Building Pathfinder

Frequently asked questions

Who would use the Embodied Carbon Pathfinder?: Pathfinder is primarily an educational tool that will introduce users to life cycle assessment and will help them gain a high-level understanding of the embodied carbon implications associated with various combinations of design decisions for the archetype buildings. Some may wish to use it in early design or pre-design for general guidance, when a custom life cycle assessment (LCA) study may not yet be feasible. Pathfinder does not replace tools that perform live LCA on a user’s specific project.
What’s the difference between this tool and the Impact Estimator?: The Impact Estimator is a whole-building LCA tool that can model any work of construction and delivers live LCA results. The Embodied Carbon Pathfinder, on the other hand, is displaying fixed data that was pre-calculated in the Impact Estimator for three specific archetype buildings. Results shown here are only roughly applicable to any building other than the ones modeled.
What’s the difference between this tool and other embodied carbon tools?: This tool is built on results from the Athena Impact Estimator for Buildings, with high-quality regionalized life cycle inventory data in the background, with the full building core and shell included in the model scope, and with the full life cycle modeled. Other tools may not be as comprehensive in scope and boundary and may be relying on less consistent or less regionally appropriate background data. On the other hand, this tool is not doing a live calculation on user-specified material types and quantities as with some other tools, which means this tool is less project-specific. There are always trade-offs between accuracy and simplicity in these kinds of tools. One feature unique to this tool is the ability to quickly modify the design variables and visualize results across multiple options.
Is this tool applicable to other geographic regions?: The archetype buildings and the LCA results are specific to Vancouver, Canada but are generally applicable for other areas of British Columbia. Results may be significantly different for other regions due to different transportation grids, building code requirements and electricity grid carbon intensity. More regions and building archetypes will be added as funding allows.
How were the archetypes determined?: Building archetype designs were developed after review of multiple building permit applications for similar buildings and Morrison Hershfield knowledge of the building industry in the region. The archetypes are fictional buildings but intended as representative of the actual building market.
How were the design variables determined?: The types of variables and the available iterations within each category were determined based on construction industry practice, feasibility, and significance for embodied carbon.
How were the results generated?: The Athena Impact Estimator for Buildings (Version 5.4.0103) whole-building life cycle assessment (LCA) software tool was used to generate results. For each archetype, every combination of variables was modeled in the software, generating over a million sets of results. Impact Estimator results were slightly adjusted where workarounds were needed due to gaps in the background data.
What building components are included and excluded in the results?: The LCA model for each archetype includes the complete building structure above and below grade, the building envelope above and below grade, and all glazing systems. Parking garages are included. Excluded: ceiling or floor coverings, finish materials, paint, interior walls, mechanical and electrical systems, and site components. Note the gypsum board on the inside of exterior walls is included.
What life cycle stages are included?: The system boundary for the LCA models includes the product, construction, use and end of life stages excluding operational energy and water (in other words, the A1-A5, B1 to B4, and C1 to C4 life cycle stages).
How accurate are these results?: The data used was developed with Athena’s Impact Estimator tool, so the results are as accurate as the Impact Estimator allows and only as applied to the building archetype. The difference between an actual design and the building archetype would normally represent the largest error. However, it is important to note that there is uncertainty in all whole-building LCA results due to data gaps, methodology issues, and the inherent uncertainty because of the multiple assumptions that must be made for cradle-to-grave LCA. All whole-building LCA results should be viewed as an approximation.
How applicable are these results to a particular design project?: These results are specific to the archetypes that were modeled and therefore would represent only a rough approximation for a different building. More accurate results for a particular design project require the use of whole-building LCA software like the Impact Estimator.
What are the limitations of this tool?: This tool is not providing live LCA – it is using pre-calculated results. These results are specific to the archetypes and geographic region that were modeled and therefore would represent only an approximation for a different building or different location. More accurate results for a particular design project require the use of whole-building LCA software like the Impact Estimator.
What is GWP?: Global warming potential (GWP) is one output of life cycle assessment. The GWP result for a whole-building LCA (excluding operational energy) is often identified as “embodied carbon.” GWP is measured in mass of carbon dioxide equivalent (CO₂e). It represents emissions of CO₂ and other greenhouse gasses (methane, nitrous oxide and ozone) resulting from the use of materials and energy through the life cycle of a building.
Why is the GWP range here different than other published ranges?: The results from different LCA studies are often not comparable, due to different scopes, system boundary, methods, assumptions, background data, tools and so forth. With so many ways that one study can differ from another, two unrelated whole-building LCAs can be an order of magnitude apart. This means that the magnitude and range of GWP values in this study are only relevant within the context of this study and are not comparable to a different study.
Is every possible combination of variables possible in the tool?: No. In order to limit the size of the database and make the tool faster, some combinations of variables were disallowed. Disallowed combinations were limited to unlikely or impractical combinations in real world applications. For example, it is very unlikely that a concrete floor will be supported on wood columns, so selecting this combination is not possible in the tool.

