Conquering GRESB waste reporting: a practical guide to closing the data gap.

Before reading the article, ask yourself these 3 questions:

1. Data Fragmentation: How many hours per month do you spend manually collecting PDF invoices from dozens of different waste haulers across your portfolio?
2. Accuracy vs. Estimation: Are you still relying on "volume-to-weight" estimations instead of actual, measured weight data?
3. Audit Readiness: Can you provide a digital, auditable trail for every kg of waste reported in your last GRESB submission within 5 minutes?

For portfolio managers and ESG directors, "GRESB season" is a high-stakes sprint. The GRESB Portal opens on April 1 each year for the annual Real Estate and Infrastructure Assessments. Participants have a strict three-month window to submit data, with the portal closing on July 1.

While energy and water data have become relatively streamlined, waste management remains the most difficult, fragmented, and frustrating component to track. This guide explores how to bridge the ESG data gap, automate collection from multiple haulers, and ensure your reporting is fully auditable to improve your GRESB Data Coverage score.

Why waste is the "final frontier" of GRESB Data Coverage.

Unlike utilities with centralized providers and standardized meters, waste management is highly fragmented. Some haulers only send invoices, others send PDF reports, and only a few provide digital portals. Aggregating this into the standardized, auditable format GRESB demands is a massive resource drain.

There is a structural reason for this. Electricity arrives through one meter, from one supplier, on one billing cycle, in one unit. Waste leaves a building in mixed streams, collected by several contractors on different schedules, measured in whatever unit each contractor happens to bill in — lifts, containers, cubic metres, sometimes tonnes — and often with no measurement at the building at all. The number on the invoice is frequently a price, not a weight.

Investors are increasingly sophisticated, scrutinizing the quality of data underpinning the score. We spoke with Izabela Makowska-Kwiecińska, Associate Director at Colliers, about these evolving expectations:

"GRESB has moved beyond a simple compliance exercise; it is now a critical indicator of operational maturity and risk management for investors. The market is demanding transparency. When a portfolio struggles to produce basic operational data - like waste generation - it raises red flags about overall management quality."

The danger of estimations and data gaps.

In the past, many portfolios relied on estimations to fill gaps. But as the benchmark matures, the tolerance for estimations is shrinking. GRESB rewards actual, auditable data.

Izabela further notes that ignoring this misses the strategic picture:

"Waste data has historically been the 'messy corner' of ESG reporting because it’s so difficult to capture accurately at scale. But you cannot manage what you cannot measure. Accurate waste data isn't just about improving a GRESB score today; it’s the foundation for developing genuine circular economy strategies and zero-waste goals for tomorrow."

The practical risk is not that an estimate is wrong by a few percent. It is that an estimate cannot be defended. When an investor or assurance provider asks where a figure came from, "our contractor's standard conversion factor applied to an assumed number of lifts" is a materially weaker answer than a weighbridge ticket. The first is an opinion; the second is a record.

Know which kind of data you actually have.

Before improving anything, sort every building's waste data into one of four tiers. Most portfolios have never done this explicitly, and the exercise alone usually explains the score.

1. Measured at source. The waste is weighed as it is deposited, per stream, at the building. Strongest evidence, and the only tier that gives you data between collections.
2. Weighed by the hauler. A weighbridge ticket or a hauler report stating actual kg per collection. Solid, provided the tickets are retrievable rather than summarised in an annual PDF.
3. Converted from volume. Container size multiplied by number of lifts multiplied by an assumed density. Acceptable as a stopgap, but the density assumption is doing the work, and it is rarely revisited.
4. Estimated. Benchmarks, per-square-metre factors, or last year's number carried forward. This is a placeholder, not data.

Tag every building and every stream with its tier. A portfolio that is 60% tier 3 does not have a collection problem, it has a measurement problem — and buying a better reporting tool will not change the tier.

Where the gaps actually come from.

