Analysis of the economic feasibility and reduction of a building’s energy consumption and emissions when integrating hybrid solar thermal/PV/micro-CHP systems

The aim of this paper is to assess the performance of several designs of hybrid systems composed of solar thermal collectors, photovoltaic panels and natural gas internal combustion engines. The software TRNSYS 17 has been used to perform all the calculations and data processing, as well as an optimisation of the tank volumes through an add-in coupled with the GENOPT® software. The study is carried out by analysing the behaviour of the designed systems and the conventional case in five different locations of Spain with diverse climatic characteristics, evaluating the same building in all cases. Regulators, manufacturers and energy service engineers are the most interested in these results. Two major contributions in this paper are the calculations of primary energy consumption and emissions and the inclusion of a Life Cycle Cost analysis. A table which shows the order of preference regarding those criteria for each considered case study is also included. This was fulfilled in the interest of comparing between the different configurations and climatic zones so as to obtain conclusions on each of them. The study also illustrates a sensibility analysis regarding energy prices. Finally, the exhaustive literature review, the novel electricity consumption profile of the building and the illustration of the influence of the cogeneration engine working hours are also valuable outputs of this paper, developed in order to address the knowledge gap and the ongoing challenges in the field of distributed generation

Understanding the Efficiency of Mn4+ Phosphors: Study of the Spinel Mg2Ti1-xMnxO4

We present a spectroscopic study of Mn-doped Mg2TiO4 as a function of pressure and temperature to check its viability as a red-emitting phosphor. The synthesis following a solid-state reaction route yields not only the formation of Mn4+ but also small traces of Mn3+. Although we show that Mn4+ photoluminescence is not appreciably affected by the presence of Mn3+, its local structure at the substituted Ti4+ host site causes a reduction of the Mn4+ pumping efficiency yielding a drastic quantum-yield reduction at room temperature. By combining Raman and time-resolved emission and excitation spectroscopies, we propose a model for explaining the puzzling nonradiative and inefficient pumping processes attained in this material. In addition, we unveil a structural phase transition above 14 GPa that worsens their photoluminescence capabilities. The decrease of emission intensity and lifetime with increasing temperature following different thermally activated de-excitation pathways is mostly related to relatively small activation energies and the electric−dipole transition mechanism associated with coupling to odd-parity vibrational modes. A thorough model based on the configurational energy level diagram to the A1g normal mode fairly accounts for the observed excitation and emissionthe quantum yieldof this material

Calibration Methodology for CFD Models of Rooms and Buildings with Mechanical Ventilation from Experimental Results

This chapter describes a methodology for the development and calibration of computational fluid dynamics (CFD) models of three-dimensional enclosures for buildings with combined forced and natural convection from experimental result. The models were validated with physical test measurements of room air temperature. The developed CFD models included a model of an internal wall-mounted air conditioning (HVAC) split unit. The methodology proposed here aims at selecting the correct grid size and the appropriate boundary conditions from experimental data. The experimental campaign took place in an empty office room within an educational building. A set of experiments was performed with varying boundary conditions of two main variables, the fan speed of the HVAC unit and the surface wall temperature of the opposite wall to the HVAC unit. The developed CFD models used the standard k-ε turbulence model and the SIMPLE algorithm. The variable of interest was the room air temperature and its distribution within the internal environment. The application of the methodology has shown satisfactory results, finding a maximum error of 9% between the CFD model and the experimental result. This methodology can be used by other researchers to calibrate CFD models in existing rooms and then carry out detailed studies of temperature distribution, comfort and energy demand analysis

Influence of Wood Properties and Building Construction on Energy Demand, Thermal Comfort and Start-Up Lag Time of Radiant Floor Heating Systems

