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•The installation of solar water heaters does not guarantee energy savings.•The potential of solar water heater cannot be dissociated from socioeconomic and behavioral factors.•In ...Brazil, low-income families are not using effectively solar water heating system.•Users committed to low water/energy consumption achieved a higher solar fraction by SWHS.
The inclusion of solar water heaters available through subsidies of the Brazilian government has benefited more than 300,000 low-income families. Although these subsidies are important for wide implementation of this technology, the actual system performance is unclear. Moreover, it is unclear whether the performance is affected by user behavior in the context of complex socioeconomic issues. The objective of this research is to assess the influence of human behavior on the potential savings induced by solar water heaters. The research strategy integrated qualitative and quantitative measurements. We applied the cluster analysis technique to identify five homogeneous subgroups for a case study in Londrina, Brazil, in which a detailed measurement procedure was implemented to gather data on these subgroups over one year. The measurements were conducted to gain a better understanding of the factors affecting electricity consumed by showering. This study shows that the benefits of solar heaters vary according to the user and use of the technology. The annual energy savings averaged 9.51–18.6kWh per person. A lack of technological understanding and the difficulty in effectively mixing hot and cold water were the main factors contributing to the inefficient use of the system.
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•Environmental control should address thermal comfort and energy efficiency simultaneously•Optimization algorithm with user sensitivity and PCS effect can save energy•Thermal preference is ...recommended for personal models and PCS performance evaluation•New technologies minimize user interaction demand to monitor personal variables•New types of PCS maximize mobility through wearable solutions
Personal conditioning systems (PCS) enable increased thermal comfort and acceptability conditions in a wider temperature range, resulting in energy savings. Many studies analysed the thermal effect and energy efficiency of these systems, although the association between these two goals in practice is not that simple. In order to identify possible answers to understand what remains to be discussed on this subject, a review of recent publications on PCS was carried out, mainly focused on its implementation in shared office spaces. The reviewed publications shed some light on the use of personal comfort models associated with environmental control for system automation, as well as the development of new technologies that facilitate data acquisition and the proposition of new personal conditioning systems. The application and proposition of wearable systems and the development of textiles for smart clothing is an identified trend seeking greater mobility and flexibility of PCS use, although its integration to environmental management systems is challenging. Thus, this review discloses some questions that should be considered for the implementation of PCS and personal comfort models in real environments, including some insights based on current publications on the subject.
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The main goal of this research is the proposal of an integrated approach, considering sustainability indicators related to energy life cycle of the building, for evaluation of energy ...efficiency measures with adaptation to climate change in Brazilian social housing projects. A Sustainability Index in the Energy Life Cycle was proposed that includes indicators associated to environmental, energy, economic aspects and user thermal comfort. A case study applied in the city of São Paulo, considered a representative project of the sector and cases with energy efficiency adaptation measures for three climate scenarios, considering climate change. The integrated approach highlighted the importance of the initial selection of materials, considering their associated impacts as well as the thermal and energy performance of the building during its life time, and the importance of climate change for the operational phase of the building. With the Sustainability Index in the Energy Life Cycle, large reductions were obtained comparing cases with adaptation measures to current practice. Results of this research contribute to improve project’s decisions with the incorporation of a holistic approach for the projects that are being produced for the housing deficit, considering better energy performance and lower resource consumption for users and the country in the long term.
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Abstract Thermal insulation from clothing is one of the most important input variables used to predict the thermal comfort of a building's occupants. This paper investigates the clothing pattern in ...buildings with different configurations located in a temperate and humid climate in Brazil. Occupants of two kinds of buildings (three offices and two university classrooms) assessed their thermal environment through 'right-here-right-now' questionnaires, while at the same time indoor climatic measurements were carried out in situ (air temperature and radiant temperature, air speed and humidity). A total of 5,036 votes from 1,161 occupants were collected. Results suggest that the clothing values adopted by occupants inside buildings were influenced by: 1) climate and seasons of the year; 2) different configurations and indoor thermal conditions; and 3) occupants' age and gender. Significant intergenerational and gender differences were found, which might be explained by differences in metabolic rates and fashion. The results also indicate that there is a great opportunity to exceed the clothing interval of the thermal comfort zones proposed by international standards such as ASHRAE 55 (2013) - 0.5 to 1.0 clo - and thereby save energy from cooling and heating systems, without compromising the occupants' indoor thermal comfort.