In our experience, the same handful of failures account for most missing or unusable waste data across a portfolio:

• Partial years. A building switches hauler in August and nobody retrieves January–July from the outgoing contractor. Ten months of good data plus two missing months is often treated the same as a year of poor data.
• The landlord/tenant split. In multi-let assets, some tenants arrange their own collections directly. That waste is generated by the building and is invisible to the landlord's contract. Decide early whether you are reporting landlord-controlled waste or whole-building waste, write the decision down, and apply it consistently across the portfolio — an inconsistent boundary is worse than a conservative one.
• Construction and fit-out waste mixed in. A tenant fit-out can generate more tonnage in a fortnight than the building does operationally in a year. Left in the operational figure, it destroys year-on-year comparability and any intensity metric built on it.
• Rejected and contaminated loads. A recycling load downgraded to general waste at the sorting facility changes your diversion rate but frequently never reaches the property team.
• Unit drift. One contractor reports tonnes, another kilograms, a third cubic metres, and a spreadsheet column silently mixes them. This is the single most common cause of a figure that is wrong by a factor of a thousand.

A month-by-month routine beats an annual scramble.

The portfolios that report well are not the ones with the best submission-season process. They are the ones for whom submission season is uneventful, because the data was already correct in March. A workable monthly routine:

1. Collect within the month. Chase missing hauler data while the contractor can still find it. A request in June about the previous October has a low success rate.
2. Normalise on arrival. Convert to kilograms per stream at the point of entry, not at the point of reporting, and record the source document alongside the number.
3. Check the shape of the data. Look for months that are zero, months that are double, and streams that vanish. A building that reported no glass for three months has a data problem, not a glass problem.
4. Record the tier and the gap. Where data genuinely does not exist, log it as a known gap with a reason. A documented gap is a manageable problem; an undocumented estimate is a liability.

Before you submit: a short checklist.

• Twelve months present for every asset, with any missing period explicitly identified rather than silently interpolated.
• One unit throughout, with the conversion factors used written down and dated.
• Every figure traceable to a source document, portal export, or weighing record.
• Operational waste separated from construction, fit-out and one-off clearances.
• Diversion figures reflecting what the facility actually did with the load, not what the bin was labelled.
• The landlord/tenant boundary stated once and applied everywhere.
• Year-on-year movements over roughly 20% explained before someone else asks.

The solution: automated portfolio waste reporting.

The traditional method - manual calls, emails, and Excel - is broken. The solution lies in a specialized waste intelligence platform that acts as the "middleware" between haulers and ESG platforms.

How WasteTracker Solves GRESB Pain Points:

• Automated Data Flow: Digitizing invoices and reports automatically to eliminate manual entry errors.
• Data Standardization: Converting diverse units (liters, bins, containers) into standardized kg/tons across all countries in your portfolio.
• Audit Trail & Real-Time Data: Every data point is backed by the source document or a smart meter registration.
• Portfolio Coverage: Rapidly increasing the percentage of buildings reporting actual data to boost your GRESBData Coverage score.

4 steps to data-driven GRESB success.

A typical implementation across any EMEA property takes just 30 days:

1. Discovery: We map your current waste processes and identify hauler data sources.
2. Formalities & Setup: Connecting hauler accounts and installing WasteTracker Terminals for precision weighing.
3. Onboarding & Monitoring: Training staff and ensuring data flows correctly into the Admin Panel.
4. Insight Analysis: Reviewing clean, aggregated data for ESG reporting and waste reduction strategies.

Conclusion: focus on strategy, not spreadsheets.

Most of the checklist above can be started this month with a spreadsheet and a list of contractors, and doing so is worthwhile whether or not you ever change systems. What a spreadsheet cannot do is hold the audit trail, keep the units honest across a dozen countries, or tell you in February that a building stopped reporting in November.

By utilizing specialized technology to handle the "heavy lifting" of data collection, you ensure the data landing in platforms like Measurabl and subsequently GRESB is accurate and complete. Stop chasing haulers and start managing your footprint.