1,721,063 research outputs found
Genetic optimization of external fixed shading devices
No full textIn the present paper a genetic optimization (GO) has been carried out on an office room with a south facing window in order to design an optimal fixed shading device. Two different glazing systems have been taken into account, one standard double glass and an high performance glazing system specifically designed to prevent high sun loads. The shading device is a flat panel positioned parallel to the window and inclined by its horizontal axis. The device shades the window from direct sun penetration reducing the cooling loads in summer, but also affecting daylight and heat loads in winter limiting the sun gains, therefore the impact on the overall building energy consumption is investigated. A genetic optimization has been performed for identifying a possible geometry with the lower energy impact. Lighting loads, computed by the DAYSIM code, have been considered as inputs for the code ESP-r which drives the energy computation. The results demonstrate that electrical energy absorbed by the lighting system has to be always taken into account in designing energy efficient shading devices
Extension of the CFX 4.4 code for Periodic Heat Transfer Analysis
No full textThe CFX 4.4 code has been utilized to simulate the thermal field in periodic geometries subjected to uniform wall temperature boundary conditions. The problem is of great interest for compact heat exchanger development where complicated repetitive geometries are invariably utilized to augment the heat exchange surface. In presence of uniform wall temperature no periodic thermal field exist, therefore a proper non dimensional temperature has been defined leading to a new periodic boundary condition implemented in the CFX 4.4 code by means of the user Fortran subroutines. The extended code has been tested with some typical problems in forced convection in periodic domains with two and three dimensional geometries. The results obtained demonstrate the correctness of the adopted approach along with the capability of the commercial code CFX 4.4 to be adapted to the users demands
GENETIC OPTIMIZATION OF EXTERNAL FIXED SHADING DEVICES
No full textA genetic optimization approach has been used for the design of an external shading device in an office with a window and
different glass characteristics. The primary energy consumption for heating cooling and lighting have been minimized.
Simulations have been performed using the energy code ESP-r and lighting simulation package DaySim, the optimization loop
has been driven by the software tool modeFRONTIER. In the present paper a Genetic Optimization (GO) has been carried on
an office room with a south facing window. Two different glazing systems have been taken into account, one standard double
glass and an high performance glazing system specifically designed to prevent high sun loads. The shading device is a flat
panel positioned parallel to the window and inclined by its horizontal axis. The device shades the window from direct sun
penetration reducing the cooling loads in summer, but also affecting daylight and heat loads in winter limiting the sun gains,
therefore the impact on the overall building energy consumption is investigated. A genetic optimization has been performed for
identifying a possible geometry with the lower energy cost impact. Lighting loads computed by the DaySim code have been
considered as inputs for the code ESP-r which drives the Energy computation on an hourly basis. The results demonstrate that
electrical energy absorbed by the lighting system has to be always taken into account in designing energy efficient shading
devices
L'Ottimizzazione per il Risparmio Energetico negli Edifici
No full textPer raggiungere gli elevati standard richiesti i progettisti possono avvalersi di nuovi strumenti presenti sul mercato. Tra questi assume sempre maggiore importanza la simulazione dinamica del sistema edificio-impianto. Diversi sono i software disponibili, sia commerciali che open-source, che consentono un'accurata analisi delle prestazioni sia degli involucri edilizi sia dell'interazione di questo con sistemi impiantistici sempre più complessi. Il vantaggio rispetto al tradizionale calcolo semistazionario su base mensile o stagionale, è quello di poter effettuare analisi orarie o suborarie che consentono di prevedere compiutamente la dinamica dell'edificio, naturalmente a spese di un tempo di calcolo maggiore e soprattutto di un impegno ed una competenza richiesta decisamente maggior
A General Procedure for deriving Stabilized Space-Time Finite Element Methods for Advective-Diffusive Problems
No full textA procedure to derive stabilized space–time finite element methods for advective–diffusive problems is presented. The starting point is the stabilized balance equation for the transient case derived by Oñate using a finite increment calculus approach. A description of the new stabilization method and a procedure for computing the stabilization parameter of the space–time solution is given. The efficiency of the stabilization approach is shown in the solution of some transient advective–diffusive problems, including the non-linear Burger's equation. Copyright © 1999 John Wiley & Sons, Ltd
STABILITY CHARACTERISTICS OF TIME INTEGRATION SCHEMES FOR FINITE ELEMENT SOLUTIONS OF CONDUCTIVE-TYPE PROBLEMS
No full textFAST energy and daylight optimization of an office with fixed and movable shading devices
