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Controlling efficiency

Graeme Rees, vice president of the Building Controls Industry Association (BCIA), discusses the efficient management of buildings post-lockdown, and how a new Technical Guide can help ensure building controls perform to their maximum potential

Graeme Rees, vice president of the Building Controls Industry Association (BCIA)

The world is certainly a very different place today than it was just six months ago, but with people beginning to return to work we are all wondering what the new normal will look like as we learn to live in whatever a normal world becomes. 

As we need to learn to adapt so too do our buildings. Many have been left empty for some time and with government advice to continue working from home if you can, a good proportion of general office spaces will only be operating at a much reduced occupancy level and are likely to continue in this way for some time yet. 

CIBSE has issued guidance for building owners, occupiers and operators on procedures and practices to follow to ensure buildings are not only brought back online safely and efficiently but are operated slightly differently to ensure the safest environment for occupants. For example, adjustments to the control systems on ventilation plant to operate supply and extract ventilation at higher volume flow rates and to avoiding recirculation wherever possible. Also, extending operating hours to at least two hours before occupancy and two hours after should a 24- hour operation not be possible. 

Safety first 

Of course, at first glance these measures appear to contradict any energy saving routines one may have already deployed, indeed the situation today is without doubt a matter of safety first. 

However, with a well-appointed, up to date, control system, achieving adjustments of this nature are relatively simple to implement and may even be done remotely on the many premises that benefit from secure remote connectivity. 

The current crisis situation aside, the principles of automatic adjustment based upon demand has been at the heart of building control philosophies for years. Scaling a setpoint back or ramping a speed up based on a sensor measurement is exactly what building controls do. Doing just this to keep occupants comfortable is the goal, doing it in the most energy efficient way the ultimate prize. 

Comfort and efficiency are the two key words. Where comfort once meant ‘warm’, today we consider comfort to also encompass elements of the well-being of the building occupant. Keeping occupants at a comfortable temperature is a given, but we also consider the amount of fresh air, the humidity, light levels, (including artificial vs natural daylight) noise, smells and the new agenda topper... occupancy level. 

Where once owner occupiers were concerned about people density per square metre, it is now a case of space between people…..per square metre. Where once building control technology was used to guide an occupant to a free hot desk, this same technology can be used to guide occupants through less dense areas of a building, avoiding crowds to clear, and cleaned, work spaces. 

All of the above relies on the building control systems, the vast majority totally hidden from sight. 

Doing all of the above efficiently relies on the skills and experience of the control system design engineers. To achieve logical operation is one thing, to achieve that in a super-efficient way requires training, experience and the tools, software and equipment that deliver reliable and precise control of the mechanical and electrical systems within our buildings. 

Getting it right 

Comfort and efficiency is achievable whatever scale the building or budget, but not every building has the application for every system described, so where would you begin to understand what controls are actually needed? After all, our buildings account for over 40% of the global energy consumption with commercial premises more than half of that figure. Getting it right is clearly important from a cost perspective and importantly an environmental and sustainability perspective too. 

Moreover, getting it wrong.….the lack of or simply poorly implemented building controls have been seen to be accountable for w of the 10 reasons our buildings do not perform as efficiently as they were designed, with energy consumption and costs being as much as twice as that intended. 

The European directive BS EN 15232-1:2017 Energy Performance of Buildings: Impact of Building Automation, Controls and Building Management, gives control manufacturers and design engineers criteria and methodologies to achieve significant energy savings with well designed, commissioned and maintained control systems. 

The BCIA has published a helpful guide which makes sense of the European directive; called The Impact of Controls on the Energy Efficiency of Buildings. Making the subject very easy to digest, it helps the stakeholders of our buildings understand what is essential, what is possible and how to get the most efficient results. 

BACS EFFICIENCY

BS EN 15232-1:2017: Energy Performance of Buildings. Impact of Building Automation, Controls and Building Management, defines four levels of Building Automation & Control System (BACS) efficiency, from A to D: 

A: High energy performance BACS and Technical Building Management System (TBM ) 

B: Advanced BACS and TBM 

C: Standard BACS 

D: Non-energy efficient BACS 

To achieve the highest level of efficiency, the amount of energy delivered into a room or space should be based solely on the demand of the consumer(s), i.e. those occupying the space, effectively creating an accurate closed loop system. The energy demand signals could be derived by the interaction of the consumers themselves (e.g. adjustment of thermostats) or, more effectively – as defined within Class A system requirements - by automated measurement systems (e.g. occupancy sensors, temperature and CO2 measurement, light level sensors, etc.) which reduce or eliminate human interaction and, therefore, the potential to waste energy. 

BCIA member companies (manufacturers and systems integrators alike) use the BS EN 15232 Standard as a guiding light for control system design and operation. As an Association, the BCIA recommends that all modern building control systems should meet at least Class B performance rather than the baseline Class C which, it is felt, leaves too many gaps for inefficient energy performance.

23 September 2020

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