User Guide

Project location is used to derive climate and fuel information and grid emissions factors. Only United States data is currently available, but additional locations will be rolled out in subsequent versions.

Electricity grids are utilizing increasingly more renewable energy. The CARE Tool defaults to a conservative rate of renewables growth. If you would like to model an alternative grid emissions scenario, select a pre-generated Cambium scenario or enter your own anticipated year of grid decarbonization.

• “Default” will use a static grid scenario, meaning that the current state of the grid will remain constant in the future.
• “Select Scenario” will allow you to choose from dropdown options that reflect different degrees of decarbonization between now and the year 2050.
• “Enter Your Own Grid Decarbonization Year” will interpolate a constant reduction in grid emissions between now and the year provided. Consider this option if your building is located on a central plant or district utility system that is decarbonizing on its own timeline.

This is the number of years over which your building scenarios will be analyzed. Rather than a full building life, CARE encourages evaluating emissions in the near-term. Consider aligning with relevant climate target dates, for example through the year 2030 or 2040.

Input the gross floor area of the existing building.

The type of structure selected impacts the user options offered for embodied carbon of Structural System Reuse. The selected system determines the types of structural materials that would likely be employed for repairs, upgrades, or retrofits.

• 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 window-to-wall ratio is the proportion of glazing to opaque wall on the building’s exterior. It impacts the embodied emissions of Envelope Reuse options.

• Selecting default will use a typical value of 35%.
• Enter your own to override this value or to explore the impacts of this variable.

Only two building use types are available within the tool.

The primary building use is the building use associated with the highest overall percentage of the building, by floor area.

For a description of each use type and associated space use characteristic inputs, refer to the ENERGY STAR Portfolio Manager Glossary.

The CARE Tool uses the Zero Tool to estimate a default building energy use intensity (EUI) based on the user-defined location, size, and use.

If you already know your building’s EUI, select Enter Your Own EUI.

If you do not know your EUI but have utility data, select “Enter Utility Data” to input energy consumption by fuel source. For each type of energy in the building, enter the fuel source, the amount of that type of energy consumed, and the associated units.

Operational emissions are calculated based on the building’s fuel split, a standard gas emissions factor, and the electricity grid emissions of the user-provided location.

The floor area reused may equal the existing building floor area, or it may be less if portions of the existing building are demolished.

If the reuse includes an addition, select the “Yes” Addition radio button. Input fields related to the addition will populate throughout the Building Reuse tab. These additional input fields will not be visible if no addition is indicated.

The CARE Tool offers separate primary and secondary uses for the reused floor area and for the addition. This allows the reused floor area and added floor area to have distinct energy uses and emissions, which may occur in the case of large additions and/or additions with their own distinct mechanical systems.

Establish an energy use baseline.

An operational emissions baseline will automatically be calculated based on the EUI.

• If there is no change in floor area or use type from the Existing Building, the Reuse  EUI and Emissions Baseline will pre-populate with the existing building energy information previously entered. 
• To use the Zero Tool to estimate a new EUI if use type and/or floor area have changed, select Default EUI.
• If you already know the EUI of your reused building, select Enter Your Own EUI.

Set an energy use target for the reused building.

• Use the target reduction slider to indicate an anticipated or actual reduction in energy use from the baseline set above. As the slider is adjusted, the Reuse EUI will auto populate in the field below. 
• If you know the Reuse EUI but not the percentage reduction target, adjust the slider until the Reuse EUI field reads the correct value.
• Indicate if the reuse will result in all electric systems and equipment in the building (no fossil-fuel powered systems or equipment). This input will impact the reuse emissions intensity.

Set an energy use target for the Addition (if applicable).

• If the addition has a distinct EUI target from reused portions of the existing building, follow the same process described above to set the target reduction. This may occur if the addition’s square footage is large compared to the existing building, if an addition is operated on distinct systems, or if the addition is required to meet energy code performance values distinct from the reused portions of the building.

Set targets for renewable energy

• Adjust the slider to reflect the percentage of the total reused building’s electricity demand that is anticipated to be met with renewables. This will impact the operational emissions.

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 Use

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.

Interior reuse

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.

Addition

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.

Modifiers

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.

The floor area of the new building is not required to equal the floor area of the reused building. For an apples to apples carbon comparison, consider setting the building areas equal to each other. In many real world applications, the new building may be larger than what it is replacing.

For additional guidance, reference the Building Use sections above.

Establish an energy use baseline. An operational emissions baseline will automatically be calculated based on the EUI.

• To use the Zero Tool to estimate a New Building EUI, select Default EUI. If you already know the EUI of your new building, select Enter Your Own EUI.

Set targets for renewable energy

• Adjust the slider to reflect the percentage of the total reused building’s electricity demand that is anticipated to be met with renewables. This will impact the operational emissions.

Select the Structural System type of the new building to establish its embodied emissions.

• 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.

Modifiers

The modifiers offer options for alternative materials choices or performance that impact the embodied emissions intensities of your building. These options perform the same as the modifier options offered in the Building Reuse section.