Case Study #8
Desert Botanical Garden – West Greenhouse Operable Shade Structure
“A Game Changer”…“A Model for Sustainability”…”A Turning Point”…”Unbound by Convention”…”World Leading Green Building”…”Inspiring”…”Happy Plants.”
These were some of the goals set for this project that came out of an intensive Integrative Design Process involving over forty participants for the Desert Botanical Garden. The group worked together to determine the top 18 goals and then set about designing the master site plan through several workshops. Everyone participated in these exercises, from the architects, engineers, general contractors, Garden staff, board members, volunteers, biologists, and trustees. These events built trust and consensus. The client helped with the engineering, the engineers used creativity to help the designers, and staff helped design the buildings- all to ensure the project moved along swiftly, efficiently, and with the client’s best interests at heart.
Energy modeling and extensive costing scenarios provided the client and design team with information to make the very best decisions. Phase I included site work for the entire horticulture center masterplan including automated state-of-the-art greenhouse. Plants are the central focus of the Garden, thus the greenhouses are placed at center. Its 24’x24’ grid extended over the site to provide future shading of paths and buildings to reduce overall site heat gain. The greenhouses are clad in energy-saving polycarbonate cladding, which unlike glass diffuses light for greater plant health.
Greenhouses have layers of operability to provide an optimum environment for the special collections they house. Operable external louvers, operable roofs, operable internal shades, evaporative cooling, heating, and fans are all be adjusted individually for each bay. A control system allows staff to set parameters such as temperature, humidity, and lighting levels which are sensed and controlled automatically to keep levels optimal for plant health and save energy.
Based on UV testing of multiple components and recommendation by our Greenhouse Consultant the team determined that we need multiple levels of solar and UV control. To avoid adding fire sprinklers at the upper operable louvers the City of Phoenix allowed us to utilize a perforated metal panel with 50% opacity. This panel consisted of a bent panel design with custom milled fittings to a strut system that connected to 27 motors. With technology embedded in the motors, we were able to connect the louvers to our Priva Smart Greenhouse Automation and Climate control systems. Based on programmed settings for temperature, wind, time of day and day of year the louvers operate to optimize both shading and allowance of critical UV rays that the plants need. The combination of the operable louvers, polycarbonate roofs that allowed us to “flush” the interior space at night and operable fabric cloth allowed us to optimize are critical natural elements that allowed the collection to thrive.
Utilizing the standard sizing of a typical greenhouse structure allowed us to standardize the building into a 24’ x 24’ x 24’ grid system. Oversized gutters on the west end of the structure allowed us to capture rainwater into galvanize cisterns that were used to water the plants.
The louvers mimic the role of the Sonoran Desert’s nurse plants which shelter less hardy-skinned specimens under their lacy leaves. They can be adjusted to any angle and programmed to track the course of the sun like a sunflower, providing a consistent amount of sun exposure. If desired, the caretakers can operate the array like a gigantic Venetian blind by pivoting them all in synchronicity, or they can activate separate bays to create different shade zones. Opportunities to build something completely unique on such a grand scale as this greenhouse don’t come along often, but we crave the opportunity to solve more problems like it. It was a fun and challenging way to iterate Swiss architect Le Corbusier’s concept of a house as a “machine for living”.
The plants have never been happier.