Establishment of Short Reference Years for Calculation of Annual Solar Heat Gain or Energy Consumption in Residential and Commercial Buildings

Summary

This paper describes an automatic procedure to generate short series of hourly weather data that can be considered as representative for the outdoor climate during the year, because it possesses the same statistical properties as the measured weather data from which it has been derived. This short series is called a Short Reference Year (SRY).

The procedure involves the following steps: analysing the weather data statistically, modelling the weather variations and generating new hourly values of the weather variables — the SRY — by means of random number generators. The procedure consists of program WEATHER for the analysing and modelling of the weather data, program SRYEAR for the generation of the SRY and one or more subprograms to prepare the data set. The advantage of this procedure is the ability to describe the climate mathematically; this leads not only to a lot of additional statistical information about the weather, that can be usefull for various kinds of energy calculations, but also to a high degree of flexibility in changing the length of the series without re-analysing the original weather data set.

SRY’s of the Netherlands, Denmark and France are generated by this procedure and afterwards they are tested according to the test procedure as defined by the workgroup “Methods for Short Reference Years”.

In general the heating and cooling loads, calculated with these SRY’s are within 6% of the multiyears’. The results of the hot water system agree very well for the Netherlands and Denmark; the deviation for France is rather high.

It is now possible to generate SRY’s for various locations with this automatic procedure; for energy calculations and hot water systems the errors are acceptable Low.

Work is going on to modify program SRYEAR for the generations of SRY’s which can be used for extreme values calculations or design conditions.