The change over time of energy performance of large chillers used in commercial and institutional buildings is seldom presented in the literature. Most studies are based on measurements of small capacities of residential air-conditioners and heat pumps. Authors found in the literature only three papers on this topic. This paper presents the evidence-based assessment of long-term performance of two identical large capacity chillers that serve the cooling system of a university campus. The paper presents the estimation of uncertainty of direct and derived measurements by using as example measurements recorded at 15 min time intervals by the building automation system during the summer of 2016. First, the paper verifies the hypothesis that weekly values of coefficient of performance (COP) of these large chillers do not change significantly over the summer of 2016. Second, the t-test also verifies the hypothesis of no significant change of seasonal COP values from 2009 to 2017. Third, a linear correlation-based model shows a variation of COP values by 1-2% per year between 2009 and 2017. The results show that the seasonal variation of COP is not statistically significant.

商业和机构建筑中使用的大型冷却器的能源性能随时间的变化很少在文献中介绍。大多数研究都是基于对住宅空调和热泵小容量的测量。作者在文献中发现只有三篇关于这个主题的论文。本文介绍了对为大学校园的冷却系统提供服务的两台相同的大容量冷水机的长期性能的循证评估。本文使用楼宇自动化系统在 2016 年夏季以 15 分钟时间间隔记录的测量值为例，介绍了对直接测量值和派生测量值的不确定性的估计。首先，本文验证了以下假设：性能系数 ( COP) 的每周值) 的这些大型冷水机组在 2016 年夏季没有显着变化。其次，t 检验还验证了2009 年至 2017 年季节性COP值没有显着变化的假设。第三，基于线性相关的模型显示了COP值在 2009 年至 2017 年之间以每年 1-2% 的速度递增。结果表明，COP的季节性变化在统计上并不显着。