Modélisation et simulation d'une cellule test en plein air pour l'évaluation énergétique des composants d’enveloppe

The article presents the thermal modelling and simulation work that will constitute the basis for the design of an outdoor test cell. The facility aims at characterizing the thermo-physical properties of transparent and opaque envelope components under real weather conditions, and to study the impact of different air-conditioning configurations on the indoor thermal comfort and indoor air quality. The response delay of the calorimetric measure is particularly critical when trying to achieve a good quality of measurement in rapidly-varying weather conditions. For this reason, the thermal behaviour of the test cell has been described, by means of a lumped parameter model, to simulate a range of operating conditions. The results are used to evaluate the thermal inertia of different solutions, refine the design choices and the most promising control strategies. The article presents the thermal models used to compare the test cell to a traditional installation in terms of calorimetric accuracy under transient external conditions

Design choices and thermal simulations of a new test cell facility

The paper presents a new test cell facility, named Box Office and under development at the Ecole Spéciale des Travaux Publics (ESTP Paris) for the analysis and characterization of the thermo-physical properties of building envelope components under real climate conditions. The facility will allow to obtain reliable estimates of thermal performance indicators of transparent and opaque building elements. Particular care has been taken in the design phase in order to minimize or to monitor all sources of uncertainty, such as (i) conductive heat losses through the test cell envelope, (ii) time lag of response to transient outdoor conditions, (iii) levels of airtightness and of resistance to vapour or water penetration. Highly variable solar conditions can seriously affect both the correct functioning of outdoor test facilities and the indoor climate conditions in the cell. For this reason, the thermal behaviour of the Box Office was simulated in Matlab environment, implementing a lumped-parameter model, and results are used for refining the design choices and selecting the most promising operative conditions and control strategies. The output of test cell experiments will be beneficial to various target groups, such as designers and manufacturers (to boost the research and development of new products), research centres (to fully understand and model the physical phenomena occurring in a controlled space facing real outdoor conditions) and potential clients, who ask for economically affordable solutions guaranteeing high levels of Indoor Environmental Quality

Multi-objective optimization of a nearly zero-energy building based on thermal and visual discomfort minimization using a non-dominated sorting genetic algorithm (NSGA-II)

Multi-objective optimization methods provide a valid support to buildings' design. They aim at identifying the most promising building variants on the basis of diverse and potentially contrasting needs. However, optimization has been mainly used to optimize the energy performance of buildings, giving secondary importance to thermal comfort and usually neglecting visual comfort and the indoor air quality. The present study addresses the design of a detached net zero-energy house located in Southern Italy to minimize thermal and visual discomfort. The optimization problem admits four objective functions (thermal discomfort during winter and summer and visual discomfort due to glare and an inappropriate quantity of daylight) and uses the non-dominated sorting genetic algorithm, implemented in the GenOpt optimization engine through the Java genetic algorithms package, to instruct the EnergyPlus simulation engine. The simulation outcome is a four-dimensional solution set. The building variants of the Pareto frontier adopt diverse and non-intuitive design alternatives. To derive good design practices, two-dimensional projections of the solution set were also analyzed. Finally, in cases of complex optimization problems with many objective functions, optimization techniques are recommended to effectively explore the large number of available building variants in a relatively short time and, hence, identify viable non-intuitive solutions

Conception of a new test cell facility for characterizing building envelope components

Outdoor test cells have been extensively used for analyzing the thermo-physical properties of building envelope components under real climate conditions. The paper presents a new test cell facility, under development at the Ecole Spéciale des Travaux Publics, du Bâtiment et de l'Industrie (ESTP Paris) within the framework of a collaboration between the end-use Efficiency Research Group of Politecnico di Milano and ESTP. The facility will allow to obtain reliable estimates of thermal performance indicators of transparent and opaque building elements. A particular care has been taken in the design phase in order to minimize or to accurately evaluate all sources of uncertainty, such as (i) conductive heat losses through the test cell envelope, (ii) time lag of response to transient solar conditions, (iii) levels of airtightness and of resistance to vapour or water penetration.

