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Blind Faith

Updated: Jun 29, 2020

Lighting controls may help save energy but implementing an automated lighting solution that drastically lowers costs and drives improvements in wellbeing often requires a more holistic approach. Karl Walker of Beckhoff and Harry Doling of Umbra Shading look at why automated blinds could be the missing piece of the building automation jigsaw.

Speak to anyone in the industry about building automation and chances are the conversation will centre around either heating, cooling, ventilation, lighting or a combination of the four. There are, however, other aspects of building automation that are equally effective in terms of enhancing comfort levels for building occupants and reducing energy consumption. Automated blind control is one such function.

It’s well documented that lighting alone accounts for the largest electricity consumption percentage in a commercial building – sitting at around 44 per cent – but effectively controlling the lighting in combination with shading can eliminate 60 per cent or more of those lighting energy costs. On top of this, controllable shades can reduce building heat loss by anywhere between 3-29 per cent dependent on the type of shades.

Unfortunately, despite being included in the BS EN15232 building controls standard which measures the overall impact a building automation system has on energy usage, automated blinds are often omitted altogether or ignored in favour of a cheaper option. Some building designers favour fixed louvre shading on the building exterior but, as the name suggests, the louvres cannot be moved and are therefore rendered redundant for the majority of the working day, unless the sun happens to be sitting in the perfect spot for a few minutes.

In an era where energy performance is becoming more and more important to commercial building owners and operators – as well as being front-and-centre of the public’s mind - every energy saving system matters. In order to achieve Class A status as classified in BS EN15232 – the pinnacle of an effective Building Energy Management System (BEMS) – any automated shading or blind controls installed must be integrated with lighting and HVAC functions. Once fully integrated, the blinds can be retracted to make the most of natural daylight when conditions are such that artificial light isn’t required. Similarly, if the temperature outside begins to rise and heat generated by the sun can be used to warm the interior of the building, shading can be adjusted and heating systems turned down in order to avoid wasting energy. Thermal surveys of a building will show that windows ‘leak’ the most heat – therefore, if the building is unoccupied during the hours of darkness it makes perfect sense to have all of the blinds closed so that heat generated during the day is retained as well as it can be within the walls of the building.

Blinds that are integrated with lighting and HVAC systems not only offer the potential to save energy, they can also boast direct links to increased occupant satisfaction and wellbeing. Manual or motorised blinds are clearly better than nothing at all but both require manual input and are regularly forgotten about or ignored – a situation that can lead to artificial lighting coming on when it isn’t needed.

The WELL Building Standard references shading and the different levels available, stating that all windows larger than 0.55m2 should have shading devices that automatically engage when light sensors indicate that sunlight could contribute to glare at workstations and other seating areas. Similarly, both BREEAM and the SKA assessment model stipulate that daylight glare control systems should be designed to maximise daylight levels under all conditions – something that can only be achieved properly by incorporating shading into the building automation system.

Intelligent blinds can make use of a sun tracking algorithm which takes into account the orientation of the building, the position of every window and even the placement of neighbouring buildings that have the potential to cast shadows. Whether the sun is out or hidden by clouds, its position can be accurately plotted and when used in combination with sensors, the conditions are constantly monitored so that building occupants can be sure of a reliable, dynamic shading solution and minimal glare. Essentially, the daylight detectors will ensure that unnecessary lighting is switched off and blinds will open automatically and, as an added control, temperature sensors will ensure that if solar gain is causing the air conditioning to switch on then the blinds will close again and switch the lights back on.

We don’t always see it as often as we’d like but the sun is omnipresent and, though it may throw up certain challenges in the form of unwanted glare and occasional overheating, it represents an immense source of free heat and light – something that building designers and operators should be considering from the outset.

So, why do we rarely see fully-automated shading control in our buildings? Unfortunately, the blinds themselves are usually included as part of “fixtures and fittings”, along with items such as coat hooks, bookshelves and notice boards, with cabling infrastructure (power and network connections to each window) rarely considered as part of the consultant’s remit. In fact, window shading is often a post-construction fitout item, by which time it’s too late to easily retro-fit an automated system.

Automated shades alone can dramatically improve working conditions, but by integrating them into a building automation system alongside the more traditional heating, cooling and lighting elements, the last piece of the automation puzzle can be put firmly in place, giving us the complete picture when it comes to energy saving and occupant satisfaction.

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