• Center for Sustainable Landscapes at Phipps Conservatory and Botanical Gardens

    Pittsburgh, Pennsylvania

Center for Sustainable Landscapes

Pittsburgh, Pennsylvania

Phipps Conservatory and Botanical Garden’s mission is to inspire and educate all with the beauty and importance of plants, advance sustainability and human and environmental wellbeing through action and research, and to celebrate its historic glass houses. The mission of the organization is evident in the Center for Sustainable Landscapes (CSL). A restored brownfield is now a productive place that takes what it needs from what is available to it, and provides a healthy environment for life to thrive. True to the Phipps mission, the ongoing work at the CSL is based on recognizing vital and positive connections between people, plants, beauty, health, and focuses on awakening children to nature and encouraging sustainable, healthy lifestyles.

The CSL's goal to meet the Living Building Challenge helped create a building that, over course of the 2013 calendar year, demonstrated that it operates as net zero energy facility. Moving forward, the operations team continues to engage occupants into how the facility maintains a net zero energy status, and continues to actively monitor performance with constant feedback loops to operators and occupants.  

Use the icons below to find out how this project approached each Petal of the Challenge.


Photo: © Denmarsh Photography, Inc.

Limits to Growth

Site condition prior to project start: The Center for Sustainable Landscapes project was built on brownfield site previously developed by the City of Pittsburgh’s Department of Public Works. 

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Photo: © Denmarsh Photography, Inc.

Early energy models helped inform the project's design during its development.  Because available space for renewable solar photovoltaic systems was limited, the net zero energy goal presented a significant challenge for the design team. This team managed to overcome this challenge by employing an integrated design approach.

The final concept design energy model showed an EUI of 19 kbtu/sf‐year with an energy usage for the building at 117,623 kwh per year. A 125.25 kW PV Solar Array was chosen for the project that was estimated to produce 135,655 kWh per year. During the 2013 calendar year, the CSL was net positive on energy by 3,425 kWh, with an actual EUI of 20 kbtu/sf‐year

Annual Energy Use
 129,876 kWh
Simulated/designed: 117,623 kWh

Annual Energy Generation
Energy Generated:
133,301 kWh
Energy Use Intensity: 20 kbtu/sf


End Use Breakdown
1st Floor Plug Loads: 18,749 kWh/yr
2nd Floor Plug Loads: 9,152 kWh/yr
Exterior Site Power: 2,720 kWh/yr
Site Lights: 3,537 kWh/yr
Geothermal Pumps: 7,607 kWh/yr
Elevator: 1,943 kWh/yr
Interior Lighting: 10,179 kWh/yr
Berner Unit - HVAC RTU: 73,246 kWh/yr

Type + size of renewable energy system(s) used: The Solar World 125 kW solar system is made up of one ground and two roof mounted arrays, and the 10kW vertical access wind turbine is located northeast of the building. The system diagram below details the locations of the solar arrays and the wind turbine.

Diagram courtesy of The Design Alliance

Design and Building Systems

The 21,892 sf building is designed to serve as an office, classroom, research, and library space for the Conservatory. The general purpose of the building is educational and demonstrational, as well as to provide work space for employees and volunteers. The building consists of two main regularly occupied floors with a third, non‐occupied, floor in the atrium. The exterior of the atrium is constructed mostly of glass, allowing for an interior greenhouse that can support plant life in a minimally tempered interior environment. The rest of the building is constructed so as to ensure optimum energy performance in the tempered spaces.

The building is concrete and steel construction with a wood façade and metal frame windows. The glazing is high performance, low‐E, double pane windows, that in some locations, are operable. A green roof has also been installed to reduce heat island effect and impervious coverage, while at the same time providing an excellent thermal barrier between conditioned and non‐conditioned spaces.

Mechanically, the building is primarily served by an under floor air distribution (UFAD) system. UFAD was selected because of its efficiency and low energy consumption relative to comparable systems. The UFAD provides optimum comfort control while at the same time preventing over ventilation by reducing ventilation to unoccupied air volumes. The UFAD system introduced ventilation air directly into the breathing zone and allows heat from internal loads to stratify above the occupants. When outside air conditions permit, the building is cooled by natural ventilation through motorized operable windows and full economizing cycle on the rooftop unit. The atrium is not mechanically conditioned. HEPEX Tubing for a future radiant hydronic heating system is installed to temper the space in the heating season (if this proves to be necessary), and no cooling is provided to the atrium in the cooling season. Instead, the atrium relies totally on natural ventilation. Computational Fluid Dynamics (CFD) models of the atrium were created to evaluate feasibility and practicality.

