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Jessica Elliott asks: is energy management without good data possible?

The energy we expect a building to use when we design it and the energy it actually uses when it’s operational rarely match up. Managing our energy usage is increasingly important to businesses, people and the UK Government, so why is this still the case?

Why energy management matters
At its heart, energy management is about our country’s commitment to reduce carbon dioxide emissions, and our desire to be good, responsible citizens of the world. Good PR also plays a part as many of a company’s staff, clients and investors will want to work with or for a company that is committed to reducing its energy usage.

For most companies though, good energy management is fundamentally about cost. There are few companies out there who don’t want to run their business more efficiently, and managing energy costs has an obvious financial benefit. With finite resources it’s essential companies understand their energy operating profile – if not, they’ll find that energy costs continue to rise, and the amount they have to spend on fundamental business resources decreases.

The data needed to make good decisions
The energy usage data we use to design our buildings is generated and collated in a number of places – the CIBSE benchmarks, the UK building regulations and Carbon Trust, to name a few. Each pull their data from different sources and provide different, and sometimes contradicting, information to designers. Add into the mix websites like Carbon Buzz that provide design and Post Occupancy Evaluation (POE) data which is also different and you can see why designers struggle to set realistic energy targets for buildings that have been informed by one true source of information.

This is evident in the fact that most newly constructed buildings use up to one and a half times more energy than they were designed to use (reference: Carbon Buzz). This isn’t something that happens gradually – from the minute you ‘switch on’ the building, there’s a good chance it will start to use more energy than you anticipated.

To address this we need to get good, ‘in operation’ data to understand how our buildings are actually performing. This comes from two important sources: meters and POE studies.

A big element of keeping track of energy usage that people often underestimate is meters. Part L of the building regulations mandates that a metering strategy must be prepared for new buildings, but more often than not, designers are not considering how end users will use the data collected by meters.

In most cases, the main energy meters can report total energy usage, but in some buildings there are insufficient meters to provide a complete picture of where energy is being used. New developments in smart metering mean we can get detailed usage profiles down to individual equipment levels. But even if buildings have smart meters, if users don’t understand how to read them, it’s as useless as having no meters at all.

It may seem simple, but collecting, analysing and understanding data from meters is something that takes careful consideration and time. Having a metering strategy in place, and knowing in advance how you’re going to use the data, is essential to getting the most from your data, but is something that is often overlooked.

Post Occupancy Evaluation (POE)
Another key element to sustainable energy management is POE, which enables an analysis of a building’s expected vs actual performance. If the correct meters are installed, you can use POE to break down a building’s energy usage into categories (small power lighting, lifts, heating, etc.) and then compare it to design data to understand if the building is using more or less energy than you anticipated. Even when buildings are designed with the best energy efficiency intentions, POE is a ‘must have’ as we make assumptions throughout our design and without a POE you’ll never know if the building is actually doing what you want it to do.

For example, if your lights are using twice as much energy as you expected, you can delve deeper into the operating profile of the equipment, to answer questions like:

  • Could we start switching lights off earlier or intermittently when they’re not in use?
  • Can we fine tune our lighting system to use less power?
  • Is the lighting doing more than it needs to for the building users?
  • Are the lights running as well as they should be running?

Corrective actions like the above can be taken to address any big gaps found in POE, but ultimately your design assumptions have to be accurate. We need reliable benchmark data and robust design stage estimates of energy usage to compare our POE data back to. Documents such as the Chartered Institution of Building Service Engineers (CIBSE)’s TM54 document aims to help designers make better estimates of energy usage at design stage, but to do this accurately we need robust benchmark data to compare it to.

Sharing data for good energy management
Energy management will remain high on the UK’s priority list for years to come, and many companies are starting to recognise that it’s important to carry out POE to make sure their buildings aren’t consuming more energy than they expected them to. However, there are still far too few companies who understand the benefit of sharing this POE data with the wider industry.

Currently, the sharing of building energy data is voluntary, although Government ‘soft landings’ will require that all government departments undertake POE on their buildings. EPC ratings for new buildings being sold or rented and Display Energy Certificates (DEC) for government buildings visited by the public are the only mandatory mechanisms we have to share comparative data. Unfortunately, this data does not reflect actual building operation as it is design data based on a set of assumptions about the building’s operation. It also excludes small power and equipment usage.

If we shared all of the data we collect in POE, it could be used not only to create more intelligent designs, but to inform policy and help us set informed and achievable standards. Without good data, our policy and standards may go in the wrong direction. Transparency and sharing information is key to making sure this doesn’t happen.

The UK’s design community needs one source of data that gives them the full picture of how much energy buildings use in practice. To do this, the industry can no longer be reluctant to share their data, and must sign up to the idea that sharing anonymised information is a good thing. Ultimately, our commitment to more energy efficient buildings needs to trump commercial sensitivities.

We need to work together to ensure we have the data we need to meet our energy usage aspirations.

Jessica Elliott is an associate mechanical engineer at Atkins. Atkins is one of the world’s most respected design, engineering and project management consultancies. It builds long-term trusted partnerships to create a world where lives are enriched through the implementation of its ideas.