LEED v4 BD+C MRc1 Building Life-Cycle Impact Reduction Option 4 (International & North America)

What is LEED v4 MRc1 Option 4 about?

This guide will walk you through how to do a life cycle assessment for the LEED v4 MRc1 Building Life-cycle Impact reduction credit, option 4: Whole building impact assessment using One Click LCA.

The purpose of the LEED v4 BD+C MRc1 Building Life-Cycle Impact Reduction, Option 4 credit is to conduct a life cycle assessment of the project’s structure and enclosure to show a minimum of 10% reduction in building material life cycle impacts compared to a baseline in at least 3 different impact categories, with global warming potential being one of those as mandatory requirement. No impact category assessed as part of the life-cycle assessment may increase by more than 5% compared with the baseline building. If the design team can show improvement in all of the 6 categories they will get the additional exemplary credit.

This guidance applies for following for One Click LCA tools:

• LCA for LEED, International (using CML impact assessment methodology)
• LCA for LEED, US (using TRACI impact assessment methodology)
• LCA for LEED, Canada (using TRACI impact assessment methodology)

This guidance is planned to be used along with the credit reporting template, which you can find as a downloadable attachment at the bottom of this page, in addition to an example report. The template reports can be filled in and submitted for LEED LCA credits:

• One Click LCA reporting template for LEED v4 Mrc1 – CML (Europe, Rest of the World)
• One Click LCA reporting template for LEED v4 Mrc1 – TRACI (US, Canada)
• One Click LCA for LEED v4 Example report

The MRc1 credit option 4 is suitable for new construction (buildings or portions of buildings).

LEED impact categories and units

In life cycle assessment projects, the potential to cause environmental harm is assessed over the project’s whole lifetime for specified environmental impacts. Building service life for LEED is estimated to be at least 60 years for all building types; in One Click LCA you will need to enter the calculation period for your building.

In LEED, the life cycle assessment is done for six different environmental impact categories. The impacts are expressed as quantities of a matter that has the potential to cause such impacts, but they do not represent the actual harm eventually caused. For instance, global warming potential represents the amount of CO2e gases released, however the final impact could be the acceleration of the polar melt.
Below are the LCA impact categories for LEED LCA and their descriptions:

• Global Warming Potential describes how much a product contributes to climate change. When an LCA considers only this impact category, it’s called the carbon footprint.
• Ozone Depletion describes the damage caused to the Ozone Layer in the stratosphere.
• Acidification describes how much product acidifies the environment, resulting in acid rain.
• Eutrophication describes the flow of nutrients to ecosystems, resulting in algae growth.
• Tropospheric Ozone describes the quantity of summer smog-causing gases emitted.
• Depletion of non-renewable energy resources describes how many fossil resources are withdrawn.

In the calculations, all the different emissions from evaluated life cycle stages are collected and normalised to a common unit. In the case of Global warming potential, the reference is the warming potential (radiative forcing) of CO2 emissions e.g. how much heat 1 kg of CO2 will tie into the atmosphere. The warming potential of all the other cases is compared to the CO2 and based on that the quantities are normalised to the common unit. For instance, the warming potential of methane is 24 times higher than CO2 so 1 kg of methane emissions will be 24 kg of CO2equivalents. Impact assessment methodology defines the relative weight of different emissions and the normalisation unit. In LEED v4 CML, TRACI and ReCiPe methodologies are accepted. Out of these methods, TRACI is commonly used in North America and CML is required by the EN standard and is, therefore, de facto the required methodology in Europe and also widely used internationally.

Below is a chart summarizing how TRACI, CML and ReCiPe differ in showing calculations for the different impact categories.

LCA impact indicator units	TRACI 2.1	CML 2002	ReCiPe
Global warming potential (greenhouse gases)	CO2e	CO2e	CO2e
Depletion of the stratospheric ozone layer	CFC-11-eq	CFC-11-eq	CFC-11-eq
Acidification of land and water sources	SO2e	SO2e	SO2e
Eutrophication	N eq	PO43e	P eq
Formation of tropospheric ozone (photochemical oxidant formation)	NOxeq	C2H4e	kg NMVOC
Depletion of non-renewable energy resources	MJ	Weight or volume of raw material	Kg oil eq

One Click LCA supports both TRACI 2.1 and CML (2002 – November 2012 or newer). LEED tools for US and Canada support TRACI 2.1 methodology and the versions for Europe and international users support CML (2002 – November 2012 or newer). In One Click LCA all of the datasets follow ISO14044 standards and thus, the data is automatically compliant with the required standards and required impact assessment methodology.

What is included in the scope?

The material scope required for LEED is specified in the following table. This includes the materials for the structure and the envelope. Out of scope materials may be included, however adding them will not provide any extra credit.

Element	Included	Comment (mark if something is not relevant)
Standard foundations	Yes
Special foundations	Yes
Slab on Grade	Yes
Basement excavation	No
Basement Walls	Yes
Columns	Yes
Beams	Yes
Floor Construction	Yes
Floor / Ceiling Finishes	Optional, not needed for MRc1 credit	Optional
Roof Construction	Yes
Exterior and Semi-exterior Walls from cladding to finishing	Yes	Semi-exterior elements separate conditioned space from unconditioned space or that encloses semi-heated space (e.g., attic, crawl space, and basement)
Exterior Windows	Yes
Exterior Doors	Yes
Roof Coverings	Yes
Roof Openings	Yes
Load-Bearing partitions	Yes
Other Partitions	Optional, not needed for MRc1 credit	Optional
Interior Doors	Optional, not needed for MRc1 credit	Optional
Fittings	No
Stair Construction	Yes
Stair Finishes	Optional, not needed for MRc1 credit	Optional
Wall finishes	Yes	For included walls only
Parking structures	Yes
Parking lots	No

As per LEED v4 specification, the following elements are excluded from the analysis: electrical and mechanical equipment and controls, plumbing fixtures, fire detection and alarm system fixtures, elevators, and conveying systems, excavation and other site development, and parking lots.

