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INTRODUCTION

The goal of this research initiative was to calculate and evaluate the embodied energy of building materials and to find the total amount of embodied energy in a design project. Currently, the building industry has primarily focused on reducing operational energy of buildings. However, the manufacture and transportation of building materials account for about 6% of all energy used annually in the U.S. (source: Architecture 2030). As we drive down the energy use of buildings, we expect that embodied energy will become increasingly important.

Our research focused on evaluating existing calculation tools and on collecting embodied energy data from available sources such as the University of Bath’s ICE database and manufacturers’ Environmental Product Declarations (EPDs) and Life Cycle Assessments (LCAs). The lack of appropriate calculators drove us to develop our own tool and to apply our research findings by calculating the embodied energy of two corporate interiors projects. For this phase of the research, we only looked at interior architecture products and furniture.

Our investigation led us to better understand the energy embodied in the materials we specify, identify the relative impact of categories of building products, and consider new approaches to selecting them. The result of our initial research was the development of three resources, which will be used on future projects:1. Mbod-E: an interactive embodied energy calculator2. Material LIFE: an embodied energy material selection guide for designers3. BIM integration of embodied energy data

6% of all energy consumed annually in the U.S. is used for the manufacture and installation of building components.

Figure 1. New Cannon Design office in Chicago IL

RESEARCH IN PRACTICECalculating and Assessing the Embodied Energy of Construction Materials

Marion Marcenac Lawson, Sustainability ConsultantChristopher Lambert, Sustainability ConsultantRand Ekman, AIA, Director of SustainabilityPeter Hourihan, Director of Research

Cannon Design, Chicago and Washington D.C. offices

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FINDINGS

Cannon Design Chicago Office

The Chicago Office relocation project is a 60,205 square foot build-out of one floor in an office tower. Embodied energy was calculated for all the materials used in the project, excluding ancillary furnishings and mechanical equipment. The unit typically used to measure embodied energy is megajoules (MJ), where 1 MJ is equal to 0.948 kBtu.

The total embodied energy for this interiors project was calculated to be 5,151,150 MJ or 85.6 MJ/sf (81.1 kBtu/sf). Figure 2 below illustrates the distribution of energy based on material type. The two most energy-intensive categories were movable furnishings and floor finishes.

Cannon Design Washington D.C. Office

The Washington D.C. Office project is also an interior build-out measuring 20,336 square feet. The total embodied energy for the project was 860,740 MJ or 42.3 MJ/sf (40.1 kBtu/sf). The value per square foot was significantly lower than the Chicago project because a large percentage of existing work stations were reused. Therefore, the most energy-intensive categories in the Washington D.C. office were interior partitions and floor finishes.

The Cannon Design Washington D.C. Office project has 42.3 MJ of energy embodied in each square foot of space.

The Cannon Design Chicago Office project has 85.6 MJ of energy embodied in each square foot of space.

RESEARCH IN PRACTICE

Figure 2. Chicago office embodied energy distribution

Figure 3. Washington D.C. office embodied energy distribution

2%

52%

13%4%

6%

19%

4%

Interior Partitions

Interior Doors

Wall Finishes

Floor Finishes

Ceiling Finishes

Movable Furnishings

Movable Furnishings (workstations only)

Interior Partitions

Interior Doors

Wall Finishes

Floor Finishes

Ceiling Finishes

Movable Furnishings

Movable Furnishings (workstations only)

Staircase

29%

3%

7%25%

10%

8%

13%

5%

Setting an Embodied Energy Baseline

The total value of embodied energy per square foot of the Chicago and Washington D.C. offices vary significantly. However, if we ignore the staircase in the Washington D.C. office and movable furnishings in both offices, we find that the numbers are more comparable between the two projects (Figure 4). The difference between the two projects illustrates the importance of reusing materials - especially furniture - whenever possible to decrease the total embodied energy of the project. Both projects also show that a large percentage of a project’s embodied energy is found in floor finishes and partitions.

Comparing Embodied and Operational Energy

To better understand the magnitude of the embodied energy of the Chicago project, we compared embodied energy (85.6 MJ/sf or 81.1 kBtu/sf) to modeled energy use. Operational energy was projected to be 31.1 kBtu/sf, so the energy embodied in the interior architectural components and furnishings is equivalent to 2.6 years of energy consumption.

If we added in the embodied energy of mechanical, electrical, and plumbing equipment (outside the scope of this research), we would see that embodied energy equates to an even longer term of operational energy use. This comparison is particularly important in a commercial tenant improvement project because leasehold is measured on a short-term (sometimes as little as five years) basis. Longer lease periods and re-use of existing systems help mitigate the embodied energy impact on a project’s energy footprint. For a full building, Architecture 2030 projects that embodied energy is equivalent to 17-20 years of operational energy use.

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Excluding furniture, partitions and floor finishes have the largest amount of embodied energy and account for 67% of all embodied energy in both interiors project.

Figure 4. Comparison of two office projects by ASTM categories (measured in MJ/sf)

Figure 5. Comparison of operational and embodied energy

81.1 kBtu/sfembodied energy

0.6years0.6years

1year

1year

2.6 years of operational energy

at 31.1 kBtu/sf/yr

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0 CHICAGO

41.5 MJ/SF

WASHINGTON D.C.

34.4 MJ/SF

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CONCLUSIONS

Development of Tools for Cannon Design

Our research led us to create three tools that help integrate embodied energy in our practice: Mbod-E, Material LIFE, and BIM integration. Mbod-E is an Excel-based interactive calculator organized according to ASTM Uniformat II categories. Designers enter material quantities, and Mbod-E calculates the embodied energy for that material as well as for the entire project. It is our intent that this calculated value will be tracked for all our projects to establish an embodied energy benchmark.

In addition to a calculator, we designed Material LIFE as an embodied energy guide for designers to use when making material selection decisions. The document is organized with the same categories as Mbod-E and provides visual comparisons of products used for similar applications.

We integrated the embodied energy values we calculated using Mbod-E into the material properties of Cannon Design’s BIM families to facilitate calculations for entire projects. This approach takes advantage of the software’s automated quantity calculations by tracking and totaling embodied energy in project material schedules. By incorporating embodied energy values into material properties, we hope to eventually be able to model and make decisions using embodied energy in all our projects.

What This Means for the Building Industry

Our research showed there is a need for embodied energy calculators and design guides in the building industry. The tools Cannon Design has developed will lead us to create a more thorough calculator and design guide that will include structure, enclosure, mechanical, electrical, and plumbing equipment.

To be able to efficiently track embodied energy, designers need to push manufacturers to provide LCAs and EPDs for their products as part of the specification process. Requesting this data should become standard practice so that embodied energy can be a design driver that helps us reduce the overall energy footprint of our projects.

RESEARCH IN PRACTICE

Figure 6. Mbod-E embodied energy calculator (left) and Material LIFE (right)

Contact information:mlawson@cannondesign.com

Designers need to understand a project’s energy budget as having two line items: embodied and operational energy.

To reduce the energy footprint of buildings, the building product industry needs to rapidly increase transparency and information quality.