Improving summer energy performance of highly insulated buildings through the application of a thermal analysis by numerical simulation

The work presented in this paper is aimed at deepening the optimisation of the energy performance of highly insulated buildings in summer conditions through the application of an original methodology of thermal analysis. The methodology, already presented in a previous work (Ballarini et al., 2011), allows us to investigate the building energy balance and identify the most important parameters affecting the energy performance under certain conditions. The analysis is developed through the application of a dynamic simulation tool (EnergyPlus). The methodology consists of analysing the different contributions to the convective energy balance on internal air and their interrelations with different boundary conditions. Each contribution is split according to the dynamic driving forces of outdoor and indoor environment, i.e. external air temperature, solar radiation, internal air temperature and internal heat sources, and it is referred separately to the specific groups of components that exchange heat with internal air. This work focuses on the application of the above thermal analysis to a highly insulated single-family house in summer conditions, in two different Italian climatic zones. The methodology provides the mean values and the standard deviations of the contributions to the convective energy balance on internal air, and allows both to identify the main causes of low energy performance and to quantify the effects of possible retrofit or operational measures. As an exemplification, the effect of increasing the air change rate by natural ventilation during the night is investigated. The results show how the energy performance could be improved also in highly insulated buildings located in warm climate

Improving summer energy performance of highly insulated buildings through the application of a thermal analysis by numerical simulation

The work presented in this paper is aimed at deepening the optimisation of the energy performance of highly insulated buildings in summer conditions through the application of an original methodology of thermal analysis. The methodology, already presented in a previous work (Ballarini et al., 2011), allows us to investigate the building energy balance and identify the most important parameters affecting the energy performance under certain conditions. The analysis is developed through the application of a dynamic simulation tool (EnergyPlus). The methodology consists of analysing the different contributions to the convective energy balance on internal air and their interrelations with different boundary conditions. Each contribution is split according to the dynamic driving forces of outdoor and indoor environment, i.e. external air temperature, solar radiation, internal air temperature and internal heat sources, and it is referred separately to the specific groups of components that exchange heat with internal air. This work focuses on the application of the above thermal analysis to a highly insulated single-family house in summer conditions, in two different Italian climatic zones. The methodology provides the mean values and the standard deviations of the contributions to the convective energy balance on internal air, and allows both to identify the main causes of low energy performance and to quantify the effects of possible retrofit or operational measures. As an exemplification, the effect of increasing the air change rate by natural ventilation during the night is investigated. The results show how the energy performance could be improved also in highly insulated buildings located in warm climates

A comparative analysis of different future weather data for building energy performance simulation

The building energy performance pattern is predicted to be shifted in the future due to climate change. To analyze this phenomenon, there is an urgent need for reliable and robust future weather datasets. Several ways for estimating future climate projection and creating weather files exist. This paper attempts to comparatively analyze three tools for generating future weather datasets based on statistical downscaling (WeatherShift, Meteonorm, and CCWorldWeatherGen) with one based on dynamical downscaling (a future-typical meteorological year, created using a high-quality reginal climate model). Four weather datasets for the city of Rome are generated and applied to the energy simulation of a mono family house and an apartment block as representative building types of Italian residential building stock. The results show that morphed weather files have a relatively similar operation in predicting the future comfort and energy performance of the buildings. In addition, discrepancy between them and the dynamical downscaled weather file is revealed. The analysis shows that this comes not only from using different approaches for creating future weather datasets but also by the building type. Therefore, for finding climate resilient solutions for buildings, care should be taken in using different methods for developing future weather datasets, and regional and localized analysis becomes vital

Observation of long-lived polariton states in semiconductor microcavities across the parametric threshold

The excitation spectrum around the pump-only stationary state of a polariton optical parametric oscillator (OPO) in semiconductor microcavities is investigated by time-resolved photoluminescence. The response to a weak pulsed perturbation in the vicinity of the idler mode is directly related to the lifetime of the elementary excitations. A dramatic increase of the lifetime is observed for a pump intensity approaching and exceeding the OPO threshold. The observations can be explained in terms of a critical slowing down of the dynamics upon approaching the threshold and the following onset of the soft Goldstone mode

Improving energy modeling of large building stock through the development of archetype buildings

12th Conference of International Building Performance Simulation Associatio

La riqualificazione energetica del patrimonio edilizio residenziale europeo: il progetto di ricerca EPISCOPE

L’articolo illustra metodologie e risultati di analisi energetiche condotte su alcuni parchi edilizi residenziali europei nell’ambito del progetto IEE-EPISCOPE. La finalità della ricerca è verificare se l’attuale tendenza della riqualificazione sia sufficiente per conseguire le riduzioni di emissioni fissate dall’UE. I risultati mostrano che gli obiettivi saranno difficilmente raggiungibili senza l’applicazione di interventi più efficaci e l’incremento del tasso annuo di ristrutturazione

