声明称，尽管移动窗热测试设备（MoWiTT）主要用于研究在整个白天周期内通过开窗系统的动态净能量流，但它也经常用于测量夜间U值。注意，这些测量的优点是结合了特定时间和位置的真实环境条件产生的外膜系数，而不是依赖于实验室对某些假定的平均或极端条件的模拟。另一方面，莫维特是一个比实验室热箱复杂得多的设施，潜在误差的来源也相应地更大。讨论了从直接测量数据推导夜间U值的方法，以及随机误差和系统误差的影响。 关键词:Windows、移动设备、测试、美国、夜间、测量、准确性、传输引用:研讨会论文，马里兰州巴尔的摩，1992年

States that although the Mobile Window Thermal Test Facility (MoWiTT) is designed primarily for studying the dynamic net energy flows through fenestration systems over the full diurnal cycle, it is also frequently used to measure nighttime U-values. Notes that these measurements have the advantage of incorporating the exterior film coefficient resulting from the true ambient conditions at a particular time and location, rather than relying on a laboratory simulation of some assumed average or extreme condition. On the other hand, the MoWiTT is a much more complicated facility than a laboratory hot box, and the sources of potential error are correspondingly greater. Discusses the method of deriving the nighttime U-value from directly measured data and the effect of random and systematic errors.KEYWORDS: Windows, mobile, testing, USA, nighttime, measuring, accuracy, transmittance