Precise and reliable meteorological data are necessary for building performance analysis. Since meteorological conditions vary significantly from year to year, there is a need to create a test reference year (TRY), to represent the long-term weather conditions over a year. In this paper two different TRY data models were generated and compared: TRY and TRY-2. Both models where created by analysing every 3-hour weather data for a 30-year period (1984–2013) in Alūksne, Latvia, provided by the Latvian Environment Geology and Meteorology Centre (LEGMC). TRY model was generated according to standard LVS EN ISO 15927-4, but to create second model - TRY-2, 30 year average data were applied. The generated TRY contains typical months from a number of different years. The data gathered from TRY and TRY-2 models where compared with the climate data from the Latvian Cabinet of Ministers regulation No. 379, Regulations Regarding Latvian Building Code LBN 003-01. Average monthly temperature values in LBN 003-01 were lower than the TRY and TRY-2 values. The results of this study may be used in building energy simulations and heating-cooling load calculations for selected region. TRY selection process should include the most recent meteorological observations and should be periodically renewed to reflect the long-term climate change.

Increasing global demand for energy resources leads to actions that optimize the usage of these resources. To make actual and reliable calculations for energy usage and to be able to determine the optimal heating systems, it is necessary to know the latest climate conditions in the area. One of the methods to determine the climate conditions is to generate a test reference year (TRY) for this area. In this paper the TRY of Riga, the capital city of Latvia, was generated by applying the standard LVS EN ISO 15927-4. To generate TRY, four parameters were used: temperature, relative humidity, cloud coverage and wind velocity. The Latvian Environment Geology and Meteorology Centre (LEGMC) provided the meteorological data used in this research. TRY was generated by analyzing meteorological data for thirty-year period (1984-2013) in Riga. The results were compared with the data from Latvian Building Code LBN 003-15, and it showed a deviation in average temperature values that can be explained by the climate change in this area.

Abstract. Increasing global demand for energy resources leads to actions that optimize the usage of these resources. To make actual and reliable calculations for energy usage and to be able to determine the optimal heating systems, it is necessary to know the latest climate conditions in the area. One of the methods to determine the climate conditions is to generate a test reference year (TRY) for this area. In this paper the TRY of Riga, the capital city of Latvia, was generated by applying the standard LVS EN ISO 15927-4. To generate TRY, four parameters were used: temperature, relative humidity, cloud coverage and wind velocity. The Latvian Environment Geology and Meteorology Centre (LEGMC) provided the meteorological data used in this research. TRY was generated by analyzing meteorological data for thirty-year period (1984-2013) in Riga. The results were compared with the data from Latvian Building Code LBN 003-15, and it showed a deviation in average temperature values that can be explained by the climate change in this area.