EPDS and LCA of Precast Concrete Commercial Buildings


The North American Precast Concrete industry, through the Canadian Precast/Prestressed Concrete Institute [CPCI], the National Precast Concrete Association [NPCA], and the Precast/Prestressed Concrete Institute [PCI], has released  Environmental Product Declarations [EPDs] in three key precast concrete product categories. The EPDs will allow architects, engineers, building owners, and other specifiers to better understand the environmental impacts of precast and prestressed concrete products.

The precast concrete industry wide EPDs are now available for the following products: Architectural and Insulated Wall Panels, Structural Precast Concrete Products and Underground Precast Concrete Products.

Third-party verified EPDs
An EPD is a standardized, internationally recognized, comprehensive tool for providing information on a product’s environmental impact. Information in the EPD documents is based on an ISO-compliant Life Cycle Assessment [LCA] and verified by a third-party. The detailed analysis considers all processes in the manufacturing of a product, including raw material and energy extraction, preliminary production and the manufacture of end products.

EPDs and LEED
The industry-wide EPDs are issued within clearly defined product groups based on the precast concrete Product Category Rules [PCR]. Using products with EPDs can contribute to LEED credits. LEED v4 has incorporated a new credit for EPDs that have been third-party verified by an approved program operator. For more information on LEED credits, visit www.usgbc.org and www.cagbc.org.

The EPDs were independently prepared by Athena Sustainable Materials Institute in accordance with ISO 14025 and ISO 21930; the Product Category Rules for Preparing an Environmental Product Declaration for Precast Concrete [UN CPC 3755], March 2015; and ASTM international’s EPD program operator rules. They were also independently verified by ASTM International [in accordance with ISO 14025) and by Industrial Ecology Consultants (in accordance with ISO 14025 and the Product Category Rules].

CPCI, NPCA and PCI are the leading technical resources [Body of Knowledge (BOK)] for the precast concrete industry in North America. From this BOK, building codes, design guides, educational programs, certification, sustainability programs, and new research ideas are derived. This joint industry initiative develops, maintains, and disseminates the BOK necessary for designing, fabricating, and constructing sustainable and resilient precast concrete structures.

The EPDs can be obtained as follows:
Architectural and Insulated Wall Panels - downloads.cpci.ca/418/download.do
Structural Precast Concrete Products - downloads.cpci.ca/419/download.do
Underground Precast Concrete Products - downloads.cpci.ca/420/download.do


SUMMARY OF CONCRETE FINDINGS

In order to better understand concrete's environmental performance in the context of building construction, use, and end-of-life, a life cycle assessment (LCA) of a typical commercial building with five variations of building envelope and three variations of structural framing in two Canadian locations was conducted. The building types were modeled in two cities representing two Canadian climates: Vancouver, British Columbia—a cool climate (Climate Zone 5C)—and Toronto, Ontario—a cold climate (Climate Zone 6A). This LCA study (1) was a cradle-to-grave LCA, done in accordance with ISO standards. Since the LCA included a comparative assertion intended to be disclosed to the public, an independent external committee of LCA and technical experts critically reviewed the methodology and results.

 *Note: The Thin-Brick Veneer utilized bricks 13-16 mm (1/2 to 5/8”) thick, cast into the face of the precast concrete panels.

 

Concrete Call-outs

1. During Occupancy (60 and 73 year scenarios) the buildings with the lowest global warming potential (GWP), regardless of location and service life, were the buildings with precast concrete envelope and cast-in-place concrete structure (P-C, Pi-C, and Pib-C).
2. During Occupancy (60 and 73 year scenarios), as with GWP, the buildings with the lowest total primary energy (TPE), regardless of location and service life, were the buildings with precast concrete envelope and cast-in-place concrete structure (P-C, Pi-C, and Pib-C).
3. During Occupancy (60 and 73 year scenarios), the buildings with the highest TPE and GWP (60 and 73 year scenarios) were all steel structures, regardless of location and service life, with curtain wall envelope and steel structure (CW-S) having the highest TPE and GWP in all cases.
4. With energy simulation, it was found that the interior thermal mass inherent in cast-in-place concrete and precast concrete floors (compared to concrete toppings on metal deck) reduced annual heating energy use by 6 to 15% and reduced annual energy use by 2 to 3%.
5. Operating energy was responsible for 54 to 75% of the GWP in Vancouver (the range represented service lives of 60 and 73 years, respectively), and in Toronto, 90 to 91% of the GWP was due to operating energy (dependant on service life).
6. Operating energy accounted for 90 to 97% (depending on location and service life) of the cradle-to-grave embodied energy (TPE).
7. For all the building types in Toronto and Vancouver, for operating energy from cradle-to-grave, electricity use was responsible for the majority of impacts in most of the impact categories, including: global warming,  acidification, respiratory effects, eutrophication, photochemical smog, solid  waste, ozone depletion, and total primary energy; both fossil and non-renewable.

