Carbon Reduction Measures
To determine a decarbonization target for the project, carbon reduction measures can be applied to scenarios. C.Scale highlights salient carbon reduction measures that can be consistently modeled with available data. The set of carbon reduction measures included in C.Scale do not represent an exhaustive list of possible emission reduction strategies.
Reuse
Building Reuse
The percentage of existing building materials to remain on-site and be used in the project, reducing the demand for new materials.
Form and Massing
Building Perimeter
The user-declared perimeter of the building. In the absence of a user input, C.Scale assumes the building is an extruded square.
Floor-to-Floor Height
The vertical distance between building floors in feet. The default value is 13’.
Window-to-Wall Ratio (WWR)
The ratio of windows to total wall area. The default value is .45.
Energy Use
All Electric Building
The elimination of all onsite combustion and provision of 100% of the project’s energy use from electric sources.
EUI Target
Clean Power Purchase
The purchase of clean power through Direct Ownership, Green Retail Tariffs, Power Purchase Agreements (PPAs), Community Renewables or Utility Renewable Contracts (the five categories of renewables for which credit can be claimed in AIA 2030 commitment reporting) equivalent to the selected percentage of total energy use. The purchase of unbundled RECs should not be counted as a clean power purchase in C.Scale.
Solar Photovoltaic (PV) Array System Design
The addition of a solar PV array on the project site. The size of this array can be input in three forms:
Percentage of Load. The solar PV area size is calculated to account for the input percentage of building energy load.
Nameplate Capacity. The solar PV area size is input by its nameplate capacity in kW.
Area. The solar PV area size is input by its total area in square feet.
Solar PV orientation
The ability of solar PV arrays to produce electricity is related to their geometry and siting. Not all projects sites, such as partially shaded sites, will have an optimal solar orientation. This toggle has two options:
Optimal. There is no impediment on the site to maximum solar exposure.
Suboptimal. There is solar potential on the site, but it is partly compromised. A 20% penalty on solar energy production will be assessed.
Structure
Primary Structural System
Specification of a structural system other than the system modeled in the baseline. Note that this is not strictly a carbon reduction measure, as the substitution of some structural systems with some others can lead to an increase in embodied emissions.
Secondary Structural System
Specification of a secondary structural system, and its associated percentage of the overall building structure.
Structural Material Intensity
Concrete Specification
Steel Specification
The specification of hot-rolled structural steel, cold-formed steel (including steel deck), and reinforcing bar. These estimates do not correspond to a specific EPD, as there are many options for achieving a certain level of performance. Most carbon intensities for structural materials in C.Scale are national averages, as material supply chains for major structural materials are typically national (or global) in coverage.
Timber Specification
The specification of lumber, plywood/OSB, and engineered timber elements. These estimates do not correspond to a specific EPD, as there are many options for achieving a certain level of performance. Most carbon intensities for structural materials in C.Scale are national averages, as material supply chains for major structural materials are typically national (or global) in coverage.
Responsibly-Sourced Timber
In C.Scale, we identify three criteria contributing to the claim that wood products are responsibly sourced. While C.Scale does not prevent the user from counting the carbon storage benefits on other terms (as the list is nonexhaustive), we recommend meeting at least two out of the three criteria below in order to claim climate benefits from carbon storage.
Enclosure
Solid Exterior Wall Specification
The specification of the solid exterior wall assemblies. These specification levels do not describe specific assemblies. When specific data is not known, the C.Scale app includes pre-defined carbon intensities, defined by the levels of ambition. When more data is available, C.Scale allows you to define specific cladding assemblies, exterior insulation types, and wall framing assemblies. C.Scale will use your description of the solid exterior wall (i.e., any declarations of specific materials) to subset our library of solid exterior wall assemblies (~1200) to only those meeting your criteria. This allows the user to know the range of potential carbon intensities available both within and between their declared design.
Solid Exterior Wall Service Life
The length of time over which a majority of the solid exterior wall will be replaced.
Solid Exterior Wall Assemblies Configurator
The Solid Exterior Wall Assemblies Configurator is designed to support the input of more detailed, project-specific data.
To begin using this feature, turn on Use Assemblies within the Solid Exterior Wall accordion.
Once turned on, click the Configure Assemblies to start editing Solid Exterior Wall Assemblies.
This opens up a pop-out for Solid Exterior Wall Assembly Configurator. This automatically generates an R-Value, Service Life, and Carbon Intensity, which can be changed as needed.
You can choose the assembly options as you see fit to tailor them to your requirements. These options will continue to evolve based on ongoing feedback.
Thin Brick
EIFS
Fiber Cement
Wood Siding
Profiled Metal Panel
Composite Metal Panel
Glass Fiber Reinforced Concrete
Stone Veneer
Terracotta
To add and edit additional Solid Exterior Wall Assemblies, simply click on the 3-dot menu on the right side and choose Duplicate.
Customize as needed and ensure the Area(%) adds up to a 100%, validating the area.
Click Update to see changes to the carbon emissions values in the Enclosure accordion.
