Italian Climate Research Articles

Heating and cooling energy recovery for an HVAC system: economic analysis for the Italian climate

SUMMARY In this paper the economic analysis of the energy recovery in all-outdoor-air HVAC systems for the Italian climate is performed. The energy recovery device considered here is the same for both heating and cooling periods. During the summer season, the energy saving is achieved by evaporative cooling. The performances of the hybrid innovative HVAC system and the traditional system are calculated hour by hour by following the test reference year (TRY) prole. Such analysis is carried out taking into account simultaneously, the trend of some climatic indexes computed in order to (i) better understand the in#uence of climate on the HVAC system behaviour, (ii) obtain a swift feasibility analysis of the energy recovery system and (iii) perform a rough operating cost estimate of the traditional HVAC system. Copyright 2001 John Wiley & Sons, Ltd.

Comparison between total and sensible energy recovery HVAC systems for the Italian climate

SYNOPSIS In this paper an economic comparison between the sensible and the total energy recovery for HVAC systems in the Italian climate is dealt with. Both all-outdoor-air and mixed-air systems are considered. During the summer period, the energy saving by the sensible device is achieved by evaporative cooling. The performance of the hybrid innovative HVAC system and the traditional one, for both the heating and cooling season, are calculated hour by hour following the Test Reference Year (TRY) profile.

Heating and cooling energy recovery for an HVAC system: Economic analysis for the Italian climate

SUMMARY In this paper the economic analysis of the energy recovery in all-outdoor-air HVAC systems for the Italian climate is performed. The energy recovery device considered here is the same for both heating and cooling periods. During the summer season, the energy saving is achieved by evaporative cooling. The performances of the hybrid innovative HVAC system and the traditional system are calculated hour by hour by following the test reference year (TRY) prole. Such analysis is carried out taking into account simultaneously, the trend of some climatic indexes computed in order to (i) better understand the in#uence of climate on the HVAC system behaviour, (ii) obtain a swift feasibility analysis of the energy recovery system and (iii) perform a rough operating cost estimate of the traditional HVAC system. Copyright 2001 John Wiley & Sons, Ltd.

00/02903 Cooling energy consumption and operating costs: evaporative all-air and air-and-water systems in the Italian climate

00/02903 Cooling energy consumption and operating costs: evaporative all-air and air-and-water systems in the Italian climate

Variations of Temperature and Precipitation in Italy from 1866 to 1995

Series of annual and seasonal temperature and precipitation representing respectively northern and southern Italy are compared for trend, interannual variability and periodicity in the period 1866–1995. Temperature and precipitation trends are almost always anticorrelated except in winter in the North where an anomalous behavior is evident till about 1980. The result is that the Italian climate has become warmer and drier especially in the South since about 1930.The interannual variability does not present significant maxima, but only minima that cannot be related tothe start of a trend either for temperature or for precipitation. The power spectra of the series show broad significant peaks containing the quasi-biennial oscillation and other well known periodicities probably due to solar cycles or to the North Atlantic ocean-atmosphere oscillation (NAO).

Cooling energy consumption and operating costs: evaporative all-air and air-and-water systems in the Italian climate

The economic analysis for running two kinds of hybrid air conditioning systems: all-air and air-and-water, both with add-on evaporative cooling stages, is studied in this paper. Single-duct, single-zone, constant volume systems are dealt with. Processing the climatic data of the European ‘test reference year—TRY’ for Italy, a comparison of such systems' performance versus the relative traditional one is performed. Energy consumption and operating costs are evaluated by an appropriate computer code written with the aim of: (i) making plain the input/output of data; and (ii) displaying very friendly software masks as well as useful graphical elaboration. On the basis of outdoor air state, calculations are performed according to two different procedures: (a) hourly, following the TRY profile; and (b) for each bin, 1°C wide, in which the simultaneous dry- and wet-bulb temperatures fall. Copyright © 2000 John Wiley & Sons, Ltd.

