Energy Efficiency in Buildings: Both New and Rehabilitated

Buildings are one of the main causes of the emission of greenhouse gases in the world. Europe alone is responsible for more than 30% of emissions, or about 900 million tons of CO2 per year. Heating and air conditioning are the main cause of greenhouse gas emissions in buildings. Most buildings currently in use were built with poor energy efficiency criteria or, depending on the country and the date of construction, none at all. Therefore, regardless of whether construction regulations are becoming stricter, the real challenge nowadays is the energy rehabilitation of existing buildings. It is currently a priority to reduce (or, ideally, eliminate) the waste of energy in buildings and, at the same time, supply the necessary energy through renewable sources. The first can be achieved by improving the architectural design, construction methods, and materials used, as well as the efficiency of the facilities and systems; the second can be achieved through the integration of renewable energy (wind, solar, geothermal, etc.) in buildings. In any case, regardless of whether the energy used is renewable or not, the efficiency must always be taken into account. The most profitable and clean energy is that which is not consumed

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

uhuMEB : design, construction, and management methodology of minimum energy buildings in subtropical climates

Knowledge of buildings0 energy efficiency has advanced thanks to research carried out in recent years. Many of the discoveries in this field have recently been incorporated into mandatory construction regulations for each country. However, not many of the architects and engineers involved in the construction industry clearly know how to achieve those goals in their designs. This document is based on the extensive experience in architectural design, the integration of renewable energies, the energy simulation of buildings and data acquisition, and analysis of the research team involved. It is presented in a practical and holistic approach and focused in subtropical climates. A structured methodology for the proper decision-making process during all the different stages of a minimum energy building (MEB) is likewise presented. The proposed methodology depicted aims at providing architects and engineers with a systematic and orderly step-by-step procedure and incorporates the instrumentation/control and data analysis as essential elements that support the validation of the expected results from the design, the construction, and the operation phase of the building. The paper develops a case study that illustrates the proposed methodology. This new methodology for MEB in subtropical climates constitutes an innovation in this field.This work has been funded by the DPI2017-85540-R Project supported by the Spanish Ministry of Economy and Competitiveness and by the European Union Regional Development Fund. Some parts of the study have been funded by the resources of the research team "Control y Robotica (TEP192)" from the University of Huelva (Spain)

Contribuciones desde la arquitectura y la ingeniería a los edificios de energía mínima

