearly zero-energy buildings, requiring its adoption from 2021 by all new buildings and existing ones submitted to major renovations. European Union member states must also ensure minimum energy requirements for buildings in order to achieve cost-optimal levels during their life cycle. Cost optimality and nearly zero-energy buildings are important concepts in European Union energy policies. These concepts are related, but one is more focused on costs, while the other is more concerned with low energy consumption and on site-renewable energy harvesting. If these approaches result in major differences in the selection of the best package of retrofit measures, then the transition from the cost-optimal concept to nearly zero-energy buildings might be problematic. To assess the most cost-effective solutions to achieve net-zero, a building in Porto, Portugal, was analysed. This determined not only the most cost-effective retrofit solutions but also compared these net-zero solutions with those resulting from the cost-optimal calculation. Both approaches lead to similar results, indicating that the transition between ‘cost optimality’ to ‘nearly zero-energy buildings’ could occur in Portugal.

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 ...

Life-cycle costs and impacts on energy-related building renovation assessments

AbstractMany regulations and initiatives to promote the reduction of energy consumption and carbon emissions have been implemented in the building sector. However, they are mostly targeted at new buildings. In order to reach the goals that are being established, while it is necessary to implement measures in new buildings, this is doubly the case for existing buildings, which correspond to the majority of the European building stock. Building renovation improves buildings’ energy performance and reduces the carbon emissions related to the operation of the building, but this involves adding new materials and technical systems. The production process of these new materials uses energy (embodied energy) and releases carbon emissions. In this sense, to evaluate the relevance of the embodied energy in building renovation, the International Energy Agency Energy in Buildings and Communities (IEA EBC) project, Annex 56, developed a methodological framework to evaluate the cost-effectiveness of building renovation...