Although many buildings claim to be green, low energy, or high performance, it is rarely clear on what evidence or data these claims are based. If claims of high performance are to be credible, it is essential that a common set of measurements be used and the results reported against meaningful and consistent benchmarks. Such protocols are also needed to give usable feedback to building designers and operators when measured performance does not match design intent and expectations. This book provides a standardized set of protocols over a range of accuracies and costs that can be applied consistently to the assessment of building performance, in both the United States and internationally.