Radiant floor heating is becoming increasingly popular in cold climates because it delivers higher comfort levels more efficiently than conventional systems. Wood is one of the surface coverings most frequently used in radiant flooring, despite the widely held belief that in terms of thermal performance it is no match for higher conductivity materials if a high energy performance is intended. Given that the highest admissible thermal resistance for flooring finishes or coverings is generally accepted to be 0.15 m(2)K/W, wood would appear to be a scantly appropriate choice. Nonetheless, the evaluation of the thermal performance of wooden radiant floor heating systems in conjunction with the building in terms of energy demand, thermal comfort, and start-up period, has been insufficiently explored in research. This has led to the present knowledge gap around its potential to deliver lower energy consumption and higher thermal comfort than high-thermal-conductivity materials, depending on building characteristics. This article studies the thermal performance of wood radiant floors in terms of three parameters: energy demand, thermal comfort, and start-up lag time, analysing the effect of wood properties in conjunction with building construction on each. An experimentally validated radiant floor model was coupled to a simplified building thermal model to simulate the performance of 60 wood coverings and one reference granite covering in 216 urban dwellings differing in construction features. The average energy demand was observed to be lower in the wood than in the granite coverings in 25% of the dwellings simulated. Similarly, on average, wood lagged behind granite in thermal comfort by less than 1 h/day in 50% of the dwellings. The energy demand was minimised in a significant 18% and thermal comfort maximised in 14% of the simulations at the lowest thermal conductivity value. The vast majority of the wooden floors lengthened the start-up lag time relative to granite in only 30 min or less in all the dwellings. Wood flooring with the highest thermal resistance (even over the 0.15 m(2)K/W cited in standard EN 1264-2) did not significantly affect the energy demand or thermal comfort. On average, wood flooring lowered energy demand by 6.4% and daily hours of thermal comfort by a mere 1.6% relative to granite coverings. The findings showed that wood-finished flooring may deliver comparable or, in some cases, higher thermal performance than high-conductivity material coverings, even when their thermal resistance is over 0.15 m(2)K/W. The suggestion is that the aforementioned value, presently deemed the maximum admissible thermal resistance, may need to be revised

Effect of Wood Properties and Building Construction on Thermal Performance of Radiant Floor Heating Worldwide

Due to its relatively lower thermal conductivity, the suitability of wood is called into question when selecting the flooring material best suited to radiant heating systems. The European standard EN 1264 considers floorings with a thermal resistance over 0.15 m2 K/W to be out of scope. This belief was partially disproved in a previous article that studied wooden floors for Madrid’s climate. However, the effect of climate still needs to be addressed. The present study extends the previous research to worldwide climates and aimed to answer the following questions: (1) Do the lowest thermal conductivity woods present good thermal performance when used in radiant floors? (2) Should the flooring have a maximum thermal resistance value? (3) Is the standard thermal resistance limit of 0.15 m2 K/W objectively justified? And (4) Do the answers of the preceding questions depend on the climate and the construction characteristics? To answer these questions, 28 cities were selected according to the Köppen–Geiger climate classification. In each city, 216 different dwellings were simulated with 60 wood floorings and one of low thermal resistance as a reference, comprising a total of 368,928 cases. Thermal performance was evaluated in terms of three parameters: energy demand, thermal comfort, and start-up lag time. Consequently, the answers to the previous questions were: (1) The lowest thermal conductivity woods can be used efficiently worldwide in radiant floor heating systems with start-up lag times close to that of the reference flooring; (2) There is no limit value for thermal resistance for floorings that can be applied to all dwellings and climates; (3) No objective justification was found for establishing a thermal resistance limit for flooring of 0.15 m2 K/W; and (4) Climate and construction characteristics can play an important role in the correct selection of flooring properties, especially in severe winters and dwellings with the greatest outdoor-exposed envelope and the worst insulation