Comparison of two Sorghum genotypes for sugar and fiber production

A comparative analysis of the growth and yield performances of two late maturing and productive sweet and fiber sorghums has been conducted, with the perspective of their introduction in temperate Italian climate areas as competitive multi-product crops. Sweet type sorghum `Wray' ( Sorghum bicolor (L.) Moench ssp. bicolor), and the nonsweet type, `H173' (hybrid Sorghum bicolor (L.) Moench× Sorghum docna var. technicum), were grown in a field trial under well-watered conditions in northern Italy (latitude 44°3′N, longitude 11°2′E). During the crop cycle, growth analysis were performed by collecting data from both non-destructive and destructive samplings. Fundamental growth indexes were calculated as a function of accumulated growing degree days (GDD) from sowing. Yield traits were evaluated at soft dough maturity. Sweet and fiber crops reached soft dough maturity after 1250 GDD and did not statistically differ for total and main stem yields. Mean values of 27 and 20 t ha −1 dw, respectively, were detected. The sucrose content was more than three times higher and the cellulose and lignin contents 40–50% lower in `Wray' as compared to `H173', whereas the level of reducing sugars was similar. Both sorghum types can be considered as interesting new crops which might provide an energy production higher than 10 000 kcal m −2, a potential production of around 6000 l ha −1 of ethanol (sweet), and up to 15 t ha −1 of structural polysaccharides (fiber). The rate of leaf formation on the main stem and their final number were similar between the two genotypes. Until the growing differentiation point, one new leaf was visible every 40.5 GDD, thereafter the same growth process required around 123 GDD. During the period of early leaf formation, the fiber type showed a greater tillering ability which positively affected early canopy area and growth parameters. On the other end, the sweet sorghum crop presented enhanced dry matter accumulation capacity after the growing differentiation point as compared to the fiber crop (42.7 and 27.7 g m −2 d −1, respectively). This could be the result of higher leaf thickness and leaf area duration.

Energy saving potential integrating multi-stage evaporative technology in HVAC systems for Italian climate

SYNOPSIS Evaporative cooling, extensively used in dry climates, can be justified in wetter areas by integration into HVAC systems; in this way the saving-energy technique will not always replace mechanical cooling, but has to be integrated with commonly employed equipment. In this paper Test Reference Year (TRY) data for Italy were processed to estimate using potential of multistage integrated evaporative HVAC systems. Specific humidity and wet-bulb temperature were computed to define five regions for external air, and then to evaluate hours per year and relative energy saving for each of these regions and Italian climatic areas. The systems subjected to comparison were a multi-stage evaporative—direct, indirect and mechanical—and a traditional mechanical one; both all air, single duct, single zone, constant volume systems with wet-bulb economizer. The method of analysis is based on a strongly simplified approach. It is not intended as a substitute for accurate modelling schemes to simulate building and system behaviour, but as a tool to estimate the energy saving potential related to the Italian climate. The following parameters have been assumed as constant throughout: sensible heat ratio of the conditioned space, adiabatic saturation and heat exchanger effectivenesses, indoor space and supply air temperatures and relative humidities. Outside air temperature and relative humidity are assumed to change hour by hour following the TRY profile. Energy savings are evaluated hourly, the mass flow rate of the supply air being kept constant. Seasonal energy savings for the majority of the climatic areas appears to be encouraging, ranging between 28% and 67% (space air temperature and relative humidity: 26°C −60%) or 36% and 74% (space air temperature and relative humidity: 26°C −70%). If it is assumed that the system operates always with 100% outside air (also for regions with outside wet-bulb air temperature greater than space wet-bulb air temperature) energy cooling requirements display different trends for different climatic areas.

96/05491 A critique of estimates of the cost of damage to building material due to atmospheric attack

The development of radiant cooling has stimulated an interest in new systems based on coupling ventilation with radiant cooling. However, radiant cooling systems may cause condensation to form on an active surface under warm and humid conditions during the cooling season. This phenomenon occurs when surface temperature falls below dew point. To prevent condensation, air humidity needs to be reduced with a dehumidification device or a mechanical ventilation system. There are two main options to achieve this. The first is to use dehumidification devices that reduce humidity, but are not coupled with ventilation, i.e. devices that handle room air and leave air change to infiltrations. The second is to combine a mechanical ventilation system with dehumidifying finned coils.This study analyzes the floor radiant cooling of a typical residential apartment within a multi-storey building in three Italian climate zones by means of a detailed simulation tool. Five systems were compared in terms of both indoor thermal comfort and energy consumption: radiant cooling without dehumidification; radiant cooling with a soft dehumidification device; radiant cooling with a dehumidification device which also supplies sensible cooling; radiant cooling coupled with fan coils; and radiant cooling with a mechanical ventilation system which dehumidifies and cools.