The entire system is served by a roof top air handling unit (AHU‐1). One dedicated rooftop unit serves the under floor system for the entire building. The unit consists of a filter module (MERV 9 pre‐filters and MERV 13 final filters), recirc/mixing box module, exhaust fan with VFD, enthalpy wheel module, tricoil module, supply fan with VFD and water cooled compressors. The unit provides approximate 12,000 cfm supply air with the ability to go to a full economizer cycle when outdoor air conditions allow. The unit responds to CO2 demand control ventilation. The tri‐coil design includes a DX coil sandwiched in between a glycol run around loop. The run around loop and associated fractional horsepower pump provides pre‐cooling and reheating to increase dehumidification capacity. The desiccant coated total enthalpy recovery wheel provides free heating, cooling, dehumidification and/or humidification depending on the season. The system capacity is based on loads and ventilation requirements as calculated using Trane Trace 700 software program. All occupied spaces are ventilated with outdoor air (OA) in accordance with ASHRAE 62.1‐2004 with the intent of meeting LEED Indoor Environmental Quality Prerequisite 1, Minimum IAQ Performance and Credit 2, Increased Ventilation. Thermal comfort conditions comply with ASHRAE Standard 55‐2004 within all mechanically ventilated spaces.

A geothermal well system has also been installed as part of the energy conservation measures. The wells are 510 feet deep and twenty feet on center from well to well. These wells feed water cooled compressors for both heating and cooling loads by providing tempered water to the AHU in the winter and cool water during the summer. All HVAC equipment is controlled via a direct digital control (DDC) building automation system (BAS), and all metering pertaining to HVAC work records data in conjunction with the BAS. 

Monitoring Methods: Solar PV monitoring at the Phipps CSL was conducted using an EMON Metering system for the first three months of the year until the Sunny Boy Portal, a web-based monitoring tool came online in April.  The Sunny Boy Portal system is online and can be accessed remotely on the web and has applications for smart phones.  

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Photo: Renee Rosensteel

Rights to Nature

The Center for Sustainable Landscapes does not block access, diminish the quality of fresh air, sunlight and natural waterways for any member of society or for adjacent developments. 

The CSL is located within the 15 acre Phipps Conservatory campus. The CSL project is built into the north facing slope of the Phipps campus, and is bordered by an inaccessible steep hillside to the south. To the West is parking, and to the East is the stormwater lagoon and surrounding landscape. No building facades or roofs are shaded by the CSL at any time of the year.

Fresh Air
No noxious emissions are emitted from the CSL which is a combustion free facility, and all operational emissions are Red List compliant. The project does not compromise any surrounding structures or properties from the ability to use natural ventilation.

Natural Waterways
No natural waterways exist within close proximity to the CSL project.

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Photo: Cory Doman

Project Website
Center for Sustainable Landscapes
Phipps Conservatory and Botanical Gardens

Tour Information

Center for Sustainable Landscape Tours

Beauty Narrative Phipps Conservatory and Botanical Gardens

Phipps Conservatory and Botanical Garden’s mission is to inspire and educate all with the beauty and importance of plants, advance sustainability and human and environmental wellbeing through action and research, and to celebrate its historic glass houses. The mission of the organization is evident in the beauty and spirit of the Center for Sustainable Landscapes. A restored brownfield is now a productive place that takes what it needs from what is available to it and provides a healthy environment for life to thrive. True to the Phipps mission, the ongoing work at the CSL is based on recognizing vital and positive connections between people, plants, beauty, health, and focuses on awakening children to nature and encouraging sustainable and healthy lifestyles.

The Center for Sustainable Landscapes (CSL) at Phipps Conservatory and Botanical Gardens incorporates green building technologies, passive strategies and natural processes in tandem to generate all its own energy and treat and reuse all water captured on its site. As part of the Phipps experience, which attracts over 250,000 guests a year, the CSL is uniquely positioned to communicate the importance of restorative design and health human scale spaces.