En el capítulo 1 de esta tesis doctoral planteamos una visión general de la tesis doctoral, destacando las innovaciones, las aportaciones científicas y la transferencia de resultados de investigación Nevada a cabo hasta la fecha de su depósito. En el capítulo 2 de esta tesis doctoral realizamos una revisión exhaustiva sobre el estado del arte en materia de conocimiento científico y regulatorio en relación con la eficiencia energética de los edificios. Este capítulo termina con un apartado dedicado al concepto de MEB, donde se aporta una propuesta de definición de nZEB en España. El capítulo 3 de esta tesis doctora!: Cálculo de la difusividad térmica del terreno mediante la medida directa de su temperatura, Aplicación a los sistemas de geotermia de muy baja entalpia, viene a realizar una aportación para la incorporación de esta forma de energía renovable a edificios MEB en clima subtropical. En él se desarrolla una metodología científica para el cálculo exacto de la difusividad térmica de un terreno; de forma sencilla y, sobre todo, económica. Para ello, utilizando los ensayos de geotecnia exigidos por la normativa de seguridad estructural, medimos la temperatura del terreno a la profundidad donde va a ser instalada el sistema geotérmico de muy baja entalpia (VLEGE). Esta medida, realizada mediante una sonda experimental desarrollada por el equipo de investigación, permite calcular mediante un desarrollo analítico la difusividad térmica del terreno, que constituye el parámetro fundamental para el diseño y dimensionado de la VLEGE. El capítulo 4 de este trabajo: Medida simple, rápida y de bajo coste de la transmilancia térmica en la edificación, pretende conseguir edificios MEB a través de la mejora de la capacidad de aislamiento de su envolvente, En él se desarrolla un sistema de medida rápido, barato y fácil de usar, que permite tomar al mismo tiempo múltiples medidas en un mismo edificio, o incluso en edificios colindantes, cuando se trate de la rehabilitación energética de una manzana o de un barrio completo. Para ello se ha desarrollado un sistema que, al contrario de lo que se hace actualmente, no precisa medir difusividad del calor como tal en la envolvente del edificio, sino sólo obtener medidas de temperatura que, a través de ia ecuación diferencial de Fourier, conocida en algunos ámbitos como Ley de enfriamiento de Newton, nos da el valor de la transmilancia térmica {U-Valué) de la envolvente. El capítulo 5 de esta tesis doctoral: uhuZEB: Metodología de diseño, construcción y operación de edificios de consumo de energía mínimo en clima subtropical, viene a realizar una aportación metodológica fundamental para la integración operativa de las distintas fases de desarrollo de un MEB en clima subtropical. Estas distintas fases incluyen la negociación, el diseño arquitectónico, la ingeniería de instalaciones, l gestión de la construcción y la fase de operación y mantenimiento del MEB. Una herramienta clave para la implementación de esta metodología es el modelo de información del edificio (BIM), con un nivel de desarrollo (LOD) específico para cada fase. Al final del capítulo se incorpora un caso experimental real para la validación paso a paso de la metodología desarrollada. Se trata de una vivienda unífamiliar aislada en clima subtropical denominada Casa Zaranda. En ella se demuestra, de manera pormenorizada, la validez de la metodología propuesta para el diseño de edificios MEB en clima subtropical. El capítulo 6 de esta tesis doctoral: Rehabilitación energética a escala territorial, se trata de una investigación completa y auto contenida sobre las contribuciones realizadas a la rehabilitación energética a escala de barrio, para la mejora significativa de la eficiencia energética en una región de clima subtropical en Andalucía. Si bien en el capítulo 5 se experimentó con una vivienda unifamiliar de nueva construcción, lo cual permitió poner en valor la metodología desarrollada aplicada a obra nueva, este capítulo 6 constituye una segunda y más amplia prueba experimental aplicada a la rehabilitación energética de viviendas sociales en las ocho capitales de la Comunidad Autónoma de Andalucía. Finalmente, en el capítulo 7 de esta tesis doctoral resumimos las principales conclusiones y los desarrollos futuros que se derivan del trabajo de investigación realizando, con incidencia en las nuevas líneas de investigación que se abren en el campo de la eficiencia energética en edificios.In chapter 1 of this doctoral thesis we present an overview of the thesis, highlighting the innovations, the scientific contributions and the research transfer results carried out until the date of its deposit In Chapter 2 of this doctoral thesis we conducted a comprehensive review of the state of the art in scientific and regulatory knowledge regarding the energy efficiency of buildings. This chapter finish with a section devoted to the MEB concept, where a proposal for the nZEB Spain’s definition is provided. Chapter 3: Ground thermal diffusivity calculation by direct soil temperature measurement. Application to very low enthalpy geothermal energy systems, comes to make a contribution for the incorporation of this kind of renewable energy to MEB buildings in subtropical climate. It develops a scientific methodology for the exact calculation of the thermal diffusivity of a soil. In a simple and, over all, economic way. To do this, using the geotechnical tests compulsory in the structural safety regulations, we measure the temperature of the soil to the depth where the very low enthalpy geothermal system (VLEGE) is going to be installed. This measure, carried out by an experimental probe developed y the research team, allows the thermal diffusivity of the terrain to be calculated through an analytical development, which is the fundamental parameter for the design and dimensioning of the VLEGE. Chapter 4: Simple, quick and low-cost measurement of thermal transmittance in buildings, aims to achieve MEB buildings by improving the insulation capacity of its envelope. It develops a quick, inexpensive and easy to use measuring system that allows multiple measurements to be taken at the same time in a single building or even in adjoining buildings when it comes to the energy retrofitting of an quartier or a complete neighborhood. A system has been developed that, contrary to what is done today, does not need to measure heat diffusivity in the building envelope. It only needs to obtain temperature measurements that, using the Fourier differential equation, known in some areas such as Newton’s cooling law, gives us the value of the thermal transmittance (U-Value) of the envelope. Chapter 5: uhuMEB: Methodology of design, construction and operation of minimum energy consumption buildings in subtropical climate, is making a fundamental methodological contribution for the operational integration of the different phases of development of an MEB in subtropical climate. These different phases include negotiation, architectural design, facility engineering, construction management and the operation and maintenance phase of the MEB. A key tool for the implementation of this methodology is the building information model (BIM), with a specific level of development (LOD) for each phase. At the end of the chapter, a real experimental case is shown for the step-by-step validation of the methodology. It is a detached house in a subtropical climate called Casa Zaranda. Chapter 6: Energy retrofitting at territorial level, this is a complete and self-contained research on the contributions made to energy retrofitting at neighborhood level, for the significant improvement of energy efficiency in a subtropical climate region of Andalucía. Although in Chapter 5 it was experimented with a newly built single family dwelling, which allowed to put in value the developed methodology applied to new work, this chapter 6 constitutes a second and more extensive experimental test, applied to the energetic retrofitting of social housing in the eight main cities of Andalusian region. Finally, in chapter 7 of this thesis, we summarize the main conclusions and the future developments that derive from the research work carried out, focusing in the new research lines that are opened in the field of energy efficiency in buildings