Delitos a través redes sociales en el Ecuador: una aproximación a su estudio

The present work shows the conceptualization of the main crimes, which are commonly commented on as means of social networking sites. It gathered information such as methods and techniques used by criminals or so-called cybercriminals on the internet to approach their victims and create an environment conducive to achieving their mission. So, mainly, we investigated the legal framework to deal with these practical delights, which are considered common practices are currently carried out, taking advantage of the access of information offered by social networks such as Facebook, which focuses our study for being considered The social networking sites with the largest number of active users, after which the new integral penalty code of Ecuador was consulted, to verify the existence of a legal framework that penalizes this type of anti-legal behaviors in social networking sites. The observation of the different websites of law enforcement agencies was carried out in order to obtain information that contributed to the development of the present study. Techniques such as the interview and survey were used, which were applied to the fiscal agents and elements Of the Judicial Police to determine what are the current processes that are followed in the investigation of this type of crimes, obtaining results that are opposed to reality with very few tax instructions and processes regarding this subject under study.El presente trabajo muestra la conceptualización de los principales delitos, que se comenten comúnmente usando como medio las redes sociales. Se reunió información como métodos y técnicas que usan los delincuentes o denominados ciberdelincuentes en la internet para acercarse a sus víctimas y crear un ambiente propicio para lograr su cometido. Así, principalmente, se investigó el marco jurídico para hacer frente a estas prácticas delicias, que si bien son consideradas prácticas comunes actualmente se realizan, aprovechando el acceso de información que ofrecen redes sociales como Facebook, en la cual se enfoca nuestro estudio por ser considerada la red social con mayor número de usuario activo. Posterior a esto se consultó el nuevo código integral penal del Ecuador, para verificar la existencia de un marco legal que penalice este tipo de comportamientos antijurídicos en las redes sociales. Se realizó la observación de los diferentes sitios web de las fuerzas del orden del país, con el fin del obtener información que aporte al desarrollo del presente estudio, se emplearon técnicas como la entrevista y encuesta, las cuales fueron aplicadas a los agente fiscales y elementos de la Policía Judicial para determinar cuáles son los procesos actuales que se siguen en la investigación de este tipo de delitos, obteniendo resultados que se contraponen a la realidad con muy pocas instrucciones fiscales y procesos referentes a este tema en estudio

CaCu3Ti4O12: Pressure dependence of electronic and vibrational structures

The effects of pressure in electronic and vibrational properties of the double perovskite CaCu3Ti4O12 have been investigated in the 0-25 GPa range by optical absorption and Raman spectroscopy. Besides a full structural characterization, we aim at unveiling whether the ambient Im3 crystal structure is stable under high pressure conditions and how its giant dielectric permitivity and electronic gap varies with pressure. Results show that there is evidence of neither structural phase transition nor metallization in CaCu3Ti4O12 in the explored pressure range. We have observed the eight Raman active modes associated with its Im3 crystal phase and obtained their corresponding frequency and pressure shift. Moreover, the direct electronic band gap (2.20 eV), which is mainly associated with the oxygen-to-copper charge transfer states, increases slightly with pressure at a rate of 13 meV GPa?1 from 0 to 10 GPa. Above this pressure is almost constant (Eg = 2.3 eV). The results highlight the high stability of the compound in its Im3 phase against compression.This work has been supported by the Spanish Ministerio de Ciencia, Innovaci´on y Universidades (Projects MAT2015-69508-P, PGC2018-101464-B-I00 and MALTA-Consolider Team RED2018- 102612-T). E.J. thanks for an FPI research grant (Ref. BES-2016-077449)

Origin of the piezochromism in Cs2CuCl4: Electron-phonon and crystal-structure correlations

