Assessment of aerial thermography as a method of in situ measurement of radiant heat transfer in urban public spaces

Una propuesta de nuevas estrategias para la mejora del medio ambiente urbano, usando termografía aérea para el cálculo de la temperatura media radianteUrban public spaces are an essential part of the urban environment, supporting social relationships and pro- moting a healthy lifestyle among citizens. However, the high value of urban land has led to an over-urbanisation of cities, increasing urban heat stress and decreasing the number and size of public spaces. Rising air temper- atures in cities – known as the urban heat island effect (UHI) - combined with global warming, make public spaces less comfortable. For these reasons, there has been a growing concern to improve the thermal comfort of urban spaces. Thermal radiation is a determining factor in urban thermal comfort and is normally summarised in a value called mean radiant temperature (TMRT). In the past, conventional methods have been used to calculate it, such as net radiometers and globe thermometers. In recent years, the scientific community has used ground- based handheld thermal cameras for its quantification. However, there is a lack of literature on the use of aerial thermography for this purpose (i.e. an unmanned aerial vehicle (UAV) equipped with a thermal infrared device). Given this gap in the literature and the advantages in time, versatility and accuracy of these systems, this paper presents a new method for assessing the measurement of radiant heat transfer in a pedestrian urban space using aerial thermography. From the surface temperatures of the infrared imagery collected by the UAV, TMRT was estimated at multiple points in a pedestrian area of a subtropical city (Huelva, Spain) during a typical summer day. In order to verify accuracy of the proposed method to estimate the TMRT, a microclimate urban simulation was carried out using ENVI-met v5. The comparative analysis of the measured and simulated dataset verified the applicability of aerial thermography for the measurement of radiant heat transfer (with R2 values of 0.98 for the data set and 0.8 for the data of each time period). To conclude, new strategies were proposed to improve urban thermal comfort and to make cities more sustainable.Funding for open access charge: Universidad de Huelva/CBUA. Proyecto SALTES (P20_00730): Smartgrid with reconfigurable Architecture for testing controL Techniques and Energy Storage priority. Programa Operativo FEDER 2014-2020 Junta de Andalucia

Design recommendations for the rehabilitation of an urban canyon in a subtropical climate region using aerial thermography and simulation tools

Outdoor public space is the setting for everyday social interaction where activities take place in order to satisfy collective urban needs. It is important to achieve climate-friendly urban design in order to ensure acceptable urban thermal comfort, especially in over-urbanised city centres during summer periods. In this research, an urban canyon street located in the historical centre of the subtropical city of Huelva (Spain) was analysed. After a survey carried out by in situ meteorological sensors and airborne infrared sensors (equipped on an unmanned aerial vehicle, UAV), the current thermal comfort was analysed in terms of PMV and PPD at different times of a typical summer day (11:00 h, 15:00 h and 19:00 h) with the aim of formulating design recommendations to improve its performance in terms of urban comfort. Then, thermal comfort was evaluated in different scenarios where feasible mitigation strategies (replacement of materiality, addition of vegetation and sun shading ele- ments) were applied to classify them according to their effectiveness using the ENVI-met simulation tool. The results of the current scenario showed that, due to its N-S orientation and its aspect ratio (H/W), the urban comfort depends drastically on the day hour variation. A comfortable thermal environment is achieved at all points of the urban canyon as a result of the shade generated by the buildings during the morning and afternoon. However, in the central hours of the day the feeling of thermal discomfort was alarming (PMV values of +3 and PPD values above 90%). The proposed mitigation measures showed a considerable improvement in urban thermal comfort, with the addition of vegetation being the most effective solution (with an improvement in PMV value of 42% and a reduction in PPD value of 43%). The combination of all the proposed measures in a single scenario showed encouraging results in the rehabilitation of public spaces in use.This work has been funded by the Research Center for Technology, Energy and Sustainability (CITES) at the University of Huelva. This work has been also funded by Proyecto SALTES (P20_00730): Smartgrid with reconfigurable Architecture for testing controL Techniques and Energy Storage priority. Programa Operativo FEDER 2014- 2020 Junta de Andalucia. Funding for open access charge: Universidad de Huelva/CBUA

A Critical Review of Unmanned Aerial Vehicles (UAVs) Use in Architecture and Urbanism: Scientometric and Bibliometric Analysis

