Good lighting design is a balancing act

Planning a lighting installation in a commercial building is a complex task and although for many the primary concern is energy efficiency you must also ensure that the correct type of lighting is specified for each different area of the building. Stewart Langdown of Wila lighting explains why the specification process must therefore take into account visual comfort, ambience, direction of light and glare in order to achieve the best results.

No evolution of any lamp has been as dynamic as that of the LED and over the last few years its popularity in commercial applications has grown tenfold as a result of its energy efficiency characteristics and its ability to provide a quicker return on investment.

But with every success story comes a word of caution and inevitably this comes as a result of experience, because while LEDs are an exceptional solution for the commercial environment, the use of the latest technology should not be at the expense of a good lighting design. Many people have gone down the route of replacing all of their office lighting with LEDs but because the installation hasn’t been designed properly the resultant installation does not achieve the desired results.

So while it may be true that many of the best designers sometimes disregard the basic principles of design there is usually a reason which is rooted in the need for an artistic rather than practical approach. In a commercial building light needs to be practical and therefore we need to stick to the general rules of lighting design in order to achieve a well-lit space which meets the needs of the occupants while being as energy efficient as possible.

Good design

One of the first things to note is that practical does not necessarily have to mean boring and therefore sticking to good design principals can still give you a lighting installation with a wow factor – in fact I can name hundreds of different buildings which stand out for their ingenious lighting design but still provide a comfortable working environment.

In the same way many buildings with exceptional lighting can still boast energy efficiency credentials and so the key to good design is in finding the most appropriate solution for the building rather than simply installing a random mix of the latest energy efficient or ‘trendy’ products.

Visual function, comfort and ambience are perhaps the key considerations and are dealt with in the European standard EN 12464-1. It sets out the requirements for lighting design in the workplace but deliberately allows scope for intelligent solutions and innovative techniques. What this means is that designers can still get that all important ‘wow’ factor – but within the parameters of the essential elements of lighting which are required for everyday visual tasks.

So for example it takes into account the fact that light from luminaires can be reflected on PC screens, laptops and other surfaces causing premature fatigue, eye strain and general ill health – all of which can easily be avoided through the appropriate arrangement of luminaires.

By attributing the basic principles of good lighting design, the space which is being illuminated and the layout of the luminaires is all taken into account enabling the designer to assess the level of glare which is produced from different perspectives in a room or office space. By doing this it is possible to reduce the impact of glare on workstations and provide a well-lit space which has a positive impact on the health and wellbeing of the occupants.

New technology

The issue of new technology is another area of concern for lighting installations as the growing popularity of LEDs has brought with it a whole new problem – that of colour consistency where there is a combination of a large number of LEDs.

As with any other light source, the colour temperature of an LED will dictate whether it emits a warm or cooler light and the higher the colour temperature the cooler the resultant light effect will be. However, the problem here is that not all whites are the same and as a result a batch of warm white can vary from 3500K to 4000K, and those in a batch of cool white could range from 4000K to 6500K.

I don’t need to tell you that this is a problem because nobody wants to see a wide variety of different whites in one space. The consistency of the colour is therefore of vital importance to achieving the desired results. Due to the production process, LED chips demonstrate differing features with respect to chromaticity coordinates and luminosity class and therefore in order to limit this dispersion, a selection and classification of the LED chips is carried out.

This process, known as binning, ensures that white LEDs with the same colour rendition properties are selected and placed into batches and as a result a batch of LEDs from the same bin have the same colour appearance. What this means for the lighting design is that consistency can be guaranteed across the installation and luminaires which are arranged adjacent to each other will not exhibit any perceptible difference in colour.

But once again I must inject a note of caution. The increase in popularity has led to a large influx of new LED manufacturers – and not all of them are quite as cautious when it comes to colour consistency. As far as LEDs are concerned you get what you pay for and sadly there are still many installations which are testament to the fact that there is a vast difference between cheap and cost effective when it comes to consistency.

Take a serious view

In this current age of austerity we are all looking for a way to make savings and lighting is certainly an area where we can achieve efficiencies – but we need to ensure that these savings are made in the right place.

There is well documented evidence that people are more productive in a well-lit environment and it is important that the specification process takes this into account. So before you select the latest technology as a way to make savings think very seriously about the design of the lighting installation because it is possible to achieve that all important ‘wow’ factor in an environment which meets the needs of the occupants – but only if it is specified correctly at the outset.

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