Ny alternate of conventional Air Conditioner

What you're after is an HVAC system. Heating, Ventilation, and Air Conditioning.

Excerpt from HVAC Wikipedia article:

The three central functions of heating, ventilating, and air-conditioning are interrelated, especially with the need to provide thermal comfort and acceptable indoor air quality within reasonable installation, operation, and maintenance costs. HVAC systems can provide ventilation, reduce air infiltration, and maintain pressure relationships between spaces. The means of air delivery and removal from spaces is known as room air distribution.

??? Venting a portable A/C does not require "modifying" the window at all. You open the window, insert the exhaust-hose plate, close the window onto it, perhaps stuff some foam between the upper and lower pane, and you're done, without modifications to the window...