The facility is located on the Phipps campus’ southwest corner, nestled into the hillside on a 2.6-acre remediated brownfield lot once used as Pittsburgh’s Department of Public Works storage facility and service yard. The site had been paved over several times and suffered decades of environmental devastation. The storage facility was rehabilitated to serve as a support structure for the CSL. Underground gas tanks formerly used to fuel municipal vehicles were cleaned for reuse as storage for sanitary water. Indigenous, sustainable plants and soil were brought in to rebuild the hillside nearly from scratch. Today, a terraced garden leads downhill from the roof to the ground floor of the CSL, allowing visitors to walk through a trail of native plant communities, including wetland, rain garden, water’s edge, shade garden, lowland hardwood slope, oak woodland and upland groves. Between the surrounding landscape and the building’s green roof, over 250 species are represented, providing habitat for local fauna and serving as a demonstration for residential application of native plants.

In order to achieve the building’s net-zero energy goal, the CSL team had to maximize efficiency. The CSL’s orientation maximizes southern sun exposure, and the incorporation of light shelves, louvers and overhangs contribute to a projected 80 percent daylight autonomy while minimizing summer cooling loads and contributing to heating in winter. The building envelope and high performance wall and roof insulation reduce heating losses and cooling loads. Fourteen 510-foot-deep geothermal wells provide a 70% reduction in heating and cooling energy needs. A Building Management System monitors, controls, and provides feedback to ensure efficient operations. The building is designed to operate at an estimated 19.5 kBtu/sf/yr, a nearly 80 percent reduction compared to traditionally designed office spaces. Its energy is provided by photovoltaic arrays and a vertical axis wind turbine, together capable of producing up to 140,000 kWh/yr. Surplus power is directed to the other campus facilities.

Photo: © Denmarsh Photography, Inc

Every material element of the CSL was subjected to a thorough analysis of ingredients and their sources to ensure transparency. Pushing manufacturers to closely examine their supply and manufacturing chains, forging solutions, and training construction crews and subcontractors to properly document materials, the CSL project team emerged with findings which will ease this important process for future projects.

The project site can store enough water onsite to meet the buildings needs reducing impact on water conveyance and municipal sewage treatment. Rainwater is captured from not only the CSL site but the substantial rooftop space of the adjacent Tropical Forest Conservatory. Among the storm water treatment system’s principal components is a lagoon which replicates natural water treatment processes that occur in wetlands and marshes while providing habitat for native plants, fish and aquatic turtles. It is expected that captured storm water, supplemented by well water, will offset seven million gallons of potable water to the campus annually. Sanitary water from the CSL and adjacent maintenance building is treated by a constructed wetland that utilizes plants, sand filtration and UV filtration to disinfect the water to gray water standards. An Epiphany Solar Water System, in one of its first deployments anywhere, uses parabolic solar dishes to generate heat and power multi-stage distillation units to further treat sanitary system water to pharmaceutical standards. This water is used to water Phipps’ sensitive orchid collection.

In keeping with the outreach efforts of Phipps, the CSL is designed to maximize public interaction, beauty, and inspiration. Through talks and presentations, docent-led tours and dynamic science education programs, Phipps uses the CSL as a platform to reinforce the importance of human/environment interactions with particular emphasis on green space in the city, urban gardening, healthy food initiatives and urban-based sustainable building practices. Phipps’ is also conducting conservation psychology research on the effectiveness of art and communication as tools for changing the way that people interact with the world around them. As increasing numbers of people discover the visionary concepts at work at the CSL, as well as the potential for replication, they will be encouraged to mount similar projects at the home, business and community levels. Additionally, in the CSL’s dedicated indoor and outdoor classroom spaces, Phipps gives area children a chance to connect to nature, fostering the growth of tomorrow’s environmental stewards. 

The beauty and spirit of the CSL is recognizable on numerous levels and the work taking place at the project is inspiring and awakening people to understand the true benefits of allowing ourselves to live, play, and work in harmony with nature.

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Photo: Joshua Franzos

Project Costs
Total Cost (land excluded): 15,656,361
Soft Costs: $3,927,714
Hard Costs: $11,728,647

Creative Financing Opportunities

Foundations/Trusts: $10,118,000 (61%)
Individuals: $3,160,070 (19%)
Government Grant-Makers: $1,992,529 (12%)

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