Energy consumption and thermal comfort in buildings are heavily affected by weather conditions. This study investigated the impact of climate change on thermal comfort conditions and on heating and ...cooling energy demand in dwellings in three cities in Brazil. Scenario A2 of the Intergovernmental Panel on Climate Change was selected to be used in the study. To quantify the impact, the Climate Change World Weather File Generator was used to produce weather data for future typical meteorological years, such as 2020, 2050 and 2080. The EnergyPlus computer programme was used to estimate the indoor air temperature and the annual heating and cooling energy demand in the future. In order to maintain the energy consumption in the houses at the level it is nowadays, passive design strategies such as solar shading, low absorptance and thermal insulation were assessed. Results show that there will be an increase in the annual energy demand ranging from 19%–65% among the three cities in 2020; 56%–112% in 2050; and 112%–185% in 2080. In the coldest city, the annual heating energy demand will decrease by 94% in 2080 due to an increase in the average temperature and global solar radiation. The use of passive design strategies may reduce up to 50% the future annual cooling and heating energy demand in houses in Brazil.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Green roofs offer several environmental and social benefits to urban life. However, such roofs require a greater amount of materials than conventional roofs. The life cycle assessment (LCA) is an ...appropriate tool that has been used to obtain the potential environmental impacts associated with green roofs throughout their life cycle. This paper aims to review the literature related to the LCA of green roofs, responding: which materials and layers were used in green roofs in LCA studies; which processes were considered in each life cycle phase; which types of roofs have already been compared to green roofs through LCA; which measures are taken to reduce the environmental impacts of green roofs; which methods were used to assess the economic feasibility of green roofs over their life cycle and what were the purposes of such analyses; and which LCA studies included public perceptions about the green roofs. Our findings indicate that the materials used in the green roof layers vary among the articles. However, polymeric materials are usually used for all the layers, except for the substrate. Cradle to grave is the most common approach. Within this approach, more than half of the articles considered cooling and heating energy, which may significantly influence the life cycle analysis results. Most studies reviewed agreed that green roofs cause less environmental impacts than conventional and white roofs. The use of byproducts or recycled materials may further improve the performance. In most studies, public perception is not included in the analysis. Regarding the economic approach, both life cycle cost and life cycle cost-benefit are used to compare green roofs economic viability with other roof systems. In addition to discussing studies reported in the literature, this article also recommends future research to improve the performance of green roofs.
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•This paper reviews the LCA studies on green roofs in the literature.•Cooling and heating energy significantly influence the environmental impacts.•Green roofs usually cause less environmental impact than conventional roofs.•Byproducts, recycled and local materials have to be studied more deeply.•Studies should focus on LCA in a cradle to cradle approach.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Rainwater harvesting has been studied in different countries as a way of easing water availability problems and reducing potable water demand in buildings. The most important factor relating to the ...efficiency of a rainwater system is the correct sizing of the rainwater tank. Therefore, the objective of this article is to assess the influence of rainfall, roof area, number of residents, potable water demand and rainwater demand on rainwater tank sizing. The analysis was performed by using computer simulation and by considering daily rainfall data for three cities located in the state of São Paulo, Brazil. The roof areas considered were 50, 100, 200 and 400 m²; the potable water demands were 50, 100, 150, 200, 250 and 300 l per capita per day; the rainwater demands were taken as a percentage of the potable water demand, i.e., 10% to 100% at increments of 10%; and the number of residents was two and four. Results indicated a wide variation of rainwater tank sizes for each city and also for each parameter. The main conclusion that can be made from the study is that rainwater tank sizing for houses must be performed for each specific situation, i.e., considering local rainfall, roof area, potable water demand, rainwater demand and number of residents. Therefore, sizing rainwater tanks according to local tradition is not recommended as it may incur low efficiency.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Over the past decade, rising water and energy consumption in educational institutions has become a topic of increasing attention among the scientific and policy communities. This work assesses the ...potential for water and energy savings in 100 public schools in southern Brazil. There was great variation in the water consumption (0.81–35.43 l/student/day) and also great variation in the energy consumption (0.31–66.47 kWh/student/month). Two schools were selected for assessing the implementation of a rainwater harvesting system and improvements in the artificial lighting system. One of the schools has high water and energy consumption, while the other has low consumption. In the school with high consumption, the potential for potable water savings by using rainwater varied from 2996 to 5431 l/day; and the payback period ranged from 20 to 36 months. The potential for energy savings by improving the artificial lighting system was 62%; and the payback period was just five months. In the school with low consumption, the potential for potable water savings by using rainwater ranged from 542 to 1574 l/day; and the payback period ranged from 46 to 83 months. As for the improvements in the artificial lighting system, there was an increase of 13% in the monthly energy consumption due to the current low illuminance levels in the classrooms. The results show the importance of choosing strategies for decreasing water and energy consumption in schools. Such strategies are usually economically and environmentally feasible, bringing significant reduction to the consumption of water and energy.
