Project design objectives
The objective for the living wall at Pier 4 was a combination of several. With the living wall in place there was an obvious beautification of the rooftop terrace. Bringing the element of nature to the private roof top terrace improves the aesthetics and gives the tenants a very pleasant place to gather, relax and socialize. An outspoken objective from ownership is to improve biodiversity, the living wall with its lush plantings and seasonal flowers strongly enhances the ability for natural habitat on the roof. For both sustainability reasons and cost efficiency the owner selected the Sempergreen system as it has the capability to sustain plant life through the cold Boston winter months eliminating substantial plant replacement needs. The living wall was a critical part to lead up to the LEED GOLD certification.
Site specifics
The living wall is located on the roof top terrace of a 12-story building on one of the seaport piers in Boston MA. The walls are facing the water and are partly North-East and partly North-West facing with limited direct sunlight, especially in the winter months. Obviously, a challenging application especially considering Boston winter climate. Appropriate irrigation equipment, site specific plant species and careful plant management make it possible to sustain plant health year-round. The wall is approximately 60’ wide and 20’ tall and wraps around an opening towards building entrance.
Irrigation System
The Sempergreen living walls are irrigated with a Sempergreen Plant Care System consisting of a wide variety of sensors to ensure all plants are appropriately and consistently provided with water and nutrients. The plant care system monitors the moisture content in the wall, adjust irrigation schedules accordingly and provides plants with microbursts of nutrients through the irrigation water. The system will be calibrated to a point where its wasting none of the irrigation water and the gutter will be there just for emergencies. The proprietary fully automated winter watering system continuously monitors the outdoor temperatures and responds to freezing temperatures with a customized watering schedule every day of the winter as plants need water throughout winter as well. All sensor data is being communicated with service technicians and alarm messages will warn the technicians of any inconsistencies giving them the opportunity to resolve an issue before plants are affected by it.
Obstacles and challenges
The biggest challenge on this project was how to sustain plant health in the rather harsh environment on the rooftop in Boston MA. It is fair to say that our first winter was not a success. A frozen pipe caused a cascade of problems. In addition, the wall is facing towards the bay and the ocean and so during the already cold winter months an underestimated strong and harsh wind would beat up a specific portion of the wall leaving several plant species struggling.
To eliminate the same issue in the years to come Sempergreen Services adjusted several elements to the system, updated the plant palette, and improved the maintenance protocols both pre- and post-winter. Additionally, the air-tunnel effect was remedied by installing a ‘windbreaker’ in the ocean-side patio opening to reduce the harsh winds that would otherwise reach the wall throughout winter.
The second and all subsequent years were a much greater success, in 2021 we barely had to replace any plants and so we were able to prove our client and partners that indeed the system would be able to deal with such challenging conditions.