How to complete an assessment in One Click LCA

1. Create a new design

2. Fill in the building materials query of the design either manually or by import.
Add all of the materials required by the calculation scope (see above).

You are allowed to use either average data, manufacturer-specific EPDs (recommended) or similar products from another manufacturer. Use net quantities (amounts of material installed in the building); the on-site losses of materials would be included in module A5 but that is excluded from the calculation by credit specification.

This information will be used to calculate the raw material harvesting, transportation and manufacturing impacts in A1-A3.

3. Once the correct materials and quantities are provided, set the transportation distances from material manufacturer to the project site and transport methods.

The default transportation distances can be set up from the project’s LCA parameters page. If they are chosen, any material will use the average distance unless a more specific one is given in the query. This information will be used to calculate the impacts of material transportation in A4.

4. Finally, check the material service life.

This information will be used to calculate the material replacements for B4 impacts.

Material service life means how long each material will last in your building. If the service life is less than the service life of the building, the material will have to be replaced. From an environmental impacts point of view, this means additional emissions from the production of new material that is needed to replace the old one.

Each of the materials in One Click LCA database has a default service life. However, as the exposure conditions of the materials may vary, it may be good to check that the service life matches the condition of your building. It is especially important to check the external wall and roof material service lives’ as the weather conditions may vary greatly between areas.

5. Optional: Adjust the localisation of each material as needed (expert feature).

This information will be used to compensate for any material data chosen from another area to match your project’s local material manufacturing conditions.

6. Fill in the building area query. This information will be used as a divider for the results in a separate result row and it will help you to understand how the results compare to other projects. Gross floor area is required.

7. Fill in the calculation period query. This is the required service life of the building. LEED recommends a service life of at least 60 years. Product replacements and maintenance are calculated for this period.

Next steps:

After you have done one calculation you can create as many additional designs you wish either by copying the first one or by creating a new empty one. This can be used for creating a baseline or to create additional 'what if' scenarios. To copy a design click its name and choose 'Copy'. To create a new one press the '+ Add a design' button on the project main page.

Once the Baseline design is completed, create a copy of it and name it 'Proposed design'.

Requirements for the baseline

To make sure that the baseline and proposed models can be accurately compared, the following aspects must be kept the same in both the baseline and the proposed building:

• LCA scope requirements. The functional unit and system boundary must be identical for the baseline and proposed buildings. Basically, this means that you’ll have to use the same calculation tool for both.
• Size. The gross floor area of the baseline and proposed buildings must be the same. The two designs can have different massing, provided the gross area is the same.
• Function. The baseline and proposed buildings must serve the same programmatic function. If the project is a mixed-use residential building with retail on the first floor, the baseline building must have the same program, but the elements can be in different locations in the building. If the project is a hospital with stringent air quality and humidity control, both the baseline and the proposed cases must meet those functional requirements.
• Orientation. The orientation—the directional exposure—of the baseline and proposed buildings must be the same, but the shape may differ. Orientation must be the same because exposure to the sun affects solar heat gain within the building and will skew LCA results for energy performance.
• Location. Both the baseline and the proposed buildings must be located in the same ASHRAE 90.1–2010 climate zone and assumed to be on the same site.
• Operating energy performance. The baseline and proposed buildings must meet EA Prerequisite Minimum Energy Performance by adhering to the requirements of ASHRAE 90.1–2010, Appendix G, Opaque Assemblies, Vertical Fenestration, Skylights, and Roof Solar Reflectance and Thermal Emittance sections because comparing an energy-efficient proposed building with an underperforming baseline building will skew the results. Increasing wall mass or insulation unnecessarily in the baseline building to show dematerialization in the proposed building is not acceptable. Energy modelling for either building is not required for this credit.

Other portions of the baseline building may be modified from the basic ASHRAE 90.1 requirements to capture the LCA goals of the project team.

As a summary:

You are allowed to	You are not allowed to
Optimize and reduce the mass of your actual building (from any studied part of the building)	Increase wall mass or insulation unnecessarily for the baseline building to show dematerialization
Change the structures and design of the building, including stud spacing, floor-to-ceiling heights, changes in the use of beams and pillars	Use a different area for the baseline building and actual design (specified as gross area)
Identify opportunities to make design changes to use lower -emissions materials or specify the use of specific products with quantified life-cycle impacts	Omit required parts of the envelope and structure: footings and foundations, structural wall assembly (from cladding to interior finishes), structural floors and ceilings (not including finishes), roof assemblies
Include additional elements, such as interior nonstructural walls or finishes (no extra credit)	Include excavation, site development, parking lots or building technologies and systems

Click here for more information on baseline strategies. 

Tips & Tricks

Once you have met the requirements to achieve your desired credits, you can fill in our reporting template below to write the report. 

Video guide for carbon reduction

Create further changes until you reach your goal for the credit. Check our tips for reducing carbon and other environmental impacts in the video below.

Note: To improve the video quality once the video has begun, you should open 'Settings' (gear icon), then select 'Quality', and choose the highest available resolution.

Attachments