Energy-saving number crunching
Matt Pickard of Trend Controls answers readers’ questions about capturing data from a building energy management system (BEMS) and how to use it to make substantial cost and energy savings.
I’m looking at ways to reduce my building’s carbon emissions and save money. Why should I go to the trouble of collecting energy-usage data via my BEMS?
An investigation carried out by The Carbon Trust in 2010 analysed large private- and public-sector organisations, and found significant potential for cost effective emissions reductions through energy-efficiency measures.
In the non-domestic building sector the investigation suggested that reductions of 70 to 75% could be made by 2050 at no net cost by using technology that exists today. While the exact figure quoted is something of a moot point, there’s no doubt that technologies exist that can help achieve enormous savings.
As the saying goes, ‘If you can't measure it you can't manage it.’ Given that up to 84% of a building’s energy usage can be under the control of a BEMS, it is without doubt the most effective way to gain a true understanding of where savings can be made.
Using a BEMS allows clear targets and objectives to be set. Intelligent technology can assist with on-going analysis of how energy is being consumed by different building services and suggest remedial action where necessary.
I’m concerned about the amount of data that I will need to obtain from my BEMS in order to make informed decisions. What are the most important things I need to consider?
Any data collected is meaningless unless they is measured against energy consumption and the root causes of it. As part of the BEMS set-up, process utility tariffs, CO2 ratings and cost and consumption targets should all be configured — while normalisation criteria also need to be specified to allow comparisons between different areas within a building or to benchmark consumption against a set of pre-defined profiles.
The number-one priority is to have a set of clearly identified and defined objectives that outline exactly what it is you are looking to achieve. Whether it’s a 10% year-on-year reduction or a 5% lower electricity bill, the principle is the same.
Setting a realistic goal necessitates a thorough understanding of how you are already managing energy in your building. This will necessitate data about current consumption patterns and knowing what is using it and in what quantities.
A BEMS can only collect accurate information if it is fully optimised. This may involve calling in an expert integrator to adjust setpoints and check that items such as boilers, chillers, air conditioning and pumps are working correctly. Furthermore, a full audit could be carried out to ascertain where energy could be saved and configure reduction targets.
I’ve carried out a full investigation into my building’s energy usage. How do I make the data I have collected work for me?
Almost every aspect of a building-services infrastructure can be reconfigured to save energy. However, some areas may provide higher gains than others. Therefore, a strategic approach to using the data you have at your disposal will help identify the quick wins.
Data must be meaningful — in other words it must be understood by those reviewing it and presented in a way that makes prioritising actions as straightforward as possible. Ultimately, this is what makes data from a BEMS infinitely more useful than the information found on a utility bill.
Configuring a BEMS to account for profiles, rules and exceptions will facilitate a better understanding of how a building works and differentiate correct energy use from what may appear to be an anomaly — saving valuable time and effort.
For example, a spike in energy use at 5.00 a.m. when a building is empty may seem like a cause for concern. However, if it transpires that this spike was due to the plant operating to protect the fabric of the building from frost conditions, then it would not require further investigation.
A state-of-the-art BEMS uses ‘rules’ to explain why energy-related events occur, like in the example above. However, in the event of genuine overuse an alert will be created that as well as being flagged up on the display panel will also be sent to designated individuals via an email or text message.
Having gone through this process, how do I make capturing data work for me in the long-term?
Acquiring, managing and acting upon BEMS-related data should be considered a long-term objective.
Meaningful data from a BEMS will not only facilitate accurate and effective day-to-day energy management, it will also enable the development of long-term strategies that can drill down into all aspects of a building. Year-on-year profiling will identify where further ongoing efficiencies can be made, such as reducing heating and cooling loads and optimising plant operation.
An energy-reduction programme requires an holistic approach, as all building services are linked and making savings in one area will have a knock-on effect in another. Therefore, a constant process of assessment and adjustment must be undertaken across a building’s entire infrastructure.
Matt Pickard is a duty team leader with Trend Control Systems.