Francisco José Sánchez de la Flor

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• Doctor Ingeniero Industrial
• Full professor at Universidad de Cádiz

This work presents a study of a ventilated hollow core slab system (VHCS) that obviates the need to completely replace the slab of an existing residential building. It is assimilated to a heat exchanger to allow its effectiveness to be studied as a function of the area and airflow rate. The balance between the energy consumed by the fan and the hea...

Novel Ultra-Low Charge (ULC) ammonia chillers are being investigated as a highly efficient and sustainable solution in the field of refrigeration with natural fluids. These chillers were conceived to minimize the refrigerant charge using air-cooled condensers, semi-hermetic compressors, and direct expansion evaporators, becoming reliable solutions...

The article is devoted to an overview of the current situation in the renewable energy sector of the Russian Federation. The modern structure of electricity generation in Russia is shown. The main barriers hindering the more active development of renewable energy, as well as the potential for the development of renewable energy use, are considered....

This work presents a new parametric correlation for 2D enclosures with forced convection obtained from CFD simulation. The convective heat transfer coefficient of walls for enclosures depends on the geometry of the enclosure and the inlet and outlet openings, the velocity and the air to wall temperature difference. However, current correlations not...

The temperatures required by ultra-low temperature applications, ranging from -50°C to -100°C, cannot be reached economically with single stage systems because of the limitation of the compression ratio. Different types of solutions such as cascade or two-stage systems could be implemented to achieve the desired working conditions. However, these s...

Sustainable passive design strategies can reduce the energy consumption of buildings. In this regard, inner courtyards act as microclimate modifiers that enhance the perception of comfort in the surrounding environment. The present study, through a pooled analysis of experimental and numerical data, intends to assess the beneficial effect that the...

Environmental restrictions on the use of fluorinated refrigerants are turning the attention to natural solutions. Ammonia is historically proven as a refrigerant that requires low purchasing costs, has superior thermodynamic properties, and exhibits great values of coefficient of performance. Therefore, considering ammonia safety issues, solutions...

The 2030 climate and energy framework includes EU-wide targets and policy objectives for the period 2021–2030 of (1) at least 55% cuts in greenhouse gas emissions (from 1990 levels); (2) at least 32% share for renewable energy; and (3) at least 32.5% improvement in energy efficiency. In this context, the methodology of the cost-optimal level from t...

Refrigeration industry is adopting a proactive strategy to phase out fluorinated greenhouse gases by more sustainable working fluids. R744 is a natural refrigerant widely proposed for commercial refrigeration. Its use in cascade and booster cycles allows a combined cooling and freezing production. However, when single-stage evaporation at low tempe...

Featured Application Multi-objective optimization problem: to minimize the annual heating demand of the building and the standard deviation of the annual demand of the different dwellings. Avoiding excessive insulation reduces the risk of overheating in summer. Abstract Buildings are known to be responsible for about a third of energy consumption...

The natural refrigerant R744 seems to be the long term solution to be imposed in the food retail industry, where low and medium refrigeration temperatures are usually required, despite the technical difficulties related to high the pressure, especially in warm climates, leading to trans-critical operation with the consequent COP reduction. To overc...

Residential buildings built in the middle of the last decade, at the height of the real estate bubble, must fulfil the global thermal transmission coefficient of the building (Kg) according to the Basic Building Standard (NBE) CT-79 about thermal conditions in buildings, previous to the implementation of the Basic Document of Energy Saving of the T...

This study presents the results of a numerical and experimental study of the position of the baffles in a solar air heater in order to improve its thermal and hydraulic performance. The numerical study was performed on four cases corresponding to different placements of baffles with Reynolds numbers ranging from 2370 to 8340. The experimental model...

The Urban Heat Island phenomenon is an increasingly important global issue. Understanding the physical characteristics of cities is critical, which is why many studies based on mobile measurements are currently being developed. However, it is highly challenging to compare them due to the various methods that are employed. Therefore, the present wor...

To understand the importance of implementing energy-saving technologies in educational buildings, it is necessary to assess current energy consumption. The main goal of the article is to show the level of energy consumption of educational buildings in Russia. The main method of the study is to collect information from various sources and to analyze...

The main reasons for the high energy consumption of residential multi-apartment buildings in Russia are the lack of motivation of developers in the construction and equipment of new buildings with a high energy efficiency class, as well as the insufficient number of energy metering devices. The main solution to the problem may be state support for...

The reduction of energy consumption in the residential sector presents substantial potential through the implementation of energy efficiency improvement measures. Current trends involve the use of simulation tools which obtain the buildings’ energy performance to support the development of possible solutions to help reduce energy consumption. Howev...

This research seeks to quantify the economic condemnation that residential buildings' end users have to endure, despite being built in the middle of the last decade, in full real estate bubble. They strictly comply with the Basic Building Standard CT-79 on thermal conditions of buildings, prior to the entry into force of the Technical Building Code...

