Why Your Building Isn’t as Green as You Think

Everyone’s Talking About Sustainability—But Something’s Not Adding Up

Sustainability is a huge topic in Real Estate. Look at any Real Estate company’s website and you’ll see an entire section dedicated to the topic, often with ambitious NetZero targets defined, and senior dedicated staff assigned the task of reducing carbon emissions across a portfolio.

A major strategy for most building owners is to invest in improving the Energy Performance Certificate (EPC) of the building. The EPC is an assessment of the quality of the building against a range of environmental criteria. The theory is the higher quality the building, the less carbon emissions it will generate. That theory, however, doesn’t hold up in practice. Study after study is showing that buildings are generating significantly more carbon than their design or EPC would expect. The difference between the Design/Expected efficiency and the Actual/In-Use efficiency is known as the Performance Gap.

All of this is well known. The major question is: what causes the Performance Gap, and how can it be solved?

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The Trouble Starts with HVAC

The main cause of the Performance Gap is Heating, Ventilation and Air-Conditioning (HVAC). On average, HVAC accounts for 50% of the energy consumed in buildings. In offices, the percentage is even higher. Since HVAC represents such a high proportion of energy consumption in a building, it’s vital that it works efficiently. Yet, it is the most inefficient and unpredictable energy consumer in a building. Lighting, by contrast, is entirely predictable. Calculating the energy consumed by lighting is the sum of the wattage of the lights and the time they are on.  

The challenge with HVAC is there are, quite literally, so many moving parts – Heating, Cooling, Fans, Pumps, Air Handling Units, valves, dampers, radiators, fan coil units, and more. In larger buildings this HVAC ‘ecosystem’ is managed by a Building Management System (BMS). It is no surprise  there are inefficiencies in such complex systems.

Sometimes the inefficiencies stem from poor design, or badly commissioned equipment, or BMS systems set up with the wrong schedules or setpoints. These sorts of flaws can be identified and rectified and represent the ‘low-hanging fruit’ of HVAC inefficiency. But a significant Performance Gap remains, even when these issues are addressed.

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Why Control, Not Equipment, Is the Real Game Changer

Ultimately, the problem with HVAC – and the solution – lies in control. Think of more familiar examples of complex environments, like a football team or an orchestra. Getting top performance from these entities isn’t simply a matter of putting talented individuals together and giving them the best equipment and communicating a game plan. There has to be a coordinated synergy where each element is bringing out the best in the other elements. The system/team/group has to perform holistically. That synergy is achieved by good management. There are countless examples of football teams that are transformed in performance and success by the arrival of a new manager. 

The equivalent in HVAC is the control commands sent from the Building Management System (BMS) to the individual pieces of HVAC equipment. Normally the control commands generated by a BMS focus on making HVAC deliver specified comfort levels during defined hours of the week. Given the number of moving parts in large HVAC systems, it requires a lot of complex commands to deliver comfort within those parameters.

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You Can’t Optimise What You Don’t Understand

But there are a lot more factors at play than Indoor Air Quality setpoints and schedules. Every building has a unique combination of HVAC equipment, Building Fabric, Occupancy Behaviour, and Weather Conditions. This combination is the Environmental Signature of the building. Unless all of these factors are incorporated into control commands that are coming from the BMS then the HVAC System can’t perform at its maximum efficiency. 

BMS systems are not designed to factor in all these variables, and even if they were, it can take months to properly identify and define each building’s Environmental Signature and design and automate the perfect control commands to match that unique Signature. 

When the perfect control commands are implemented, extraordinary results are achieved. Buildings of any EPC rating have seen HVAC energy consumption drop by 60%-80%. 

Closing the Performance Gap in this way requires a specialist skillset. BMS Engineers don’t have time to monitor each HVAC system to understand its unique Environmental Signature, and Facilities Managers don’t write BMS code that automates the perfect control of their buildings. 

HVAC Optimisation solutions narrow the Gap between Design Efficiency and Actual Efficiency. The best HVAC Optimisation solutions, designed to match each building’s unique Signature, can close the Performance Gap entirely.