Getting started

The data presented here is derived from whole-building life cycle assessment (LCA) models of typical ("archetype") buildings in British Columbia, Canada. As such, Pathfinder is intended to be used as an educational tool only and does not represent any particular building or design.

Find out more through the tabs on the left, or watch the video tutorial.

How to Use This Tool

Brush Filtering: Brushing is a way to filter data. Drag vertically along an axis to highlight and display only that range of values. To remove a brush, click the axis' background. Any number axes can be brushed/filtered at once.
Invert Axis: Click an axis label to invert its scale.
Keep Selected Data: Use the 'Keep Selection' button to filter out data not currently containing ANY of the currently brushed ranges.
Exclude Selected Data: Use the 'Exclude Selection' button to filter out data that contains ALL values in the currently brushed range.
Pin a Scenario: Click on a row in the data table to 'pin' it. This highlights the line on the graph as well as in the data table.
Show Pinned Only/Show All: Toggle between viewing only pinned scenarios or all data.
Unpin All: Click on "Unpin All" to unhighlight any 'pinned' scenarios.
Reset Brushes: Use the "Reset Brushes" button to remove all brushes.
Reset Filters: Use the "Reset Filters" button to undo all 'keeps' and 'excludes'.
Reset All: Use the "Reset All" button to remove all brushes, pins, keeps, excludes and colour scheme settings.

Methodology

The tool is intended to provide higher level guidance on the potential effect of design choices on embodied carbon. It uses building archetypes and explores variations in design on that archetype.

Building Archetype Selection

Three separate building archetypes were considered: A high-rise residential building, a mid-rise residential building, and a stacked townhome. All archetypes are assumed to be located in Vancouver BC. Building archetype designs were selected after review of multiple building permit applications for similar buildings and using our knowledge of the building industry in the region. The designs selected for each archetype are fictional but are believed to be representative of what might be expected for these archetypes in these regions.

Building Variables

Variable types and iterations explored were developed with the intent of achieving realistic possible changes and/or changes that could result in significant change in embodied impact. These were selected based on review of existing building permit applications, using our knowledge of the building industry and embodied impacts, and with the input of others in the LCA and design industries.

