Determine the embodied emissions resulting from the building reuse scenario.
For each building system category in this section, if you know the embodied carbon value of the reuse approach, adjust the user selections to best reflect the known embodied carbon value.
Structural system reuse
Note: because structural systems typically represent the largest proportion of upfront carbon within a building, selections in this category will have a significant impact on the overall reuse embodied carbon.
Adjust the slider to represent the range of structural scope for the renovation, ranging from no work (0%) to work equal to a complete new building structure (100%). Slider value should reflect structural interventions appropriate to the type of structure selected in the “Existing Building” tab, and the resulting embodied carbon will reflect the existing structure typology.
Minor work such as new framing around mechanical openings or minor reinforcing of damaged elements will be on the low end (~0%-5%), structural upgrades to strengthen floor capacity or rebuild certain areas will be higher, and a project that retains only the facade but rebuilds the interior will represent the highest end (up to 100%).
If the existing building requires a major lateral upgrade, check the lateral upgrade box. This is likely if the building is in a high hazard zone for earthquakes or hurricanes, or may be required by other factors such as change in use. If a high percentage of structural scope is selected using the slider above, this check box may be redundant.
Envelope scope is described in three categories: exterior walls, windows/glazing, and roofing. Select the dropdown option from each category to represent the approach to each part of the building.
For exterior walls, select one of the below dropdown options or leave blank if there is no scope at the exterior:
- Minor: clean/seal/coat — This option represents a minimal amount of work to the exterior. It will likely apply if the building is in good condition requiring only cosmetic repairs, including stucco crack repairs of exterior repainting.
- Minor: 50% masonry repair/repointing — The embodied carbon of this option is derived from data about the GWP of repointing, but it may be applicable to other face systems that require only partial repair.
- Medium: 100% masonry repair/repointing — This applies to masonry buildings that are in poor condition and require extensive masonry repointing, repair, or rebuilding.
- Major: Replace 50% of exterior wall assembly, including insulation — This option represents a complete replacement or overcladding of ~50% of the building facade area, including a full envelope assembly of cladding, support, and insulation.
- Major: Replace all exterior wall assembly, including insulation — This option represents a complete replacement or overcladding of the building facade area, including a full envelope assembly of cladding, support, and insulation.
For windows/glazing, select one of the below dropdown options:
- Minor: weatherstrip/restore frames — If the existing windows are remaining in the building but receiving some level of restoration or sealing, select this option.
- Medium: reglaze frames — This option assumes that the existing window sashes and trim are retained but the glass is replaced. You might use this option if you are reglazing a historic window or replacing an IGU in an existing window.
- Major: replace windows — This option represents the embodied carbon of completely new window systems.
For roofing, select one of the below dropdown options:
- Minor: restore/repair — Select this option if 25% or less of the existing roof requires repair.
- Major: replace all roofing, including insulation — This option assumes the replacement roof assembly would be equivalent to a roof installed on a new building.
If the exterior walls of the building are insulated from the interior, select the Insulate Walls checkbox. This approach is common for existing or historic buildings where the exterior cannot be insulated from the exterior. If you have selected 100% new cladding in the “Exterior Walls” category above, do not check this box as insulation is already included.
The CARE Tool offers three levels of interior renovation. For each of the options, use the sliders to indicate the percent of total floor area undergoing that level of interior renovation. The total input for the three levels cannot exceed 100%.
- Restore/Refurbish Finishes — Use this slider to indicate the percent of total floor area with refurbished or restored finishes, including conservation of finishes or other treatments that do not include wholesale replacement of materials such as refinishing floors or minor patching of walls.
- New Finishes —Use this slider to indicate the percent of total floor area where flooring, paint, ceilings, or other finishes are replaced but spaces are not reconfigured (new walls are not constructed).
- Rebuilding/Reconfiguration — Use this slider to indicate the percent of total floor area where interior partition walls are being rebuilt, either in the same locations or in a new configuration. This option includes new flooring, walls, paints, ceilings, and other finishes for newly reconfigured spaces.
Mechanical, Electrical, Plumbing Systems Reuse
The options here approximate minor, medium, and major degrees of work to building systems. Select no changes to existing if there is no renovation to the systems, else select one of the three options. Note that emissions from refrigerants are not included.
- Minor: Repair/Refurbish — Consider this option if the existing systems are fairly new and require minimal repair.
- Medium: Replace Equipment, Reuse Distribution —Select this option if equipment such as boilers, air handling units, or cooling towers will be replaced or upgraded, but distribution such as piping and ductwork can be reused.
- Major: Replace All Systems — Select this option if there are no existing systems to reuse or if they have exceeded their service life.
If an Addition is included in your building reuse, select the Structural System type for it. Select Wood for wood framed or timber construction. Select Hybrid for buildings with mixed structural systems that use a combination of wood and a heavy system such as concrete, steel, or masonry. This includes historic masonry bearing wall buildings with timber framing and contemporary podium construction. Select Steel/Concrete for standard commercial construction.
The modifiers offer options for alternative materials choices or performance that impact the embodied emissions intensities of your building reuse and addition.
- Low Embodied Emissions Concrete — Check this box if your renovation, and addition if applicable, will use low emissions concrete, for example one with a high percentage of substitute cementitious material like fly ash.
- Responsibly Sourced Timber — Check this box if your renovation, and addition if applicable, will use responsibly sourced timber (e.g. timber with an FSC or similar certification.) This option accounts for biogenic carbon (carbon stored in natural materials).
- Low Embodied Emissions Envelope — Check this box if your renovation, and addition if applicable, will use a low embodied emissions cladding, such as a wood rainscreen, or low embodied emissions insulation, such as straw or hemp-based products.
- High Performance Mechanical, Electrical, Plumbing Systems — Check this box if the building systems in your renovation, and addition if applicable, will perform more efficiently than code required minimum for energy efficiency. Selecting this option will result in an increase to the embodied emissions of your Mechanical, Electrical, and Plumbing Systems. This selection does not impact inputs made under the Operational Energy and Emissions section.