How Operational Green Building Certifications Improve Portfolio Sustainability Benchmark Scores

Image

By Todd Feist, Director, Sustainability Programs, IREM^®

What is GRESB and the GRESB Real Estate Assessment?

GRESB is a global ESG assessment and benchmarking system for real assets. It provides standardized, validated sustainability data that investors and managers use to compare performance and inform decisions. The GRESB Real Estate Assessment is the annual submission used by real estate companies and funds to report ESG practices and building performance, which are then validated, scored, and benchmarked. 

Why GRESB Affects Capital Decisions

For many real estate investors, GRESB submissions have shifted from “nice to have” to expected. Scores are used to compare managers, inform due diligence, and guide capital allocation. If you’re leading sustainability on the ownership side, the question is simple: where can your score actually move? If you’re in third-party property management, it’s just as real. How do you deliver measurable GRESB value and show owners you can execute? 
The most reliable answer often starts with building operations. 

Where Most Teams Look First and Stall Out

The GRESB Real Estate Assessment for standing investments is commonly understood as having two main scoring components: 

• Management (30 points): policies, governance, reporting 
• Performance (70 points): how buildings actually perform

Image

Newer participants often start with management because it’s easier to document. That’s a smart approach, and the IREM (Institute of Real Estate Management) Certified Sustainable Property (CSP) certification can support this phase, especially for teams getting started. But after a year or two, many teams hit diminishing returns. Policies are in place, governance is mature, and point gains flatten. 

Most of the Remaining Opportunity Lives in Performance

"The biggest misconception about improving a GRESB score is that it's about writing better policies, as most participants have already maxed out the management side,” says Josh Kiser, senior project manager, Americas sustainability advisory, at CBRE, Inc. “The real opportunity lives in the performance data, and that's the property manager's domain. The property manager who builds tenant rapport, captures whole-building data consistently, and maintains it in a platform like ENERGY STAR Portfolio Manager is creating points the rest of the organization simply can't manufacture from a spreadsheet." 

Performance is where operations count because it looks at what’s happening in your buildings, including: 

• Energy and water use 
• Waste diversion 
• Greenhouse gas emissions 
• Tenant engagement 
• Building certifications 

Because these metrics are benchmarked against peers, steady operational improvements can lead to meaningful score movement. “Data coverage and year-over-year improvement drive the majority of the points,” Kiser says, “and the hardest data to capture is also the most valuable: tenant spaces account for most of a building's energy use, yet they're the most common blind spot in any submission.”

Utilities often report at the meter rather than the whole-building level, and without green lease clauses or submetering in place, leased-space consumption never makes it into the assessment at all. GRESB has fundamentally reoriented from rewarding what you say you do to measuring what your buildings actually do, and that puts on-site teams at the center.” Building certifications are another big part of that story. 

Why Operational Certifications Matter in Performance

Operational certifications carry significant weight in GRESB’s building certification scoring. In the 2026 GRESB Real Estate Assessment, design/construction (BC1.1) and operational certifications (BC1.2) are combined at the portfolio level and benchmarked to produce a single certification score, with a maximum of 8.5 points. Energy ratings (BC2) can contribute an additional two points, for a total of 10.5 points. 

While design and construction certifications (BC1.1) contribute to GRESB scoring, operational certifications (BC1.2) carry the largest weight and are the primary driver of top performance. In practice, portfolios without operational certifications rarely achieve maximum certification scores. 

Why Operational Certifications Help Beyond the Score

Operational certifications aren’t just one-time wins. They’re frameworks that ask property teams to: 

• Track energy, water, waste, and indoor environmental performance year-over-year 
• Keep practical sustainability policies in place 
• Apply those policies to day-to-day decisions 

 For owner-side sustainability leads, that turns board-level commitments into asset-level practice. Net-zero plans only work if building teams know what to track, maintain, specify, and improve. For property managers, this is already the work. Certification gives it a recognized structure, plus a way to show owners your impact in a format GRESB recognizes. 

The Coverage Problem That Slows Most Portfolios

The challenge usually isn’t whether to pursue certification. It’s scale.

Many premium certification programs were designed for trophy assets. High fees and complex documentation requirements can make it difficult to scale across an entire portfolio. Challenges are especially common with triple-net assets, properties with separately metered tenant or resident spaces, and the Class B and B+ assets that make up a significant share of many institutional portfolios. That often leads to a few flagship plaques and a long tail of uncertified assets that drag down certified floor-area share. 

