Building envelopes and social housing in southern Europe energy assessment of the residential social stock of the city of Seville under the climate change scenario

Las viviendas sociales construidas sin criterios de aislamiento térmico constituyen uno de los conjuntos más importantes del parque de viviendas de las ciudades del sur de Europa. Habitualmente sus ocupantes disponen de recursos limitados para el mantenimiento de las condiciones ambientales interiores con sistemas de acondicionamiento térmico, soportando largos periodos de tiempo de ausencia de confort y salubridad en los hogares, pese a que estos hogares están ubicados en ciudades de climas habitualmente calificados como benignos. Tal es el caso del parque de viviendas de Sevilla, ciudad elegida para el desarrollo de esta tesis. Se ha constatado que la reducida cantidad de energía usada normalmente para el acondicionamiento térmico de estas viviendas tiene como consecuencia, en la mayoría de los casos, que el potencial de ahorro en el consumo de energía sea muy limitado. Por tanto, resulta necesario un cuidadoso diseño de las intervenciones en este parque de viviendas. El trabajo propone una metodología de análisis del parque edificado residencial basada en la caracterización de su envolvente térmica, y que podría ser replicable para las diferentes zonas urbanas del sur europeo. Se han identificado cuáles son las características principales que tienen afección sobre el comportamiento energético del parque residencial, y se ha establecido una catalogación de su envolvente térmica, atendiendo no solo a los elementos constructivos que la constituyen, sino también a aquellos aspectos morfológicos con influencia en este comportamiento. El análisis no se efectúa únicamente de un modo global en el periodo de estudio, sino que incluye un estudio de la distribución temporal de soluciones y sus resultados, identificando los aspectos más representativos para los diferentes momentos del periodo, normalmente por décadas. El objetivo principal de esta investigación es presentar un estudio de amplio espectro sobre el comportamiento energético de la vivienda social de una de las grandes ciudades españolas, Sevilla, situada en el sur de España y, cuyas condiciones climáticas son representativas de las áreas más meridionales del sur de Europa. Con unas condiciones benignas en invierno y extremas en verano, la reflexión sobre el acondicionamiento térmico de sus viviendas, especialmente las de tipo social, ha sido subordinada habitualmente a aspectos economicistas. Este trabajo busca, entre otros objetivos, aumentar el conocimiento detallado del parque edificatorio existente de la ciudad y su relación con el comportamiento energético y control ambiental. Pretende ser un avance respecto a estudios más generales, mayoritarios hasta ahora, aportando una visión individualizada de las diferentes soluciones que podemos encontrarnos en el periodo temporal en el que se construye casi la mitad del parque de viviendas actual, ya que se centrará fundamentalmente en el periodo que transcurre entre el final de la Guerra Civil española (1939) y la aparición de la Norma Básica de la Edificación CT-79 (1979). Los edificios objetos de estudio la literatura científica anglosajona los denomina non insulated buildings. Una de las principales novedades del estudio, en el contexto de las edificaciones urbanas, es la consideración de que la climatología local no es inmutable; presenta transformaciones continuas, motivadas tanto por la propia variabilidad natural como por la influencia antropogénica, bajo los denominados procesos de cambio climático (CC). El clima que afecta a los edificios ha sufrido, y sufrirá, modificaciones que tendrán una repercusión directa en el comportamiento energético de las viviendas. Se ha realizado un análisis de las características de esta evolución y de las principales interacciones con estos edificios, y se ha generado un escenario de evaluación futuro, con el fin de poder definir relaciones, entre la situación actual y la futura, sobre los factores que caracterizan el comportamiento energético del edificio y el modo de uso de la