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The main objective of the study was to determine the effect of impregnation of the paper core with acetylated starch on the mechanical properties and absorbed energy in the three-point bending test of wood-based honeycomb panels under varying temperatures and relative air humidity conditions. Nearly six hundred beams in various combinations, three types of facings, three core cells geometries, and two paper thicknesses were tested. The experiment results and their statistical analysis prove a significant relationship between the impregnation of paper with modified starch and mechanical properties. The most effective in absorbing energy, the honeycomb panels, consisted of a core with a wall thickness of 0.25 mm and a particleboard facing. [ABSTRACT FROM AUTHOR]

Fire activity in 288 areas (2.5° N × 10° E) in the Arctic region (50°–70° N, 0°–360° E) was analyzed using about 4.4 million satellite hotspot (HS) data from 2002 to 2021. A total of 21 high fire density areas from eastern Europe to western Canada were selected, and their fire–weather conditions during each active fire period were analyzed using about 1820 various weather maps at the upper and the lower air level. Analysis results showed that the active fires in the Arctic region occurred under the fire–weather conditions associated with the northward movement of cut-off high (COH) and warm air masses detached from the south caused by large westerly meandering (LWM). LWM is a sign of the beginning of an active fire period. Very active fires on HS peak days occurred several days after the start of the northward movement of COHs and under mainly high-pressure conditions in the upper air and strong wind conditions in the lower air. The time lag of these several days suggests that we may be prepared for very active fires. The fire–weather analysis approach described in this paper has shown that future large-scale fire outbreaks are predictable. [ABSTRACT FROM AUTHOR]

Accurate values for the climatic conditions in an air cavity, hereby called the microclimate, are crucial when calculating and simulating the performance of a ventilated roof and façade system. The climatic stress of its components and their mould and rot potential influence the long-term durability of the roof or façade. A scoping study is conducted to gain an overview on research and the scientific literature on the microclimate of air cavities in ventilated roofing and claddings in Nordic climates. From the body of the research literature, 21 scientific works were of particular interest, and their findings are summarized. The review shows that only a limited number of studies discuss the microclimate of air cavities. Roofs are discussed to a greater and more varied degree compared to façades and air cavities behind solar panels. However, the results cannot be compared and validated against each other to generally describe the microclimate of air cavities, as the surveyed papers approach the subject differently. This knowledge gap indicates that calculations and simulations can be performed without knowing whether the results represent reality. If the structure of ventilated roof and façade systems are only designed based on experience, it can be difficult to be proactive and adapt to future climate changes. Further studies are needed to determine the relation between the exterior climate and the air cavity microclimate, so that future climate predictions can be used to simulate the long-term performance of ventilated roof and façade systems. [ABSTRACT FROM AUTHOR]

A sustainable use of active heating, ventilation, and air conditioning (HVAC) systems is crucial for minimum energy consumption. Currently, research studies are increasingly applying adaptive setpoint temperatures, thus reducing considerably the energy consumption without influencing comfort levels excessively. Most of them, however, are focused on the limit values of adaptive comfort standards without considering the tolerance in users' adaptation capacity. This research study analyzed various tolerance ranges in the recent adaptive thermal comfort model from EN 16798-1:2019 used in setpoint temperatures. The study focused on the south of Europe, considering 47 cities in Spain, 18 cities in Portugal, 13 cities in Greece, and 20 cities in Italy. In addition, such cities were analyzed in three climate scenarios: present time, 2050, and 2100. The results showed that values prefixed by EN 16798-1:2019 for new buildings (tolerance of 0.00 °C) produced significant savings with respect to the static model and that each progressive improvement in users' thermal expectations in 0.25 °C increased the energy consumption between 6.57 and 9.31% in all scenarios analyzed. Even applying a thermal tolerance of 1.50 °C, energy savings are currently produced with respect to the static model. This tendency increases in future scenarios until a thermal tolerance of 1.75 °C. The results of this paper provide greater knowledge about the possible energy increase that the improvement in users' expectations would produce. [ABSTRACT FROM AUTHOR]

This article provides an overview of residential vapor-compression air conditioners operating under high ambient temperatures (HAT). For the purpose of this article, a minimum temperature criterion, 40 °C and above, was developed to evaluate studies that were conducted at HAT. Several HAT organizations and projects were launched with the purpose of assessing the performance of low-GWP (GWP = global warming potential) refrigerants when operating under HAT and accelerating the transition to such refrigerants. Previous studies of air conditioner improvements (i.e., for condensers, evaporators, compressors, and refrigerants) were discussed under HAT conditions. This article also explores the challenges, the possible design modifications, and several limitations of air conditioners operating under HAT. Condenser improvements showed an 18 to 50% higher coefficient of performance (COP) and an 8 to 30% higher cooling capacity. Only one study was found for evaporator enhancement under HAT which improved the COP by ~7% and cooling capacity by ~10%. Experimental compressor improvements achieved 2 to 17 °C lower discharge temperature and up to 15% higher cooling capacity, whereas the COP ranged from −4% to +3% of the baseline values. Under HAT conditions, several A2L refrigerants exhibited an attractive performance compared to R-410A while none outperformed R-22 in terms of both cooling capacity and COP. Considering R-22 alternatives, all A1 refrigerants exhibited lower COP, A2L refrigerants achieved comparable COP, and A3 refrigerants reached higher COP. [ABSTRACT FROM AUTHOR]