How CSP Supports Portfolio-Scale Certification

IREM created the IREM CSP certification to fit the existing building reality. The CSP is a holistic operational certification that covers:

• Energy 
• Water 
• Health 
• Recycling 
• Purchasing

Seven existing building property types are eligible:

• Multifamily
• Office 
• Industrial 
• Retail 
• Health care 
• Senior housing 
• Self-storage 

The CSP is recognized by GRESB as an operational green building certification program and earns “full points” (weight 1.0) under BC1.2 when reported correctly at the asset level. GRESB weights certifications using one of three validation statuses: full points (1.0), partial plus (0.6), or partial minus (0.3). 

The CSP also offers a volume program for companies pursuing 10+ certifications alongside an active ESG reporting practice (such as GRESB, GRI, CDP, or S&P CSA). For GRESB participants, that volume pathway can make pricing more predictable and supports a single, multi-asset strategy instead of one-off plans. 

What Expanded Coverage Can Mean for Your Score

How much BC1.2 can move depends on portfolio size, asset mix, and how quickly you can increase certified floor area within a reporting cycle. To make planning easier, IREM offers an interactive CSP GRESB Points Pathway tool . It helps teams estimate potential BC1.2 contribution ranges and model CSP fees at the right volume tier, with comparisons to other operational certification options. It’s a practical starting point for owners and management partners who want to connect certification decisions to GRESB outcomes. 

"Certifying an entire portfolio rather than one building at a time changes everything,” Kiser says. “You standardize documentation, benchmark every asset using the same scale, and turn certification from a one-time event into an ongoing performance program. For existing buildings, across the board consistency is what makes data credible to investors and useful to operators.”

Kiser adds that the advantage of running green building certifications across a whole portfolio is that “it standardizes practices from building to building. Management performance becomes measurable and comparable rather than anecdotal. Using a portfolio-wide green building certification tool allows this to happen and for CBRE to serve its investor and portfolio clients at scale, delivering sustainability value to the real estate lifecycle holistically. The effects show up directly in GRESB scores and fund-level reporting in a way single-certified buildings cannot. The portfolio is the story; the individual building is just a chapter." 

Timing Matters

Image

For owners targeting the next GRESB cycle, IREM’s Nov. 1 priority deadline is a useful planning anchor. Qualifying first-time CSP applications submitted by Nov. 1 are guaranteed application reviews in the year they’re submitted. Teams that start the volume conversation now are more likely to complete certifications within the reporting year and reflect that progress in the next investor-facing score.

Operational discipline isn’t new work. It’s work portfolios already need to do. The CSP helps you document it, standardize it, and get credit for it. 

FAQs 
How many companies participate in the GRESB Real Estate Assessment? 
In 2025, 1,002 fund managers submitted 2,382 GRESB Real Estate Assessments, including 84 new managers reporting for the first time. GRESB also reported 239 entities participating in the inaugural Residential Component.

For broader context, GRESB publicly states that its annual assessments span thousands of real estate portfolios (plus infrastructure funds and assets) and are collectively valued at almost $9 trillion, serving more than 150 institutional and financial investors worldwide. 

What part of GRESB do operational certifications affect most? 
Operational certifications primarily impact BC1.2 in the performance component. BC1.2 awards points based on certified floor-area share with a valid operational building certification.

How does the CSP fit into GRESB? 
The CSP fits into GRESB under performance, in building certifications, within BC1.2 (Operational Building Certifications). The CSP can help increase the certified floor-area share that drives BC1.2 scoring. 

Does the CSP count as full GRESB credit? 
Yes. Each CSP earns “full points” status (weight 1.0) under GRESB’s BC1.2 indicator when it’s valid and reported correctly at the asset level. BC1.2 scoring multiplies the validation-status weight by certified floor area, ownership percentage, and a time factor based on certification age. 

Is the CSP only for select property types? 
The CSP is available for seven property types: multifamily, office, industrial, retail, health care, senior housing, and self-storage. Limited data doesn’t have to stop certification. With due diligence and tenant collaboration, even triple net properties can move forward. 

Can a property earn more GRESB points if it holds both a design and construction certification and an operational certification ? 
Not beyond the overall scoring limits. Having both can improve your result.

In the 2026 GRESB Real Estate Assessment, design and construction certifications (BC1.1) and operational certifications (BC1.2) are evaluated separately and aggregated at the portfolio level for scoring. BC1.1 can contribute up to 7 points and BC1.2 up to 8.5 points, within a total of 10.5 points for building certifications. 

Because scoring is benchmarked across portfolios, having both types of certifications can strengthen overall performance. However, operational certifications carry the largest weighting and are typically the primary driver of top scores.

Todd Feist is director of sustainability programs at IREM®, where he leads the development and growth of sustainability-focused professional education, certifications, and industry partnerships. During his tenure at IREM, he has worked across both sustainability programs and IREM Knowledge Solutions, supporting IREM’s certification and credentialing programs, exam development, and professional education initiatives.