LED Lighting in an Edwardian House

LED lighting is becoming a mature technology.  It is an affordable technology and in the right environment can reduce energy consumption and costs.  It has taken some time and some product evolution to make them work in our Edwardian semi, but progress is being made.

When the house was built in 1901 it was lit by gas, an extensive network of pipes can be found beneath the floorboards and in the walls.  The living room was lit by a gas chandelier and a mantle over the fireplace.  This scheme was short lived and electric lighting appears to have been installed around 1910.  Typically, each room had a single ceiling fitting and I guess there were some standard and table lamps for sewing, reading and writing.  Later owners added some wall lamps.  When we acquired the house in the early 1990s, the living room was illuminated with approximately 1,500 lumens supplied by one 100 and two 40 watt incandescent lamps.

In 2006 the household electricity consumption with incandescent lights was around 25 kwh/day, sometime around the end of the year I spent approximately £100 and replaced the incandescent bulbs with CFLs and the consumption quickly dropped to 10 kwh/day.  The early CFLs fell a little short of expectation, the life, whilst longer than that of an incandescent bulb was less than the 8,000 hours stated on the packet and there was a short delay before the bulb emitted enough light to read by.  After a couple of years, the technology matured, failures were rare and the price started to fall.  The information on the packaging suggests that the luminous efficiency of CFLs is about 50-60 lumens/watt which is a significant improvement on incandescents which are around 10 lumens/watt.  The great thing about CFLs is that they were a straight swap for the incandescents.

Sometime in 2012(?) I purchased a couple of LED lamps for a cost of around £25.  Whilst these entertained me, they did not win the hearts and minds of my family and have been banished to my workroom.  There were two issues, the first was that the light emitting element was a surface not a quasi sphere like the CFL, thus the diffuse light from the ceiling was lost making the room appear dark.  Secondly, the individual LED elements were small making them distractingly bright.  This fine example of  rustic Bauhaus is still my desk light:

The problem of glare has been partly solved by changing light shades to ones which provide an element of diffusion.  However, there is a limit to the amount of modification that is economically possible, replacing light fittings and adding new ones is expensive, not least because of the redecoration that is needed afterwards.

The attraction of LED lighting is the high luminous efficiency, current LED lamps seem to be capable of 80 – 100 lumens/watt.  Thus whilst we have been using 40 watts to light a room with CFLs, this might drop to 20 watts or less with LED’s.  This is not going to have the effect that the migration to CFLs did, in part, because the process is taking place slowly, but out household energy consumption is drifting downwards.

For a couple of years, “360” degree bulbs which can substitute CFLs have been available.  The first ones I found were small with an output of around 300 lumens for 3 – 4 watts, a couple of these have replaced 10 watt CFLs in passages where lights are left on all night and we have probably achieved payback in about 12 months.

This lamp in the picture might be the breakthrough which displaces CFLs in our house given time.  This one appears to draw about 4 watts and produce about 400 lumens, the elements are larger than previous versions so glare is not such a problem and it fits in existing light fittings.  My guess is that larger versions of this will become available as the technology evolves.


About SolarBucket

I trained as a mechanical engineer in the 1970's and then spent most of the following 25 years doing sums and software for Oil and Gas Exploration. Current interests are the study of wind and solar resources.
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