Climate Mitigation and Adaptation Strategies for Roofs and Pavements. A Case Study at Sapienza University Campus

The progressively emerging concept of urban resilience to climate change highlights the importance of mitigation and adaptation measures, and the need to integrate urban climatology in the design process, in order to better understand the multiple effects of combined green and cool technologies for the transition to climate responsive and thermally comfortable urban open spaces. This study focuses the attention on selected mitigation and adaptation technologies; two renovation scenarios were designed and modeled according to the minimal intervention criterion. The study pays attention to the effect on surface temperature and physiological equivalent temperature (PET) of vegetation and high albedo materials characterizing the horizontal boundaries of the site. The Sapienza University campus, a historical site in Rome, is taken as a case study. These results highlight the importance of treed open spaces and the combination of permeable green pavements associated with cool roofs as the most effective strategy for the mitigation of summer heatwaves and the improvement of outdoor thermal comfort

Resilient cooling of buildings: state of the art review

Name of the research project : IEA Annex 80 – Resilient Cooling of Buildings Publisher: Institute of Building Research & Innovation ZT GmbH, AustriaThis report summarizes an assessment of current State-of-the Art resilient cooling strategies and technologies. It is a result of a collaborative work conducted by participants members of IEA EBC Annex 80. This report consists of four chapters. In the first chapter are included relevant technologies and strategies that contribute to reducing heat loads to people and indoor environments. These technologies/strategies include Advanced window/glazing and shading technologies, Cool envelope materials, Evaporative Envelope Surfaces, Ventilated Envelope Surfaces and Heat Storage and Release. In the second chapter are assessed cooling strategies and technologies that are responsible for removing sensible heat in indoor environments: Ventilative cooling, Evaporative Cooling, Compression refrigeration, Desiccant cooling system, Ground source cooling, Night sky radiative cooling and High-temperature cooling systems. In the third chapter various typologies of cooling strategies and technologies are assessed inside the framework of enhancing personal comfort apart from space cooling. This group of strategies/technologies comprise of: Vertical-axis ceiling fans and horizontal-axis wall fans (such fixed fans differ from pure PCS in that they may be operated under imposed central control or under group or individual control), Small desktop-scale fans or stand fans, Furnitureintegrated fan jets, Devices combining fans with misting/evaporative cooling, Cooled chairs, with convective/conductive cooled heat absorbing surfaces, Cooled desktop surfaces, Workstation micro-air-conditioning units, some including phase change material storage, Radiantly cooled panels (these are currently less for PCS than for room heat load extraction), Conductive wearables, Fan-ventilated clothing ensembles, Variable clothing insulation: flexible dress codes and variable porosity fabrics. In the fourth chapter technologies and strategies pertinent to removing latent heat from indoor environments are assessed. This group includes Desiccant dehumidification, Refrigeration dehumidification, Ventilation dehumidification, and Thermos-electric dehumidification.Preprin

Low-energy resilient cooling through geothermal heat dissipation and latent heat storage

Conventional passive cooling techniques provide limited benefits in extremely hot climates in southern Asia, characterised by high daytime and night temperatures and frequent climate-related disruptions, such as power cuts. This study proposes and demonstrates a novel low-energy and resilient cooling solution for extremely hot regions in southern Asia. The novelty lies in the combination of geothermal heat dissipation and latent heat storage, specifically designed for the particular conditions of extremely hot climates in Southern Asia; considering the influence of climate-related disruptions such as power cuts, whose frequency is increasing in the region; and using discomfort hours as an indicator to measure the passive survivability of buildings in the absence of air-conditioning (following the adaptive comfort model). A numerical model was developed in TRNSYS for optimal sizing and configuration of the phase change material (PCM) integrated into a ceiling panel using a typical multi-family building archetype in three climatic regions of Pakistan. A parametric numerical analysis was performed concerning different PCM melting temperatures, amount of PCM, convective heat transfer capacity, and equivalent thermal conductivity. Moreover, daytime was considered the period with a higher probability of power cuts. The results showed how integrating PCM-based ceiling panels with geothermal heat dissipation can mitigate discomfort hours by 28 % in extremely hot climates, 55 % in very hot climates, and 91 % in hot climate areas with intermittent access to electricity. Latent heat storage maximised the benefits of geothermal heat dissipation by extending thermal comfort periods by 13 % and 18 % in extremely hot and very hot climates compared to the scenario without PCM. This low-energy resilient cooling solution, integrating PCM as a cool battery, can keep the home cool for longer when electricity is unavailable. This study demonstrates the importance of considering the specific climate-related disruptions from these extremely hot regions in building design, such as extreme heat events or power cuts, to enhance the heat resilience capacity of cities

Heat mitigation strategies in winter and summer: Field measurements in temperate climates

