The lighting world usually displays very little sympathy for its history. Commercially driven, there’s little advantage to hankering after old technology; after all, we’ve come such a long way in the last hundred years. But while we insist on looking to the future, there are other people who care passionately about our urban heritage and these are the folks who have been grimly holding onto gas lighting in some of our major cities. But the days of gaslight could be numbered.
To get an idea of how widespread gas lighting installations still are:
- Berlin has over 35,000 gas lights, the largest network of gas lighting in the world
- Boston, Massachusetts, has more than 2800 gaslights, chiefly in the city's historic districts such as Beacon Hill
- London still has around 1500 gaslights, mainly in Westminster where they light the Royal Parks, the outside of Buckingham Palace and many of the lanes in Covent Garden
- Cincinatti has retained over 1000 gaslights in historic districts
- New Orleans has been able to hold onto some gas lighting in the French Quarter
Conservation groups lobby for these romantic hark-backs to the 19th century to be preserved. Although things are are not always what they seem, the Gaslamp Quarter of San Diego was named thus only in the 1980s to give it a faux-historic veneer. The actual gas lights came later.
In London, the gas mantles are hand-lit every evening by a team of British Gas engineers. In an unlikely volte-face by the Daily Mail, the newspaper described this inefficient, labour-intensive, task as ‘enchanting’ and 'the most magical job in Britain’. (Daily Mail: 24 November 2014)
There is, of course, a problem. Gas lighting is very inefficient both in terms of energy usage and maintenance. A recent exercise by Selux, in Berlin, demonstrates the extent of the issue.
The luminous performance for gas lighting is poor. Selux quotes figures suggesting an efficacy of less than two lm/W for the tested gas mantles, with power ratings up to 900W for a gas mantle array.
There is an LED future
As with so much else involving the introduction of LED into our lives, an alternative is now being suggested for replacing the gas mantle. LED retro-fit modules are being developed to re-create the appearance and effect of the gas mantle. A number of heritage lighting companies are looking at the possibility of using LED mantles that have almost the exact appearance of the traditional gas mantle.
Figures from Selux indicate how successful a transfer from gas mantle to equivalent LED mantle can be:
- An almost equivalent colour temperature of around 2800K
- An energy reduction of over 95 percent
- Improved light distribution, reducing upwards light emission
- Improved glare control by the addition of an anti-glare shield
- Reduced maintenance costs, removing the need for daily lighting and periodic mantle replacement
- Dimming control becomes an option, reducing energy usage still further
But before we get too excited
Let’s remember, LED mantles are intended to be an accurate replacement for the gas originals, and that means that their light output is negligible. The 900W array, described by Selux, delivers a paltry 1350lm, little more than a 100W tungsten lamp. Compare that with the modest performance of the 50W SON lamp, at +4000lm, and we see the gulf between the Victorians and ourselves.
In Westminster the gas lighting installations are either exempt from standards, such as in the Royal Parks, or the lanterns are supplemented with building-mounted floodlighting to achieve required illuminance levels.
Gas lighting installations are not intended to perform as a modern lighting installation. They are there to reflect our heritage and, however inefficient they may be, that cultural demand will remain for the foreseeable future. But that doesn’t mean that it’s the end of the story.
A more attractive outlook
Exchanging gas mantles for LED mantles may be a step too far for some die-hard traditionalists, but the development of the LED mantle could represent a new lease of life for the ‘mantle array’. In the same way that the LED has rejuvenated the filament lamp, it could be that the attractive appearance of the LED mantle could see more exterior schemes returning to its historic lighting roots.
By removing the nostalgic limitations on light output it is possible to create LED mantle arrays with higher outputs, offering a halfway house, perhaps, between the sentimental theatricality of Victorian street furniture and the demands of modern lighting performance.
There are many decorative and ornamental applications for this type of lighting; we can bridge the gap between Victorian lantern design and contemporary design, using the LED mantle array.
So the next time you’re walking along a city centre ‘gas-lit’ shopping mall, look again at those mantles. Could they be? Surely not!