Greenroofs.com Project of the Week: 10/24/11
PECO Main Office Building
47,000 sf.  Greenroof

Year: 2008
Owner: PECO Energy
Location: Philadelphia, PA, USA
Building Type: Corporate
Type: Extensive & Intensive
System: Other
Size: 47,000 sq. ft.
Slope: 1%
Access: Accessible, By Appointment
Google Maps: link
YouTube Video: link

Project Description & Details

Located on top of an eight-story section of the PECO (Philadelphia Electric Company) building, the rooftop garden holds growing media up to 8 inches thick; the greenroof development is part of the company’s recently-announced comprehensive environmental initiative with a range of programs over the next several years.

This retrofit project was established with low-maintenance pre-vegetated Sedum mats by Sempergreen over a specially formulated growing media. Because of the dead load restrictions, the extensive greenroof media was designed to be extra-lightweight. The Roofmeadow Type I extensive greenroof assembly weighs 17 psf when fully saturated. The cool green Sedum carpet is punctuated by pathways, lit seat walls and Roofmeadow Type III intensive native perennial beds located over zones with a higher dead load capacity. In partnership with the Pennsylvania Horticultural Society, PECO co-sponsors public greenroof tours that attract architects, developers and engineers intent on learning more about vegetated assemblies.

Designers/Manufacturers of Record

Architect: William Craig, Architect and Re:Vision Architecture
Structural Engineer: Michael D. Pieroni, Robert E. Lamb, Inc.
Installation: Former Roofmeadow Network Contractor, Michael Furbish, Furbish Company, LLC
Vegetated Mat Provider: Sempergreen
Greenroof System: Roofmeadow Types I and III
Growing and Drainage Media: SkyGarden, Stancills, Inc.

Additional Info

Headquartered in Philadelphia,  PECO is an energy delivery subsidiary of Exelon Corporation and is the largest electric and natural gas utility in Pennsylvania, serving approximately 1.6 million electric customers and 490,000 natural gas customers in southeastern Pennsylvania.  Approximately 90% of PECO’s customers are residential and the remaining 10% are commercial and industrial.

PECO is taking major steps to demonstrate its environmental leadership.  In 2008 PECO embarked on the first phase of a five-year major environmental initiative to preserve the environment and help customers become more environmentally responsible.

Along with other initiatives and policies, the company received ISO 14001 certification, the internationally recognized standard to help organizations minimize their  impact on the environment.  See the very informative video, “PECO’s Environmental Initiative” below which also has time lapse photography of the greenroof installation:

For example, in addition to the 47,000 sf greenroof  atop the Main Office Building headquarters – which was largest greenroof in the state of Pennsylvania on an existing building –  the PECO Crown Lights were updated with the installation of 2 million energy-efficient LEDs (light-emitting diodes) with color capacity, resulting in a 40% energy savings.

As the result of a centuries old combined sewer system, the city of Philadelphia is plagued with a serious water pollution problem.  The PECO Main Office Building sits on the densely developed Schuylkill River banks in the heart of Center City and the roof footprint is 95% of the lot area.

In an effort to solve the onerous CSO issue and comply with the Federal Clean Water Act, the city is incentivizing green infrastructure as a key solution, with the added advantage of providing additional environmental benefits for the adjacent cityscape.  Initiatives include  Green Cities, Clean Waters Plan,  Philadelphia’s 25-year plan to protect and enhance their watersheds by managing stormwater with innovative green infrastructure.

“The Philadelphia Water Department developed the Green City, Clean Waters plan to provide a clear pathway to a sustainable and resilient future while strengthening the utility, broadening its mission and complying with environmental laws and regulations.” ~ Green Cities, Clean Waters Plan

Shown below on the roof, Howard Neukrug is the Water Commissioner at the Philadelphia Water Department and the man behind the Green City, Clean Waters Plan:

The PECO green roof is under management with the  Pennsylvania Horticultural Society (PHS) which leads regular tours of the roof by appointment and on special  occasions.

“In order to safely accommodate guests, the roof area used for tours and gatherings is separated from the rest of the expanse by a self-ballasting, ADA compliant railing for pedestrian safety. The railing provides a secure barrier without requiring the attachment to the roof deck or penetration of the waterproofing membrane.” ~  Roofmeadow Case Study

The  43,000 square foot  extensive portion is unirrigated and was planted with drought resistant vegetation using 12 different species of Sedums.  The remaining  2,000 square foot  intensive portion is planted with perennials and ornamental grasses indigenous to Pennsylvania  and uses a partial base capillary irrigation system, providing moisture without losing any water into the atmosphere.

Due to weight concerns, the growing media is a specially formulated lightweight blend specified by Charlie Miller and the pre-vegetated mats were produced with the same blend by Sempergreen.  On site in Philadelphia, a second batch of extra lightweight media was distributed before the mats were unrolled. The growing and drainage media for the extensive areas and the intensive beds and planters were provided by SkyGarden.

“We made a very definite decision to choose plants that were drought resistant or drought tolerant.” ~ Liz Williamson of PECO in 6abc.com.

The green roof has recovered from die back of some species during the hot, dry summer of 2010; the vegetative cover is now more diverse and vigorous than ever.  The Roofmeadow maintenance program is being followed and documented.

“Roofmeadow and PHS closely track the native plants to identify those that are best able to endure the harsh conditions of a windy, riverside rooftop.”  ~  Roofmeadow Case Study.  Download it here.

Along  with the City of Philadelphia, the PHS is co-hosting the upcoming 9th annual  Green Roofs for Healthy Cities 2011 CitiesAlive Green Roof & Wall Conference on November 30 – December 3 (read more about the Conference here).

Drew Beecher, president of PHS, and Philadelphia Mayor Michael Nutter were filmed for  this promotional video below  on top of the PECO greenroof – click to see:

Public outreach and education are very important to PECO – if you can’t make it for CitiesAlive, do call PECO when in town to set up a tour.  The PECO Main Office Building is located at 2301 Market Street, Philadelphia, PA 19103  – visit their website here.

Did we miss something?  We’d love to hear from you!  Click  here to see more information about this project in  The International Greenroof & Greenwall Projects Database.  See how you can submit yours  here.

Love the Earth, Plant a Roof!

~ Linda V.