Towards a Living Lab for Enhanced Thermal Comfort and Air Quality: Analyses of Standard Occupancy, Weather Extremes, and COVID-19 Pandemic

Maintaining indoor environmental (IEQ) quality is a key priority in educational buildings. However, most studies rely on outdoor measurements or evaluate limited spatial coverage and time periods that focus on standard occupancy and environmental conditions which makes it hard to establish causality and resilience limits. To address this, a fine-grained, low-cost, multi-parameter IOT sensor network was deployed to fully depict the spatial heterogeneity and temporal variability of environmental quality in an educational building in Sydney. The building was particularly selected as it represents a multi-use university facility that relies on passive ventilation strategies, and therefore suitable for establishing a living lab for integrating innovative IoT sensing technologies. IEQ analyses focused on 15 months of measurements, spanning standard occupancy of the building as well as the Black Summer bushfires in 2019, and the COVID-19 lockdown. The role of room characteristics, room use, season, weather extremes, and occupancy levels were disclosed via statistical analysis including mutual information analysis of linear and non-linear correlations and used to generate site-specific re-design guidelines. Overall, we found that 1) passive ventilation systems based on manual interventions are most likely associated with sub-optimum environmental quality and extreme variability linked to occupancy patterns, 2) normally closed environments tend to get very unhealthy under periods of extreme pollution and intermittent/protracted disuse, 3) the elevation and floor level in addition to room use were found to be significant conditional variables in determining heat and pollutants accumulation, presumably due to the synergy between local sources and vertical transport mechanisms. Most IEQ inefficiencies and health threats could be likely mitigated by implementing automated controls and smart logics to maintain adequate cross ventilation, prioritizing building airtightness improvement, and appropriate filtration techniques. This study supports the need for continuous and capillary monitoring of different occupied spaces in educational buildings to compensate for less perceivable threats, identify the room for improvement, and move towards healthy and future-proof learning environments

controlled inlet airflow in ventilated facades a numerical analysis

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Let's hear it from the cities:On the role of renewable energy in reaching climate neutrality in urban Europe

Renewable energy sources have emerged globally as a key lever to ensure energy security and to promote climate mitigation. Cities need to exploit this energy transition, but how they are building their strategies and actions is undetermined. A new dataset, collected through the European 100 Climate-Neutral and Smart Cities Mission, offers unique insights on the 362 cities which expressed the ambition to reach climate neutrality by 2030. Insights include their level of preparedness, ambition, capacity and the risks envisaged in the pursuit of zero-emission and greener futures. This study focuses in particular on the role of renewable energy across high greenhouse gas emitting sectors in cities (e.g. buildings, mobility, waste and industry). It analyses i) the status quo for renewable energy generation, consumption, and policymaking, ii) the key measures to enhance and upscale renewable energy deployment in the near future, and iii) how policies and relevant instruments will evolve to curb emissions and accelerate the energy transition. The insights that emerge from the analysis are discussed in relation to existing evidence, to inform future research strands and forms of assistance for cities. Overall, for cities to deliver on large renewable projects, efforts need to be intensified, barriers need to be lifted and multi-governance approaches must be operationalised.</p

On the cooling potential of elastocaloric devices for building ventilation

Refrigerants in vapor-compression systems have a global warming potential thousands of times that of carbon dioxide, yet their spread on the market is unrivalled. Elastocaloric systems, based on solid state cooling, feature among the most promising alternatives. In this paper, an elastocaloric device for air ventilation (ECV) composed by parallel and serial connection of multiple shape memory alloy (SMA) films, is investigated via volume-based finite difference simulation in MATLAB and dynamic building simulation in TRNSYS considering eight cities across the globe. The models assume experimentally demonstrated thermal parameters for the elastocaloric phase transformation around room temperature and a single-storey reference building. The ECV operates according to an optimized, energy-saving logic that includes load partialization and recirculation. Parametric analyses suggest that moderate terminal velocities (∼2 m/s) and a climate-specific design aimed at maximizing the use of the ECV device at nominal cooling capacity are key to reach building cooling needs reductions up to 70% in the considered scenarios. Partialization results in enhanced energy flexibility and conservation, whereas recirculation extends the ECV usability to extreme heat conditions. In absolute terms, the ECV works best under hot climates (e.g. Cairo, Dubai, Brisbane), with monthly cooling load reductions about 2/3-fold compared to cold locations (e.g. Milan, Hobart). The performance is extremely sensitive to the ventilation rate. Thermal zones requiring 1 to 2 air changes per hour are best suited. These findings provide initial insight into design criteria, opportunities and limitations on the use of elastocaloric devices for building ventilation to guide future experimental verification. © 2021 International Solar Energy Societ

Kurtosis of momentum and displacement distributions in biphenyl

We apply the method of moment expansion, in terms of standard deviation and kurtosis, to the nuclear momentum and displacement distributions of hydrogen in biphenyl. In particular, we present first-principles calculations and we compare them to deep inelastic neutron scattering experiments, for the nuclear momentum distribution, and to X-ray diffraction, for the displacement distribution, so as to investigate the degree of anisotropy of the single-particle local potential. We find that, in the spirit of the central limit theorem, as a function of the increasing number of vibrations affecting a nucleus, the nuclear displacement distribution becomes more isotropic, as was the case of the nuclear momentum distribution, yet the trend is not monotonic with two local maxima at 125 meV and 20 meV