Is the DIF Technique Suitable for the Italian Climate

In Northern Italy, two trials have been performed on Lilium and poinsettia cultivars to control plant height by day–night temperature regimes. Two identical glasshouse compartments have been used for the experiments: one maintained at standard conditions (the same minimum and ventilation temperatures during day and night), the other with minimum day temperature lower than night. Cultivations of lilies and poinsettias started in Winter and Summer 1993, respectively, with different climate conditions (cold in winter and hot in summer). Results on Lilium indicated that a good control of greenhouse temperature can be achieved in Italy's winter climate, even on sunny days; the best height reduction (30%) was obtained on Lilium longiflorum cv. `White American', compared to other Lilium species. Test on poinsettia have been based mainly on controlling ventilation of the glasshouse to raise temperature in the first part of the night and to lower it during the first daytime hours.

Statistical Predictability and Parametric Models of Daily Ambient Temperature and Solar Irradiance: An Analysis in the Italian Climate

Abstract Stochastic–dynamic models are discussed for both air temperature and solar irradiance daily time series in the Italian climate. Most of the methodologies discussed in this paper are well known and established for processes having a Gaussian distribution. However, a technique is presented that allows statistical inferences for non-Gaussian processes. Applying these models to 20-year time series, their predictability is analyzed for five meteorological stations of the Areonautica Militare Italiana. The following results were obtained: 1) the seasonalities in both the mean and the standard deviations of measured data are well fitted by simple periodic models; 2) the short range statistical fluctuations of the analyzed variables are well described by first order autoregressive processes whose parameters have constant values for all five stations. For the sake of brevity results are presented only for one station (Napoli).

Behavior of hourly solar irradiance in the Italian climate

This article deals with analysis of hourly solar radiation data for performance calculations of solar systems. The factors affecting hourly solar radiation are discussed. Then a correlation to estimate hourly values is proposed, showing how it can be considered independent on month and Italian locality. Correlation is fitted by a second-order polynomial: variance about mean correlation is also analyzed. In this way, hourly irradiance distributions, having the same mean and variance as real data, can be generated. Then validation of the whole procedure is performed.

Statistical correlation between hourly and daily values of solar radiation on horizontal surface at sea level in the Italian climate

The knowledge of hourly data of solar radiation is required for many practical applications. Since hourly data are measured only in a few stations, it is quite useful to have methods to calculate hourly values starting from daily data. In this paper we analyse the hourly data measured in Italian stations and propose a method to estimate hourly solar radiation. The approximation introduced by our method in estimating mean values is comparable with its statistical error. The curves we obtain are independent of season and station and depend only on the ratio K of experimental global solar radiation to extraatmospheric radiation. They can be fitted by paraboles whose coefficients can be written as a simple analytical expression of the K ratio. The variance of experimental data around means has been analysed. The statistical method we propose allows to reproduce the distribution of hourly values of solar radiation in a satisfactory way starting from the daily values of solar radiation A partir de l'analyse des donnees horaires de stations italiennes on propose une methode d'estimation du rayonnement solaire horaire. Les courbes obtenues sont independantes de la saison et ne dependent que du rapport K entre le rayonnement solaire global experimental et le rayonnement extra-atmospherique

Behaviour of ambient temperature on daily basis in Italian climate

The authors analyse the daily ambient temperature time series in five Italian stations for twenty years (1958-1977). It is shown that these time series are well described mathematically as composite series of two periodic components (one in the mean and the other in the standard deviation) and one stochastic component. Furthermore the stochastic component is stationary and follows the first order linear autocorrelation model of dependence. The only significant harmonic of the periodic components is the one relative to the basic period (365 days). Performance of the model is tested by comparing the statistics of generated and experimental data.