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Transparent PV (TPV) layers allow solar energy exploitation across the thermal, daylighting, and energy conversion domains. However, the current power conversion efficiency (PCE) and visible transmittance (VT) features of such systems may hinder the effectiveness of such solutions when the global performance of the building envelope is considered. In this study we assessed, from a multi-domain perspective, if the performance of façade configurations based on commercially available TPV layers can compete with the performance of façade configurations based on more conventional (opaque) PV solutions. The outcome of this research is thus, on the one hand, a better, evidence-based understanding of the current performance levels of this technology – whether it is mature enough for successful uptake, and which applications are the most relevant – and on the other hand, evidence-based recommendations for product development paths to make TPV systems more competitive for a wider range of applications. In this simulation study we employed a simple room with standardised user patterns and requirements, and repeated the analysis in multiple European climates, to make our results as generic as possible. We carried out the analysis by computing and comparing the performance across the three different domains (total energy use, daylighting, and energy conversion), thanks to a co-simulation environment, of south-facing façade configurations with different TPV or opaque BIPV solutions, which were parametrically changed in terms of window-to-wall ratio, glazing type, and BIPV system. The results showed that TPV systems provided global performance levels that were, in a large range of cases, worse than those of other façade configurations integrating only opaque PV layers and conventional glazing. The trade-off between solar/visual transmittance and absorptance, necessary to ensure a certain PV conversion output in TPV layers, led to a worse global (multi-domain) performance in all the investigated climates. When a fully glazed façade is an absolute design requirement, TPV-based façades can give a better total energy performance than solutions without any PV conversion feature, while providing acceptable daylighting exploitation. However, these envelope solutions showed a worse performance compared to other configurations with a better, more balanced window-to-wall ratio, with BIPV only on opaque surfaces. Accordingly, these findings have implications for both recommended applications of today’s TPV systems and technology development directions. Current TPV systems may be suitable for large, glazed surfaces (such as atria or roofs above circulation spaces) where visual performance requirements are less tight than in office or dwelling settings. TPV solutions can become more competitive for broader façade applications if a PCE of at least 3 times the current value is achieved without reducing the VT. Increasing the VT while keeping the current PCE could also be a suitable research trajectory to enable TPV systems that provide a better balance in solar energy exploitation. Combining a TPV with more advanced glazing solutions (e.g., vacuum insulation or thin-glass glazing) can, however, only marginally expand the range of usability of these systems.

Personal comfort systems (PCS) that warm or cool local body parts promise individual thermal comfort, energy saving and (metabolic) health in non-neutral thermal environments. However, research on work performance while using a PCS is scarce. We previously tested a PCS that warms the extremities and cools the head and reported that the PCS improved thermal comfort during a ramp of 17-23C but did not at a stable temperature of 25C. In the current study, its effects on cognitive performance, subjective measures and task-induced heart rate measures are investigated. Eighteen participants completed two randomized, eight-hour-long dynamic office scenarios: one is PCS scenario and another one is without PCS scenario. The results show warming the extremities slightly slowed reaction time for a simple task at 19C (p < 0.05) whereas it exerted no effect on complex task performance in 17-21t. At 25C however, cooling the head improved complex task performance (p = 0.053), which derived from participants' effort increase, whereas it did not affect simple task performance. These findings suggest that the PCS' effects on cogni-tive performance depended on the task type. Cooling the head, independent from its influence on thermal comfort, plays a significant role in complex cognitive performance in slightly warm conditions.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Deep coaxial borehole heat exchangers (CBHEs) have been considered to enable cost and energy savings in building energy systems. However, achieving improved performance requires optimal design and operation of the CBHE. This work presents a case study for a building energy system in Finland, for which a hydraulic diagram was developed to incorporate a number of deep CBHEs (800 m to 2400 m) with multiple operating modes. To evaluate the techno-economic feasibility with optimized operating strategies, a four-step methodology is introduced, combining steady-state modelling, dynamic simulation and system optimization. The systems with a CBHE were found economically feasible compared to a district heating connection, enabling lower annualized total system cost (18.3–26.3%) and operating costs (49.1–53.5%). With deeper CBHEs, the main cost reductions originated from improved heat pump performance, increased operating flexibility and decreased capacity requirements of process components. However, the benefits partly decreased non-linearly with increased CBHE depth. Economic feasibility displayed the highest sensitivity to the price of electricity, with a relatively smaller impact for deeper CBHEs. Furthermore, maximizing the heat pump performance was found economically more significant than achieving a high borehole heat extraction rate.

Data simulated for occupancy profiles, usually based on standard occupancy schedules, must be validated against real measurements, and many studies have pointed out the gap between them. This problem is more pronounced in homes that are not heated by grid-connected energy sources, such as wood-burning stoves, because the meter cannot provide a real-time estimate. In Central-South Chile, 74% of homes are heated by wood stoves, causing an acute problem of air pollution in several urban areas. The government is trying to solve this problem, but at the moment there is no data on occupancy profiles, hence it is not possible to estimate the energy intensity for heating. This exploratory study aims to clarify to what extent occupancy profiles can be estimated from PM 2.5 pollution levels. To this end, publicly available data on PM 2.5 concentrations in 17 cities in central-south Chile was used as a proxy to build occupancy schedules for homes heated by wood stoves. The results show that there is a clear relationship between pollution levels and occupancy intensity, and that the latter does not follow the schedules outlined in international standards or building codes. The results and methodology can be replicated in cities where air pollution is driven by wood stoves, allowing public authorities to have access to accurate occupancy schedules and providing them with reliable data to address local air pollution problems, Project “ANID Fondecyt Regular 1200551-Energy poverty prediction based on social housing architectural design in the central and centralsouthern zones of Chile, Index to analyze and reduce the risk of energy poverty”, funded by the National Agency for Research and Development (ANID, in Spanish), The research group “Confort ambiental y pobreza energ´etica (+CO-PE)” of the University of the Bío-Bío, the Thematic Network 722RT0135 “Red Iberoamericana de Pobreza Energ´etica y Bienestar Ambiental” (RIPEBA) financed by the call for Thematic Networks of the CYTED Program for 2021, and the Thematic Network 723RT0151, Red Iberoamericana de Eficiencia y Salubridad en Edificios” (IBERESE) financed by the call for Thematic Networks of the CYTED Program for 2022 for supporting this research, Universidad de Granada / CBUA

The classification of the energy efficiency of buildings with the use of the energy performance certificate, con- stitutes a common practice for the building energy assessment performance community. The main stream in the field is the so-called asset rating, that is the calculation of the energy performance of buildings, whereas another option for the definition of the energy class of a building relies on its measured performance, named operational rating. Despite the fact that significant progress has been achieved in the field of smart sensors and smart buildings, effective solutions related to the employment of Industry 4.0 practices, such as Building Information Modelling (BIM) or digital twins are not employed for the operational rating of buildings energy performance. This study aspires to introduce a comprehensive framework for the operational assessment of buildings energy performance, with the use of advanced tools and practices for building digitization. For the purpose of this study, a relevant set of operational indicators was employed, with the purpose to provide information, both to the landlords and the tenants, related to the actual energy performance of the building. The novelty of this study relies on the fact that for the extraction of the operational rating, a digital twin environment was used, employing smart sensors, real time measurements and a BIM environment. Within this study, the proposed concepts are demonstrated in a case study building of mixed used. This study aims to shed light to the development of practices for the remote and smart real time energy assessment of building units.