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
The reduction of the building’s EUI by any of a number of strategies. If the you have not entered a custom EUI, the EUI is estimated via ZeroTool.
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.
Concrete Specification
The specification of concrete with lower embodied carbon emissions. Choices are described in narrative form below, and the underlying data is listed in C.Scale's whole life carbon methodology. Narrative descriptions are approximate; there are many options that can yield similar carbon intensities.
Steel Specification
The specification of structural steel, steel deck, and reinforcing bar with lower embodied carbon emissions. Choices are described in narrative form below, and the underlying data is described in C.Scale's whole life carbon methodology. Narrative descriptions are approximate; there are many options that can yield similar carbon intensities.
Timber Specification
The specification of lumber, plywood/OSB, and engineered timber elements with lower embodied carbon emissions. Choices are described in narrative form below. Narrative descriptions are approximate; there are many options that can yield similar carbon intensities.
Responsibly-Sourced Timber
In accordance with ISO 21930, the carbon content of biogenic materials can only be counted as carbon-storing if the timber comes from a forest managed with sustainable practices. An example of this is timber from an FSC-certified forest. For more information, please refer to C.Scale methodology for stored and avoided carbon emissions or the procurement guidance from the Climate Smart Wood Group.
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
Opaque Enclosure Specification
The specification of the opaque envelope assemblies. These specification levels do not describe specific assemblies. Instead, they approximate the 80th, 50th, and 20th percentile of the distribution of all opaque enclosure options.
Opaque Enclosure Refresh Rate
The length of time over which a majority of the opaque enclosure will be replaced.
Transparent Enclosure Specification
The specification of the transparent enclosure assemblies. These specification levels do not describe specific assemblies. Instead, they approximate the 80th, 50th, and 20th percentile of the distribution of all transparent enclosure options.
Transparent Enclosure Refresh Rate
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 Refresh Rate
The length of time over which a majority of the roofing will be replaced.
Interior
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.
Interior Fit-Out Refresh Rate
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 Refresh Rate
The length of time over which a majority of the MEP systems will be replaced.
PV Specification
Embodied carbon in solar photovoltaics arrays is calculated using values from the peer-reviewed literature. A citation to the current data source is available in in the Reference Data Sources section of this guide.
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.
Sitework
Planted Area
Set the percentage of site area, minus the building footprint, which is planted. This planted area is assumed to be a low carbon storage landscape, such as no-mow turfgrass or other herbaceous perennials. 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
The specification of the pervious and impervious surfaces on the building site (outside the building envelope. 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 Refresh Rate
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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