A date in the diary

A Building Energy Management System (BEMS) must be given attention throughout the year in order to maximise its potential. Daniel Taylor, National Operations Leader at Trend Control Systems, explains why a 24/7/365 approach to BEMS optimisation can ensure optimum comfort conditions and help improve energy savings.

The UK’s weather is anything but boring – in early March we had sub-zero temperatures and plenty of snow thanks to the ‘Beast from the East’, yet by late May some parts of the country experienced 30°C heat and started the longest heatwave since 1976. Such dramatic fluctuations mean that a BEMS must be agile, flexible and responsive, as extreme temperatures can be particularly problematic for a wide variety of reasons that need to be addressed throughout the year.

Under the weather

We’ve all experienced the effects of poor comfort conditions and the negative effect they can have on productivity and our sense of wellbeing. While energy management is important in buildings, the focus should also be on the people that occupy them and BEMS technology can be used to improve their engagement.

Modern airtight buildings can suffer from poor quality air. Ensuring they operate in ways that ensure optimum comfort conditions as soon as heating, ventilation and air conditioning (HVAC) is switched on, will be time well spent.

A stuffy and polluted environment makes it difficult to concentrate, and hard to remain alert and focused. Studies have also backed up the theory that low air quality can reduce productivity through symptoms such as headaches, dizziness, nausea, aches and pains, shortness of breath or chest tightness, eye and throat irritation, blocked or running nose, and skin irritation. It can also exacerbate seasonal affective disorder (SAD), stress, depression, backache and other cardiovascular ailments.

It should also be remembered that increased productivity offers a significant return on investment (ROI). This was highlighted by research from the UK Green Building Council (UKGBC), which found that temperature can negatively affect productivity by 2 percent for each 1°C above the ideal temperature and 4.7 percent for each 1°C below. Furthermore, good air quality can improve productivity by up to 11 percent – something that can have a massive impact not just the bottom line but also on maintaining a happy and engaged workforce.

Feeling good

This is where a BEMS can prove invaluable in terms of providing fresh, clean air that is not only comfortable to work in, but healthier too.

A BEMS should automatically control to pre-defined setpoints – constantly tracking changes in both external and internal temperatures and light quality, and adjusting the HVAC and lighting before any occupants even notice. Furthermore, the data it produces allow building and facilities managers to better analyse, understand, reconfigure and improve a building’s internal environment by having information presented in an organised and informative way.

It is also worth noting that optimum temperature conditions don’t just apply to people – depending on the building’s use, they can affect paintings, artwork, medications or even animals. Uncontrolled temperatures can also lead to equipment malfunction – IT is the lifeblood of most modern organisations, so keeping the operating temperatures of equipment within manufacturers’ guidelines is vital to maintain business continuity. Therefore, it is advisable to configure alarms to be activated when conditions fall outside of any predetermined critical point.

Time for action

A BEMS is ideal for carrying out energy monitoring, as it will often possess unused capacity, have an existing service arrangement and generally be better supported than a stand alone energy logging application. The equipment itself may also be more robust and modular and, in the case of a modern BEMS, have the capability to carry out virtual energy measurements from plant run times. So, it makes sense to determine whether changing monitoring requirements can be met by an existing BEMS system and, if not, investigate whether some simple upgrades or reprogramming is required.

As employees begin their summer holidays, most companies experience a degree of downtime. This is an ideal situation for a programme of BEMS optimisation, for instance using a plant on a demand-led basis at this time of year is the ideal strategy for reducing wear and tear, and making use of resources such as free cooling. With a demand-led strategy, when specific areas need different levels of HVAC, this can be achieved using as little energy as possible.

For example, many buildings have a central air handling unit (AHU) to supply air at a constant temperature to fan coil units (FCU) that carry out the local temperature control. Chillers are activated whenever the AHU return air temperature is above a setpoint, resulting in all the cooling being handled by the chillers, which are energy intensive and costly. Furthermore, whenever outside air is below the required supply temperature, an AHU has to heat it up but, sometimes, due to internal heat gains, this air then has to be mechanically cooled – wasting both gas on heating and electricity on cooling. Finally, ineffective use of an optimiser results in an increase in the air conditioning time zones during hot weather, so that during warmer months plant is set permanently to run for longer hours than normal.

Strategic direction

In this situation the answer is to initiate a strategy where, if cooling demand is between 0-50 percent, fresh air dampers modulate to meet this requirement by using fresh air only, without the need to initiate chillers. If this free cooling is not sufficient and the cooling demand continues to rise above 50 per cent, only then can chillers be activated. To make this more effective, the supply air setpoint can also be reduced to make maximum use of the fresh air cooling effect.

This type of strategy makes good economic sense too, as the recently introduced DCP 228 regulation relating to Distribution Use of System (DUoS) charges has affected how electricity charges are calculated. This has led to a reduction of charges in red zones while amber and green are making up the difference. This means that most business customers will see a rise in costs, so using free cooling whenever possible throughout the day will lower demand on the National Grid and save money for the site.

Cold comfort

During the colder months, before things get too chilly and energy demand increases, it’s a good idea to implement an optimum start/stop (OSS) strategy.

OSS offers 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. Conversely, OSS can work well in the summer months to ensure that a building is cool enough during periods of occupancy.

Covering all bases

While the ability of a BEMS to reduce energy use and save money is without question, organisations should remember that an improved working environment that has the health, happiness and wellbeing of occupants at its core offers a significant ROI through improved productivity, less absence as a result of illness and highly motivated personnel. In addition to being at the forefront of the drive towards energy efficiency, the advantages of enhanced comfort conditions through the use of a BEMS are considerable and complement the energy savings that can be achieved.

For further information please call Trend Marketing on 01403 211888 or email marketing@trendcontrols.com.