Sustainability and green building have taken the real estate investment world by storm. We’ve been working with some of the biggest REITs and institutional property owners on Solar as a Service–and we’ve witnessed firsthand as our clients have set lofty corporate environmental objectives and launched major internal initiatives aimed at greening their portfolios.

But an interesting question arises when you consider that most of these green building initatives are focused on new construction. How will sustainability be applied to existing buildings? How will those buildings compete in an increasingly green-built world? And what options to building owners have to prevent their buildings from becoming obsolete?

Jim Thomas, chairman of Thomas Property Group, put it plainly when I saw him speak at the PREA conference earlier this year. To him the sustainability of new buildings was old news. He challenged the audience to think about how they would protect the value of their current non-green portfolio investments, “Every new office building being built will be green. The interesting question is what will happen to all those existing assets?”

This is where solar power and our service have a very important role to play. Rooftop solar is an ideal way to enhance the sustainability of an existing asset–unlike many other green building solutions, solar does not require major re-engineering of a building’s systems. It integrates easily with the existing structure and electrical system and can be deployed in less than a year. And a solar array is like a “big, green billboard” advertising the sustainability of a building.

In other words, Solar as a Service is an ideal way for property investors to drive sustainability into their existing portfolio–quickly and with almost no risk or additional cost. It enables them to enhance the competitive position of older properties in increasingly green markets. And that’s critical to maintaining asset value rather than letting it erode due to obsolescence.