Test Reference Year Research Articles

Estimation of the energy output of a photovoltaic power plant in the Austrian Alps

An output simulation is one of the first steps in planning a photovoltaic power plant (PVP) at a certain location. Various computer codes already exist to assess the energy output of a PVP, when fed with the relevant meteorological data. For the alpine area, however, there is no appropriate data considering the altitude of the site available. A computer code has been written to check the available raw data for plausibility and to fill in missing data synthetically. On the basis of 6 yr of measured data a test reference year (TRY) has been developed for the town of Leonding and the summit Loser. They are located just 80 km apart but have a 1250 m difference in their altitudes. For comparison, these new TRYs, together with other already existing TRYs from different places in a surrounding area of about 300 km, are used for calculation of the expected energy output of a PVP. A clear increase of energy yield with higher altitude can be observed. The summit Loser (1550 m), with the highest altitude investigated in this study, proved to be the most productive location. Besides the clearer sky and snow reflection, the lower temperature as well as better cooling of the panels by the wind in the Alps contribute to the higher amount of energy output.

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.

Reduced weather data for building climatization and application to 29 European locations

A method for setting up a reference year of reduced temperature data, proposed by Klein and Erbs, has been applied by us to 29 European locations for which an official test-reference year is available. This reference year of reduced temperatures may be utilized in computer programs for analysis of the thermal behaviour of buildings. The effectiveness of the method has been tested by calculating the annual energy demand in 29 European locations for three modules with different thermophysical characteristics.

Generation of a test reference year for Ibadan, Nigeria

A test reference year for the city of Ibadan, Nigeria has been generated from a 10 yr global solar radiation data set using the Finkelstein-Schafer statistics. The representative year was identified for each month and the corresponding global solar radiation tabulated for ease of use in such applications as the performance analysis of solar systems.

Solar swimming pool heating: Description of a validated model

In the framework of a European Demonstration Programme, co-financed by CEC and national bodies, a model was elaborated and validated for open-air swimming pools having a minimal surface of 100 m 2 and a minimal depth of 0.5 m. The model consists of two parts, the energy balance of the pool and the solar plant. The theoretical background of the energy balance of an open-air swimming pool was found to be poor. Special monitoring campaigns were used to validate the dynamic model using mathematical parameter identification methods. The final model was simplified in order to shorten calculation time and to improve the user-friendliness by reducing the input values to the most important ones. The programme is commercially available. However, it requires the hourly meteorological data of a test reference year (TRY) as an input. The users are mainly designing engineers.

Generation of representative weather—Year data for Saudi Arabia

In recent years, the computation of load and energy requirement in buildings, energy conservation studies in buildings, and the design of solar systems are not accomplished using long-term averages of weather data as inputs, but preferably with data-sets representative of the climatological features of the site that are generated for this purpose. Such data-sets are the test reference year, typical meteorological year and weather year for energy calculations. In this paper, the basis, the selection procedure and the use of each of these data-sets are discussed. Also, an attempt is made to generate typical weather years for the cities of Dhahran, Riyadh, Jeddah, Khamis-Mushayt and Hail, using the standard meteorological data obtained by measurements by the Meteorology and Environmental Protection Administration.

Proposal of a numerical procedure to select Reference Years

A procedure is presented which can be used to create, from many years of available past weather data, a Reference Year consisting in 8760 hourly values of a few chosen meteorological quantities. Such “year” corresponds to a “typical” year for the considered locality, regarding both the occurrence and the persistence of different meteorological situations, in all months. This approach is a modification of the procedure used in the production of Test Reference Years or of Design Reference Years. In this approach, the frequency distributions relative to single months in the database are compared with the long-term frequency distribution of all the months “with the same name.” Furthermore, the correlation between subsequent subsequent daily values is taken into account.