energía. Dada la dependencia directa de la climatología en las condiciones del ambiente interior de los edificios, los procesos de Cambio Climático generan una modificación de su respuesta energética. Esta situación altera tanto la evaluación de la envolvente energética, como las predicciones sobre las repercusiones previsibles de las diferentes estrategias actuales de intervención y mejora energética sobre el parque de viviendas. Se analiza la capacidad de la envolvente, bajo diferentes hipótesis de trabajo, de actuar como moderador y elemento de protección frente a las acciones climáticas, tanto las actuales como las previstas en un futuro próximo. Se establecen valores de los potenciales de reducción de la demanda de energía en estos edificios, ya que el consumo se verá afectado por los muy diferentes condiciones de uso y operacionales, y por los rendimientos (eficiencias) de los diferentes sistemas térmicos, por lo que su variabilidad es muy elevada. A partir de ellos se generan las bases de discusión sobre los márgenes reales que las técnicas de intervención tienen en la reducción del consumo energético. Aunque el análisis y evaluación se centra fundamentalmente en la ciudad de Sevilla, tanto la metodología de trabajo como los procedimientos de clasificación son replicables a otras ciudades y ámbitos urbanos del sur de Europa. Aplicando esta metodología, la investigación desarrollada en la tesis se presenta en cuatro bloques de análisis más un quinto bloque de conclusiones y líneas futuras de trabajo, junto El segundo Volumen, o cuerpo complementario, recoge resultados detallados, tanto de los procedimientos y métodos propuestos como de los experimentos realizados. Se ha generado una catalogación edificatoria del parque existente, junto una base de información de detalle de los edificios que lo componen. Se incorpora el conjunto de modelos de desempeño energético de los edificios representativos del periodo, bajo los diferentes escenarios de evaluación.Social housing built without thermal insulation criteria makes up one of the most important parts of the social housing stock in the cities of southern Europe. Occupants in such housing often have limited resources to use climate control systems to maintain indoor environmental conditions, and often go for long periods of discomfort and unhealthy conditions at home, even though these properties are located in climates generally classified as mild. This is the case of the housing stock in Seville, the city chosen to carry out this thesis. It has been shown that, in most cases, the reduced amount of energy normally used to thermally condition these properties means that potential energy consumption savings are severely limited. In consequence, all interventions in this housing stock must be thought through with great care. The main aim of this research is to present a wide-ranging study on the energy performance of social housing in one of the largest cities in Spain, Seville. This city is located in southern Spain, and has climate conditions which are representative of the southernmost areas of southern Europe. The paper proposes a methodology for analysing residential housing stock based on the characterisation of their thermal envelopes, which could be replicated for different urban areas of southern Europe. The main characteristics which influence the energy performance of the housing stock have been identified and their thermal envelopes have been catalogued, dealing not only with their comprising construction elements but also those morphological aspects which influence this performance. Rather than simply providing an overview of the study period, this analysis also includes a study of the temporal distribution of solutions and results, and identifies the most representative aspects of the different times of the study period, normally by decade. One of the most important innovations is the introduction in the analysis of climate change processes, in order to know ¿and, in consequence, deal with¿ the changes it is envisaged will be necessary for buildings to respond to different scenarios.Premio Extraordinario de Doctorado U

