NEW YORK CITY-Dutch real estate firm OVG Real Estate pledged $1 billion toward sustainable building practices Wednesday at the Clinton Global Initiative’s annual meeting. This is the firm’s second such commitment.

Over the next five years, OVG’s fund will focus on retrofitting existing buildings in C-40 cities, Coen van Oostrom, founder and CEO of OVG Real Estate tells GlobeSt.com. It’s a need that’s brought about by the age of the existing stock of buildings in cities like London, Paris and New York.

“The big difficulty that we see around the world is that in the current stock—in New York, in London, in Paris—so many buildings have been built 100 years ago or have been built 20 years ago and they’re using an enormous amount of energy,” van Oostrom says. “What we want to do is give as many examples as possible in those 40 big cities of how to retrofit those buildings. For example, we’re now negotiating with the city of London to see if we can buy a couple of buildings that the city owns.”