A Work in Progress – Lighting

This weblog post is inspired by Friday’s shopping trip to Jula and Clas Ohlson, two Swedish equivalents of a hardware chain store, in Steinkjer, about 30 km north-east of Cliff Cottage, Vangshylla. On this shopping trip, I ended up buying a number of LED lighting components, not for any specific purpose but for playful learning. There was one impulse purchase, five meters of string lights with sparkly effect!

This is the walkway on the entry level of Cliff Cottage with Trondheim Fjord in the distance. String lighting illuminates the driveway, with 480 LED lights. Two hundred and forty string lights have been temporarily placed along the walkway, to brighten up November, while bags of insulation patiently wait to be fitted into the floor of the attic.

Lighting the stairway

According to my timeline, sometime in 2020, the house will be have a new main stairway. I intend to make it myself, using solid oak. It is difficult to buy hardwood, especially in rural Trøndelag. My solution will be to buy solid oak kitchen counter material which comes 26 (H) x 600 (D) x  2 400 (L) mm ( or about 1″ x 24″ x 96″) , and to cut it into suitable pieces, four treads to a countertop. Materials will cost me about NOK 4 000 (USD 500). Getting someone to make a stairway would cost at least five times that price. Here is a link to what I am thinking about: https://www.biltema.no/bygg/oppbevaringshyller/hylleplate/eikebenkeplate-2000031432 Biltema can be translated as “car theme”, and is the same in Swedish and Norwegian. It is yet another Swedish chain, even more dominated by male customers, than the two chains previously mentioned.

Before, I start building a new stairway, I want to experiment with lighting. Yes, there will be lighting from above, but I am particularly interesting in lighting each tread, so that old people can distinguish the nosing, and avoid falling. On the two bottom-most treads, I intend to drill holes and fit 4mm (Christmas) lights into them, at about 50 mm intervals. On the next two treads (three and four from the bottom), I intend to fit 100 lm spotlights, one on each side of each tread. If I come across new ideas, I will try them out as well, trying to put the most controversial closest to the bottom.

A Work in Progress

I have no intentions of living in a “finished” house. While the timeline for major improvements stretches over four years from 2018-01-01 to 2021-12-31, the intention is to allow continuous improvement, and to have the house serve as a laboratory in three areas: 1) smart house (computer control using sensors, actuators and communications components), 2) energy reduction with an emphasis on solar thermal energy, 3) assistive technology, including adaptive and rehabilitative devices for the elderly, as well as the general population.

Lighting – The Theory

A lumen (symbol lm) is a measure of the total amount of light visible light emitted by a source in any particular direction.

Lux is a measure of illuminance, how much light there is on a given surface area. One Lux (lx)  equals one lumen per square meter.

Lighting Requirements

Here is a list of lighting requirements in lux for various household activiites. The list has been compiled without recording sources. There is considerable variation in what people need, and standard values will not suit everyone.

Activity Lux
Direct sunlight 32 000 – 100 000
Daylight 10 000 – 25 000
Full moon 1
Kitchen/ workshop ambient 100
Kitchen/ workshop task 500
Dining/ living area ambient 50
Reading/writing 400
General task 300
Bathroom ambient 50
Bathroom task 300
Laundry 300
Sewing 500
Garage/ carport 100
Detailed task 1 000

Ambient Room Lighting

1. What type of room is it? In this example, it will be assumed that the room is a kitchen.

2. Ambient lighting for a kitchen requires 100 lx.

3. What is the size of the room? For illustrative purposes, assume it is 4 000  x 3 000 mm (4 by 3 meters). This gives an area of 12 square meters.

4. To find the number of lumens, multiply the lux requirement from step 2 by the area from step 3: 100 lx/m² x 12 m² = 1 200 lm.

Clas Ohlson has a 450 mm diameter ceiling light that provides 1 500 lm that would be suitable: https://www.clasohlson.com/no/DOT,-dimbar-tak–og-vegglampe,-45-cm/36-7305-2

Dot, a dimable 450 mm ceiling light to provide sufficient ambient lighting in a kitchen.
Model 36-7503-2
Energy class A
Bulb type LED
Power 24 W
IP class IP54
Dimable Yes
Lumens 1500 lm
Colour temperature 2700 K
Colour rendering index (Ra) 80
Lighting time 1.5 s
Temperature range – 20 to +40 °C
Number of lighting cycles 15 000
Lifetime 30 000 h
Replacable light source No

Task Lighting

1. Where is the task lighting? In this example, the focus will be on a kitchen counter top – the same one that the stairs were made out of, but this time used more conventionally.

2. Task lighting for a kitchen requires 500 lx.

3. What is the area where the task is taking place? The countertop measures 600 mm x 2 400 mm = 1.44 m², this could be rounded up to 1.5 m².

4. To find the number of lumens, multiply the lux requirement from step 2 by the area from step 3: 500 lx/m² x 1.5 m² = 750 lm.

I had hoped to find something equivalent at Jula, but found this set of downlights at Clas Ohlson: https://www.clasohlson.com/no/LED%20downlights/Pr365874000

As the specifications indicate, 4 downlights would be required to meet the task lighting needs of the countertop work area.

