Microclimate analysis and mitigation for enhancing energy and comfort performance of Near Zero Energy Settlements in Italy

The need for more sustainable and healthier cities is becoming increasingly urgent, as buildings represent a strong, growing source of GHG emissions and energy consumption worldwide. Urban population is also in continue expansion, so it is important to shift the focus from single-building to settlement scale, taking into account inter-building phenomena and moving towards more sustainable districts and cities. In this view, the present work proposes a multi-scale approach, by which outdoor microclimate optimization goes together with building thermal-energy assessment, applied in a residential near zero energy settlement in Italy. Both aspects are considered at different urban scales, starting with a single-building analysis and then progressively extending the field of action, to investigate how microclimate improvements implemented at district scale could result in major benefits in terms of urban heat island attenuation, human thermal comfort and buildings thermal-energy performance. Microclimate mitigation strategies, e.g. the increase of vegetation and the introduction of highly-reflective, permeable pavements and envelope materials, lead to a reduction of up to 13% on annual buildings energy consumption. This reduction rises by extending the mitigated area, reaching about 22% of buildings energy savings when microclimate improvements are applied in the whole settlement. This approach allows for an assessment of the optimal district size for ensuring better building energy performance and environmental quality.