Reflective materials applied to opaque building components are becoming increasingly important because of their benefits in terms of thermal comfort and energy savings. Because of their optical properties, reflective materials stay cooler than standard materials under the same conditions; therefore, they are also known as cool materials. This paper presents a review on the state of the art of the application of reflective materials on buildings' walls and roof. The thermal performance of these materials has been analyzed using different methodologies. Thus, the reported studies can be classified into seven categories: roof as a component, test cells, computational fluid dynamics, building simulation, monitored buildings, calibrated simulation, and mesoscale modeling. The paper describes the results obtained by means of these methodologies, the main characteristics of the models and, when available, the optical properties of the standard and cool materials. (C) 2014 Elsevier B.V. All rights reserved.