Assessing the Environmental Impact of Thermal Transmittance Tests Performed in Façades of Existing Buildings: The Case of Spain

Thermal transmittance tests constitute an appropriate tool to assess the energy performance of existing buildings. The heat flow meter method and the thermometric method are the most used experimental methods. One of the main criteria to guarantee appropriate test conditions and the representation of results is to ensure a high thermal gradient. For this purpose, heating or air conditioning systems should be used from three to seven days. Most studies related to experimental methods have addressed the appropriate test conditions; however, the environmental impact related to these conditions have not been analyzed. This study analyzes the energy consumption and the CO2 emissions related to the conditions of the thermal gradient required for tests. An energy analysis of 129,600 cases located in Spain was conducted. The results showed that heating systems are the best option to perform thermal transmittance tests, whereas air conditioning systems do not guarantee appropriate test conditions. As for the energy consumption and the percentage of hours with an appropriate thermal gradient, the adequacy of the heating setpoint temperature according to the predicted estimations of the external temperature during tests would mitigate their environmental impact. The reason is that, in certain cases, the increase of the setpoint temperature does not improve test conditions. Also, the use of heating systems would imply short test durations. Finally, the selection of small rooms with a small façade length would reduce the percentage of CO2 emissions between 31.37% and 36.1%. The results of this study could guarantee a more sustainable performance of thermal transmittance tests. In addition, the results could be used to perform life cycle analysis on buildings where thermal transmittance tests are performe

Internationalization Based on Content Modification Combined with Project Management Methodology: An Application in a Spanish Postgraduate Course in Building Engineering

Internationalizing university studies can be something of a challenge for courses related to engineering and architecture because their content is mainly focused on the standards of the country. In this regard, the content of the degree programmes in building engineering in Spain is based on the Spanish Building Technical Code. For this reason, this paper analyses experimentation conducted in a postgraduate course in building engineering of the University of Seville. The goal of the study was to internationalize the course content of that course appropriately. For this purpose, a combined approach was developed based on using ISO standards and including appropriately the modifications through a project management methodology to reduce risks. Experimentation was conducted for three academic years: 2018/2019–2020/2021. The results showed that ISO standards were appropriately implemented in the teaching course content and accepted by students. Likewise, the use of a project management methodology could be an opportunity to improve teaching course content, thus reducing the risk related to the modifications of this process

Analysis of the impact of the use profile of HVAC systems established by the Spanish standard to assess residential building energy performance

State regulations play an important role to guarantee an appropriate building energy performance. As for the Spanish regulation, the limitation of energy consumption should be analyzed with simulation tools by using operational profiles. The profile of operational conditions of HVAC systems in residential buildings limits the use of heating and cooling systems. This paper studied the limitations of the residential profile in energy assessment processes through simulation tools. A case study was analyzed with three operational approaches and was placed in 8131 Spanish cities. The results showed that the use limitations of cooling systems lead to ignorance of an important percentage contribution in the cooling energy demand in some months of the year. The use of an operational profile with an extended calendar for cooling systems for the entire year would imply a more appropriate knowledge of the building energy performance in order to know the fulfilment of the state regulation and its correct energy classification

Influencia en el rendimiento energético en edificios históricos provocado por el entorno urbano y las modificaciones de proyecto: el caso de la Casa Duclós

Los edificios históricos constituyen parte fundamental del patrimonio cultural tangible de la sociedad actual. El cumplimiento de las exigencias de ahorro energético para mitigar el cambio climático, sin embargo, puede verse limitado aquí debido a las características propias de estos edificios. Además, en el caso de las construcciones históricas, los principios de diseño bioclimático aplicados por los arquitectos, desde principios del siglo XX hasta la actualidad, pueden haber perdido efectividad. Ello ocurre, a veces, por las modificaciones en proyecto o por efectos del desarrollo urbanístico. En este estudio se analizan estos dos aspectos en un determinado edificio histórico ubicado en Sevilla: la Casa Duclós de José Luis Sert. Este presenta modificaciones en la cubierta, cuando se compara la proyectada y la construida. Asimismo, su entorno urbano se ha transformado desde que la Casa fue edificada. Para el análisis expuesto en este artículo, se realizaron simulaciones energéticas utilizando datos climáticos correspondientes al periodo 2000-2019. Los resultados muestran la influencia que tuvieron las modificaciones de la cubierta proyectada y la expansión urbanística en el rendimiento energético del edificio, con respecto a la concepción original del inmueble.Historic buildings are a fundamental part of the tangible cultural heritage of today's society. However, complying with energy saving requirements to mitigate climate change may have limitations caused by the characteristics of these buildings. Also, in the case of historical buildings from the early 20th century to the present, bioclimatic design principles applied by architects may have lost their effectiveness. This occurs, sometimes, because of project modifications or due to the effects of urban expansion. In this study, these two aspects are analyzed in a case of a given historic building located in Seville: The Duclós House by José Luis Sert. This building has modifications on the roof, when comparing its projected and built version. Likewise, its urban environment has changed since it was built. For the analysis presented in this article, energy simulations were carried out using weather data from 2000 to 2019. The results show the influence that the modifications of the projected roof and the urban expansion had on the energy performance of the building compared to the original conception of the property