 

Portland Limestone Cement (PLC)

When Portland Limestone Cement (PLC) was used in the manufacture of precast concrete and the production of cast-in-place concrete, environmental impacts were reduced. The GWP is reduced 6 to 9% and total primary energy is reduced 4 to 7%. Although the absolute reduction is higher for precast concrete, the higher percent in these ranges are cast-in-place concrete because there is less portland cement per cubic metre on a mass-basis compared to precast concrete. There were also significant reductions in impacts associated with acidification, respiratory effects, eutrophication, smog, water use, non-renewable energy, and renewable energy (non-biomass).

Over the life of the buildings, when PLC is substituted for RPC in concrete at the rate of 12%, the environmental impacts are reduced. The data showed that a 12% replacement of PLC for RPC, reduced the GWP by approximately 60,000 kg CO2 eq. The entire reduction occurred in the manufacturing stage. Since the absolute GWP of the of the buildings in Vancouver was less than those in Toronto, the relative reduction due to PLC was less in Toronto than in Vancouver, but the absolute reduction was approximately the same. Comparing just the manufacturing stages, the percent reduction was approximately 5% (4.6% in Toronto, 4.7% in Vancouver). When compared from cradle-to-grave, the percent reduction was 1.6 to 1.8% in Vancouver and 0.3 to 0.4% in Toronto. 

 

Other Significant Impact Categories

1. The three buildings with the lowest acidification potential in Toronto were the buildings with conventional precast concrete envelope and cast-in-place concrete structure (P-C, Pi-C, and Pib-C).
2. The six buildings with the lowest respiratory impact in Toronto were buildings with precast concrete envelopes.
3. The three buildings with the lowest photochemical smog potential in Toronto were the buildings with precast concrete envelope and cast-in-place concrete structure (P-C, Pi-C,  and Pib-C).
4. Buildings with precast concrete or cast-in-place concrete structures had less impact in the water use category than buildings with steel structure.
5. Buildings with precast concrete or cast-in-place concrete structures had less abiotic resource depletion than buildings with steel structure.

The concrete industry is dedicated to developing and promoting low environmental impact building design, complementing such current efforts as the new Energy Code and ASHRAE‘s Advanced Energy Design Guidelines to encourage the elimination of thermal bridging in building facades and the increased use of thermal mass.

 

References and Acknowledgements

LCA Project Team
•    Medgar Marceau, Building Science Engineer, Morrison Hershfield (Project Leader)
•    Dr. Lindita Bushi, Senior Research Associate, ASMI
•    Jamie Meil, Managing Director, ASMI
•    Matt Bowick, Research Associate, ASMI
•    Wayne Trusty, Past President, ASMI
•    Mark Lucuik, Building Science Specialist, Morrison Hershfield
•    George J. Venta, Venta, Glaser & Associates
•    Hua Sheng He, Building Science Consultant, Morrison Hershfield

LCA Critical Review Committee
•    Dr. Paulina Jaramillo, Chair, Civil and Environmental Engineering, Carnegie Mellon University
•    Dr. Hafiz Elhag, British Precast Concrete Association
•    Dr. Trevor Grounds, Former Chairman of the British Precast Sustainability Committee, Former Co-chair of the UK cement and concrete LCA
•    Dr. Eric Masanet, Lawrence Berkeley National Laboratory


For more information please contact:

Commissioner
Canadian Precast/Prestressed Concrete Institute
Contact: Rob Burak, President
#100 - 196 Bronson Avenue, Ottawa, ON, K1R 6H4
Tel:(613) 232-2619; Fax:(613) 232-5139
www.cpci.ca

LCA Project Team
Athena Sustainable Materials Institute
Contact: Jamie Meil, Managing Director
119 Ross Avenue, Suite 100, Ottawa, ON, K1Y 0N6
Tel: 613.729.9996; Fax: 613.729.9997
http://www.athenasmi.org

Morrison Hershfield
Contact: Medgar Marceau, Project Leader
Suite 810, 10900 NE 8th Street, Bellevue, WA  98004
Tel: 425 289 5936; Fax: 425 289 5958
www.morrisonhershfield.com