On the Cost-Optimal Design: Comparison of Quasi-Steady-State and Dynamic Simplified Methods of Calculation of H/C Energy Needs

The Directive 2010/31/EU promotes the improvement of the energy performance of buildings within the European Union, by taking into account indoor climate requirements and cost-effectiveness. Thus, the cost optimisation is one of the main objectives of the EU regulatory framework concerning the energy performance of both new buildings and existing buildings subject to refurbishment actions. When assessing the cost-optimal levels of energy performance, the calculation of the energy needs is usually carried out by means of CEN standards or equivalent national calculation methods, based either on steady-state or on dynamic simplified models. However, many research studies have pointed out the limitations of the steady-state approach, especially for high performance buildings. The aim of this work is to study how the calculation method - quasi-steady or dynamic - of the energy needs for heating and cooling, impacts on the final optimal design. This is done through the application of a cost-optimal procedure to a single-family house located in Milan. The building energy needs for space heating and cooling are calculated by means of the quasi-steady-state monthly method specified by the Italian standards and the simplified hourly dynamic model of ISO 13790. The performance of the thermal systems is then assessed by means of the national standards (UNI/TS 11300), while the global cost is evaluated by means of EN 15459. Several design options with increasing levels of energy efficiency are applied to the case study. The cost-optimal solutions derived from the application of the two methods are compared, and the reasons for the deviations are discussed

EPR enlightening some aspects of propane ODH over VOx\u2013SiO2 and VOx\u2013Al2O3

In the oxidative dehydrogenation (ODH) of propane to propylene VOx-based catalysts prepared by name pyrolysis (FP) showed more selective than those prepared by impregnation. Furthermore, samples prepared by the same method were less active, but more selective when VOx was supported on SiO2 than on Al2O3. In order to assess V local structure, V4+ ions showed useful labels to characterise these catalysts by EPR spectroscopy. Indeed, the spectrum of a (10 wt%V2O5) FP-prepared VOx/SiO2 catalyst was typical of isolated, tetragonally distorted, paramagnetic complexes of V4+ forming a monolayer on the sample surface with a strong out-of-plane V4+-O bond. In a sample with identical composition, but prepared by impregnation, this bond showed a bit weaker. Furthermore, ferromagnetic domains of clustered V ions formed in the latter sample, hindering at least in part the accessibility to the catalytically active V-based centres. This gives evidence of the higher dispersion of V in the sample bulk provided by the FP preparation method with respect to conventional ones. A by far weaker V4+-O bond was revealed by the EPR spectrum of a (10%V2O5) VOx/Al2O3 sample, accounting for its higher oxygen availability, leading to higher activity, but lower selectivity. However, the same catalyst, when prepared by impregnation, showed a ferromagnetic resonance pattern so intense that no EPR spectrum was detectable at all and no information on the V4+-O bond strength was available in that case. Such semi-quantitative index of the V-O bond strength can be used as an index of oxygen availability, as a tool to assess catalytic activity and selectivity to the desired olefin

Creatividad desde las neurociencias

La creatividad es una de las capacidades más importantes de los seres hu- manos, quizás una de las cuales nos distingan del resto de las especies. Investigar también es una acción humana de gran relevancia. Toda tesis doc- toral, todo artículo científico relevante ha de ser original y por tanto nece- sita de una mirada creativa. En este artículo vamos a tratar de explicar la importancia de la creatividad desde las aportaciones de las neurociencias y plantearnos en qué medida podemos introducir elementos de creatividad en nuestras investigaciones: ¿dónde está la clave de la creatividad?,¿qué pueden aportar las neurociencias a la creatividad para seguir investigando

Validació d’un test de natació, avaluant la velocitat aeròbica màxima (VAM) per tal de calcular els ritmes d’entrenament per a triatletes i nedadors

L’objectiu del present estudi és validar un test de natació avaluant la Velocitat Aeròbica Màxima (VAM) per a prescriure ritmes d’entrenament. Set triatletes i nedadors van nedar 400 m a la màxima intensitat possible, després van realitzar una prova triangular per avaluar la VAM. Una setmana més tard, es va mesurar el temps i la distància límit a VAM, així com el llindar làctic individual mitjançant un test progressiu composat per sis repeticions de 200 m a diferents velocitats. Una setmana després, els dos primers tests van ser repetits (retest). Tenint en compte que la mostra utilitzada per a desenvolupar el present estudi és molt petita i que l’índex de repetibilitat de la prova de VAM s’allunya un 3 % de l’interval de confiança, cal dir que existeixen diferents indicis com ara la duració del temps límit, la menor velocitat i el major VO2màx respecte a la prova de 400 m, que ens porten a pensar de que aquesta eina pot arribar a ser vàlida agafant una mostra d’estudi mol més gran