Studies about thermal comfort in mixed-mode buildings have been performed in order to better understand this type of building and its influence on occupants’ thermal perception. However, there is ...still no consensus amongst researchers regarding whether mixed-mode buildings should be evaluated separating each mode of operation (natural ventilation or air-conditioning) and whether adaptive thermal comfort theory applies to both modes of operation. Does the mode of operation of a mixed-mode building, ceteris paribus, influence occupant thermal comfort perception? Trying to answer such questions, field studies on thermal comfort were conducted in three mixed-mode office buildings in the city of Florianópolis (a temperate and humid climate), Southern Brazil. Buildings were equipped with mechanical cooling systems and operable windows, both controlled by occupants. Thermal comfort questionnaires were collected at the same time and location that environmental variables were measured by microclimate instruments. Almost 5500 questionnaires were answered by occupants of the three buildings in both modes of operation over the four seasons. Analysis of the results indicated that occupants’ thermal perception was influenced by the mode of operation. Adaptive thermal comfort models were developed for natural ventilation and air-conditioning mode of mixed-mode buildings. This work found no evidence to support a single adaptive model for mixed-mode buildings. During natural ventilation mode, occupants adapted to indoor temperature fluctuations as predicted by the adaptive thermal comfort theory. On the other hand, during air-conditioning operation a weak adaptive relation (indoor comfort temperature vs. outdoor climate) was observed – a range of about 4°C of indoor temperature fluctuation may be used for the operation of the air-conditioning system without compromising thermal comfort, which could help saving energy. This work is a first step towards building an adaptive model of thermal comfort for Brazilian subtropical climate.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The Griffiths method is widely used in thermal comfort studies to derive building users’ comfort temperature, or thermal neutrality as it is sometimes known. A single value (so called the Griffiths ...Constant, typically 0.5/°C) is prescribed as a representation of thermal sensitivity of building occupants to indoor temperature variations, which in turn is used to estimate indoor thermal neutrality from a subject's actual thermal sensation vote at a measured room temperature. Despite the Griffiths Constant of 0.5/°C having been used widely across the thermal comfort research literature and in some generic standards, the constant was derived exclusively from office building data and its applicability across different typologies is yet to be rigorously validated. The objective of this study is to quantify how sensitive people are to temperature variations inside a building, and to investigate if thermal sensitivity differs between different contexts (including building typologies, modes of ventilation, outdoor climatic types, and genders). A collection of thermal comfort field studies in different building typologies containing around 11,500 datasets was used to statistically derive building users’ thermal sensitivity, i.e. the rate of change in thermal sensation per unit change in indoor temperature within a day. Our results suggest that occupant thermal sensitivity does vary depending on building typologies and building ventilation mode. In naturally ventilated spaces users are about half as sensitive to temperature variations as in air-conditioned spaces. Age, gender and climate are found to be factors that can also influence thermal sensitivity of building occupants. Our findings imply that reliance on a universal thermal sensitivity value, the Griffiths Constant, in comfort temperature (neutrality) calculations should be avoided because it is in fact a variable.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This study aimed to evaluate the financial feasibility of rainwater harvesting and greywater reuse in a multifamily building located in Florianópolis, Brazil. A building, consisting of two blocks ...with 60 flats each, was chosen to obtain data about the number of residents, building characteristics, potable water consumption, and rainwater and greywater demands (obtained by means of questionnaires and water measurements). The financial feasibility analyses considered rainwater and greywater systems separately and together. The impact on the urban stormwater drainage system was evaluated through the reduction of stormwater runoff. The energy consumption in the operational phase of each system was estimated through the amount of energy consumed by the motor pumps to supply one cubic meter of water. The potential for potable water savings through the use of rainwater—that supplies water for washing machines—was approximately 6.9%. The potential for potable water savings through the use of greywater—that supplies water to toilets—was approximately 5.7%. Both systems were feasible. The payback period for rainwater harvesting systems ranged from 57 to 76 months. For greywater systems, the payback period ranged from 127 to 159 months. When considering both systems working together, the payback period ranged from 89 to 132 months. The rainwater harvesting system can reduce 11.8% the stormwater volume destined to the urban stormwater drainage system in relation to the current contribution volume. Energy consumption was approximately 0.56 kWh/m3 of treated water for the rainwater harvesting system and 0.89 kWh/m3 of treated water for the greywater system. Rainwater and greywater were considered economically feasible, especially for higher inflation scenarios. Furthermore, such systems are interesting alternatives in terms of impacts considering urban drainage and energy consumption.
