José Manuel Salmerón

Climatic applicability of downdraught cooling in Europe

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−WBT) and 25°C−WBT, and in the cooling requirements for each location. The meaning of the climatic characteristics will be explained in the text; as the first climatic characteristic represents the potential of using the evaporative systems to cool the air, and the second one shows the potential of cooling the building with a system that theoretically could supply the air in wet bulb conditions. The potential opportunity of using different types of downdraught cooling solutions, such as passive downdraught evaporative cooling and hybrid downdraught cooling, as an alternative to conventional air conditioning was assessed for different climate regions. A detailed version of a part of the Europe map will be done in order to take into account the particularities of a country like Spain. This set of maps will show the same parameters but with more resolution. Finally, six cities representing major climatic regions were selected for climatic analysis. This resulted in the identification of three climate zones for downdraught cooling application in Europe, and the suggestion of appropriate design strategies for each one of them.

Analysis of a PHDC (Passive and Hybrid Downdraft Cooling) Experimental Facility in Seville and its Applicability to the Madrid Climate

Abstract The potential application of Passive and Hybrid Downdraught Cooling to residential buildings is explored using an experimental facility constructed and tested in Seville, Spain. The experiment was devised as a prototype of the downdraught evaporative cooling system for the Nottingham University entry to the 2010 Solar Decathlon Europe competition. The experiment shows that peak evaporative cooling is obtained with an airflow rate of 2000 m3/hour (about 25 air changes per hour) and an evaporation rate of 8 L/h of water. The resulting indoor temperature in the space can be from 1 to 2 degrees above the inlet temperature. Wind forces can improve the performance but are not reliable and the air supply inlet should therefore be baffled to prevent negative impacts. Naturally driven evaporative cooling requires a control system which can vary the water supply rate in response to changing internal and external conditions. The use of exhaust fans can provide reliable performance, irrespective of external wind pressures, which suggests that a hybrid system (a combination of naturally and fan driven airflow) will be more robust in responding to variable conditions.

Potential of Night Ventilative Cooling Strategies in Office Buildings in Spain - Comfort Analysis

Abstract Night ventilation has been applied successfully to many passively-cooled or low-energy office buildings. This paper analyses the thermal comfort achievable in office buildings in Spain according to European standard EN 15251:2007. Furthermore, the comfort level is evaluated using the Degree Hours (DH) criteria and the maximum indoor temperature. Considering the high interest of architects and engineers in the evaluation of optimal comfort condition as a function of building typology (8 typologies), glazing ratio (30% and 60%) and climate (12 different Climate Zones), a total of 192 different study cases were simulated. For every case, an optimal air change per hour (ac/h) that can range from 1 to 50 ac/h was then determined. The research shows that passive night ventilation should be considered as an effective strategy for all Spanish Climates to reduce cooling demand in buildings with high daily internal gains (i.e. office buildings), improving comfort conditions and flattening peak temperatures.

The globe thermometer in comfort and environmental studies in buildings

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 in their investigation by not having low cost tools that can provide information for their studies. This article is a review of the present state of art about the globe thermometer. It describes how to build your own globe temperature sensor and describes experiments that illustrate the feasibility of using a black globe thermometer with 40 mm diameter.

Gestión y rehabilitación energética de edificios existentes: procedimiento experimental de diagnosis y caracterización energética

Resumen Uno de los factores esenciales para la gestion y rehabilitacion energetica de edificios existentes es establecer un procedimiento practico y eficiente, a partir del control distribuido y de la monitorizacion inteligente, tratando de automatizar los procesos de funcionamiento, conocer el estado de las instalaciones, monitorizar las variables criticas y recibir informacion on-line y off-line del rendimiento de las mismas con el fin de asegurar las condiciones de confort en un contexto de consumo de energia racional. Todo ello se concretiza en el desarrollo de un nuevo modelo para la prediccion del consumo energetico de edificios. Esta prediccion se realiza en dos niveles: horario, con un modelo derivado de las funciones de transferencia aplicadas a la edificacion, y diario, con un modelo simplificado a partir del anterior. El objetivo es conseguir un consumo inteligente de energia, y sobre todo eficiente a traves de la implementacion progresiva de medidas de ahorro de energia

A monitoring system for identification and validation of the energetic model of a building using Wireless Sensor Networks

Buildings are, at a large extent, responsible for the carbon footprint, and regulation laws are emerging to reduce it. To this end energy saving policies must be established per individual building, involving building analysis and modeling, model identification and validation, proposal of actions to improve the energy efficiency, estimation of energy savings using that building model, implementation of the improvement actions, and experimental verification of the energy savings. The final objective is not only a reduction in the greenhouse emission, but also to get monetary savings that make these improvement actions attractive to building owners or holders. A key element in this process is the ability of measuring a set of variables regarding energy consumption, climate, and operating conditions of the building, Wireless Sensor Networks (WSNs) is a suitable technology for this proposal, due to its installation easiness, low cost and good performance. In this paper, an application layer has been designed on top of a ZigBee protocol for identification and validation of the energetic model of a building for the purposes of increasing its energy efficiency. A practical implementation in the 20.000 m2 School of Engineering, University of Seville, is also shown where one hundred sensors were deployed in a section of the building. A hybrid network (wired and wireless) has been used to cover such a large area taking profit of existing infrastructure.

Ventilación natural: estudio aerodinámico mediante CFD de extractores pasivos y captadores de viento

La ventilacion natural se ha ganado protagonismo en los ultimos tiempos como una medida de ahorro de energia para edificios. Los dos principios fundamentales de ventilacion natural son el tiro natural por diferencia de temperatura, y la fuerza del viento. El articulo pretende analizar la aerodinamica de los captadores y extractores de viento mediante fluido-mecanica computacional, optimizando las geometrias de estos elementos, y dando como producto del trabajo un modelo simplificado para poder tenerlos en cuenta el calculo aeraulico de las instalaciones de ventilacion y climatizacion de los edificios. Concretamente, se caracteriza una base de geometrias de captacion de viento, y se elabora una guia para el diseno de geometrias de extraccion ofreciendo varias de ellas como producto del trabajo realizado.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 mechanics, optimizing the geometries of these elements, and giving a simplified model as a result of the work, so as to include it in the aeraulic calculation of the buildings’ air conditioning systems. Therefore, a base for wind catching geometries has been characterized, and a guide for the design of extraction geometries has been developed; several of them are offered as a result of the work undertaken.

Natural ventilation: CFD aerodynamic study about passive extractor and windcatcher

La ventilacion natural se ha ganado protagonismo en los ultimos tiempos como una medida de ahorro de energia para edificios. Los dos principios fundamentales de ventilacion natural son el tiro natural por diferencia de temperatura, y la fuerza del viento. El articulo pretende analizar la aerodinamica de los captadores y extractores de viento mediante fluido-mecanica computacional, optimizando las geometrias de estos elementos, y dando como producto del trabajo un modelo simplificado para poder tenerlos en cuenta el calculo aeraulico de las instalaciones de ventilacion y climatizacion de los edificios. Concretamente, se caracteriza una base de geometrias de captacion de viento, y se elabora una guia para el diseno de geometrias de extraccion ofreciendo varias de ellas como producto del trabajo realizado.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 mechanics, optimizing the geometries of these elements, and giving a simplified model as a result of the work, so as to include it in the aeraulic calculation of the buildings’ air conditioning systems. Therefore, a base for wind catching geometries has been characterized, and a guide for the design of extraction geometries has been developed; several of them are offered as a result of the work undertaken.