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Montgomery County, MD (January 4, 2024) – The Montgomery County Green Bank (Green Bank) proudly announces the appointment of Tim Zhang as the new Chief Investment Officer, and Mariann Zylstra as the new Chief Credit Officer, effective January 2, 2024.

As the newly appointed Chief Investment Officer, Zhang brings demonstrated expertise in making equity and credit investments across diverse sectors, including real estate, affordable housing, consumer, and clean energy. Zylstra previously served as the Green Bank’s Director of Underwriting, and has 20 years of progressively responsible positions at commercial banks in various cities across the U.S along with nonprofit executive roles.

“We’re delighted to welcome Tim as the Green Bank’s new Chief Investment Officer and promote Mariann as the Chief Credit Officer. Their combined leadership experience, with solid foundations in commercial banking and finance management, will contribute significantly to advancing the Green Bank’s mission of equitably accelerating clean energy investment and positive climate impact,” says Bonnie Norman, Green Bank Board Chair.

Prior to joining the Green Bank, Zhang served as Principal and Vice President of Indirect Investments at Middleburg Community, a fully integrated multifamily developer and property management company based in Tysons, VA. His professional background also includes roles in investment management at Sunac, Taikang Asset Management, and CMC in Asia. Zhang received a Master of Business Administration from New York University and a Bachelor of Science degree in Finance and Business Management from the University of Maryland.

“I’m honored to join the remarkable team at the Green Bank. Together, we will leverage partnerships and sound financial strategies to drive impactful investments, fostering a sustainable future for all in Montgomery County,” states Tim Zhang.

Prior to working for the Green Bank, Zylstra was Senior Vice President and Commercial Banking Market Leader for KeyBank in Seattle, where she also led a Business Banking team. Over the years her community service has included executive and board roles with several nonprofit organizations including The MS Society, the Economic Development Council serving greater Seattle, United Way, and SCORE. Mariann received a Master of Business Administration from Indiana University and a Bachelor of Science degree from Central Michigan University.

Mariann Zylstra expresses her sentiment on the transition from Director of Underwiring to Chief Credit Officer, “I eagerly anticipate providing ongoing support to talented and motivated colleagues. Together, we will persist in aligning underwriting and credit policies with the mission and goals of the Green Bank.”

About the Montgomery County Green Bank

The Montgomery County Green Bank is an independent, 501(c)(3) nonprofit dedicated to helping businesses and residents affordably implement energy efficiency, clean energy, and climate-resilient solutions. The Montgomery County Green Bank supports Montgomery County, MD by driving investment into energy efficiency and clean energy through lending and investment partners in the region. These efforts include working with homeowners, renters, nonprofits, and commercial entities of all varieties. For more information, visit

Media contact: Tyniah McDuffie, Director, Communications and Community Engagement