How to optimise a Building Energy Management System (BEMS)

Andrew Paddock, Sales Director at Trend Control Systems guides you through the process of optimising a Building Energy Management System (BEMS) in seasonally related bite-sized chunks. With the summer over and temperatures beginning to drop, in this blog he looks at what to do over the autumn months.

With a fabulous summer and the added bonus of one of the warmest Septembers on record now behind us, the morning chill and darker evenings suggest that autumn has now set in. It’s also the time when heating systems are reactivated after the summer and therefore preparing BEMS for the colder days ahead is vital to ensure that plant operates as it should and comfort conditions are maintained.

Those of you that have read my previous blogs looking at winter, spring and summer respectively, will hopefully concur with my view that carrying out changes in a series of smaller tasks makes the entire process more manageable. So with no further ado, let’s look at what to address during the months of October, November and December.

With the demand for heating systems now evident, a BEMS that is set up to use optimum start/stop (OSS) can offer an efficient and automatic way of maintaining space temperatures while controlling the amount of energy used to achieve them. By using a rolling profile of when a setpoint was achieved the previous day and by monitoring outside temperatures, an OSS calculates a start time for the heating system, so that a building is warmed up when the occupation period begins.

So why should you make this a ‘must do’ activity for October? Put simply, with no OSS set up, or even one that is poorly configured, a building will take time to warm up to a specific setpoint – which depending on plant efficiency could take hours rather than minutes! Maximum warm-up times can also be set to ensure that if the buildings take a long time to warm up the heating is not being asked to run on a 24/7 basis by the OSS.

November marks the start if the triad period and this should be the focus of attention for this month. Triad demand is measured as the average demand on the system over three half hours between November and February. These three half hours comprise the times highest system demand.

Each electricity supplier is charged a fee for the peak load it imposed on the National Grid during those three half hours of the previous winter and to recoup this financial outlay it imposes an incentive on users to minimise consumption at peak times – usually between 16:30 and 18:30. This means that a BEMS should be used to reduce demand between these times without adversely affecting a site’s environmental conditions.

In my last blog I talked about the benefits of having a BEMS ‘bureau’, which allows a building to be controlled remotely, not just to make time and setpoint changes, but also to respond to plant alarms, carry out remote diagnostics, temporary fixes, liaise with maintenance contractors and look at energy problems.

It can also be used to respond to triad warnings by changing the time settings of the heating and ventilation systems within a site. These changes incorporate an individual time zone adjustment for each area of a building, reducing the site’s demand during the three triad half-hours. Therefore, it pays to assess whether there is any proactive demand management within your site’s control strategy and, if not, do something about it.

As we approach the deep midwinter energy demand and use will reach its peak and it is during this period that a BEMS will really come into its own. However, my final recommendation for the month of December relates to how a BEMS can be used to not only provide information about how effectively a building is controlled, but also offer intelligence about the business activity that goes on inside.

The run up to Christmas is a key time for retail businesses and they will be using all available methods to maximise the revenue from shoppers. A modern BEMS contains considerable data gathering and computational capability and a range of software exists for retrieving, storing, displaying and analysing data that is logged within the BEMS.

To illustrate my point, I was recently involved on a project for a national retail chain that was looking for the most cost effective way of obtaining information about store footfall. We decided to install a light beam that is broken every time a shopper enters the premises, with the information logged in the BEMS alongside energy use data. What’s more, a web based reporting front end was implemented to allow authorised personnel with Internet provision to access the information.

I hope that after reading this short series of blogs you will now feel that year round BEMS optimisation is much easier than you first imagined. A BEMS should always be considered a work in progress and focusing on individual monthly projects can make the task less onerous, while also maximising any energy and cost saving opportunities provided by this technology.


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