La riqualificazione energetico ambientale degli edifici, ottimalità in funzione dei costi e zero energia

Il settore edile è ritenuto cruciale per raggiungere gli obiettivi 20/20/20 dell’UE. L’Europa mira inoltre a conseguire riduzioni delle emissioni di gas serra nei settori residenziale e terziario rispettivamente dell’88% e 91% rispetto al 1990 entro il 2050. Con la revisione delle due direttive Energy Performance of Buildings Directive (EPBD) e Energy Efficiency Directive (EED) e la pubblicazione delle Regulation e Guidelines che stabiliscono un methodology framework for calculating cost-optimal levels of minimum energy performance requirements for buildings and building elements cost-optimal, si è impostato il quadro generale per procedere lungo questa direzione. Due meccanismi saranno decisivi per lo sviluppo del settore edile: il principio degli edifici a energia quasi zero e il Il principio di ottimalità in funzione dei costi

Multi-objective optimization of a nearly zero-energy building based on thermal and visual discomfort minimization using a non-dominated sorting genetic algorithm (NSGA-II)

Multi-objective optimization methods provide a valid support to buildings’ design. They aim at identifyingthe most promising building variants on the basis of diverse and potentially contrasting needs. However,optimization has been mainly used to optimize the energy performance of buildings, giving secondaryimportance to thermal comfort and usually neglecting visual comfort and the indoor air quality.The present study addresses the design of a detached net zero-energy house located in Southern Italyto minimize thermal and visual discomfort. The optimization problem admits four objective functions(thermal discomfort during winter and summer and visual discomfort due to glare and an inappropriatequantity of daylight) and uses the non-dominated sorting genetic algorithm, implemented in the GenOptoptimization engine through the Java genetic algorithms package, to instruct the EnergyPlus simulationengine.The simulation outcome is a four-dimensional solution set. The building variants of the Pareto frontieradopt diverse and non-intuitive design alternatives. To derive good design practices, two-dimensionalprojections of the solution set were also analyzed. Finally, in cases of complex optimization problemswith many objective functions, optimization techniques are recommended to effectively explore the largenumber of available building variants in a relatively short time and, hence, identify viable non-intuitivesolutions

Improved methods for the calorimetric determination of the solar factor in outdoor test cell facilities

Calorimetric methods for the performance assessment of building components have been largely applied in indoor laboratories and under steady-state conditions. Although effects of one or more outdoor weather parameters are sometimes mimicked by means of dynamic schedules, they never fully reproduce the complex interactions of the stochastic processes typical of real climate. The present work introduces improved measurement procedures to determine the solar factor under dynamic conditions, applicable to outdoor test cell experiments and which take into account the variation of internal energy in the control volume. An in-depth uncertainty analysis has been conducted in order to highlight the most relevant uncertainty sources and to suggest improvements to the measurement techniques. Based on an iterative application of the uncertainty analysis, we developed and optimised two new strategies to extract and measure the solar load entering through a test sample and a new design concept of test cell facility, which allows the configuration to be adapted according to various test objectives. In order to accurately analyse the storage and delay effects of the thermal capacities within the control volume of the calorimeter, lumped-parameter models of three alternative designs (the two proposed strategies and a reference, traditional one) have been developed and coded in Matlab. The simulation results suggest that, compared to a traditional solution, the two proposed solutions offer a higher measurement accuracy and measurement precision in the determination of the solar factor. In addition, the results indicate that rapidly variable solar irradiance levels are detrimental to the accuracy level of the solar factor measurement; therefore tests should be carried out under stable clear sky conditions

Retrofit of a Kindergarten Targeting Zero Energy Balance

Old buildings that are severe energy wasters and provide low indoor environmental quality (IEQ) form a large fraction of the European building stock. These buildings represent nevertheless, an asset that should be re-evaluated in order to promote local communities development. This paper describes the study that supported the design for the zero energy retrofit of a kindergarten as part of a renovated smart district. The work will substantially reduce the energy needs for heating and cooling while improving IEQ. Prefabricated modules, including mechanical ventilation and solar shading are proposed and particular attention is given to natural, mechanical and hybrid ventilation

Energy retrofit for a climate resilient child care centre

Climate scientists have developed and refined climate change models on a global scale. One of the aims of these models is to predict the effects of human activities on climate, and thus the delivery of information that is useful to devise mitigation actions. Moreover, if they can be properly downscaled to a regional and local level, they might be useful to deliver support for adaptation actions. For example, they may be used as an input for the better design of the features of buildings in order to make them resilient to climate modification, e.g., able to passively control heat flows to produce comfortable indoor conditions not only in the present climate, but also in future climate conditions. Taking into account the future weather scenarios that show an increase in the global temperature and climate severity, a likely consequence on building energy use will be a substantial shift from space heating to space cooling, and potentially uncomfortable thermal conditions during the summer will became a major challenge, both for new and existing buildings. In this paper, a deep energy retrofit of a child care centre located in Milan (Italy) is analysed on the basis of future weather scenarios; the analysis aims to identify to what extent choices that are made nowadays on the basis of a typical meteorological year may succeed to provide acceptable energy and indoor environmental performance throughout the future decades. The analysis confirms that climate change might require the installation of active cooling systems to compensate for harsher summer conditions over a long-term horizon, however, in the mid-term, passive cooling strategies combined with envelope refurbishment may still guarantee thermally comfortable conditions, and they will reduce energy cooling needs when active cooling is eventually installed