Building Archetype Descriptions

Description	High-Rise Residential	6-Storey Mid-Rise Residential	Stacked Townhomes
General Information
Building Length (m)	25	75	12
Building Width (m)	25	25	6
Floor to Floor Height (m)	3	3	3
Number of Floors	30	6	3
Gross floor area (m²)
Floor Live Load (kPa)	2.4	2.4	2.4
Service Life (years)	60	60	60
Window to Wall Ratio	40%-60%	30%-60%	10%-25%
Beam Span (m)	8	6	6
Joist Span (m)	6	3	3
Footing	300mm x 100mm below columns and perimeter walls
Slab on Grade	100mm concrete slab
Below Grade Walls	200 mm concrete
Beam Types
Concrete	Baseline	Baseline
Steel		x
Glulam	x	x
LVL (with load bearing walls)		x	Baseline
Column Types
Concrete	Baseline	Baseline
Steel		x
Glulam	x	x	x
None (load bearing walls)		x	Baseline
Exterior Wall Types
Steel Stud	x	Baseline	x
Wood Stud (infill)		x	x
Wood Stud (load bearing)		x	Baseline
Wood Stud OVE			x
Curtain Wall	x
Window Wall	Baseline	x
Concrete Block	x
Precast Concrete Sandwich Panel	x
ICF		x	x
CLT	x	x	x
Floor Type
Concrete	Baseline	Baseline
Hollow Core Precast Concrete	x
OWSJ with Steel Deck and Concrete Topping	x
Wood Joist with Plywood		x	Baseline
Wood I-Joist with Plywood		x	x
CLT	x	x	x
Exterior Cladding Type
Brick Veneer	x	x	x
Precast Concrete	x
Metal Panel	Baseline	x	x
Glass Panel	x
EIFS	x	x	x
PVC/Vinyl		x	x
Fiber Cement Panel		Baseline	Baseline
Exterior Wall Insulation Type
XPS	x	x	x
EPS	Included in EIFS	Included in EIFS	Included in EIFS
Polyisocyanurate	x	x
Mineral Wool Batt	Baseline	x	x
Mineral Wool Batt (medium density)	x
Fiberglass Batt	x	Baseline	Baseline
Fiberglass Batt (medium density)	x
Spray Polyurethane Foam	x	x	x
Cellulose		x	x
Roof Insulation Type
XPS	x	x	x
EPS		x	x
Polyisocyanurate	Baseline	Baseline	Baseline
Mineral Wool (medium density)	x	x	x
Roof Membrane Type
PVC	X	x	x
Modified Bitumen (SBS)	Baseline	Baseline	Baseline
BUR	x
EPDM		x	x
Glazing Type
Double Glazed (low-E, Argon Filled)	Baseline	Baseline	Baseline
Triple Glazed (single low-E, Argon Filled)		x	x
Window Frame Type
Aluminum	Baseline	Baseline	x
Fiberglass		x	Baseline
PVC		x	x
Parking Type
None (Street Parking)		x	Baseline
Surface Parking		Baseline
2 Level Parkade	x
4 Level Parkade	x
6 Level Parkade	Baseline
SCM Content in Concrete
None	Baseline	Baseline	Baseline
20%	x	x	x
30%	x	x	x
40%	x

Building Model Scope

The LCA modelling focused on the building structure and envelope above and below grade. It included the following:

Main structure including beams, columns, floor slabs, load bearing walls, shear walls foundation walls, and footings,
exterior walls and windows, including insulation and cladding, roofing membrane, vapour and air barriers, window framing and glazing.
Parking garages including structure and membranes

It did not include ceiling or floor coverings, finish materials, paint, interior walls, mechanical or electrical systems, or site components.

System Boundary

The system boundary for the LCA models included the product, construction, use and end of life stages excluding operational energy and water. This includes stages A1-A5, B1 to B4, and C1 to C4.

system boundary

LCA Results

The Athena Building Impact Estimator (Version 5.4.0103) was used to model the impact of most of the various design iterations on embodied carbon (ie. embodied global warming potential). (For more information on the background material data and assumptions, see the Impact Estimator User Manual.) The impact estimator was used to estimate both material quantities and their embodied impacts. Exceptions and work-arounds are presented below:

Insulation: There was some concern that the Athena Impact Estimator would incorrectly estimate the embodied GWP of foam insulations due to the change in blowing agents mandated by recent legislation in Canada. Our approach regarding insulation was as follows:

Available EPDs were used to estimate the GWP of all insulations (not just foam). All insulation types were reviewed to allow a more fair comparison of insulations.
For GWP estimates of foam insulations, we used only EPDs associated with HFO blowing agents. Any EPDs with HFC blowing agents were not included.
Where available, industry wide EPDs were used. Industry wide EPDs were used for polyisocyanurate and loose fill cellulose
When industry wide EPDs were not available, product specific EPDs or averages of product specific EPDs were used.
Wall insulation fibrous and foam boards were medium density, typical for commercial walls
Roof insulation fibrous and foam boards were higher density, typical for commercial roofs
EPDs were not available for medium density rock wool and medium and high-density fiberglass. For these insulations GWP was estimated by factoring similar low-density insulation GWP by the differences in density.
For all insulation types in the High-Rise archetype R-15 nominal insulation was assumed and all insulation quantities were adjusted.
For all insulation types in the 6-Storey Mid-Rise and Stacked Townhomes archetypes, 4 inches (102 mm) of insulation was assumed.

