• Energy Research

Abstract An interesting tool for testing and check phases of HVAC systems was developed, in order to evaluate thermal comfort parameters only measuring temperature and relative humidity in moderate environments, for a wide range of clothing thermal insulation. A simplified approach to thermal comfort was developed in the seventies by Rohles, who found a correlation between PMV, air temperature and relative humidity, for sedentary activity and clothing thermal insulation equal to 0.6 clo. An improvement of Rohles model is proposed, aiming to extend results in a wider range of clothing thermal insulation (0.25–1.65 clo). Data from experimental campaigns in moderate environments were used to implement a function PMV = PMV( T , RH) and diagrams PMV vs. temperature, for different values of relative humidity, were traced (nine equations and diagrams for male, female, and both sexes, and for three ranges of I cl ). Standard deviation between measured and calculated data was evaluated and a mean error on PMV of ±0.22 was found; a T-Student test was also performed and results were significant. Mean Radiant Temperature data were used to calculate Operative Temperature and to correlate to PMV and to Neutral Temperature, corresponding to thermal comfort, by means of linear regression method.

Abstract Data collected in an Italian ancient theatre were elaborated in order to compare subjective sensations evaluated by means of questionnaires to data measured in field. A simplified model, developed in a previous paper, was validated by using measured data and by comparing the results to data from questionnaires (PMV Q ). Questionnaire data vary in a wider range of values than measured ones, confirming a higher variability in the personal sensation due to the possibility of giving only whole numbers. Therefore the questionnaire PMV scale needs to be refined to a 0.5 increment (resulting in 13 values). When comparing data calculated with the simplified model developed by the Authors in a previous work to data from questionnaires, more reliable results in the prediction of PMV were found with respect to measured data. Finally, people who voted 0 were about 54%, while about 88% are in the −1 to +1 range, showing a good behaviour of the theatre, nevertheless a wide range of variability for data from questionnaires corresponds to the same value of indoor air temperature. For this reason the PMV questionnaire scale needs to be refined to a 0.5 increment (resulting in 13 values).

The kinetic behaviour of olive tree pruning (PR), two- (2PH) and three-phase (3PH) olive pomace and their blends was investigated under combustion condition using thermogravimetric analysis. PR was blended with 2PH and 3PH at different ratios (25:75, 50:50 and 75:25) and tested in the temperature range from ambient to 1000°C in order to evaluate the co-combustion behaviour. Results showed that the thermal degradation of all samples can be divided into three regions (drying, devolatilisation, char oxidation) with different combustion properties, depending on the percentage of PR. Significant interaction was detected between the fuels, and reactivity of 2PH and 3PH was improved upon blending with PR. The iso-conversional methods, Ozawa-Flynn-Wall and Vyazovkin, were employed for the kinetic analysis of the oxidation process. The results revealed that the activation energy of PR was higher than the one of 2PH and 3PH, and the minimum value was obtained for 25PR752PH sample.

AbstractThermal insulation of building envelope is very important in energy saving: a growing interest is focused on using insulating recycled and sustainable materials. The thermal and acoustic properties of innovative basalt natural fiber insulating panels were investigated. The thermal conductivity was evaluated by means of a Heat Flow meter apparatus: it is included in 0.030-0.034W/mK range. The acoustic absorption coefficient was measured by means of Kundt's Tube. The results were compared to traditional solutions with similar chemical composition, but worse mechanical resistance. The easy application of this solution could be useful especially for refurbishments.

Abstract Thermal-energy, acoustic and lighting performance of innovative glazing systems with aerogel inclusion is evaluated through in-field experiments. The study is carried out by monitoring two dedicated prototype buildings located in central Italy, and the consistency of results with in-lab analyses is investigated. Analyses showed that aerogel can decrease energy consumption for heating by up to 50% in winter, and its capability to keep the thermal zone warmer even several days after that the heating system is switched off. Acoustic analyses confirmed in-lab measurements, showing aerogel capability to increase the facade acoustic insulation index by 3 dB. Lighting analyses showed aerogel effect to lower the daily average illuminance level by about 10% during sunny days. In cloudy weather conditions, with low level of solar radiation and indoor illuminance, the effect was relatively higher. In those cases when windows include shading elements such as protruding roof or deep window pad, aerogel effect was not clearly identified through continuous monitoring. The results of this integrated in-field experimental campaign showed that aerogel filled glazing cameras represent effective and innovative solutions for energy saving in winter, useful for improving acoustic facade performance with limited penalties in terms of daylighting.

The Renewable Energy Directive (RED) of the European Union proposes default GHG emission savings values for different types of biofuels. In this paper rapeseed and soybean biodiesel chains were evaluated, comparing RED values to typical values obtained for Italian case. In compliance to the EU RED methodology, each chain was divided in four steps: biomass cultivation, transport and processing and fuel transport. Each input and output was compared to data of typical Italian chains of producing rapeseed and soybean biodiesel. For the cultivation phase, typical farming techniques in the Veneto region were assumed, employing the IPCC methodology for the calculation of N2O direct and indirect emissions. Processing step was divided in three processes: oil extraction, refining of vegetable oil and esterification of refined oil; data were obtained from the most important Italian biodiesel production plants. Results for rapeseed biodiesel showed that GHG saving for Italian chain was 49%, against 38% reported as default value in the EU RED, while for soybean biodiesel this difference was more marked (67% for Italian chain against 31%), mainly due to the fact that Brazilian cultivation was considered in the EU RED. Proceedings of the 18th European Biomass Conference and Exhibition, 3-7 May 2010, Lyon, France, pp. 2230-2235

Abstract In the present paper CFD tool was used for thermal comfort evaluation in natural convection and in transient conditions in a room by setting only the external weather conditions as input parameters. A survey in a classroom at the Department of Engineering, University of Perugia, was carried out and data required for the thermal comfort evaluation and CFD simulation model set up was acquired. The simulation model was validated with experimental data and it was used for the thermal and velocity profiles simulation and for the thermal comfort indexes calculation, according to UNI 7730.

Abstract Aerogel is a promising building envelope material that can be used to improve thermal and lighting performance. In monolithic form, aerogels allow visual interaction between the built and outdoor environments, unlike aerogels in granular form. However, the high production cost of large monoliths limits their use. In this work, monolithic silica aerogels were fabricated using tetramethyl orthosilicate as the precursor in a base-catalysed recipe, and a novel rapid supercritical extraction method. The method produces transparent aerogel monoliths in as little as six hours. A 30 × 30 cm glazing sample was constructed from nine 15-mm-thick aerogel monoliths sandwiched between two pieces of 4.7-mm-thick float glass. The glazing sample was characterized in terms of directional and hemispherical optical and visual properties. Measurements were made with an in-house-constructed spectrophotometer equipped with a 75-cm-diameter integrating sphere in the 380- to 2300- nm wavelength range with variable incidence angles. The light and direct solar transmittance are 0.69 and 0.62, while the light and direct solar reflectance are 0.25 and 0.19, respectively. The sample is also characterized by a high general colour rendering index (Ra = 96), allowing indoor visual comfort. Gonio-photometric and directional spectral transmittance measurements show negligible visual distortion and colour variation at different observation angles. The light transmittance of the prototype is lower than that of glazing units present on the market, but about 10% higher than an equivalent unit with granular aerogel. This performance is promising for applications where view through a window is required. However, the size of the samples currently fabricated with the innovative process is limited to 14 × 14 cm and they are characterized by some optical defects that must be removed if the process is to be used for commercial product.