Design Challenge

The second largest tourist attraction in Maine, with more than 150,000 visitors per year, the 270-acre Coastal Maine Botanical Gardens sought to add net zero educational and office spaces. The site was a challenge due to surrounding wetlands, topography, solar shadows and the aesthetics of the existing nearby Visitor’s Center. The Botanical Gardens wanted their architect to raise the sustainability bar of Maine’s Construction community to net zero.


Maclay Architects partnered with a Maine architect, Scott Simons, and local engineers, consultants and construction professionals. The design response focused on nature centered design along with net zero performance. The building includes light-filled public spaces for education and exhibits; and flexible classroom and meeting spaces that are connected to the gardens by outdoor terraces. The building’s glazing creates spaciousness and transparency, while the locally-sourced natural materials ground the building in its place and convey the essence of sustainability. The net zero strategy includes a 46kW photo-voltaic array, R-40 walls, R-60 roofs, R-20 foundation and triple-glazed windows. Water-reduction strategies include rainwater collection, low-flow plumbing fixtures and solar-heated hot water. Construction included one of the first uses of an innovative, high-performance, pre-manufactured wall and roof panel system for a net zero project. This enabled the building frame and enclosure to be erected in ten days in the middle of winter, in addition to providing the high-insulation and air tightness required for net zero success.


The completed building now produces 30% more power annually than it uses and serves as a teaching tool for visitors. As Maine’s first net zero energy and LEED Platinum commercial structure, the building has had a significant impact on environmental design and net zero building practices in the state. It won Vermont and Maine design and sustainability awards and the prestigious $10,000 Net Zero Energy Award from the Northeast Sustainable Energy Association. Recognition from numerous publications has broadened the building’s impact on the Northeastern environmental design community and its location at a prime U.S. tourist attraction has helped promote the importance of net zero energy.

Project Details


Boothbay, ME




8,400 sf


LEED Platinum
Net Zero
Zero Energy Certified through ILFI

Energy Intensity:

20 kBTU/sf-yr (modeled)
19.2 kBTU/sf-yr (actual)
-4.3 (actual w/renewable)

Air Infiltration:

0.105 cfm50/sf

Solar PV Array Size:

45 kW + Solar Thermal


2013 AIA Maine COTE,
Institutional/Education Citation
2012 AIA Vermont, Citation
2013 Northeast
Sustainable Energy Association, Zero Net Energy Building Award
2012 Woodworks, Eastern Wood Design Awards, Green Building
Wood Design Award

Publications & Press:

“Coastal Maine Botanical Gardens wins Top Net Zero and LEED Platinum Achievement,” Green Energy
Times, George Harvey, 2013

“Inspired by Nature”
High Performing Buildings, 2014

“Maine Makes its Mark with Greenest Building in the State,” Green Building News, 2012

“Maine’s ‘Greenest Building’ is Designed to Educate,”
Portland Press Herald,
Tux Turkel, 2011