In recent years the use of UAVs (Unmanned aerial vehicles) have proliferated in the civil sector for purposes such as search and rescue, remote sensing or real-time monitoring of road traffic, among others. In the architecture, engineering and construction fields (AEC) UAVs have demonstrated to be an ideal technology due to their optimal performance in terms of time, precision, safety and cost. Given the rapid growth of interest in this technology, this research presents a critical review of the literature on the use of UAVs in architecture and urbanism to define the most widely used techniques and delimit the fields of application based on the experimentation published by the scientific community. A scientific mapping was carried out in two stages using the VOSviewerTM software: a scientometric and a bibliometric analysis. This technique allowed us to analyse a large body of literature and bibliographic data to obtain trends, patterns and directions of this domain of knowledge. Then, a literature review was presented, highlighting the relevant information identified in the previous analysis. The fields of application of UAVs were delimited and the most commonly used payload types and the most appropriate post-processing techniques were specified, depending on the aerial mission objective. The fields of application identified included different techniques related to the generation of 3D models, land mapping, construction site monitoring, building surveying to detect structural damage and energy losses and urban remote sensing. The literature review showed that UAVs provide a useful multi-tasking tool at any stage of an architectural project. These techniques can be applied to buildings or public spaces from the design and construction processes when the project is initiated to the later stages of maintenance and inspection of the building during its life cycle

Impact of Global Warming in Subtropical Climate Buildings: Future Trends and Mitigation Strategies

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

Matching Energy Consumption and Photovoltaic Production in a Retrofitted Dwelling in Subtropical Climate without a Backup System

The construction sector is a great contributor to global warming both in new and existing buildings. Minimum energy buildings (MEBs) demand as little energy as possible, with an optimized architectural design, which includes passive solutions. In addition, these buildings consume as low energy as possible introducing efficient facilities. Finally, they produce renewable energy on-site to become zero energy buildings (ZEBs) or even plus zero energy buildings (+ZEB). In this paper, a deep analysis of the energy use and renewable energy production of a social dwelling was carried out based on data measurements. Unfortunately, in residential buildings, most renewable energy production occurs at a different time than energy demand. Furthermore, energy storage batteries for these facilities are expensive and require significant maintenance. The present research proposes a strategy, which involves rescheduling energy demand by changing the habits of the occupants in terms of domestic hot water (DHW) consumption, cooking, and washing. Rescheduling these three electric circuits increases the usability of the renewable energy produced on-site, reducing the misused energy from 52.84% to 25.14%, as well as decreasing electricity costs by 58.46%

Influence on indoor comfort due to the application of Covid-19 natural ventilation protocols for schools at subtropical climate during winter season

Thermal comfort and energy performance of our buildings has been seriously improved during the last decades with the introduction of better envelope airtightness and mechanical ventilation systems. The arrival of Covid-19 has forced us to accept new natural ventilation protocols to improve the air quality inside buildings over other characteristics of the buildings. As a consequence, it brings some negative effects, like a reduction in the control of indoor dry bulb temperature (T), and an increase in energy demand for heating and air conditioning. To evaluate these influences during a winter season, a standard classroom from a school located at subtropical climate has been selected to be monitored with air quality and comfort devices. The experiment considers two different scenarios in 2018, and 2021. At them, data have been compared with several comfort ranges from international standards and the recommendations from the Spanish Government, obtaining opposite results. The results from 2018 showed that the comfort T ranges were adequate, but CO2 concentrations rise over 2000 ppm which was unhealthy. On the contrary, in 2021 when the Covid-19 natural ventilation protocol is activated, the CO2 concentration becomes less than 700 ppm. Finally, the suggested natural ventilation protocol was proved as an efficient measure to improve air quality, but it reduces the performance of the building in terms of comfort and energy demand. Therefore, several alternative ventilation methods should be considered to keep both energy air quality building’s performance

Social criteria to develop an in use holistic urban sustainable assessment tool: UHU2SAT

Recently, several urban sustainability assessment tools (USAT) have appeared to reduce the human impact provided by the built environment. Few of them focus on the assessment of urban spaces like squares, streets, and parks, etc., but they don’t operation and maintenance (OM) phase is not considered. It would be necessary to develop an in use holistic urban sustainable assessment tool (UHU2SAT) to specifically assess urban spaces under OM phase. This paper provides a qualitative research among 188 studies, with the aim to classify them according to the impacts they pursue: environmental (ENV), social (SOC) economic (ECO) and Others. Finally, the SOC criteria are reduced up to 21 and arranged into 4 different groups: Human comfort, Urban mobility, SOC Cohesion, and Health & safety. These SOC criteria have been discussed and revised according to the literature review to identify the most suitable indicators for the UHU2SAT. Finally, it can be concluded that this methodology could also be useful to obtain ENV and ECO criteria to provide a holistic assessment of the sustainability

Impact of Global Warming in Subtropical Climate Buildings: Future Trends and Mitigation Strategies

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