The study and analysis of urban water consumption habits in different regions contribute to the development of strategies aimed at secure water reduction and distribution. Within this context, ...knowledge of global water availability and the analysis of factors that influence consumption in different regions in distinct situations become extremely important. Several studies have been carried out in a number of countries and describe different approaches. The objective of this article is to learn about the strategies used in water consumption forecast and analysis. Most of the studies analysed seek to understand the factors influencing consumption in different building types. When it comes to residential buildings, the number of residents and the influence of economic issues on water consumption have an important role in this matter. In this context, pieces of research present the use of awareness campaigns as a strategy towards water use reduction. As a contribution, this article presents a systemic view of the pieces of research conducted and their contribution to forecasting water consumption in different regions. In conclusion, one observes the importance of analysing the factors influencing water consumption in different regions and scenarios, such as during the COVID-19 pandemic. This article can help managers and researchers understand the main factors that influence water consumption and how this consumption takes place in different regions.
This study aims to analyse the technical viability and economic feasibility of rainwater-harvesting systems for single- and multifamily residential buildings in the city of Florianópolis, Brazil. ...Simulations were conducted for representative buildings in the city under different water-usage scenarios and system designs, in a total of 36 simulation scenarios. An economic analysis was performed for four scenarios over a twenty-year period. Both initial and operational costs were considered, and the net present value, internal rate of return, and payback were used as feasibility indicators. For houses, between 60.1% and 74.8% of the cases were economically feasible, achieving a discounted payback period ranging from 6.2 to 8.6 years. For flats, between 57.8% and 64.2% of the cases were economically feasible, achieving a discounted payback period ranging from 4.8 to 5.6 years. As the water tariff in the city underwent changes recently, the former and current tariff formats were compared. The current tariff format provides more economic benefits for saving potable water, and leads to a higher net present value and a shorter discounted payback period. This research stands out from previous studies as it examines a new scenario in the use of rainwater-harvesting systems.
Extensive implementation of rainwater harvesting (RWH) systems can promote substantial improvement in urban water resource management. Therefore, establishing the financial feasibility of RWH systems ...is imperative for their dissemination. This study evaluated the influence of rainfall time series indicators (average annual rainfall, seasonality index and behaviour of periods without precipitation) and design variables (catchment area, rainwater demand, number of inhabitants, potable water demand and rainwater tank size) on the financial feasibility of RWH systems in eight Brazilian cities. Correlations between rainfall indicators and financial feasibility were introduced, along with sensitivity analysis of design variables. Financial feasibility was obtained in 30% to 70% of the simulated scenarios. Initial investment and operating costs varied significantly among the eight cities according to local prices. Systems with a catchment area of 200 m2 were capable of supplying, on average, 90.5% of the maximum rainwater consumption observed in this study. Local variation of potable water tariff schemes affected the financial feasibility of RWH systems. The number of inhabitants was the most influential design variable on the financial feasibility of RWH systems, followed by the rainwater tank size. Places with lower rainfall seasonality indexes and lower incidence and duration of dry periods are likely to lead to greater financial feasibility.
