Feature image: The LEED Gold Museum Lab space in Pittsburgh, Pennsylvania was certified under LEED v4. Photo credit: Eric Staudenmaier / MuseumLab.

You may have heard that around 80% of buildings that will exist in 2050 have already been built. New buildings (even if they were all net zero energy) can’t solve the carbon crisis or the climate emergency. Because even though we will continue building new buildings, those new structures will (usually) generate a lot of embodied emissions, and they won't reduce the operating emissions from all the buildings we already have.

So, for new buildings, we need to make them out of low-carbon and carbon-storing materials, turning the new built environment into a giant carbon sink. Meanwhile, we also need to focus on reuse of existing buildings.

Existing buildings and sustainability

This means that decarbonizing existing buildings is a major priority to reduce the impact of the built environment on global emissions. While new buildings are hopefully more energy-efficient, upgrading the buildings we already have is crucial to avoid both operational and embodied carbon emissions for decades to come.

Existing buildings offer immediate opportunities for operational emissions reduction and can help us achieve an environmentally responsible and socially equitable future. This is because

Renovating an existing building has a much lower carbon footprint than building a new building (lower embodied carbon).
When a renovation includes energy efficiency upgrades, it also reduces the current operating emissions associated with that energy consumption (lower operational carbon).
Decarbonizing existing buildings through renovation opportunities comes along with opportunities to improve health and indoor environmental quality (IEQ): thermal comfort, air quality, lighting, acoustics and more.
Reusing buildings is an investment in people, by strengthening existing neighborhoods, as renovating and upgrading buildings also generates more jobs per dollar invested than new construction, and the jobs tend to be local and favor small businesses.

The three steps for revitalization of existing buildings, whether for energy efficiency or, now, for decarbonization, has essentially remained the same over the years, with the addition of one new strategy that has risen to the top in the last few years:

Eliminate on-site combustion of fossil fuels, such as through mindful electrification.
Improve building efficiency/passive strategies: insulation, windows, shading, air sealing, daylighting.
Improve systems efficiency: lighting, HVAC, water heating, appliances, controls, etc.
Offset the remainder with renewable energy: probably photovoltaics, ideally on-site.

These steps are critical for older buildings (those built 15 or more years ago), but even newer buildings constructed to LEED for Building Design and Construction standards can benefit from a reassessment, through existing third party frameworks, after five years of operation.

Young students work in an artistic maker space in an adapted older building. — The LEED Gold MuseumLab space in Pittsburgh was a LEED v4 adaptive reuse project. Photo credit: Eric Staudenmaier / MuseumLab.

Enter LEED v5 for Operations and Maintenance (LEED O+M). LEED O+M represents a crucial segment of the LEED rating system suite that has, so far, been underused, and now is the perfect time to bring it to the forefront. It focuses on maximizing the operational efficiency and sustainability of existing buildings and has evolved significantly, with LEED v5 building on larger changes from the previous update (LEED v4.1), which marked some exciting updates even over LEED v4 (particularly in using data to prove real-time performance and streamline certification efforts).

LEED v5 reflects significant market changes over the past eight years (since “Performance Score to LEED Certification Pilot Option” for LEED O+M was incorporated into the LEED v4.1 beta in 2018), introducing robust measures to address the system goals:

Decarbonization (50%) drives the industry toward a built environment independent of carbon sources across all major sources of emissions: operational, embodied and transportation.
Quality of life (25%) uses human-centric strategies to address crucial aspects of sustainable building, including human health and well-being, resilience, equity and inclusion, and community well-being.
Ecological conservation and restoration (25%) emphasizes strategies and actions that can be implemented at the individual asset level, limit environmental degradation, and seek to rehabilitate and restore ecosystems.

Addressing emission reduction challenges in existing buildings

Building owners often face significant challenges when trying to reduce emissions, including outdated infrastructure, insufficient data and financial constraints. LEED v5 offers new tools and frameworks to help overcome these barriers:

Comprehensive data use: By emphasizing the importance of data in benchmarking and tracking performance, LEED v5 enables building owners to make more informed decisions about where and how to implement efficiency improvements.
Targeted emissions reduction strategies: The framework provides specific guidance on reducing emissions through strategic upgrades and renovations, behavior change initiatives among building occupants, and continuous performance monitoring.

If you look through the public comment draft language for LEED O+M, each prerequisite and credit include a section at the bottom of the page that lists “Impact area alignment,” with color-coded boxes for each of the system goals. Across five prerequisites and 19 credits, decarbonization is tagged for 13 (nearly 70%).

Emissions is obviously tied to decarbonization. This is addressed through the Energy and Atmosphere (EA) credit GHG Emissions Reduction (12 points), the Materials and Resources (MR) credit Embodied Carbon of Interior Materials During Renovation (2 points), and the Location and Transportation (LT) credit Sustainable Transportation Performance (10 points), as well as through increased emphasis on topics like refrigerant emissions.

Large stone archways and original brickwork form the background of a children's museum. — Photo credit: Eric Staudenmaier / MuseumLab.

Students walk up a staircase next to a repurposed ironwork wall. — Photo credit: Eric Staudenmaier / MuseumLab.

The hardest part for project teams sometimes seems to be getting started and getting a handle on the data. Operational history for buildings is often largely untracked and has been lost in the function of day-to-day processing, without a lot of benchmarking or accounting on the back end. So, after creating a baseline for emissions (the first hurdle), we can set goals for reductions (the second hurdle). It’s a complex topic.