Full text linkThis paper describes the Energy and Daylighting optimization of a fixed inclined panel which shades an office room with a south exposed window. The window features also user deployable internal Venetian blinds. Energy analysis takes into account the primary energy required for heating, cooling and artificial lights. Different numerical codes have been employed in order to perform the simulations required by the optimization process: Daysim estimates the artificial light consumption based on daylighting distribution, ESP-r computes heating and cooling loads and modeFRONTIER integrates the simulation codes in an automatic optimization loop. The performance of an algorithm specifically designed to deal with problems involving long simulation times (combining response surfaces and genetic algorithms) has been successfully evaluated; the algorithm has then been applied in the optimization loop. The optimized solutions are analysed in this paper, in particular three solutions have been selected: minimum primary energy consumption, minimum hours of blind deployed and an intermediate solution. The analysis compares the primary energy consumption and daylighting performance on the basis of the Useful Daylight Illuminance indicator and the time history of illuminance on predefined locations
Multi-criteria energy and daylighting optimization for an office with fixed and moveable shading devices
Full text linkThis paper presents an optimization approach to design an external fixed shading device protecting an energy efficient office from high sun loads. The developed methodology takes into account heating, cooling and energy required for lighting appliances, along with the interaction with an internal moveable venetian blind for direct sunlight protection. The optimization process considers whole-year simulations performed with different software codes, specifically ESP-r for energy calculation and DAYSIM® for daylighting analysis, while the modeFRONTIER® tool synchronizes the simulations and drives the optimization for searching optimal solutions. The fixed shading device is a flat panel positioned parallel to the window and inclined by its horizontal axis and the optimization variables change the size, inclination and position of the device with respect to the building façade. Two exposures are considered, south and south-west, and the optimized results are reported as a Pareto front highlighting the performance of different solutions, comparing the energy and daylighting performance of the offic
DEVELOPMENT OF A STRATIFIED TANK STORAGE COMPONENT FOR ESP-R WITH EMBEDDED PHASE CHANGE MATERIAL MODULES
No full textSolar domestic hot water systems (SDHW) are very common and are considered an efficient system for exploiting the renewable energy source of the sun, for instance national Italian regulations require the adoption of SDHW systems in new buildings. Water tanks are typical components for such systems, but have a serious drawback since they require a great amount of space in buildings.
In this paper a new water tank model with embedded Phase Change Materials (PCM) modules for the ESP-r code is presented in order to assess the possibility of using reduced size water tanks with additional latent storage.
The paper describes the numerical model used to deal with phase change phenomena and the incorporation of the method into ESP-r source code. To validate the model the results of a test case have been compared with literature data. A typical SDHW system has been simulated in order to study the impact of the PCM modules inside tanks on the energy performance of the system. The results are reported using a global parameter that represents the fractional primary energy saved by using the solar system. Water temperature plots with and without PCM have been reported as well
Italian TRYs: New weather data impact on building energy simulations
Full text linkDynamic thermal simulation is attracting the interest of designers thanks to the availability of numerical codes. However, one of the main problems facing the potential users is hourly-weather data availability. In Italy, the main source for the data is drawn upon the IGDG database. It is provided by the EnergyPlus weather site and the related measurements were collected between 1951 and 1970. A new set of files, gathered between 1989 and 2014, has recently become available. Nevertheless, it needs additional work to be directly implemented in energy simulation codes, which can lead users to download and apply the already available IGDG database files. In order to evaluate the ensuing effects, 52 Italian weather file locations were selected, and two simulations were carried out on seven multifamily-house models considering the difference between the results obtained using the old and new weather data. Since the locations of the two databases do not coincide, a matching method was implemented. This paper compares the simulation results arising from the choice of the weather file pertaining to the two databases. The weather files were selected within a 50 km range and 50 m elevation difference, to minimize misrepresentative results due to different climatic conditions. The models are typical of the most widespread building typology of the Italian building stock. For each model, two building fabric types were considered, the former was poorly insulated, the latter was well insulated thanks to an advanced refurbishment activity. Simulations were carried out with the EnergyPlus software
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