By using optical absorption and Raman spectroscopy, we have investigated the effects of pressure in the structural, electronic, and vibrational properties of Cs2CuCl4 in the 0?20 GPa range. Our study has provided a complete characterization of the electronic and vibrational structures of Cs2CuCl4 in the low-pressure Pnma phase as a function of cell volume and the Cu-Cl bond length, RCu-Cl. We have focused on the electronic structure in the Pnma phase, which is mainly related to the tetrahedral CuCl2?4 units distorted by the Jahn-Teller effect. The strong piezochromism of Cs2CuCl4 is caused by the opposite shift of the charge-transfer band gap and the Cu2+ d-d crystal-field transitions with pressure. The high-pressure structure of Cs2CuCl4 above 4.9 GPa yields structural transformations that we ascribe to a change of coordination around Cu2+. The high-pressure phase appears largely amorphized, therefore any structural information from x-ray diffraction is ruled out. Here we use electronic and vibrational probes to get inside the structural information.Financial support from the Spanish Ministerio de Economía, Industria y Competitividad (MAT2015-69508-P) and MALTA-CONSOLIDER (MAT2015-71010REDC)

Energy-Efficient Envelope Design for Apartment Blocks—Case Study of A Residential Building in Spain

Buildings are known to be responsible for about a third of energy consumption in developed countries. This situation, together with the fact that the existing building stock is being renovated at a very slow pace, makes it crucial to focus on the energy retrofitting of buildings as the only way to reduce their contribution to these energy consumptions and the consequences derived from them in terms of pollution and climate change. The same level of insulation and the same type of windows is usually proposed for all dwellings in a building block. This article shows that since the improvements required by each dwelling in the same block are different, the proposed solution must also be different. The methodology is proposed for a practical case consisting of an apartment block in Cádiz, a demonstration building of the European RECO2ST project. To achieve the optimum solution for each case, a multi-objective optimization problem is solved: to minimize the annual heating demand of the building and the standard deviation of the annual demand of the different dwellings. Thanks to the use of the proposed methodology, it is possible to bring the building to a Nearly Zero Energy Building (NZEB) level, while avoiding excessive insulation that causes overheating in summer

Desarrollo de un modelo de recomendación de prendas de vestir basado en información local

Para el cliente es una experiencia abrumadora encontrar contenido de su interés dentro de una gran cantidad de opciones existentes, por lo tanto, las empresas se han visto en la necesidad de implementar nuevas metodologías que les permitan sugerir productos que se ajusten a las preferencias de sus clientes. En la industria de la moda, es un desafío sugerir productos de interés, considerando la gran cantidad de atributos involucrados en las prendas y el factor de subjetividad presente al momento de realizar una compra. El problema se abordará desde el desarrollo de un sistema de recomendación de prendas para una marca de ropa local. El objetivo de esta investigación es facilitar la toma de decisiones, mejorar la percepción del cliente sobre la experiencia de la tienda y permitir que la empresa satisfaga las necesidades del mercado. En consecuencia, el sistema de recomendación considera tres pasos diferentes durante la experiencia de compra en la marca de ropa local, el vendedor sugerirá prendas dependiendo del punto de la ruta donde se encuentre el cliente: Bienvenida, fila de pago y caja. Se utilizaron varias técnicas como el análisis de datos, el análisis de Pareto, el análisis RFM, la segmentación del mercado y las reglas de asociación, para dar una idea de los datos y transformarlos en acciones utilizables para el diseño del sistema. Para que el vendedor pueda visualizar claramente las recomendaciones fue creada una aplicación.It is an overwhelming experience for the client to find content of his interest within a wide range of existing options, therefore, companies have seen the need to implement new methodologies that allow them to suggest products that fit their customers’ preferences. In the fashion industry it is a challenge to suggest products of interest, considering the large number of attributes involved in the garments and the subjectivity factor present at the time of making a purchase. The problem will be addressed by developing a garment recommendation system for a local clothing brand. The objective of this research is to ease decision making, improve the customer perception of the store's experience and allow the company to meet the needs of the market. Consequently , the recommendation system considers three different steps during the shopping experience in the local clothing brand, the vendor will suggest garments depending on the point of the route where the client is: Welcome, checkout line, register. Several techniques like data analysis, Pareto analysis, RFM analysis, market segmentation and association rules, were used to give an idea of the data and transform it into usable actions for system design. In order that the seller can clearly visualize the recommendations, an application was developed.Ingeniero (a) IndustrialPregrad