Optimization of experimental thermal characterization methods of building envelope

En los últimos años, la creciente preocupación por el elevado consumo energético de los edificios se ha focalizado a través de la rehabilitación energética con el objetivo de reducirlo. En este sentido, la transmitancia térmica de los cerramientos determina en gran medida este consumo energético, por lo que existe un gran interés por disponer de métodos que permitan evaluarla de manera precisa. Esta propiedad se puede determinar a través de diferentes procedimientos tanto teóricos como experimentales. Todos estos métodos pueden verse afectados por una serie de factores que pueden derivar en la obtención de resultados atípicos. Aspectos tales como el uso de variables tabuladas, los errores metrológicos, la inercia térmica o los factores ambientales pueden influir de manera significativa en los resultados. Ante esta circunstancia, en esta tesis se realizaron una serie de estudios para abordar las principales debilidades detectadas en la literatura científica: el análisis del término convectivo utilizado en los métodos de termografía infrarroja cuantitativa, el análisis y la optimización del método termométrico y, por último, la estimación de la transmitancia térmica de la ISO 6946:2007 a través de mediciones in situ. Para obtener una gran cantidad de datos, se llevaron a cabo dos campañas experimentales cuyos diseños se adaptaron a las necesidades particulares de cada planteamiento. Asimismo, la combinación de los datos experimentales con otras técnicas, como procesos de simulación y la aplicación de algoritmos de aprendizaje automático, permitió desarrollar diferentes investigaciones. La utilización de las correlaciones experimentales de números adimensionales para el método interior de termografía infrarroja cuantitativa resultó ser la aplicación más adecuada para este método. En esta línea, el análisis de los datos obtenidos para este aspecto mostró que el número de resultados válidos conseguidos fue superior al de otras correlaciones experimentales interiores y exteriores. Además, la realización de los ensayos en el interior permite garantizar la disminución de la influencia de las condiciones ambientales. Con respecto al método termométrico, los resultados obtenidos en la tesis mostraron las posibilidades de aplicación del método en cerramientos, siempre que se reúnan las condiciones aceptables en dos aspectos operacionales (un gradiente térmico elevado y equipos apropiados), así como un filtrado de datos adecuados. Las limitaciones relacionadas con la carencia de otros procedimientos de cálculos para correcciones por almacenamiento de calor y las posibles desviaciones por el empleo de valores teóricos para el coeficiente de transferencia de calor total interior se resolvieron utilizando perceptrones multicapa. Finalmente, el uso de bosques aleatorios y de perceptrones multicapa permitió conseguir estimaciones ajustadas de la transmitancia térmica de la ISO 6946:2007 a través de variables medidas experimentalmente, siendo el primero de ellos el que obtuvo un mejor grado de ajuste

Improvement Options of a Social Housing Prototype in Different Climate Zones in Ecuador

Ecuador is a country with several climate zones. The zones’ characteristics are very different; however, there are social housing prototypes used in all the territories. This study constitutes the second part of the analysis of a social housing prototype in four zones (Cfb, Af, Aw, and BSh) in both the current climate situation (2020) and its projection to 2050. Improvement measures from the original dwelling block have been proposed according to the initial diagnosis, considering seven passive performance variants. A total of 56 dynamic simulations have been performed for both the current and 2050 climate scenario. The results have shown that, depending on the climate zone, improvement measures differently influence comfort ranges. In addition, the behaviour of the dwellings on the upper floor is different from those on the ground floor. This study is a starting point to show that prototype solutions of social housing should be adapted with various improvement measures and should be based on specific requirements according to their location to achieve acceptable comfort levels

