80% of the buildings that will exist in 2050 already exist. By understanding the tectonic principles and redesigning the building envelope and system, we are able to improve the energy balance of the 28 story 733 Park Avenue to become net-zero. The building’s energy performance was improved by adding a new skin to the building that seals it, preventing any energy deficiencies, introducing active solar gain on the south elevation, integrating PV cells into the energy system, and adding balconies on the west elevation.