In the international movement to combat the threat of climate change, the timely implementation of residential energy-saving practises is becoming an urgent issue. Because the number of apartments is increasing, we analysed data from home energy management systems (HEMSs) and data from questionnaire surveys of 309 households in a condominium. We focused on the seasonal variation in air-conditioning (AC) use in living-dining rooms to determine the tendency of energy use for heating/cooling related to the characteristics of flats, the profiles of residents, and energy-saving behaviours. In winter, 80% of residents mainly used gas floor heating rather than AC and 24% did not use AC in winter. In households where someone stays home for long hours, they prefer gas floor heating rather than AC in winter. These households also tend to engage in energy-saving behaviours to adjust the indoor thermal environment. There are several types of energy-saving lifestyles; therefore, effective energy-saving measures should be considered for both energy efficiency and the thermal comfort of residents. [ABSTRACT FROM AUTHOR]

The global demand for air conditioners (ACs) has more than tripled since 1990, with 1.6 billion units currently in use. With the rapid economic and population growth of countries located in the hottest parts in the world, this trend is likely to continue in the future. The aim of this study was to show the benefits of introducing air conditioners with different materials or different technologies such as inverters with high energy-saving performance on the environment and human health in Indonesia. To evaluate the environmental impacts of the different technologies, a cradle-to-grave life cycle assessment (LCA) of air conditioners was conducted using the life-cycle impact assessment method based on endpoint modeling (LIME3). As expected, the use stage has the largest global warming potential (GWP), representing more than 90% of the impact, whereas copper and nickel have the most important impact in terms of resource consumption (about 50%). We found that the impacts are heavily dependent on the country's energy mix, but reduction can be achieved by introducing better technologies. The integration factors from LIME3 were then applied to estimate the external cost of each model; the results showed that the use stage also has the most influence. Even though the impact of climate change is important, air pollution impact must be seriously considered as its impact was found to be the highest (about 60% of the total impact). The external cost was finally compared to the possible benefits produced by the introduction of air conditioning technologies during their 10-year life cycle. We found that the impacts are twice that of the benefit for the best model (USD 2003 vs. 1064); however, the novelty of this study is that the benefit was also considered. In the future, developing countries should promote AC models with inverters, refrigerants with low global warming impact such as natural refrigerants, and encourage the recycling of units as soon as possible. The energy mix for electricity production is also a key parameter to consider. [ABSTRACT FROM AUTHOR]

The growing concern about global climate change extends to different professional sectors. In the building industry, the energy consumption of buildings becomes a factor susceptible to change due to the direct relationship between the outside temperature and the energy needed to cool and heat the internal space. This document aims to estimate the energy consumption of a Minimum Energy Building (MEB) in different scenarios—past, present, and future—in the subtropical climate typical of seaside cities in Southern Spain. The building energy consumption has been predicted using dynamic building energy simulation software tools. Projected climate data were obtained in four time periods (Historical, the 2020s, 2050s, and 2080s), based on four emission scenarios defined by the Intergovernmental Panel on Climate Change (IPCC): B1, B2, A2, A1F1. This methodology has been mathematically complemented to obtain data in closer time frames (2025 and 2030). In addition, different mitigation strategies have been proposed to counteract the impact of climate change in the distant future. The different energy simulations carried on show clearly future trends of growth in total building energy consumption and how current building designers could be underestimating the problem of air conditioning needs in the subtropical zone. Electricity demand for heating is expected to decrease almost completely, while electricity demand for cooling increases considerably. The changes predicted are significant in all scenarios and periods, concluding an increase of between 28–51% in total primary energy consumption during the building life cycle. The proposed mitigation strategies show improvements in energy demands in a range of 11–14% and they could be considered in the initial stages of project design or incorporated in the future as the impact of climate change becomes more pronounced. [ABSTRACT FROM AUTHOR]

Climate change is posing a variety of challenges in the built realm. Among them is the change in future energy consumption and the potential decay of current energy efficient paradigms. Indeed, today's near-zero Energy buildings (nZEBs) may lose their virtuosity in the near future. The objective of this study is to propose a methodology to evaluate the change in yearly performance between the present situation and future scenarios. Hourly dynamic simulations are performed on a residential nZEB located in Rome, built in compliance with the Italian legislation. We compare the current energy consumption with that expected in 2050, according to the two future projections described in the Fifth Assessment Report (AR5) by the Intergovernmental Panel on Climate Change (IPCC). Implications for thermal comfort are further investigated by assuming no heating and cooling system, and by tracking the free-floating operative temperature. Compared to the current weather conditions, the results reveal an average temperature increase of 3.4 °C and 3.9 °C under RCP4.5 and RCP8.5 scenarios, estimated through ERA-Interim/UrbClim. This comes at the expense of a 47.8% and 50.3% increase in terms of cooling energy needs, and a 129.5% and 185.8% decrease in terms of heating needs. The annual power consumption experiences an 18% increase under both scenarios due to (i) protracted activation of the air conditioning system and (ii) enhanced peak power requirements. A 6.2% and 5.1% decrease in the hours of adaptive comfort is determined under the RCP4.5 and RCP8.5′s 2050 scenarios out of the concerted action of temperature and solar gains. The results for a newly proposed combined index for long-term comfort assessments reveal a milder future penalty, owing to less pronounced excursions and milder daily temperature swings. [ABSTRACT FROM AUTHOR]