While there are many strands to carbon footprint reduction, commercial lighting is probably the most visible and emblematic of the struggle.

We all know that changing to low energy light bulbs can reduce energy consumption. But such lighting is still often left on when rooms are empty, dramatically illustrated by any night-time city skyline. Plus there is the residual heat generated which causes extra load on a facility’s air conditioning plant.

Constant Daylight
Simple timers can reduce some of this overhead, as can presence detection (which automatically switches lights on and off when someone enters/leaves a room) or absence detection (which requires manual light activation but automatically switch off when someone leaves.) But now there is a smarter and greener adjunct to these tools: Constant Daylight (also known as Daylight Harvesting.)

The idea behind Constant Daylight/Daylight Harvesting is simple: using a combination of presence/absence detectors, light level detection and intelligent software, a lighting controller adjusts the lighting of a room to complement current natural light, producing a comfortable, constant lighting load which is switched off when occupancy has ceased.

One product that includes Constant Daylight/Daylight Harvesting functions is the DLC1000 Light Control Module from Durable Technologies. This Light Control Module works in conjunction with multiple DLS1000 sensors to constantly monitor for absence and light levels, adjusting lighting for a comfortable working environment, eliminating it when no-one is in the room.

Using less power
So effective is Constant Daylight that in a recent installation, on a typically overcast British spring day, the DLC1000/DLS1000 combination kept the ambient light level in a classroom of 15 sq m at a steady 300 lux and used 60 per cent less power than conventional lighting. And in some cases, a bright, sunny day enables Constant Daylight to eliminate artificial light use altogether. Obviously Constant Daylight cannot be used at night, but presence/absence detection means that full lighting is only used when a room is occupied, changing your building to a low-carbon gap in the night skyline.

Durable Technologies designed the DLC1000 Light Control Module as a KNX device, it is certified to work with any of the thousands of other KNX building controls available from manufacturers world-wide, delivering the cost saving benefits of open standards at a time when budgets are tighter than ever.

That’s why Constant Daylight/Daylight Harvesting is a powerful and cost effective tool in your quest for ever greater carbon footprint reductions.

• Can you reduce energy consumption in order to meet current standards?
• How can you improve heating/cooling, ventilation and comfort, without increasing your energy consumption?
• How can you make best use of the existing structure, e.g. the thermal mass of your building?
• How can you make use of the higher ceiling heights?
• How do you retain the appearance of architecturally important buildings whilst improving energy and comfort?
• Can you make changes with occupants in place?  Critical in a commercial environment.
• And I could go on, but you get the picture…

So when one of our customers was tasked with the design and installation of a lighting control system into a prestigious London educational establishment, all these factors and more had to be taken into account.  The project involved the refurbishment of an old building, with one wing of the building split into offices and a large open plan space. The client required a maintenance free and expandable lighting control system, which could deliver a high level of reliability.  They had already tried other systems and they simply weren’t delivering what they were looking for, until the M&E Consultants recommended KNX as a solution that could meet the rigorous specification.

Absence/presence detection was required to control lighting levels, monitor light levels and to provide constant daylight levels during the academic day.  The reduction of energy consumption/energy costs was also a critical factor and the client stressed from the beginning how they needed to clearly demonstrate that the refurbishment was contributing to the reduction of their carbon footprint.  The M&E consultant specifically selected KNX as a sustainable reliable solution that could deliver flexibility and future-proof the building to accommodate any changes further down the line.

Throughout the building, standard MK switches were installed along with 1000 lighting controllers on a BUS, IP backbone.  Everything is DSI controlled for reliability and reduced maintenance.  All of the offices are fitted with presence detectors and MK switches, ensuring flexibility, but guaranteeing energy is not wasted when the room is vacated.  The switches control presence on entry to the rooms, while the sensors switch off lighting upon leaving.  Both presence and absence detectors control the large open plan area, so that lighting is only used when necessary.

The installation complies with Part L of the Building Regulations (Conservation of fuel and power) and fully complies with the Carbon Trust’s guidelines and selection criteria by clearly demonstrating the potential for substantial greenhouse gas emission savings.  It is estimated that the new lighting control system alone will deliver around a 50% reduction in total energy consumption.

The installation needed to be completed out of term time, so the ‘plug & play’ modularity of KNX products ensured that minimum time was required on site for the actual fit and the work was completed with minimum disruption. The client is delighted with the finished installation, and has already agreed to roll out the lighting control system across the entire building, the end result of which will be one of the largest KNX installations in the country.

Client Comment

Fast Installation, Functionality, Comfort for the occupiers, Economics/Energy Saving, Extended lamp life/cost savings, KNX delivered exactly what we were looking for in what was a tricky refurb project.