Characterising Draught in Mediterranean Multifamily Housing

Social housing dating from the postwar years through the end of the twentieth century is one of the major stores of European cities’ residential stock. As it is generally characterised by a poor thermal performance and an ine cient control of energy consumption, it constitutes one of the main targets for residential heritage renewal. This study aimed to locate and quantify air leaks across building envelopes in Mediterranean multifamily housing with a view to curbing the uncontrolled inflow of outdoor air that has a direct impact on occupant comfort and housing energy demand. Airtightness tests conducted in a series of protocols to quantify draught across envelope elements were supplemented with qualitative infrared thermographic and smoke tests to locate leakage pathways. Air was found to flow mainly across façade enclosures, primarily around openings, as well as through service penetrations in walls between flats and communal areas accommodating electrical and telecommunication wires and water supply, domestic hot water (DHW), and drainage pipes. The general absence of evidence of draught across structural floors or inter-flat partitions was consistent with the construction systems in place

TVOCs and PM 2.5 in Naturally Ventilated Homes: Three Case Studies in a Mild Climate

In southern Europe, the present stock of social housing is ventilated naturally, with practice varying in the di erent seasons of the year. In winter, windows are kept closed most of the day with the exception of short periods for ventilation, whereas the rest of the year the windows are almost permanently open. In cold weather, air changes depend primarily on the air infiltrating across the envelope and when the temperature is warm, on the air flowing in through open windows. CO2, PM2.5, and TVOC concentration patterns were gathered over a year’s time in three social housing developments in southern Europe with di erent airtightness conditions and analyzed to determine possible relationships between environmental parameters and occupants’ use profiles. Correlations were found between TVOC and CO2 concentrations, for human activity was identified as the primary source of indoor contaminants: peak TVOC concentrations were related to specific household activities such as cooking or leisure. Indoor and outdoor PM2.5 concentrations were likewise observed to be correlated, although not linearly due to the presence of indoor sources. Ventilation as presently practiced in winter appears to be insufficient to dilute indoor contaminants in all three buildings, nor does summertime behavior guarantee air quality

Rethinking User Behaviour Comfort Patterns in the South of Spain—What Users Really Do

Although energy analysis techniques can contribute to substantial energy savings in housing stock retrofitting operations, the outcomes often deviate significantly from the predicted results, which tend to overestimate potential savings by overestimating the starting energy baselines, particularly in southern Europe. This deviation can be largely attributed to occupant practice relating to the use of air conditioning facilities and the temperatures at which occupants feel comfortable. The patterns observed differed widely from standard values. In this study environmental variables, primarily indoor air temperature both with and without HVAC, were monitored in occupied dwellings for a full year. The data gathered were supplemented with surveys on occupants’ temperature-related behaviour to define comfort patterns. The findings show that the standards in place are not consistent with actual comfort-accepted patterns in medium- to low-income housing in southern Spain, where energy consumption was observed to be lower than expected, mostly because occupants endure unsuitable, even unhealthy, conditions over long periods of time. A new user profile, better adjusted to practice in southern Europe, particularly in social housing, is proposed to reflect the current situation

Thermal Perception in Mild Climate: Adaptive Thermal Models for Schools

A comprehensive assessment of indoor environmental conditions is performed on a representative sample of classrooms in schools across southern Spain (Mediterranean climate) to evaluate the thermal comfort level, thermal perception and preference, and the relationship with HVAC systems, with a comparison of seasons and personal clothing. Almost fifty classrooms were studied and around one thousand pool-surveys distributed among their occupants, aged 12 to 17. These measurements were performed during spring, autumn, and winter, considered the most representative periods of use for schools. A new proposed protocol has been developed for the collection and subsequent analysis of data, applying thermal comfort indicators and using the most frequent predictive models, rational (RTC) and adaptive (ATC), for comparison. Cooling is not provided in any of the rooms and natural ventilation is found in most of the spaces during midseasons. Despite the existence of a general heating service in almost all classrooms in the cold period, the use of mechanical ventilation is limited. Heating did not usually provide standard set-point temperatures. However, this did not lead to widespread complaints, as occupants perceive the thermal environment as neutral—varying greatly between users—and show a preference for slightly colder environments. Comparison of these thermal comfort votes and the thermal comfort indicators used showed a better fit of thermal preference over thermal sensation and more reliable results when using regional ATC indicators than the ASHRAE adaptive model. This highlights the significance of inhabitants’ actual thermal perception. These findings provide useful insight for a more accurate design of this type of building, as well as a suitable tool for the improvement of existing spaces, improving the conditions for both comfort and wellbeing in these spaces, as well as providing a better fit of energy use for actual comfort conditions

Dynamic Daylight Metrics for Electricity Savings in Offices: Window Size and Climate Smart Lighting Management

Daylight performance metrics provide a promising approach for the design and optimization of lighting strategies in buildings and their management. Smart controls for electric lighting can reduce power consumption and promote visual comfort using different control strategies, based on affordable technologies and low building impact. The aim of this research is to assess the energy efficiency of these smart controls by means of dynamic daylight performance metrics, to determine suitable solutions based on the geometry of the architecture and the weather conditions. The analysis considers different room dimensions, with variable window size and two mean surface reflectance values. DaySim 3.1 lighting software provides the simulations for the study, determining the necessary quantification of dynamic metrics to evaluate the usefulness of the proposed smart controls and their impact on energy efficiency. The validation of dynamic metrics is carried out by monitoring a mesh of illuminance-meters in test cells throughout one year. The results showed that, for most rooms more than 3.00 m deep, smart controls achieve worthwhile energy savings and a low payback period, regardless of weather conditions and for worst-case situations. It is also concluded that dimming systems provide a higher net present value and allow the use of smaller window size than other control solutions