A lot of the energy reduction best practices credits will seem familiar to many, at this point: Benchmark in Energy Star Portfolio Manager, Conduct Energy Audits, Submeter Energy Use, Retrofit Controls and Lighting Systems, Continuous Monitoring and Commissioning, and On-site (or new offsite) Renewable Energy.

For carbon reduction actions, the first step is to improve your energy efficiency, then address the credits for Electrify HVAC Systems During Replacement Cycles (consider embodied carbon), Revise Travel Policies, Add EV Infrastructure, Adopt Low-Carbon Materials Policies and start some Embodied Carbon Accounting.

Practical steps toward sustainability

For building owners embarking on the path to sustainability, LEED v5 offers a structured approach:

Start with an energy audit: Understanding the current energy performance of a building is the first step toward improvement.
Implement cost-effective solutions: Quick wins like LED lighting upgrades, HVAC optimizations and enhanced insulation can yield immediate improvements in energy efficiency and cost savings.
Engage with experts: Consulting with sustainability professionals can provide tailored advice that maximizes the impact of investments.
Plan for long-term benefits: Sustainable practices should be viewed as long-term investments that offer significant returns through reduced operational costs and enhanced property values.

Building resilience and equity

As part of its broader vision, LEED v5 aims to enhance the resilience of buildings to climate-related challenges and promote equity by ensuring that all building users can enjoy high-quality, healthy and sustainable environments. The integration of resilience planning and social equity considerations into the LEED criteria exemplifies a comprehensive approach to sustainability that addresses the needs of the present without compromising the ability of future generations to meet their own needs.

Discussions on resilience are moving into the mainstream; it is great timing that we had a dedicated Resilience Working Group as an advisory to the LEED Steering Committee, responsible for making recommendations about risk assessment/management, climate adaptation and passive survivability to guide the technical development of resilience language in the LEED green building rating systems.

There’s more in the charter, but a lot of this work builds on the Assessment and Planning for Resilience and Design for Enhanced Resilience pilot credits and the Resilience Workbook developed as part of that.

The Equity Working Group was formed for the same reason to create a framework for advancing diversity, equity and inclusion in the built environment through LEED. This goes hand in hand with Quality of Life. LEED O+M currently addresses equity through:

Prerequisite: Operations Assessment (Social Impacts for the community, project team and supply chain)
Credit: Equity within Operations and Maintenance Staff

A child and teacher work on a project in a lobby surrounded by original brick and stone elements. — Photo credit: Eric Staudenmaier / MuseumLab.

Protecting and enhancing natural ecosystems

The protection of natural ecosystems is deeply embedded in LEED v5, with specific credits aimed at reducing light pollution, deterring bird collisions, managing rainwater and enhancing waste management practices. These measures not only mitigate the direct impacts of buildings on their immediate environments, but also contribute to broader ecological conservation efforts.

LEED v5 represents a significant evolution in the LEED certification standards, with a renewed focus on existing buildings. This shift is critical because it recognizes that enhancing the sustainability of existing structures is essential to achieving broader environmental goals. As we look to the future, the continued adaptation and refinement of LEED standards will be key to ensuring that they remain relevant and effective in promoting sustainable building practices worldwide. This commitment to continuous improvement is essential in our collective effort to build a more sustainable and resilient future.

When we’re talking about changing buildings—both new and existing—to change the world and slow the impacts of climate change, there’s a certain urgency that can sometimes cause stress in our systems…and LEED isn’t immune to that. Being involved with the development of this system over the past five years as a Technical Advisory Group member, chairperson and member of the Technical Committee and Steering Committee, I’ve gotten the opportunity to see how passionately so many people care about both how we can push the industry to do more and how we can act with urgency.

Another goal was to make the rating system flexible and adoptable to a wider audience. It will take all kinds of buildings, not just the Platinum performers, to decarbonize the built environment. Everyone has to start somewhere and track incremental improvements. As LEED v5 and future versions continue to adapt, I hope each will reach a wider audience and pull even more people along, while providing an avenue to reward high performers and push them into the spotlight. LEED O+M is a great tool to do just that.

Five questions for...

Sarah Gudeman, LEED AP BD+C and ID+C, LEED Fellow
Principal and building science practice lead, BranchPattern
Omaha, Nebraska

A woman in office casual attire smiles at the camera. — What inspired you to move toward a green building career?

From an early age, I’ve always had an affinity for the environment. My father managed a nature center in Austin, Minnesota, where I was born, and we spent many days outside at our family cabin on the cedar river in Iowa, growing up. Our family’s move to Omaha was functionally in service of the Nature Conservancy, when my dad took on the role of state director. I’ve always been inspired by him, his love for nature and all it entails.

What is the most exciting part of what you do at your company?

I love engineering at its core—solving complicated problems with creativity and its never-ending drive to ask “Why?” and “Why not?” My role now is exciting because I’m functionally able to support our building science practice in various services—improving commercial real estate and integrating sustainability into both new construction and ongoing operations for our customers.

What was your favorite green project ever?

The next one. I get really excited about improving and providing the best possible solutions, learning from the past, and looking forward to the future. My favorite is when customers come to us, unsure of what they want and needing help establishing what “could be” and how to get there, because education is also a passion of mine.

How would you like the world to be different for future generations?

I’m really encouraged to already see the kind of changes I think we need more of…the encouragement of asking and answering the tough questions together, acknowledging the wins with incremental improvements and celebrating how far we’ve come (while also acknowledging the work that remains).

What advice would you give an emerging professional in this field?

Find a place (or the people) where you can ask your questions and feel supported if you make mistakes.

Learn more about Gudeman.

Enhancing existing buildings through LEED for Operations and Maintenance