Longwood Gardens is funding its $250 million renovation using a combination of grants, endowment money, and issuance of tax-exempt “green” bonds. These sources will provide $200 million of the targeted sum, writes Erin Arvedlund for The Philadelphia Inquirer.

Bonds — which are essentially loans from investors who promise to repay the principal and interest — are traditionally used by companies, towns, and nonprofits to finance various projects. However, Longwood Gardens is using green bonds, a rapidly growing tool, to market to investors who are looking to back environmentally friendly projects.

This market increased to more than $500 billion last year globally, compared with $100 billion in 2017, according to the Climate Bonds Initiative. Meanwhile, Standard & Poor’s predicts that the global issuance of green bonds will pass $1.5 trillion in 2022.

“This industry is maturing as it goes,” said Eileen Perpiglia, Longwood Gardens’ associate vice president of accounting and finance.

The “green” bond money is funding the “Longwood Reimagined” expansion. It aims to upgrade the former Pierre S. DuPont family estate that is now a botanical and conservatory complex.

The issuer of the $200 million that qualify as “sustainability” bonds is the Chester County Industrial Development Authority.

Read more about funding at Longwood Gardens in The Philadelphia Inquirer.