Page 32 - Historic Churches 2013

32 BCD Special Report on Historic Churches 20th annual edition CATHEDRALC O M M U N I C A T I O N S
ADVANCES IN
LED LIGHTING
Bruce Kirk
Before we consider how church lighting
has been advanced by LED technology,
it is worth considering the development
of earlier light sources. Many of our historic
places of worship pre-date almost all forms of
‘artificial’ lighting except perhaps the candle,
and the buildings and the means by which
they were lit have developed in tandem.
Our earliest churches and cathedrals
began as dark, mysterious and solitary spaces
lit only by daylight through narrow windows.
Artificial light was provided by candles and
flaming torches, while great fires were used
as sources of both light and heat. As building
methods developed and larger window
openings became easier to build, architects
learned more about how to use natural light to
illuminate an interior, relying less on flame and
extending the hours in which these magnificent
buildings could be purposefully occupied.
In the 17th century Sir Christopher Wren
significantly changed the way daylight was used.
When building St Paul’s Cathedral he seized
almost every opportunity to harvest natural
light to enrich the interior. The technology of
artificial lighting began to develop about the
same time, and the 17th and 18th centuries
saw the increasing use of natural fuels for
lighting including whale, nut and olive oils.
Although gas lighting had developed in China
several centuries earlier, it was not until 1792
that William Murdoch used coal gas to light
his house in Cornwall. Gas lighting continued
to develop throughout the 19th century and
became widely used, particularly for street
lighting and then increasingly in commercial
and domestic properties. Gas lighting was
introduced in churches during this period,
giving rise to elaborate and extravagant gasolier
designs. Figure 1, from the parish archives at
St Mary’s Church in Painswick, Gloucestershire,
shows a set of three Arts and Crafts gasolier
designs by Messrs Hart, Son, Peard & Co in
1879. Number 71 was the chosen design.
Davy invented the first electric light bulb
in 1809 but it was not until some 80 years
later, in the early 20th century, that they came
into more common use when both Swan and
Edison developed the filament lamp. The early
1900s saw the invention of the mercury vapour
and sodium lamps, which by the 1930s had
become the norm for industrial and street
lighting applications. So the introduction
of electric light in the early 20th century by
architects and engineers was a revolutionary
intervention in our historic buildings.
When Coventry Cathedral was constructed
in the late 1950s, Basil Spence was one of
the first architects to be able to design a
new cathedral with electric light in mind.
By today’s standards the development of
electric lighting technology was then only
in its infancy and the tools available were
relatively rudimentary. Coventry underwent
a major relighting project only a few years
ago, and although this was before the onset of
credible forms of LED lighting, the principles
of luminaire positioning and their uses remain
very much as Sir Basil originally intended.
Since the 1950s, lighting technology has
developed enormously. Modern light sources
are more efficient, longer-lasting and easier
to control by electronic or other dimming
methods. In the 1960s the first lighting track
systems were invented. These became even
more important in the 1980s when low voltage
lighting came into more common use. Around
20 years ago, lighting professionals were
excited by the improvements in the colour
rendering characteristics of both fluorescent
and metal halide light sources and the ability
to dim fluorescent lighting with modern
electronic control systems. These technologies,
combined with high quality low voltage lighting,
gave designers an excellent palette of tools
to work with and lighting design began to
blossom into a ‘profession’ in its own right.
However, it was back in 1952 in Cleveland,
Ohio when a 33-year-old General Electric
scientist called Dr Nick Holonyak Jr invented
the first practical visible-spectrum light-
emitting diode (LED). Diodes (small electronic
components containing a semiconductor)
had been known to turn electrical energy into
light extremely efficiently, with far less heat
Figure 1 Set of three Arts and Crafts gasolier designs offered by Messrs Hart, Son, Peard & Co in 1879 for
St Mary’s Church in Painswick, Gloucestershire
Figure 2 New electroliers at St Mary’s, Painswick
loosely based on the design of the earlier gasoliers and
using LED lamps in frosted glass storm shades