Natural elements such as vegetation and water bodies may help reduce heat in urban spaces in summer or in hot climates. This effect, however, has rarely been studied during cold seasons. This paper briefly studies the effect of vegetation and water in summer and more comprehensively in winter. Both studies are done in courtyards on two university campuses in temperate climates. A scale model experiment with similar materials supports the previous studies. The summer study is done in Portland (OR), USA, and the winter study (along with the scale model) in Delft, the Netherlands. The summer study shows that a green courtyard at most has a 4.7 °C lower air temperature in the afternoon in comparison with a bare one. The winter study indicates that the air temperature above a green roof is higher than above a white gravel roof. It also shows that, although a ‘black’ courtyard has higher air temperatures for a few hours on sunny winter days, a courtyard with a water pond and with high amounts of thermal mass on the ground has a warmer and more constant air temperature in general. Both the summer and winter studies show that parks in cities have a lower and more constant air temperature compared to suburbs, both in summer and winter. The scale model also demonstrates that although grass has a lower albedo than the used gravel, it can provide a cooler environment in comparison with gravels and black roof

Thermal performance and energy savings of white and sedum-tray garden roof: A case study in a Chongqing office building

This study presents the experimental measurement of the energy consumption of three top-floor air-conditioned rooms in a typical office building in Chongqing, which is a mountainous city in the hot-summer and cold-winter zone of China, to examine the energy performance of white and sedum-tray garden roofs. The energy consumption of the three rooms was measured from September 2014 to September 2015 by monitoring the energy performance (temperature distributions of the roofs, evaporation, heat fluxes, and energy consumption) and indoor air temperature. The rooms had the same construction and appliances, except that one roof top was black, one was white, and one had a sedum-tray garden roof. This study references the International Performance Measurement and Verification Protocol (IPMVP) to calculate and compare the energy savings of the three kinds of roofs. The results indicate that the energy savings ratios of the rooms with the sedum-tray garden roof and with the white roof were 25.0% and 20.5%, respectively, as compared with the black-roofed room, in the summer; by contrast, the energy savings ratios were −9.9% and −2.7%, respectively, in the winter. Furthermore, Annual conditioning energy savings of white roof (3.9 kWh/m2) were 1.6 times the energy savings for the sedum-tray garden roof. It is evident that white roof is a preferable choice for office buildings in Chongqing. Additionally, The white roof had a reflectance of 0.58 after natural aging owing to the serious air pollution worsened its thermal performance, and the energy savings reduced by 0.033 kWh/m2·d. Evaporation was also identified to have a significant effect on the energy savings of the sedum-tray garden roof

Building in Historical Areas: Identity Values and Energy Performance of Innovative Massive Stone Envelopes with Reference to Traditional Building Solutions

The intrinsic nature of local rocks shaped the features of built heritage in historical centers. The resulting building culture is part of the cultural heritage itself, and must be considered when building in such areas, while it is essential to solve the issues related to traditional constructions’ weaknesses. Nonetheless, the potentialities of massive stone envelopes, particularly the importance of thermal inertia, have contributed to redefining the language of contemporary architectural culture. Nowadays, although the trend of employing thin stone cladding panels is prevalent, thick stone envelopes are gaining a renewed importance. Previous literature demonstrated that mixed building technologies or massive stone envelopes coupled with load-bearing framed structures are able to meet comfort and safety requirements and to guarantee the integration of new constructions in the consolidated urban landscape, avoiding historicist approaches. This research, through the analysis of case studies, aims to describe innovative building solutions developed by contemporary architectural culture, comparing them with traditional stone masonry walls. Moreover, thermal energy performance of such building solutions is assessed through dynamic yearly simulations. Results show that these solutions are technically and architecturally suitable to build in historical centers, because they can express urban cultural identity and guarantee good energy performance and users’ comfort

Passive cooling strategies to optimise sustainability and environmental ergonomics in Mediterranean schools based on a critical review

This article identifies and compares the passive cooling strategies used and their relationship to optimising sustainability and environmental ergonomics based on 47 case studies. The analysis of the schools has resulted in the identification of 20 passive strategies, eight parameters related to sustainability and six related to environmental ergonomics. The results show that the most used passive strategies are natural ventilation, green roofs, low thermal transmittance windows and solar shading. In contrast, the least used strategies are ventilated façades and evaporative cooling systems. In terms of sustainability, energy efficiency is present in most case studies; in contrast, the circular economy is hardly considered in schools. In terms of environmental ergonomics, thermal comfort is present in most case studies, while acoustic comfort is not assessed. Furthermore, the results show an absence of optimisation of acoustic and visual comfort, climate change adaptation measures and involvement of the educational community. This work provides a detailed understanding of the status quo for researchers, practitioners and policymakers and predicts the dynamic directions of the field. It highlights the need to incorporate passive design protocols explicitly applied to schools to achieve a sustainable and climate-resilient educational building stock within the principles of the circular economy.Spanish Ministry of Universities - European UnionUniversity of GranadaAndalusian Government POST-DOC_21_00575 FEDER-US-15547Eco-efficiency in educational centres: Innovation, Rehabilitation and regeneration" within ERDF US.20-0