Global energy consumption for cooling applications is increasing every year, accelerating the fossil fuels consumption and the CO2 emissions. To improve the performance of the vapour compression cycles, ejectors can use the low grade wasted energy as a means of heat recovery. Several proposals have been studied to improve the global Coefficient Of...

The effort made by researchers and companies to reduce the expected increase in the energy demand for cooling and air conditioning has generated an interest in ejector cooling technologies. Researchers have proposed several typologies of ejector cooling cycles. However, the Coefficient of Performance achieved by this type of cycles is still poor, m...

Our present standard of living depends strongly on energy sources, with buildings being a primary focus when it comes to reducing energy consumption due to their large contribution, especially in tertiary buildings. The goal of the present study is to evaluate the performance of two different designs of hybrid systems, composed of natural gas engin...

In most countries, energy efficiency at the residential level has been largely delegated to the dynamics of real-estate markets after setting a minimum level. This regulatory definition is in certain cases supplemented by energy performance certificates, such as in the case of the European Union. This approach is based on the understanding that avo...

This study presents new correlations for internal forced convective heat-transfer coefficients (CHTCs) in buildings. CHTCs are used by building energy performance simulation (BES) tools to estimate the annual heating and cooling demands of buildings. Most programs use constant values or correlations but do not consider in detail the 3D geometry or...

Highlights Courtyards may be a good passive strategy for enhancing thermal comfort and reducing the energy demands of buildings. It is necessary to quantify the air temperature drop in the courtyards of buildings in dominant summer climates. Computational Fluid Dynamics (CFD)-based methods have the drawback of high computational cost and complexity...

This paper presents new correlations to calculate natural convection heat transfer coefficients (CHTC) in enclosures for building performance simulation. Current work related to the development of correlations is not oriented to building enclosures, and the influence of high numbers of Rayleigh (Ra) and aspect ratio on the CHTC has not been studied...

Este trabajo tiene como objetivo calcular de forma detallada los caudales de ventilación e infiltración y analizar su influencia sobre la demanda energética de edificios con uso residencial en España. Actualmente el Código Técnico de la Edificación (CTE) es la normativa española que regula los criterios de diseño, cálculo y la ejecución de las inst...

The reasons for the inferior performance of many existing buildings and associated energy systems are diverse, but an important part-cause is insufficient attention to the influence of occupant behaviour. In smart buildings it is necessary to allow for the integration of human behaviour in the HVAC system. In addition, many researchers are limited...

Most of the energy consumed in cooling cycles comes from fossil fuels, whose reserves are becoming depleted. The aim of this article is to show the potential benefits of using ejectors in cooling systems to improve its energetic efficiency. A review of different configurations of ejector cooling systems has been carried out for being compared again...

This study presents a method for estimating the temperature reached by the active layer of dye sensitised solar cells (DSSC) by applying a mathematical model based on a second-order lumped parameter model which takes into account the thermal resistance and heat storage capacities of the different layers of the DSSC. To obtain the input necessary fo...

A novel method for adjusting the parameters of a lumped parameter model for the transient thermal response of building constructions is presented. Previous analytical adjustment methods can be complex and inaccurate, while optimization algorithms, although more accurate, require prior simulation using a high-order reference model, and so provide no...

In most of the countries, energy efficiency has been delegated to the dynamics of real estate markets, after regulating a minimum legal (although not optimal) efficiency level. So, it is expected that high efficient housing stock receives a market premium that, at least, equals the over-cost invested in improved thermal insulation and more efficien...

At present, actions for the rehabilitation of cities, districts and buildings are being promoted for tertiary as well as for residential buildings. However, the difficulty of assessing the energy savings achieved after energy efficiency improvement measures (or even worse, a combination of them which have cross effects) with enough certainty is wel...

Designing a low energy building requires to evaluate a large number of parameters: design combinations, element thermal characteristics, HVAC systems efficiencies, etc. All of them determine the space heating and space cooling energy demands, energy consumptions, and life cycle cost over the lifetime of the building. This paper presents the achieve...

In Office buildings in Chile, cooling energy demand is higher than heating demand. The climate of the country show important differences between cities by the ocean and those of interior regions. Main cities of Central Chile are Santiago and Valparaíso, both located at around 33°S. Santiago presents a Mediterranean climate, with a high temperature...

Designing a low-energy building requires the evaluation of a large number of parameter combinations. Currently, there are several software programs available that are able to calculate the energy performance and life-cycle cost. However, these programs provide little information regarding what actions will improve the energy performance and how muc...

This research focuses on the influence of outdoor convective heat transfer coefficient on thermal load calculation in Building Energy Simulation programs. In building energy is commonly used the overall heat transfer coefficient value (U-value) to characterize external walls and windows in terms of heat gam or loss through them. Thus, the higher th...

This paper aims to present the more recent advances regarding the climatic zoning based on the Climate Severity Index and its relation with the building energy requirements. Three are the major contributions in this paper, the first one is the comparison of the energy performance requirements in different European Union Member States; secondly the...