Green Building Rating Systems and the New Framework Level(s): A Critical Review of Sustainability Certification within Europe

Increasing problems regarding pollution and climate change have long been demonstrated by scientific evidence. An important portion of carbon emissions are produced by the building sector. These emissions are directly related not only to the building’s energy consumption, but also other building attributes a ecting the construction and operation of existing buildings: materials selection, waste management, transportation, water consumption, and others. To help reduce these emissions, several green building rating system (GBRSs) have appeared during the last years. This has made it di cult for stakeholders to identify which GBRSs could be more suitable to a specific project. The heterogeneity of the GRBS scenario requires the creation of a transparent and robust indicator framework that can be used in any country within the European Union (EU), which is a common EU framework of core sustainability indicators for o ce and residential buildings Level(s) with the goal to provide a solid structure for building sustainability certification across all countries of the EU. This paper provides a comprehensive review of the most common GBRSs within the EU: Building Research Establishment Assessment Method (BREEAM), Deutsche Gesellschaft für Nachhaltiges Bauen (DGNB), Haute Qualité Environnementale (HQE), and Leadership in Energy & Environmental Design (LEED), and a bottom up comparison of the influence in the final score produced by the indicators stated by Level(s). The indicators studied show a di erent influence of Level(s) indicators on every GBRS, where LEED and BREEAM were most a ected while HQE and DGNB were less so. This paper demonstrates the heterogeneity of current GRBSs in the EU scenario and the di erence between sustainability assessments, where DGNB seems to be more aligned to the current EU framework. Finally, the paper concludes with the need to work to achieve alignment between the GBRS and Level(s)

New Research Trends and Topics for Achieving Energy Efficiency in Buildings: Both New and Rehabilitated

In the Special Issue of Energies entitled Energy Efficiency in Buildings Both New and Rehabilitated that was published in 2019, a broad spectrum of research teams from around the world provided their latest findings on how to reduce energy consumption in the building sector [...

New Research Trends and Topics for Achieving Energy Efficiency in Buildings: Both New and Rehabilitated

In the Special Issue of Energies entitled Energy Efficiency in Buildings Both New and Rehabilitated that was published in 2019, a broad spectrum of research teams from around the world provided their latest findings on how to reduce energy consumption in the building sector [...

uhuMEBr: Energy Refurbishment of Existing Buildings in Subtropical Climates to Become Minimum Energy Buildings

Today, most countries in the world have mandatory regulations, more or less strict, regarding energy effciency in buildings. However, a large percentage of the buildings already built were constructed under lax or non-existing regulations in this regard. Therefore, many countries are facing the energy refurbishment of their existing buildings to reduce their carbon footprint. Depending on ambient weather conditions where a building settles, its operation with respect to the achievement of maximum energy effciency should usually be different. This happens in subtropical climates when, during the year and depending on the season, the building needs to conserve heat, evacuate it or even make an exchange with the outside to take advantage of favorable environmental conditions. This paper presents a complete methodology for conducting building energy effciency refurbishments in subtropical climates in order to convert them into minimum energy buildings. The proposed methodology is illustrated by a case study in a dwelling that includes all the stages, from the analysis of the existing dwelling to the refurbishment works, showing the final results and the subsequent dwelling operation

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%