• Energy Research

When proposing the most suitable strategies for retrofitting the residential stock it is essential to consider energy vulnerability, the current state of stock, users’ economic capacity and climate. This work analyses energy vulnerability on regional and neighbourhood scale, applied to the social housing stock in southern Spain. Three key vulnerability indicators are assessed through extensive public databases and validated parametric energy simulation models: 1) buildings energy performance, based on simulated indoor thermal comfort; 2) users’ socio-economic vulnerability, based on their income levels; and 3) climate influence, implementing future climate data into the simulations. The different energy vulnerability levels identified in the research are of great interest for retrofitting the existing stock as they help establish priority action guidelines. It is concluded that social housing in Andalusia currently exhibits a noticeable level of energy vulnerability in winter, with a greater severity of undercooling compared to overheating. In 2050, overheating in summer will significantly worsen, generally surpassing cooling. Despite of the Mediterranean climate, there are noticeable comfort differences between the cities analysed, with Cordoba and Granada being particularly relevant. Finally, a worse thermal performance in winter of the H-block typology was observed, which in summer occur for the linear block buildings.

Most educational buildings in southern Spain do not meet current energy requirements as weak thermal envelopes and the lack of cooling systems lead to severe discomfort in classrooms, especially when temperatures are above 30 °C. Given that global warming is expected to worsen this situation in coming decades, one of the first steps to be taken is to protect window openings from high levels of solar radiation by adding shading devices to reduce indoor temperatures and improve visual comfort. The aim of this research is to evaluate the reduction in thermal and lighting consumption in a classroom where a solar protection system in the form of an egg-crate shading device was installed. Two classrooms—one with an egg-crate device and another with no shading system—were monitored and compared for a whole year. The use of an egg-crate device in these classrooms reduced indoor operative temperatures during warmer periods while also improving indoor natural illuminance levels. Moreover, annual electric air conditioning consumption decreased by approximately 20%, with a 50% reduction in electric lighting consumption. These savings in electricity were largely conditioned by the use patterns observed in these ambient systems.

Due to 2030 and 2050 targets of the latest international standards, energetically retrofitting the existing building sector requires special attention. Prior to the proposal of retrofit strategies, it is necessary to analyse the current energy performance of the stock. Although simulation tools provide accurate results of energy performance at the building level, individual assessments of the large-scale stock lead to extensive data collection and huge computational resources. This paper assesses the current performance of one of the most representative building typologies in social housing stock in southern Spain, the H-typology, predicting results on indoor thermal comfort at the stock level. The physical, constructive and geometrical building characterisation and the selection of a calibrated and validated case study through monitoring are used to generate parameterized energy simulation models, providing statistically representative samples of the stock. Open-access energy simulation tools have been combined with statistical software. Conclusions reported show average annual discomfort hours of around 68%, with higher percentage of annual undercooling discomfort hours, and identify the most influential parameters on indoor thermal comfort as infiltration rate, people density and night-time natural ventilation rate. Moreover, 10 Latin Hypercube Samples per parameterized variable derived in highly representative results for thermally analysing the stock.

Abstract During the last years, there has been a significant increase in temperatures, as well as in the intensity and duration of heatwaves due to climate change, which noticeably affects summer, but also winter conditions. Thus, assessing overheating and undercooling risks in the existing stock is of the utmost importance, especially in highly occupied educational buildings with natural ventilation systems. These risks do not only affect students’ thermal comfort but their health and academic performance. Besides, COVID-19 has highlighted the energy vulnerability of schools and the complexity to adopt adequate strategies to enhance indoor environmental quality. To assess overheating and undercooling risks in educational buildings in southern Spain, a parameterized and validated building simulation model has been constructed from a representative school using monitored data. Through sensitivity analysis techniques, the most critical variables on adaptive thermal comfort in summer and winter have been determined. The study highlights the difficulty of guaranteeing a balance between indoor air quality and thermal comfort, since not only infiltration and ventilation rate have a key impact on thermal comfort, but also and more importantly ventilation schedules. These conclusions are vital to propose retrofit strategies to mitigate climate change while tackling undercooling, using parameterized building-archetype models, which allow to simulate other representative case studies in the area.