This paper addresses the viability of converting single-family residential buildings in Brazil into zero energy buildings (ZEBs). The European Union and the United States aim ZEBs implementation to ...address ‘peak oil’ and environmental concerns. However, literature shows no agreement on a consensual definition of ZEB. Seeking a Brazilian ZEB definition, this paper addresses PassivHaus and thermal comfort standards for hot climates, source metrics for ZEB, Brazil′s energy mix, residential energy end uses and Brazilian legal framework for residential photovoltaic (PV) generation. Internal Rate of Return for PV systems in two Brazilian cities is calculated under various scenarios. It shows grid parity was reached from April 2012 to November 2012 assuming residential electric tariffs of that period and the financial conditions given by the Brazilian government for the construction of new dams in the Amazon and the lowest rates offered by Brazilian banks to private individuals. Governmental decision to lower electric residential tariffs in November 2012 reduced the scope of grid parity. Later revocation of a tax exemption in April 2013 ended grid parity in Brazil. It concludes, conversely to developed countries, it is the volatile Brazilian energy policy, instead of economical barriers, the main obstacle for ZEB viability in Brazil.
•Critique on super insolated buildings as a good solution for hot climates.•PV parity already reached in some parts of Brazil.•Proposal for a zero energy building definition for Brazil.•Critique of the source metric for energy balance in zero energy buildings.•Average roof area in Brazil enough for PV array to meet average energy consumption.
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In Brazil the housing deficit is around 5.5 million houses. To address this need, the government created a programme called “My house, My life”. The main subsidies of the programme are for families ...earning up to three times the minimum wage. In order to formulate strategies for more energy efficiency buildings, it is necessary to understand the thermal and energy performance of what is being built. This article defines representative projects for typologies being built in the Brazilian social housing sector through the analysis of 108 projects considering two groups of income levels and investigates the thermal and energy performance of the representative projects in relation to the Regulation for Energy Efficiency Labelling of Residential Buildings in Brazil for two bioclimatic zones. Five representative building models were defined. Considering the most common features found on the sample, the study suggests the importance of addresing energy efficiency measures on the sector since current building techniques for social housing shows a tendency towards a low performance in relation to the thermal and energy performance criteria of the Energy Labelling especially for lower income projects. This provides a basis for future policy and allows for more in depth studies within the sector.
•Characterisation of representative typologies built for social housing in Brazil.•More recurrent building physics characteristics considered.•Energy efficiency and thermal performance of Brazilian social housing analysed.•Regulation for Energy Efficiency Labelling of Residential Buildings in Brazil used for analysis.
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The objective of this study is to analyse long-term indices for thermal comfort evaluation according to ASHRAE Standard 55 for low and elevated air speed models. This study comprehends the ...development and validation of scripts for calculating PMV/PPD, a sensitivity analysis of the input variables and identification of important sample regions which can cause thermal discomfort. A simulation experiment was performed using the EnergyPlus computer programme considering uncertainties in the metabolic rate, air speed, clothing insulation and air-conditioning set point temperatures in each zone of a hypothetical office building in Brazil. A total of 37 long-term thermal comfort indices were used for assessing the thermal comfort performance of each zone. Indices were divided into: percentage outside range of PMV and operative temperature; exceedance hours of PMV and operative temperature; degree-hour criterion of operative temperature; PPD-based; PPD weighted criterion; and operative temperature weighted criterion. The simulation experiment has shown that the different indices for long-term evaluation lead to different results but similar trends. High uncertainty was obtained which can compromise comparison of different cases. Some long-term indices were recommended for using in building simulation assessment, as well as a different index which includes both degree-hour severity of discomfort hours and PPD non-linear weighting. The difficulty in choosing an ideal index is discussed and an alternative is shown by using two or more indices to enable the correct assessment and comparison of different cases.
•An analysis of ASHRAE Standard 55 low and elevated air speed models was performed.•A performance evaluation of 37 long-term thermal comfort indices was performed.•High uncertainty was obtained for assessing comfort due to different indices.•Time and severity information are necessary for assessing thermal comfort.•Degree-hour criterion weighted by PPD was a good long-term measure.
