Whole-building life cycle assessment in LEED v4

A Practical Guide to MRc1 Credit: Building Life-Cycle Impact Reduction in LEED v4

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How to Achieve the Building Life-Cycle Impact Reduction credit (MRc1) in LEED v4 with Whole-Building LCA


In LEED v4, Whole-Building Life-Cycle Assessment can be used to deliver 3 base credits and optional exemplary and regional priority credits (or, a pilot credit in LEED 2009). This requires improving building life-cycle impacts by 10 % compared to a baseline building and showing that by using a Life-Cycle Assessment software. An easy to use building LCA software and good support can make this a very attractive credit for LEED projects.


Achieving the Building Life-Cycle Impact Reduction credits in LEED v4


The materials and resources credits have received a major overhaul for LEED v4. LEED v4 emphasizes reduction of the environmental impacts of construction materials over their life-cycle as well as choosing products which contribute to reducing burden on our environment and health.

One of LEED v4’s BD+C’s major new credits is Building life-cycle impact reduction. Here we take a deeper look into this credit, which is possible to achieve for virtually any LEED BD+C project, and how to apply it in practice. Most users will utilize Option 4: Whole-Building Life-Cycle Assessment. This section is worth 3 base credits, an optional exemplary credit, and a regional priority credit, where applicable. For users of LEED BD+C v2009 (or v3), there is a pilot credit MRpc63 Whole Building Life Cycle Assessment, for which you can follow this same process.

If you have never worked with Life-Cycle Assessment (LCA) before, this may feel like a big step for you. Most users prefer an easy to use building LCA software tailored for LEED, and like to have access to good support. Towards the end of the article we take a look at One Click LCA, a cloud-based building LCA software that lets you work the way you prefer by leveraging your design team, Building Information Models (BIM), take offs or drawings.



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
Include additional elements, such as interior nonstructural walls or
finishes (no extra credit)
Include excavation, site development, parking lots or building
technologies and systems

But first, let’s take a look at the LEED requirements for life-cycle impact reduction.



Beating the baseline: Building Life-Cycle Impact Reduction credit via Whole-Building Life-Cycle Assessment


The credit requires a LCA of the project’s structure and enclosure that demonstrates a minimum of 10% reduction compared with a baseline building.

This credit offers four compliancy options, of which the first three are available when reusing a historic or abandoned building, or reusing a major portion of building materials. Option 4: Whole-Building Life-Cycle Assessment therefore is the only one available for most LEED BD+C projects.

The LCA must be calculated for six listed environmental impact categories with three, including Global warming potential, demonstrating at minimum a 10% reduction. No category of impacts may increase by more than 5% compared to the baseline. The LCA data used must comply with ISO 14044, which is typically ensured by LCA software that conforms to LEED v4’s requirements.

To verify your improvement, you need to define your baseline and actual buildings. Let’s dig into that.


LEED v4’s baseline definition and optimization: the do’s and don’ts


The baseline and proposed buildings must be of comparable size, function, orientation, and operating energy performance.

What does this mean in practice? It may help to think of the baseline building as a building meeting the same function and size, but without all of the clever design choices that make it more efficient. Baseline buildings are defined in a different way in the US and internationally.

  • US projects: Define the wall, roof, and floor assemblies following the performance requirements of the building envelope in ASHRAE 90.1–2010 for the project’s climate zone (Appendix G, Opaque Assemblies, Vertical Fenestration, Skylights, Roof Solar Reflectance and Thermal Emittance sections).
  • International projects: Projects outside the U.S. are expected to develop a baseline building representing typical construction for their region meeting local applicable building performance requirements. Consider ASHRAE 90.1 – 2010 for a minimum set of guidelines for the building.

There is a bonus, too. If you achieve any improvement over the required credit thresholds in all six impact categories, you are eligible for an exemplary performance credit. In some countries, including Canada and Sweden, this is also a regional priority credit.

In practice, you’ll want to iterate over several design changes rapidly to see what they would mean for your project. To make this go smoothly, pick an easy to use LCA software.


Conducting an LCA need not be rocket science with the right tools, training, and support


Trying to optimize the material impacts of your project for the first time? You’re not alone. This post answers some of the common questions. But to make it work in real-life projects, we’ve built One Click LCA, a cloud-based and extremely easy to use building LCA software for LEED, with a tailored support service for LEED user challenges called the Baseline Clinic.

There are many ways to ensure that your LEED-compliant LCA goes smoothly with One Click LCA. You can invite your architect to co-work with you (or even fill in all the data for you directly in the cloud), upload the bill of materials, or use a Building Information Model (e.g. a Revit model) to automate the calculation. You can also get the volumes from drawings. Once you have your design, create a copy, modify it and iterate until you’re there. Simple!

We also provide training for new users (which you can count towards continuing education), and have a support service that helps you navigate your way through your first LCA. If you wish to use the Baseline Clinic, you’ll need to have an architect or a construction engineer on board, and we will help you identify solutions allowing you to achieve a 10% or more reduction in the material-driven life-cycle impacts of your building.

LEED v4’s Reference Guide states requirements for LCA software. One Click LCA LCA software complies with all and provides dedicated LEED-specific application to both North American as well as European LEED users. The North American version is powered by US/Canadian data and supports TRACI 2.1 and all required impact categories. The European version is powered by European data and supports CML and all required impact categories. All datasets are ISO 14044 compliant and the application provides a fool-proof template that ensures you’ll always follow the LEED template to the letter.

Found this interesting? Now that you’re mastering the theory, why not try it out in practice!

Join one of our free webinars or ask for a quote for your project at hello@bionova.fi!

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