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

The metal-poor Knee in the Fornax Dwarf Spheroidal Galaxy

We present alpha-element abundances of Mg, Si, and Ti for a large sample of field stars in two outer fields of the Fornax dwarf spheroidal galaxy (dSph), obtained with VLT/GIRAFFE (R~16,000). Due to the large fraction of metal-poor stars in our sample, we are able to follow the alpha-element evolution from [Fe/H]=-2.5 continuously to [Fe/H]=-0.7 dex. For the first time we are able to resolve the turnover from the Type II supernovae (SNe) dominated, alpha-enhanced plateau down to subsolar [alpha/Fe] values due to the onset of SNe Ia, and thus to trace the chemical enrichment efficiency of the galaxy. Our data support the general concept of an alpha-enhanced plateau at early epochs, followed by a well-defined "knee", caused by the onset of SNe Ia, and finally a second plateau with sub-solar [alpha/Fe] values. We find the position of this knee to be at [Fe/H]=-1.9 and therefore significantly more metal-poor than expected from comparison with other dSphs and standard evolutionary models. Surprisingly, this value is rather comparable to the knee in Sculptor, a dSph about 10 times less luminous than Fornax. Using chemical evolution models, we find that both the position of the knee as well as the subsequent plateau at sub-solar level can hardly be explained unless the galaxy experienced several discrete star formation events with a drastic variation in star formation efficiency, while a uniform star formation can be ruled out. One possible evolutionary scenario is that Fornax experienced one or several major accretion events from gas-rich systems in the past, so that its current stellar mass is not indicative of the chemical evolution environment at ancient times. If Fornax is the product of several smaller building blocks, this may also have implications of the understanding on the formation process of dSphs in general.Comment: 10 pages, 6 Figures, accepted for publication in Ap

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

Continuous gravity and tilt observations in an active geodynamic area of southern Italy: the Calabrian Arc system

Calabria (southern Italy) is a site of considerable seismic activity related to the ongoing evolution of the Calabrian Arc system, where a complex lithospheric structure is present. For over a century the Calabrian region has been going through a period of relative seismic quietness, yet its seismic hazard is at the highest levels in the Mediterranean basin due to several catastrophic earthquakes present in the historical records. In order to strengthen the geophysical monitoring of this region, a gravity and tilt recording station was set up in the premises of the University of Calabria. The recorded signals should allow to estimate a tidal anomaly, possibly correlated with the difference between some local feature of the lithosphere or geodynamic activity and the corresponding characteristics of the model used to calculate the reference gravity tide. We report here on the results obtained by the analysis of more than two years of continuous gravity and tilt observations at a site in the northern part of the region. The tidal analysis of the gravity records, covering the time interval May 2011 - September 2013, has provided amplitudes, amplification factors and phases of the main lunar and solar gravity tidal waves. A reliable model of the gravity tide is necessary for accurate processing of discrete absolute and relative gravimetric measurements and to detect in the gravity signals possible components correlated to major seismic activity. The Ocean Tide Load (OTL) effect was accounted for in the determination of the tidal field spectral parameters. The most widespread DDW99/ NH Earth’s model, adopted here as reference, fits the obtained results well enough. The tidal residual vectors do not highlight any significant anomaly ascribable to the complex structure of the lithosphere beneath the region. The analysis of the tilt records points out a manifest influence of the fluctuations of the air temperature on ground slope, at annual and diurnal periods. The spectral analysis highlights the presence, on both E-W and N-S components, of a significant S1 solar wave. Values of the thermal admittance, at diurnal period, have been estimated for both tilt components. A weak energy at the frequency of 1.932 cycles/day, at the limit of statistical significance, is also observed, identifiable as the main semidiurnal lunar wave M2 of the crustal tide. The amplitude and the amplification factors of such a wave are consistent with the values expected by the DDW99/NH model. Beyond everything, the obtained results of the analyses of gravity and tilt records have provided models for the gravity tide and tidal field in the Calabrian region. Moreover, it turns out that the response of the complex lithospheric structure in the Calabrian Arc system to the tidal stress field does not produce any significant anomaly related to the adopted model. Moreover, the absolute measurements of the gravity acceleration, carried out in 1994 and 2013, yielded coinciding values, implying that during the time interval of 20 years not any significant vertical movement and/or mass redistribution in the underground occurred in the area, despite its intense geodynamic activity

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

12th Conference of International Building Performance Simulation Associatio

Conversion of no/low value waste frying oils into biodiesel and polyhydroxyalkanoates

A sustainable bioprocess was developed for the valorization of a no/low value substrate, i.e. waste frying oils (WFOs) with high content of free fatty acids (FFAs), otherwise unsuitable for biodiesel production. The bioprocess was verified using both recombinant (Escherichia coli) and native (Pseudomonas resinovorans) polyhydroxyalkanoates (PHAs) producing cell factories. Microbial fermentation of WFOs provided a 2-fold advantage: i) the reduction of FFAs content resulting into an upgrading of the "exhausted waste oils" and ii) the production of a bio-based microbial polymer. Proper strain designing and process optimization allowed to achieve up to 1.5 g L-1 of medium chain length, mcl-PHAs, together with an efficient conversion (80% yield) of the treated WFO into biodiesel

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

Prefronto-cerebellar transcranial direct current stimulation increases amplituded and decreases latency of P3b component in patients with euthymic bipolar disorder

INTRODUCTION: Neurocognitive impairments have been observed in patients with bipolar disorder (BD) even during the euthymic phase of the disease, potentially representing trait-associated rather than state-associated characteristics of the disorder. In the present study, we used transcranial direct current stimulation (tDCS) applied to cerebellar and prefrontal cortices to improve the neurophysiological performances of patients with euthymic BD. METHODS: Twenty-five outpatients with BD underwent open-label prefrontocerebellar tDCS for 3 consecutive weeks. Neurophysiological performances were assessed through the examination of the P3b and P3a subcomponents of P300 event-related potential at baseline and after stimulation. RESULTS: Compared to baseline, P3b component after tDCS showed significantly higher amplitude and shorter latency (latency: Fz P=0.02, Cz P=0.03, and Pz P=0.04; amplitude: Fz P=0.24, Cz P=0.02, and Pz P=0.35). CONCLUSION: In our sample of patients with euthymic BD, concomitant prefrontoexcitatory and cerebellar-inhibitory modulations led to improved brain information processing stream. This improvement may at least partially result from neuroplastic modulation of prefrontocerebellar circuitry activity

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