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•The thermal sensation vote “slightly warm” was uncomfortable to 1/3 of the students.•Thermal comfort in hot climate is linked to “slightly cool” and “neutral” sensations.•At least 80% of thermal ...comfort was achieved at 25 °C SET in natural ventilation.•The best thermal conditions were recorded at 23-24 °C SET in air-conditioning.
The adoption of air-conditioning as a cooling strategy in hot and humid climates is common practice. In such locations, the overcooling of buildings in a concern as this leads to the dissatisfaction of the occupants and unnecessary cooling energy consumption. In this regard, a field study was carried out in the Brazilian city of São Luis (hot and humid equatorial climate) to evaluate the preferred and most comfortable thermal conditions in this context. The investigation took place in air-conditioned and naturally-ventilated classrooms, in which the environmental parameters were measured concomitantly with the application of questionnaires to the undergraduate students for thermal assessment purposes. There was a difference between the preferred thermal sensations (noticeably the “slightly cool”) and the ones considered most comfortable/acceptable (“slightly cool” and “neutral”, equally), which reflected in the preferred and most comfortable temperatures. Thermal comfort in naturally-ventilated classrooms was limited due to high air temperatures and low air speeds. The best thermal conditions in air-conditioned classrooms were found to be between 23–24 °C standard effective temperature, and more than 20% of the students were uncomfortable below 22 °C because of excessive cold when clothing insulation values were close to 0.3 clo. The results also showed that indoor air temperatures can be set as high as 26 °C without impairing thermal comfort, which could aid attempts to minimize the cooling energy consumption in this year-round hot and humid climate.
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The increasing frequency and severity of weather extremes caused by climate change evidence the need to assess buildings beyond their typical thermal and energy performance under normal operation. It ...is also essential to evaluate thermal resilience to safeguard occupants' health during extreme events and power outages. This study proposes a simulation framework to evaluate and enhance the thermal resilience of buildings against indoor overheating using an integrated set of performance metrics. This work also addresses how to aggregate resilience profiles of single buildings into the urban scale, supporting the evaluation of thermally resilient communities. This is the first step to connecting building and urban scales in a resilience analysis, seeking to further address other stakeholders' needs in the future. The application of the framework is exemplified through a case study considering three different climates in Brazil. This analysis allowed identifying cases with poor thermal resilience and essential dependence on air conditioning to guarantee the survivability of occupants during extreme hot weather. Nonetheless, by only changing the envelope's thermal transmittance and thermal mass, buildings' thermal autonomy increased up to 65% points and cooling loads were reduced by up to 61% in the hottest climate, São Luís. However, additional strategies are necessary to mitigate remaining indoor extreme thermal conditions, such as solar shading and increased air movement.
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•Proposition of thermal resilience profiles to assess buildings and communities.•Integrated set of key performance indicators associated with stages of resilience.•First step to connecting building and urban scales in a thermal resilience analysis.•Application of the framework exemplified through passively-operated buildings.•Mapping of vulnerable populations exposed to overheating.
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In equatorial, hot-humid tropical climates, users of naturally ventilated environments are commonly susceptible to heat discomfort caused by high air temperatures and thus require more air movement ...to improve thermal comfort. To evaluate the influence of relative humidity and air speed on the occupant's thermal perception, field studies were conducted in naturally ventilated and fan-assisted classrooms in São Luis City, North-Eastern Brazil. Indoor environmental variables were measured alongside questionnaires, focusing on thermal environment and air movement evaluation. The results indicated that relative humidity had a significant negative impact on thermal perception when the operative temperature was above 30 °C, while airspeed played a key role in reducing thermal discomfort. Despite the contribution of internal air movement, it was concluded that, when the indoor operative temperature exceeded 31 °C, mechanical cooling is required to achieve thermal comfort. The results also indicated the great acceptability of indoor conditions, as well as the influence of environmental variables on student's thermal perception in naturally ventilated spaces.
•Air humidity had significant impact on thermal perception in a warm environment.•Air movement attenuated heat sensation when operative temperature was below 30 °C.•Air speeds of 1 m/s and above had no additional cooling effect at 31 °C.•Operative temperature above 31 °C was unacceptable, as it was 30 °C with least 70% RH.
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