A-Label Buildings Can Still Waste Energy. Here's Why.

You've done everything right. You've invested in a modern, efficient building with top-tier insulation, high-performance glazing, and an A-rated Energy Performance Certificate proudly displayed in the lobby. So why are your energy bills still climbing?

You're not alone. Across Europe, building owners and facility managers are discovering an uncomfortable truth: an A-label EPC rating doesn't guarantee low energy consumption. In fact, research consistently shows that many certified buildings consume 40% or more energy than their certificates predict.

It's a fundamental gap between how we measure building performance and how buildings actually perform. Understanding why this gap exists is the first step toward closing it.

What an EPC actually measures

Energy Performance Certificates were designed to give buyers and tenants a standardised way to compare buildings. The rating, from A (most efficient) to G (least efficient), is based on a theoretical model of how the building should perform under standard conditions.

The assessment examines the building's physical characteristics: wall and roof insulation, window specifications, heating and cooling systems, lighting efficiency, and renewable energy sources. It then applies standardised assumptions about occupancy, operating hours, and thermostat settings to calculate predicted energy use.

This approach makes sense for comparison purposes. Without standardised assumptions, you couldn't fairly compare a building used by a skeleton crew to one packed with employees running servers around the clock.

But here's the problem: no building operates under standard conditions.

How Big Is the Gap Between EPC Ratings and Actual Energy Use?

Research consistently shows significant divergence between EPC predictions and measured consumption, particularly for higher-rated buildings.

According to research published in Energy Efficiency, energy-efficient buildings with high EPC ratings actually consume 39%to 54% more energy than their certificates predict. Meanwhile, less efficient buildings often use less than expected. The reason is straightforward: EPCs assume standardized occupant behavior and optimal system performance. Real buildings don't work that way.

A 2025 study of Norwegian municipal buildings found that seven out of eight buildings consumed more energy than their EPCs predicted, with an average deviation of 40%. Buildings with complex HVAC systems showed the largest gaps between predicted and actual performance.

Are EPC Ratings Consistent Across Europe?

The picture gets more complicated when you look across borders. Savills research found that a commercial property receiving a top grade in one EU country could berated up to four grades lower in another, simply due to different national methodologies and thresholds.

Even within single countries, inconsistencies appear. In Belgium, the same energy performance measured in kWh/m²/year receives a "C" in Flanders but a "D" or"F" in Brussels. For portfolio managers operating across multiple markets, this makes direct comparisons based on EPC grades essentially meaningless.

The Performance Gap: Why Predictions Miss Reality

The difference between predicted and actual energy consumption, known as the "performance gap", has been documented extensively across commercial and residential buildings. Several factors drive this discrepancy.

1. Occupant behaviour is unpredictable

EPC models assume people will use buildings in specific ways. They don't account for the employee who opens windows while the heating runs, the team that works late every night with all the lights on, or the server room that wasn't in the original plans.

In commercial buildings especially, actual occupancy patterns, equipment loads, and comfort preferences vary enormously from the standardised assumptions baked into EPC calculations. A building designed for 200 people operating 9-to-5 behaves very differently when 300 people work flexible hours with laptops, monitors, and personal heaters at every desk.

2. Design intent doesn't survive construction

Buildings are complex systems, and the journey from architect's drawing to finished structure introduces countless opportunities for performance to degrade. Insulation installed with gaps, air barriers punctured by services, thermal bridges created by structural elements. All of these issues don't show up in an EPC assessment but dramatically affect real-world performance.

Commissioning problems compound the issue. Building management systems configured incorrectly, sensors placed poorly, or control sequences that don't match actual use patterns can result in heating and cooling systems fighting each other or running when spaces are empty.

3. Systems age and drift

An EPC represents a snapshot in time, typically when a building is new or recently renovated. But buildings change. Seals degrade. Filters clog. Sensors drift out of calibration. Control settings get overridden and never reset.

Without ongoing monitoring and maintenance, even the most efficient building will see its performance decline. The A-label certificate on the wall doesn't update itself as the building's actual efficiency slowly erodes.

4. The methodology has blind spots

The Standard Assessment Procedure used for EPCs relies on simplified models that can't capture every factor affecting energy use. It doesn't fully account for complex thermal dynamics, the impact of building orientation and shading in specific locations, or how different systems interact under varying conditions.

Some buildings that look excellent on paper simply don't perform as expected once they're operating in the real world with real weather, real occupants, and real equipment loads.

What This Means for Building Owners and Operators

If EPC ratings don't tell the whole story, what does? The answer lies in shifting focus from predicted performance to operational performance.

1. Monitoring actual consumption

You can't improve what you don't measure. Building owners serious about energy efficiency install sub-metering to track consumption by system, zone, and time of day. This data reveals where energy actually goes and where it's being wasted.

Comparing actual consumption against benchmarks for similar buildings provides context. If your A-rated office uses twice the energy of comparable buildings, the certificate becomes irrelevant. Something in operation needs attention.

2. Closing the commissioning gap

Many performance issues trace back to systems that were never properly commissioned or have drifted from their intended settings. Retro-commissioning, a systematic process of verifying and optimising building systems, frequently delivers energy savings of 10-15% with relatively modest investment.

This isn't about installing new equipment. It's about making existing equipment work as intended: ensuring sensors are accurate, control sequences are appropriate, and schedules match actual occupancy.

3. Engaging occupants

Building users have enormous influence over energy consumption, and that influence can work for or against efficiency. Clear communication about how building systems work, easy ways to report comfort issues, and feedback on energy use can align occupant behaviour with efficiency goals.

Some buildings have achieved significant savings simply by making energy visible: displaying real-time consumption in common areas or providing departmental breakdowns that create friendly competition.

4. Continuous optimisation

Energy efficiency optimization is not a one-time thing, but an ongoing process. The most efficient buildings treat energy management as a continuous practice, regularly reviewing consumption data, investigating anomalies, and making incremental improvements.

This operational focus delivers results that no certificate can capture. It's the difference between a building that was designed to be efficient and a building that actually operates efficiently.

Look Beyond Labels

The buildings that achieve genuine efficiency aren't necessarily the ones with the best ratings. They're the ones where someone is paying attention to what's actually happening AND doing something about it.

At Next Sense, we help building owners see beyond the label to understand what's actually happening inside their buildings and where the real savings opportunities are.

If your A-rated building isn't performing like one, let's find out why.

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