Estimation of heating system energy modeling profiles based on environmental monitoring records in Central-Southern Chile

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 problemsProject “ANID Fondecyt Regular 1200551-Energy poverty prediction based on social housing architectural design in the central and centralsouthern zones of ChileIndex 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 723RT0151Red Iberoamericana de Eficiencia y Salubridad en Edificios” (IBERESE) financed by the call for Thematic Networks of the CYTED Program for 2022 for supporting this researchUniversidad de Granada / CBU

Adaptive comfort control implemented model (ACCIM) for energy consumption predictions in dwellings under current and future climate conditions: A case study located in Spain

Currently, the knowledge of energy consumption in buildings of new and existing dwellings is essential to control and propose energy conservation measures. Most of the predictions of energy consumption in buildings are based on fixed values related to the internal thermal ambient and pre-established operation hypotheses, which do not reflect the dynamic use of buildings and users’ requirements. Spain is a clear example of such a situation. This study suggests the use of an adaptive thermal comfort model as a predictive method of energy consumption in the internal thermal ambient, as well as several operation hypotheses, and both conditions are combined in a simulation model: the Adaptive Comfort Control Implemented Model (ACCIM). The behavior of ACCIM is studied in a representative case of the residential building stock, which is located in three climate zones with different characteristics (warm, cold, and mild climates). The analyses were conducted both in current and future scenarios with the aim of knowing the advantages and limitations in each climate zone. The results show that the average consumption of the current, 2050, and 2080 scenarios decreased between 23% and 46% in warm climates, between 19% and 25% in mild climates, and between 10% and 29% in cold climates by using such a predictive method. It is also shown that this method is more resilient to climate change than the current standard. This research can be a starting point to understand users’ climate adaptation to predict energy consumption

Estimating adaptive setpoint temperatures using weather stations

Reducing both the energy consumption and CO 2 emissions of buildings is nowadays one of the main objectives of society. The use of heating and cooling equipment is among the main causes of energy consumption. Therefore, reducing their consumption guarantees such a goal. In this context, the use of adaptive setpoint temperatures allows such energy consumption to be significantly decreased. However, having reliable data from an external temperature probe is not always possible due to various factors. This research studies the estimation of such temperatures without using external temperature probes. For this purpose, a methodology which consists of collecting data from 10 weather stations of Galicia is carried out, and prediction models (multivariable linear regression (MLR) and multilayer perceptron (MLP)) are applied based on two approaches: (1) using both the setpoint temperature and the mean daily external temperature from the previous day; and (2) using the mean daily external temperature from the previous 7 days. Both prediction models provide adequate performances for approach 1, obtaining accurate results between 1 month (MLR) and 5 months (MLP). However, for approach 2, only the MLP obtained accurate results from the 6th month. This research ensures the continuity of using adaptive setpoint temperatures even in case of possible measurement errors or failures of the external temperature probes.Spanish Ministry of Science, Innovation and Universities 00064742/ITC-20133094Spanish Ministry of Economy, Industry and Competitiveness BIA 2017-85657-

A comparative analysis of the international regulation of thermal properties in building envelope

To achieve the goals of reducing building energy consumption, regulations are being designed to guarantee the appropriate energy performance of buildings. Both European and South American countries establish requirements of thermal properties of building envelope according to the climate zone, thus implying notable differences in climate classifications and technical requirements. This research provides a general view of advantages and limitations between the different state regulations of three South American countries (Argentina, Brazil, and Chile) and three European countries (Spain, Portugal, and France). A total of 792 simulations were conducted with Energy Plus by considering 12 different dwelling typologies in 66 climate zones. Building envelopes were adapted to the regulations of the various countries. Results showed tendencies of performance clearly different between the South American and the European countries, with the latter being those with the lowest energy demands. The cluster analysis of distributions of energy demand revealed that buildings located in similar climates but in different countries present very different energy performances. This research opens up the discussion on the development of more demanding policies related to thermal properties of buildings. Also, the analysis at a continental scale could reduce the differences between countries and guarantee a more sustainable life for the building stock.info:eu-repo/semantics/publishedVersio