Transparent Exterior Wall Specification
The specification of the transparent exterior wall assemblies. These specification levels do not describe specific assemblies. When specific data is not known, the C.Scale app includes pre-defined carbon intensities, defined by the levels of ambition. When more data is available, C.Scale allows you to define specific glazing units, mullions, and insulation. C.Scale will use your description of the transparent exterior wall (i.e., any declarations of specific materials) to subset our library of transparent exterior wall assemblies (~1200) to only those meeting your criteria. This allows the user to know the range of potential carbon intensities available both within and between their declared design.
Transparent Exterior Wall Service Life
The length of time over which a majority of the transparent enclosure will be replaced.
Roofing Specification
The specification of the roofing assemblies. These specification levels do not describe specific assemblies. Instead, they approximate the 80th, 50th, and 20th percentile of the distribution of all roofing options.
Roofing Service Life
The length of time over which a majority of the roofing will be replaced.
Interiors
Floor Area w/ Fit-Out
The percentage of floor space that will be fitted out for occupation by building tenants. The default value is 70%. If tenant fit-out is outside the project scope, this field can be set to 0%.
Interior Fit Out Specification
The specification of the fittings, furniture, and fixtures required for the use of the building by its tenants. These specification levels do not describe specific fit-outs or materials. Instead, they approximate the 80th, 50th, and 20th percentile of the distribution of all available data on tenant fit-outs.
Interiors Service Life
The length of time over which a majority of the interior fit out will be replaced.
Services
Conditioned Area
The percentage of total floor area that is heated or cooled.
MEP Specification
Embodied carbon in mechanical systems in evaluated at two specification levels—standard performance and high performance—and is dependent of the total square footage of the building. This approach, and the data used in C.Scale, follow from the CLF study on building mechanical systems.
Baseline buildings in C.Scale are always assumed to have a standard performance system. Scenarios that achieve an EUI reduction of more than 50% below the baseline are assumed to have a high performance system.
Embodied carbon in MEP is a data-scarce category, and we cannot confidently describe the potential to reduce embodied carbon in MEP systems through specification.
MEP Service Life
The length of time over which a majority of the MEP systems will be replaced.
PV Specification
PV Refresh Rate
The length of time over which a majority of the PV systems will be replaced.
Solar ground coverage ratio
For any solar array entered as a decarbonization measure, this ratio describes the ratio of active solar cells to total array area. C.Scale's assumption is 0.7, representing an efficient solar layout.
Refrigerants
Total Refrigerant Charge
The reduction of the total quantity of refrigerants used in the buildings HVAC+R system.
Refrigerant GWP
The average global warming potential (GWP) of refrigerants used in the buildings HVAC+R system. Throughout C.Scale, three options are given for specification-related options: High Carbon, Average, and Low Carbon. Typically, these refer to the 80th, 50th, and 20th percentile of GWP values for available materials. We were unable to replicate this methodology for refrigerants, though, as the overall distribution of refrigerants skews very high–and this highly skewed distribution doesn’t represent the choices designers are making on their projects. In the refrigerant model, these three choices are keyed to specific refrigerants as follows:
Sitework
When a user enters a site area, they have the option to select whether or not the site has been previously developed. If the site has been previously developed, C.Scale treats it as a "brownfield" site with no carbon sequestered in its soil and existing landscape. If the site has not been previously developed, C.Scale treats it as a "greenfield" site with preexisting vegetation.
Planted Area
Set the percentage of site area, minus the building footprint, which is planted. To calculate emissions from the removal of above-ground biomass, C.Scale treats the site as vegetated with regionally-specific "low carbon storage" plants (such as no-mow turfgrass or other herbaceous perennials) at 50% of the site's carrying capacity. All unplanted area is assumed to be hardscape.
High Carbon Storage Planted Area
Set the percentage of the planted site area comprised of a high carbon storage landscape, such as dense broadleaf shrubs and trees in a matrix of no-mow turfgrass or herbaceous perennials.
Hardscape specification
All site area not designated as planted is assumed to be hardscaped. The specification of the pervious and impervious surfaces on the building site (outside the building enclosure. These specification levels do not describe specific materials or assemblies. Instead, they approximate the 80th, 50th, and 20th percentile of the distribution of all hardscape assemblies based on a set of standard details.
Hardscape Service Life
The length of time over which a majority of the site's hardscape will be replaced.
Jobsite
A5.2 Jobsite Emissions
Enter a custom carbon intensity (kgCO₂e/sf) for jobsite emissions related to construction activities and land use. The default value assumes 40 kgCO₂e/m² for construction emissions, which includes fuel, tools, and energy used on-site. This default is adjustable based on project-specific data. For greenfield sites, emissions from soil and vegetation are also calculated, using regional data to estimate carbon release from land development.
Demolished Area
Pre-construction demolition emissions are calculated per floor area of the demolished building, using a default factor of 35 kgCO2e/m2. This is a data-scarce category. Where project-specific data is available, this default can be overridden by the user.
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