This monograph presents the latest research developments of innovative building envelope systems. These systems have the ability to allow building structures to be responsive to changes in outdoor conditions to ensure comfortable indoor environment and acceptable indoor air quality at higher energy efficiency compared to conventional systems. In particular, the monograph overviews the basic operation principles and thermal performance of four technologies described in three chapters: (i) dynamic insulation materials that can change its thermal properties in order to better adapt the building envelope with its outdoor environment and reduce building heating and cooling thermal loads, (ii) variable reflectance coatings for application on roofs to lower and even eliminate the energy penalties associated with reduced solar heat gains during heating operation of buildings, (iii) single layer breathing walls to recover energy wasted from heat transmission inside the walls and provide air ventilation to indoor spaces, and (iv) multi-layer living walls to apply biomimetric principles and phase-change materials to adapt building envelope properties with the changing outdoor conditions.