Apartment buildings

The new data performance standard in GRESB

The specifics around data quality in ESG reporting matters – more than ever before. But how do you define quality?

GRESB is a mechanism for ESG reporting, but a GRESB rating alone holds no value without the trust from investors, tenants and regulatory authorities. And to maintain these stakeholders’ trust, GRESB reporting needs to be accurate.

Accuracy vs scale

Real estate portfolios are in an ever-changing state. Buildings are being bought, sold, leased and retrofitted on a regular basis. This leads to a conflict between accuracy and scale; the larger the portfolio, the harder it is to maintain accuracy. And since energy costs often account for 40% of the total operational cost of a building, this abstractness becomes especially pressing when it comes to utility data performance.

From 2020, asset-level data reporting is mandatory in GRESB reporting, and with that comes enhanced quality controls at the asset-level. The reason behind this is to ensure higher data quality in the sustainability benchmark, and provide capital markets with more accurate ESG performance metrics. In 2020, GRESB also implemented a new reporting structure that places a higher weighting on the performance component towards the overall score. That’s why the specifics around data quality matter – more than ever before. But, defining quality isn’t an easy task.

A new performance data standard

The good people at GRESB are working hard on defining how, exactly, data quality should be measured. How it should be reported and how it should be validated are some of the big questions they try to answer.

As of now, we know that there are four factors taken into account when assessing the validity of the data reported.

  1. Accuracy.
  2. Completeness
  3. Timeliness
  4. Lineage

Let’s break them down one by one.


Accuracy assesses whether the values reported are correct. To be considered correct, the sustainability data should be represented in a consistent and unambiguous form.

And reported values that appear to be too good to be true, or in any other way differ from expectations, should be detected, flagged and explained or corrected.


Completeness in measuring can be evaluated in multiple ways. For example by comparing the number of missed vs. expected measurements over time. And this is an important factor to consider, because gaps in meter readings are like pages missing in a novel; loose to many and it’s not at all clear what we are evaluating or what meter readings are normal, and that makes sustainability benchmarking useless.


The older the data, the harder it is to trust, because an investor or assessor might not know if the old data is reflective of the current state of the building. Valuing factors like frequency of collection will both enable you to provide the latest sustainability data to your stakeholders, it will also help you in making agile operational adjustments in the building’s energy usage.


A data point or a meter value can be transferred or transformed, and if you can’t track these changes – why should we trust the data reported from it? Establishing a clear inventory of all meters in a system, with a clear change log, is a good way to ensure both lineage and completeness.

The scrutinisation of lineage is especially important when it comes to estimations, which we can expect to become more complicated in future sustainability reporting.

Estimation methodology, now and in the future

As a general rule, GRESB Participants are required to use actual data when reporting on the Performance Component. The current requirements do allow estimations when there is some existing data, but estimating a year worth of data, or estimating consumption values for an entire missing subspace, is simply not allowed.

If you do have to use estimations, you have to disclose the estimation methodology used – and how much of the reported data is estimated. But this still doesn’t mean they’ll blindly take your word for it; if the GRESB assessors feel it necessary, they will request supporting evidence to corroborate the data you reported.

Setting a standard for estimations is tricky, because in some instances the problem of data coverage might not even be on the property owners end. Many property owners struggle with collecting tenant data, and some are at the mercy of the utility providers. In some instances, meter readings are not performed on an annual basis, or in time for GRESB reporting, and instead are estimated by the utility provider. But this might not even be considered an estimation in the eyes of the GRESB assessor – at least not if the reported data comes from an official document like an invoice.

For the new GRESB performance data standard, it looks like the technical expert group is suggesting adding focus on why data has been estimated, as opposed to just what and when. Thus, having clear lineage might become increasingly important to be able to finalise a GRESB report – especially if your data coverage is lacking.

All four factors covered

So what can we conclude from this? Property owners need processes in place to verify the accuracy, completeness, timeliness and lineage of their energy data – regardless of what type of ESG reporting is in the making. (And hey, that’s exactly what we do at Metry!) Once you’ve got a streamlined data collection process in place that yields timely and qualitative sustainability data, you minimize the risk of missing or inaccurate values – and with built-in data structuring, lineage becomes a walk in the park.

(Bragging time) Metry customers Vasakronan and Castellum have both been recognised as world leaders in sustainability. In the 2018 GRESB results, Vasakronan was ranked as one of the most sustainable property companies in the world and was also recognised as the European leader in its sector. In the 2020 results, Castellum was ranked as global leader in the office/industrial category, for the second year in a row.

Free up time to work on actual energy efficiency efforts, and let Metry take care of the hassle of data collection. We can help you get the data you need for your ESG reporting, and we’re here if you want to talk!

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