Passive solutions for more energy-efficient buildings are critical to improving our odds in the current energy crisis. This work focuses on assessing the thermal performance of different envelope construction layouts in a tropical climate through proposed indicators regarding the thermal mass degree (TMD) and insulation degree (ID). For this, a numerical study was performed for a reference building (RB) in Panama City and validated with the electricity consumption bills. Behavioral and sensitivity analyses were employed to identify critical heat gains and the most important envelope constructions, resulting in the layouts of the roof and external walls. Optimization analyses were performed to find adequate layouts to reduce the discomfort hours. Different roofs, external walls, internal partition layouts, and glazing types were evaluated. Results indicated that the adequate envelope configuration is a roof layout with low TMD and ID, along with wall layouts with high TMD and low ID.
The building envelope design constrains how much HVAC systems must work to provide comfort. High thermal mass in walls is preferable to delay heat gain, as well as reduce it. Phase Change Materials (PCMs) seem to proportionate more thermal mass without increasing wall thickness because of their high latent heat. Thus, this work studies various PCM-based envelope layouts in four case studies, H060, H100, H200, and OB, under the tropical climate of Panama City, via building energy performance simulation. Energy and thermal comfort performance were used as criteria to determine an optimal PCM-based layout for such a climate through optimization analysis and to compare PCM-based and non-PCM-based envelope layouts. Results showed that among the considered combinations, PCM-based roof configurations provide more optimum solutions than PCM-based wall configurations. The PCM layout with a melting temperature of 27 °C allowed completion of the PCM cycle throughout the year. Although other PCM layouts did not present a complete charge/discharge cycle, such as the most frequent options at H060, H100, and H200, it suggests that PCM on liquid or solid phase provides better thermal performance than other considered combinations.
The current trend of massively incorporating renewable-based generation into power systems is affecting frequency stability. This generation does not inherently provide inertia owing to its electronic interface. Therefore, many approaches have been proposed to address the problem of inertia weakening. Beyond the new trends of making new generation and storage responsive to grid needs, this study addresses the problem from the role of consumers. The use of railway consumption to contribute to frequency control tasks, without affecting train circulation, is proposed. For the first time, the provision of virtual inertia combined with primary frequency control is presented. This is achieved by means of the power consumption of ventilation and air conditioning systems, while maintaining the thermal comfort of passengers. To illustrate this new concept, a case study of a real metro line is presented. The results demonstrate the benefits of using the thermal inertia of trains to contribute to grid frequency control. Also, some insights into technical requirements and possible issues are provided. An appropriate combination of primary frequency control and virtual inertia can reduce technical requirements and provide better frequency performance. Frequency control, virtual inertia, railways, demand response, thermal comfort.
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Desde muy temprana edad, Severo Ochoa de Albornoz mostró interés por las ciencias naturales. Su empeño y el apoyo de sus profesores, lo llevaron a estudiar medicina en busca de la bioquímica. El buen desempeño académico, y la convivencia con personas destacadas, lo llevaron poco a poco a contribuir al desarrollo científico de las ciencias. Su notable producción científica, junto a las situaciones políticas de España, lo condujeron a tener vastas experiencias en el extranjero e, inclusive, nacionalizarse en EE. UU. Su trayectoria fue reconocida por muchos individuos y entidades alrededor del mundo, lo cual lo llevó a ganar un Premio Nobel y a ser un personaje influyente en varias ramas del conocimiento más allá de las ciencias naturales.
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