Hospital buildings present a significant savings potential in order to meet the objectives of H2020. The improvement of healthcare built environments contributes to improving the health of patients. In this respect, passive measurements must be prioritized, especially in relation to the weakest element of the building thermal enclosure: the window opening. Shading devices allow solar radiation and indoor temperature to be controlled, as well as improving visual comfort, mostly in buildings with a Mediterranean climate. This factor is of great importance when considering the increase in outdoor temperatures expected due to climate change. Unlike other studies in which predictive models are implemented, this paper examines a methodology based on the simultaneous monitoring of ambient variables, in real use and operative conditions, for two hospital rooms located in southern Spain. The aim of this research is to provide a comparative assessment of ambient conditions in a standard room with an egg-crate device and in a non-shaded one. The use of an egg-crate device allows a better yearly performance, improving natural illuminance levels, reducing incident solar radiation on the window, and decreasing artificial lighting consumption. However, its efficiency is greatly conditioned by the user patterns in relation to ambient systems, as the blind aperture level and the activation of the lighting system are directly controlled by users.

Abstract Given that the existing residential buildings are expected to become a huge part of the future stock due to their low replacement rate, retrofitting plans are crucial to meet 2030 and 2050 energy efficiency targets. Notwithstanding, an extensive assessment of the current energy and thermal performance of the stock must be conducted prior to the proposal of energy saving measures in order to properly tackle the retrofit process. Thus, the analysis and characterisation of the existing buildings under real variability conditions through statistical techniques is key to provide useful information at the stock level, instead of the most commonly single-building level approach. In the presented study, a statistical analysis on the most predominant variability ranges of the social housing stock of southern Spain (Andalusia) is carried out. Efforts are focused on the building characterisation of the linear block typology. To do so, an extensive database, which contains information on slightly under 39,500 social dwellings, is analysed. The conclusions reported in this study may be implemented into the construction of real case building archetypes through bottom-up building stock modelling techniques with the objective of assessing the real energy and thermal performance of the existing stock, providing useful information for public stakeholders.

One of the main retrofitting strategies in warm climates is the reduction of the effects of solar radiation. Cooling loads, and in turn, cooling consumption, can be reduced through the implementation of reflective materials such as solar control films. However, these devices may also negatively affect daylight illuminance conditions and the electric consumption of artificial lighting systems. In a hospital building, it is crucial to meet daylighting requirements as well as indoor illuminance levels and visibility from the inside, as these have a significant impact on health outcomes. The aim of this paper is to evaluate the influence on natural illuminance conditions of a solar control film installed on the windows of a public hospital building in a Mediterranean climate. To this end, a hospital room, with and without solar film, was monitored for a whole year. A descriptive statistical analysis was conducted on the use of artificial lighting, illuminance levels and rolling shutter aperture levels, as well as an analysis of natural illuminance and electric consumption of the artificial lighting system. The addition of a solar control film to the external surface of the window, in combination with the user-controlled rolling shutter aperture levels, has reduced the electric consumption of the artificial lighting system by 12.2%. Likewise, the solar control film has increased the percentage of annual hours with natural illuminance levels by 100–300 lux.

Energy retrofitting of the housing stock is a priority in current regulatory standards as a means of reducing energy consumption. The strategies used in retrofitting housing stock ought to respond both to regulatory conditions and to two challenges: specific climate conditions and the improvement of comfort conditions. These issues are especially important in the warmer regions of the Mediterranean, and will be even more so in the future due to climate change. The aim of this paper is to assess the influence that the improvement of facade insulation and the use of ventilation have on the existing housing stock. To do so, an energy evaluation is conducted using on-site monitoring of free-running conditions in test cells reproducing a residential room, both in current condition and with the retrofitted proposal, in Seville (Spain). The results obtained show limited improvement of the facade insulation when outdoor temperatures are high, as well as the influence of ventilation, mainly nocturnal, depending on the ventilation rate and the minimum outdoor temperatures.