The generation of a “typical meteorological year” for the city of Athens

In recent years, the evaluation of the efficiency of the performance of solar energy units is not done by using long-term averages of weather data as input but preferably by using data sets representative of the climatological features of the site that are generated for this purpose. Such data sets, which are usually called “Test Reference Year” or “Short Reference Year,” consist mainly of solar radiation data, but they may also include other meteorological data, like temperature wind velocity etc, which may affect the response of the units. In this article, an attempt is made for the generation of such a representative data set for the city of Athens mainly by following a method that has been proposed by Hall et al. This data set, which includes global solar radiation data and six other meteorological parameters referring to temperature, dew point, and wind velocity, has been characterized by Hall as a “Typical Meteorological Year.”

Statistical Distribution of Solar Radiation: A European Data Set of Cumulative Frequency Curves of Solar Irradiance on Tilted Planes

The monthly frequency distribution of solar irradiance has now become a common meteorological input for solar energy system sizing methods, either directly or through the concept of “Utilizability”. Cumulative Frequency Curves (CFC) of solar irradiance were investigated within the frame of the European Solar Energy R and D Programme (Project F). The aim of this study was to prepare a European data set of CFC's for various typical climates and tilted planes. An algorithm for computing global irradiance on tilted planes has been validated, using 3 years of measured data on inclined planes at Carpentras. CFC's of global irradiance for 6 tilt angles at 12 European locations have been derived, using this algorithm and the “Test Reference Years” (TRY) hourly meteorological data base. CFC's are presented for each month in the form of parameters of an orthogonal polynomial fitting. La distribution statistique mensuelle de l'eclairement solaire est devenue aujourd'huiune entree meteorologique c1assique pour les me...

Thermal performance comparisons between passive solar and conventional housing in an Irish climate

SYNOPSIS The thermal performance of a passive solar house in Ireland having high energy conservation standards is compared with that of a similar sized conventional dwelling house. In both cases the performance over a meteorological Test Reference Year is assessed using climatically responsive models developed experimentally which predict their internal temperature without heating. The results indicate that the conventional house required over three times as much auxiliary heating as the passive solar house. Solar gain accounted for over half the gross heat demand in the solar house compared to 13% in the bungalow. An added advantage of the increased utilization of solar gain was the estimated reduction in the heating season from nine to six months.

Electrocardiographic changes and peripheral nerve palsies in toxic diphtheria: Burkhardt, Edward A., Eggleston, Cary, and Smith, Lawrence W.: Am. J. M. Sc. 195: 301, 1938

The present work discusses simulation results of annual indoor illuminance distributions for two office geometries situated in Freiburg, Germany, calculated with six different RADIANCE-based daylight simulation methods. These methods are the ubiquitous daylight factor method [P.J. Littlefair, Predicting annual lighting use in daylit buildings, Building and Environment 25 (1990) 43–54.], ADELINE 2.0 [M. Szerman, J. Stoffel, ADELINE 2.0, Radlink Technical Manual, IEA Solar Heating and Cooling, Task 12.], the classified weather data according to Herkel and Pasquay [S. Herkel, T. Pasquay, Dynamic link of light and thermal simulation: on the way to integrated planing tools, 5th Int. IBPSA Conf., Prague, Sept., 8–10, 1997, Vol. II, pp. 307–312.] and two simulation procedures based on daylight coefficients according to Tregenza, namely ESP-r version 9 series [J.A. Clarke, M. Janak, Simulating the thermal effects of daylight-controlled lighting, Building Performance (BEPAC), (1) (Spring 1998).] and a new accelerated method developed by the authors. The new method calculates 145 diffuse and three ground daylight coefficients in a single raytracing run which considerably reduces the required calculation times for an annual daylight simulation. An explicit calculation of the indoor illuminances under all 4703 annual hourly mean sky luminance distributions from the Freiburg test reference year (TRY) serves as a reference case against which the other methods are tested.The simulation results reveal that the accuracy of an annual daylight simulation method is not necessarily coupled with the required simulation time. The quality of an annual simulation rather depends on the underlying sky luminous efficacy model and whether the method considers the hourly mean direct and diffuse illuminances for each time period explicitly.The two methods relying on daylight coefficients exhibit the lowest relative root mean square errors (RMSEs) for the straightforward office geometry. The results for the advanced office show that internal illuminance contributions due to external ground reflections are only considered by the new method.