By some measures, what came to be known as a "skyscraper" first appeared in Chicago with the 1885 completion of the world's first largely steel-frame structure, the Home Insurance Building. It was demolished in 1931.
Comparing PV and efficiency measures I feel compelled to point out that the statement that "Energy efficiency will generally be less expensive per kWh than solar" is just about meaningless. Here's how I would phrase it: If you know how much a PV system will cost...
To achieve energy efficiency, eco-friendly skyscrapers employ various strategies. These include: High-performance building envelope: Insulated walls, roofs, and windows reduce heat transfer and minimize energy loss.

Energy Efficiency.Why Design and Build Green. When you rate your building with Austin Energy Green Building, you contribute to Austins environmental and sustainability goals and earn recognition for your work. Learn about the benefits available to rated projects. Get Started.
Greening the Skyscraper: Energy Efficiency and Design.Skyscrapers are also becoming increasingly smart, with integrated technologies that monitor and adjust building systems in real-time to optimize energy consumption.

Energy efficiency measures fundamentally describe using less energy to deliver the same level of heating, lighting, and overall building performance. At its core, energy efficiency involves strategic approaches to reducing energy consumption without compromising living standards.