Note that it is acknowledged that relying on EPD results is not ideal, as the scope and boundary conditions may be different and EPDs are often based on singular products that may not represent a typical value. To reduce this risk each EPD was carefully reviewed to confirm similar scope and boundary conditions are similar to other LCAs in this tool. In addition, the methodology was provided to a number of LCA practitioners and specialists in the Vancouver area for comment.

Supplementary Cementitious Materials (SCMs): SCMs created an issue as a change in SCMs could potentially impact many assemblies within a building. To resolve this issue, we compared the GWP of several different SCM ranges for several different concrete based building assemblies. More specifically, we reviewed the following assemblies: Slab on grade, footings, beams and columns, concrete walls, and concrete in extra basic materials within the software. For each of these assemblies we compared 0, 20%, 30%, and 40% SCM contents. We found that changing from 0 to 20% SCM content resulting in a reduction in GWP by between 3.6 and 5.2% for the various assemblies. Similarly, changing from 0 to 30% SCM content resulting in a reduction in GWP by between 10.4 and 12.2% and changing from 0 to 40% SCM content resulting in a reduction in GWP by between 15.5 and 20.1%. For this tool, we used the average change of impacts for the different assemblies. More specifically, the following factors that were applied to all concrete based assemblies to estimate the impact of different SCM contents:

SCM content	SCM mult factors from base case
0	1
20	0.957704356
30	0.891212615
40	0.821724451

Concrete Columns: The software did not factor in the additive load on columns in taller buildings: In a building, columns support not only the floor immediately above, but also the load of a column immediately above. As such, columns effectively support loads from all floors above, so lower floor columns are typically larger than upper floor columns. To determine the real impact on column design, three real designs of tall residential buildings were reviewed (between 30 and 37 stories) and take-offs were performed for concrete columns. These take-offs were factored according to the tributary area that they support and into three categories based on floor number (1-10, 11-20, and 21-30). An average of these values resulted in a volume of concrete per m2 of tributary area. Concrete strength was also factored in by converting all columns to 30 MPa concrete, using a simple multiplication factor (ex. A 40 MPa concrete volume was multiplied by 40/30 to estimate an equivalent 30 MPa column size). Reinforcing steel within the columns was assumed to be 1% of the mass of the equivalent 30 MPa concrete.

Wood Frame Load Bearing Walls: The software did not factor in the additive load on load bearing walls in multi-story buildings: load bearing walls support not only the floor immediately above, but also the load of any load bearing walls above it. This resulted in a significant underestimation of lower floor load bearing walls in the six-story design. To resolve this issue, the wood framing for the bottom three floors of the 6-storey archetype was increased by an additional 25% to account for extra studs at window openings and interior partition walls. Note this was not considered a significant error in the stacked townhouse design as the additive effects are small and it would not be typical to change the stud spacing across the height of this type of building. These decisions were made based on a review of multiple real designs and our knowledge of the industry.

Project Team

The Morrison Hershfield team involved in the development of the tool, and this document are:

Mark Lucuik - Director of Sustainability
Kalum Galle - Team Lead, Sustainability Specialist
Emma Thomas - Sustainability Analyst
Ivan Lee - Building Science Consultant

Limitations

By nature, whole-building LCA results are uncertain and should be used as a guidepost and not an absolute. Although the archetype designs are believed to be typical for the region, actual designs will vary. The further a real design strays from the archetype design the less reliable the results.

The LCA results are specific to the region presented. Actual results can vary significantly for other regions, particularly outside of B.C.

For project-specific results, a custom whole-building LCA is needed. Access the free Impact Estimator for Buildings software tool at www.athenasmi.org.

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Building Info

Style

Brushing and Filtering