The Spanish Technical Building Code is one of the three royal decrees that were approved in Spain as a consequence of the transposition of the European Directive on the energy performance of buildings (2002/91/EU, 2002). One basic document of the Technical Building Code deals with the limitations of building energy demands. Nowadays, due to the rec...

This study describes the work on the development of climatic applicability maps of downdraught cooling in Europe; this work is presented as an extension of the work developed in the PHDC project, 2008–2010. The approach is based on a set of maps, which are based on two related climatic characteristics: dry bulb temperature–wet bulb temperature (DBT...

PHDC is an international project with the objective of promoting use of passive and hybrid cooling systems in buildings between design professionals, builders, owners and users. This article describes some of the systems PHDC analized. Under this project, work of the authors produces two tools for improving and optimization of the objective of proj...

PHDC is an international project with the objective of promoting use of passive and hybrid cooling systems in buildings between design professionals, builders, owners and users. This article describes some of the systems PHDC analized. Under this project, work of the authors produces two tools for improving and optimization of the objective of proj...

The design and performance of a passive downdraught evaporative cooling (PDEC) system are reported. This is the first application of this technique for housing in Europe. The system was integrated within a house designed and built by University of Nottingham students for the 2010 Solar Decathlon Europe event in Madrid, Spain. Testing of the thermal...

Abstract PHDC is an international project with the objective of promoting use of passive and hybrid cooling systems in buildings between design professionals, builders, owners and users. This article describes some of the systems PHDC analized. Under this project, work of the authors produces two tools for improving and optimization of the objectiv...

In recent years, natural ventilation has won popularity as an energy saving measure for buildings. There are two fundamental principles of natural ventilation: natural draft by temperature differences, and wind force. The purpose of the article is to analyze the aerodynamics of windcatchers and wind-extractors by means of computational fluid mechan...

Resumen La ventilación natural se ha ganado protagonismo en los últimos tiempos como una medida de ahorro de energía para edificios. Los dos principios fundamentales de ventilación natural son el tiro natural por diferencia de temperatura, y la fuerza del viento. El artículo pretende analizar la aerodinámica de los captadores y extractores de vient...

It has been demonstrated that there is a strong relationship between occupant behaviour and the thermal performance of dwellings. At the same time, some aspects of this behaviour, especially with respect to natural ventilation, constitute some of the most important sources of uncertainty in the field of building energy simulation. A survey about pe...

It is clear that the thermophysical properties of materials, occupancy patterns and internal gains represent some of the most important sources of uncertainty in the field of building simulation. Uncertainty and sensitivity analysis deals with this situation, since it can generate a great range of forecast values based on the distribution of the in...

It is clear that the thermophysical properties of materials, occupancy patterns and internal gains represent some of the most important sources of uncertainty in the field of building simulation. Uncertainty and sensitivity analysis deals with this situation, since it can generate a great range of forecast values based on the distribution of the in...

It has been found that, among the tools and methods available for the energy calculation of double envelope elements, there are some debatable aspects such as: the selection of correlations for calculating the convective heat transfer coefficient and the procedure for calculating the temperature of the air layer. In addition, the validation of some...

The main requirements of European Directive 2002/91/EC on the energy performance of buildings (EPBD) are the application of minimum energy performance requirements for new buildings and certification of the energy performance of buildings. Its transposition into the national law of member states of the European Union has signified the appearance of...

Passive cooling techniques such as night time cross ventilation can potentially provide substantial cooling energy savings in warm climates. The efficiency of night cooling ventilation is determined by three main factors: the external airflow rate in the room, the flow pattern and the thermal mass distribution. The aim of this paper is to analyse t...

Great efforts have been made to establish the influence of the urban climate upon the energy consumption of buildings. While many scientific articles present measured data of increased energy consumption due to building surroundings, this paper aims to present a straightforward methodology for the assessment of building performance under modified o...

The present article shows a new methodology of calculation of the direct, diffuse and reflected incident solar radi-ation, in all type of surfaces, either in open urban environments or inside buildings. This methodology is applicable in problems related to solar access (space heating in buildings, shadowing of open spaces), solar gains (space cooli...

A low energy technique for heat removal from the interior of a building under summer conditions is the employ of natural ventilation. There are several ways to promote this ventilation. The use of Trombe walls to obtain this objective is studied in the present work, with the aid of a combined mathematical- differences finites model. This is a trans...

The present paper, presents a computational model that assess the modification of the climatic variables in an urban context, and how they affect to the thermal performance of urban buildings. There is a clear interaction between both systems, and they are able to modify their mutual energy balances. Therefore, a coupling of the urban model and the...

The building sector represents a great percent-age of the total consumption of energy of a country, and of this, most is due to the existing buildings. The great number of existing build-ings in comparison with the new buildings, and the worst constructive quality in the first ones, they explain the previous asseveration. It is, therefore, of a pri...