Downlights in a kitchen, but not quite how I would use them.
Transformer, able to attach up to six downlights.

 

Model 36-5874
Energy class A+
Bulb type LED
Power 3.3 W
IP class IP20
Dimable No
Lumens 190 lm
Colour temperature 3 000 K
Colour rendering index (Ra) 80
Lighting time 0.5 s
Temperature range – 20 to +40 °C
Number of lighting cycles 100 000
Lifetime unspecified
Replacable light source No
Diameter: hole/ lamp 60/ 65 mm
Depth 15 mm

 

Deeds: Lighting

1280px-Underhill,_Kells_Lane
The first house in the world to use electric lighting and the first to use hydroelectric power. The residence of Joseph Swan, Underhill, Kells Lane, Low Fell, Gateshead, England. (photo: C. Baldwin, 2012)

Incandescent lighting

Historians Robert Friedel and Paul Israel list 22 inventors of incandescent lamps prior to Joseph Swan (1828-1914) and Thomas Edison (1847-1931). Friedel, Robert, and Paul Israel. 1986. Edison’s electric light: biography of an invention. New Brunswick, New Jersey: Rutgers University Press. pages 115–117.

While Swam may have placed the first incandescent lamp into a house, Edison’s invention was better. It used an effective incandescent material, a higher vacuum, and a higher resistance that made power distribution from a centralized source economically viable.

Historian Thomas Hughes is less concerned about the lamp, than Edison’s integrated electric lighting system. The lamp was only one component, that combined with the Edison Jumbo generator, and the Edison main and feeder distribution system. See: Hughes, Thomas P. (1977). “Edison’s method”. In Pickett, W. B. Technology at the Turning Point. San Francisco: San Francisco Press. pp. 5–22

Regardless of who is credited with its invention, the implementation of an incandescent electrical lighting system made a major contribution to improving society ever since 1880. Alas, after almost 140 years, LED technology is quickly displacing any remaining incandescent bulbs.

LED lighting

In the early 1960s, early LEDs were low-powered, producing red frequency light. Bright blue LEDs were first demonstrated in 1994. This led to the first white LEDs, which used a phosphor coating to convert some of the emitted blue light to red and green frequencies. Isamu Akasaki, Hiroshi Amano and Shuji Nakamura were awarded the 2014 Nobel prize in physics for the invention of the blue LED.

Nobel physics 2014

Nanophotonic lighting

MIT-Efficient-Incandescents_0
A nanophotonic incandescent light bulb, such as this one made at MIT, could someday replace LED lights. (photo: MIT)

Incandescent light is created by heating a thin tungsten wire to about 2 700 °C Celsius, that emits black body radiation, a broad spectrum light with warmth and a faithful rendering of colors. By surrounding an incandescent filament with a special crystal structure in the glass, energy can be recycled to the filament to create more light. This photonic crystal had to be designed for a very wide range of wavelengths and angles. It is made as a stack of thin layers, deposited on a substrate.

Luminous efficacy is a measure of how well a light source produces visible light, taking into account human eye response. The luminous efficiency of conventional incandescent lights is between 2 and 3 percent, that of fluorescents is between 7 and 15 percent, and that of most commercial LEDs between 5 and 20 percent, the new two-stage incandescents could reach efficiencies as high as 40 percent.

Research into this process is being done by Marin Soljačić, John Joannopoulos, Gang Chen, Ivan Celanovic, Ognjen Ilic and Peter Bermel at MIT.

This means that there could be a new round of lighting technology introduced at some time in the future, which results in another halving of the cost of lighting. This, however, is not a viable product for the moment, and will not be considered further.

The cost of electricity

I began researching this post by looking for rates in Vancouver (Canada), San Francisco (California) and North-Trøndelag (Norway). This research confirmed what I already new. There is no simple formula. However, I did find that the average consumer in San Francisco pays about USD 0.1534 per kWh. In North-Trøndelag it is about NOK 1.07, which is converts to USD 0.1301 per kWh. So, there is not much difference between the two locations.

The cost of light bulbs

It is becoming increasingly difficult to compare the purchase price of incandescent and LED bulbs. Incandescent bulbs just aren’t being sold in Norway. Online stores in the US assure me that 60 W incandescent bulbs can be purchased for about USD 1 each. In North-Trøndelag, a 9 W LED bulb costs about NOK 45, which converts to USD 5.45 (let’s be generous, and raise it to USD 5.50).

Assumptions & Calculations:

It is not unreasonable for a light in a residence to be used 1 000 to 3 000 hours a year, which is 2.25 to 6.75 hours a day. This would give a LED bulb a lifespan of  between 30 and 10 years.

An incandescent bulb burning for 30 000 hours will use $270 worth of electricity. (30 000 h x 60 W x $0.15/ kWh).

Tablulated data

800 lm comparison Incandescent LED
Watts

60

9

Bulb costs (USD)

1

6

Lifespan (hours)

1 200

30 000

Bulbs for 30k hours

25

1

Capital costs (USD)

25

5.50

Electricity costs (30k hours in USD)

270

40.50

Total costs (USD)

295

46

Conclusions

LED lamps reduce the cost of lighting by over 84% in comparison to the use of incandescent bulbs.