original: He even envisioned centralized air conditioning that could cool entire cities.
simplifications: He pictured city-wide central air conditioners. He even thought about creating air conditioning that could cool entire cities. He thought of air conditioning that could cool cities. He daydreamed about lowering temperatures of whole cities with central air conditioning. He imagined centralized air conditioning that could cool whole cities. He thought of a centralized air conditioning system that would be able to lower the temperature in whole cities. He also imagined air conditioning that could cool entire cities. He pictured central air conditioning to cool a city. He thought of centralized air conditioning for entire cities. He even imagined centralized air conditioning  to cool entire cities.