Methodology for the study of the indoor environment, energy consumption and resilience of heritage buildings

Historic Heritage buildings play an important role in modern societies, as they are a way of keeping your identity safe for future generations. Its conservation challenges the cultural diversity ensurance in a constantly changing world. However, it is an area characterized by the level of energy inefficiency that contributes to a large amount of pollutant emissions. In addition, global warming and the current epidemic crisis make the indoors environmental quality become a very critical point regarding to today's future. It is necessary to understand the adaptation processes and the historic city evolution, to design strategies that make the conservation of heritage compatible with improvements in the inhabitants' quality of life, allowing a sustainable conservation of the historic city. Our main objective is to establish a methodology that identifies the fundamental aspects that affect the environmental conditions and energy conditions of heritage buildings, taking into account their ability to adapt to climate change and their safety of use, within a context of energy efficiency and sustainability. This sample paper describes the formatting requirements for Conference Proceedings, and this sample file offers recommendations on writing for the worldwide readership. Please review this document because some format details have changed related to previous years

Impact of controlled ventilation systems on energy consumption in mediterranean school buildings

Current standards for indoor air quality (IAQ) in non-residential buildings demand high air renewal rates with different filtration stages and constant flow. Currently, new school buildings must incorporate mechanical ventilation systems which modify traditional heating installations in order to comply with the requirements for indoor air quality and energy efficiency. This study analyses the technical and energy outcomes involved in a school building when changing from a traditional central heating system with radiators, to an HV system which fulfils the current regulatory framework

Analysis of thermal emissions from radiators in classrooms in Mediterranean climates

Using computational fluid dynamics (CFD), this study focuses on the analysis of the thermal emissions of a typical classroom in an educational establishment in the south of Spain, and heated by radiators situated under the windows. It aims to study the way to exchange energy within the venue with this system. In order to do so a work methodology is developed which applies the Fanger method (PMV and PPD indicators) and the local thermal discomfort method to the isothermal curve sections generated by the CFD calculations, drawing up a series of lineal variation graphs on the temperature. This allows us to not only evaluate the degree of thermal comfort of the occupants in accordance with ASHRAE standards but also to carry out future comparisons between different thermal exchange system variants arising from the HVAC system. Following the application of this analysis the paper concludes that efficiency of the traditional radiator system to cope with the energy demand of the location is limited, given its incapacity to carry out a uniform exchange of energy between itself, the convective phenomena it generates, and the low relation between air volume/emitting surface, which translates into a lack of energy efficiency in the system, an aspect which is not usually contemplated in traditional analysis methods

Protocols for measuring the airtightness of multi-dwelling units in Southern Europe

The airtightness of building envelopes is one of the factors which most affects the hygrothermal conditions and the air quality of the indoor environment, as well as the energy consumption of the building. In multi-dwelling units this contributes significantly to the overall load for heating or air conditioning, making it possible to calculate the repercussion of infiltrations on the energy demand of a dwelling as between 20 to 50% of the total amount, depending on the climate zone and construction characteristics of the envelope. Hence the importance of knowing the parameters that characterise it. Pressurisation/depressurisation tests are the best method for characterisig these, but must be carried out in accordance with specific measurement procedures. The main objective of this paper is the proposal of five specific protocols for carrying out these tests in MDU, and their specific use in buildings in Southern European regions. In order to develop and validate this proposal we have carried out a series of multi test in ten dwelling units in a block recently built in the south of Spain. The results of these tests are presented and analysed here. These confirm the need for some protocols to distinguish between wet and dry spaces within the dwelling, given the difference in airtightness between them, and to expand the study indicators proposed by international regulations for a more accurate rendering of the behaviour of the envelope and the elements within it