Annual variation characteristics of degree-days and the trend analysis in Tianjin

Degree-days,to some extent,indicates the building energy consumption of heating and air conditioning systems and it's one of important meteorological parameters used by the building.Climate change led directly to the change of cooling and heating degree-days.Using 60 years of statistical data from 1951 to 2010,it was discovered that a significant change has occured in both heating and cooling degree-days: the average of heating degree-days from 1995 to 2004 has reduced 20.9% than the average from 1963 to 1972,however,cooling degree-days has a increasing trend,and the maximum value of 10-year-average was more than 1 time than the minimum value and the results of M-K test indicate that when the significant level was 0.05,significant lower heating degree-days have taken place since 1990 and cooling degree-days has a significant increase after 2005.