Lumen Method Lighting Calculation Example
Summary
TLDRThis educational video script explains the process of calculating the number of light fixtures needed to achieve a desired illuminance level in a room. It covers key concepts like the utilization factor, light loss factor, and the impact of room color and finishes on light reflection. The script provides a step-by-step example using an 8x5 meter room with a target illuminance of 200 lux, demonstrating the formula rearrangement to find the required lumen output and the number of lights. It also discusses the efficiency of LED lighting compared to fluorescent, and the importance of maintaining light fixtures for optimal performance.
Takeaways
- 🔆 The video explains how to calculate the number of lights needed to achieve a certain illuminance level on a surface within a room.
- 📐 The formula for calculating the number of lights involves the illuminance, floor area, luminous flux of the lights, utilization factor, and light loss factor.
- 🕯️ The utilization factor accounts for the reflective properties of the room, such as wall color and finish, and the number of windows.
- 🧹 The light loss factor, also known as the maintenance factor, considers how often the lights are cleaned and their performance over time.
- 💡 LED lighting is more efficient and has less light loss compared to fluorescent lighting, especially if the fittings are cleaned regularly.
- 👀 The intensity of LED lighting can be too harsh for some people, but it's generally more efficient than fluorescent lighting.
- 📝 An example calculation is provided to determine the luminous flux required to illuminate a room measuring 8 meters by 5 meters with an illuminance level of 200 lux.
- 🛠️ The formula is rearranged to solve for the luminous flux (F), which is key to determining the number of lights needed.
- 🔍 The video provides a practical example using an office area and a 600 lumens LED panel light to calculate the number of lights required.
- ⚙️ For different activities, recommended illuminance levels vary; for example, general office work areas may need 500 lux, while supermarkets might require 1000 lux.
- 🏭 The video also simulates calculating the number of lights for an engineering workshop with a requirement of 1000 lux over an area of 20 meters by 10 meters.
Q & A
What is the purpose of the formula discussed in the video?
-The formula is used to calculate the number of light fixtures (lumps) needed to achieve a certain illuminance level on a surface within a room area.
What are the two factors that account for the reduction in light output over time?
-The two factors are the Utilization Factor and the Light Loss Factor, which account for the light's deterioration due to dust accumulation and reduced performance over time.
What is the significance of the Utilization Factor in lighting calculations?
-The Utilization Factor takes into account the color of the room, the type of wall finish, the number of windows, and how reflective these surfaces are, affecting how light is distributed within the room.
What is another term for the Light Loss Factor?
-The Light Loss Factor is also known as the Maintenance Factor.
How does the cleanliness of the environment affect the Light Loss Factor?
-In a clean environment, the Light Loss Factor can be set higher, such as 0.9. In a very dirty environment, it might be set lower, such as 0.7, which increases the number of lights needed.
Why did fluorescent lighting often require tube replacement every six months?
-Fluorescent lighting would deteriorate over time, turning yellow and reducing light output, while electrical power consumption remained the same. Replacing the tubes helped maintain brightness.
How does LED lighting differ from fluorescent lighting in terms of light loss?
-LED lighting does not experience significant light loss if the fittings are cleaned regularly, making it more efficient and cost-effective compared to fluorescent lighting.
What is the formula rearranged to calculate the required luminous flux (F) for a given illuminance level?
-The formula is rearranged to F = (E * A * UF * LLF) / n, where E is illuminance, A is area, UF is Utilization Factor, LLF is Light Loss Factor, and n is the number of lights.
How many lumens are required to achieve 200 lux in an 8m by 5m room with a Utilization Factor of 0.7 and a Light Loss Factor of 0.8?
-The calculation would be 200 lux * 40 m² * 0.7 * 0.8, which equals 5600 lumens.
What is the recommended illuminance level for general work areas in offices according to the Chartered Institute of Building Services Engineers?
-The recommended illuminance level for general work areas in offices is 500 lux.
How many lamps are needed to illuminate a 20m by 10m engineering workshop to a level of 1000 lux using 25-watt LED tubes with 2600 lumens each?
-The calculation would involve using the rearranged formula for F and determining the total lumens required, then dividing by the lumens per tube to find the number of lamps needed.
Outlines
🔆 Understanding Illuminance Calculation
This paragraph introduces the formula for calculating the number of light fixtures needed to achieve a specific illuminance level in a room. It explains the importance of the utilization factor, which accounts for light reflection within the room, and the light loss factor, also known as the maintenance factor, which considers the reduction in light output over time due to dust accumulation and deterioration. The paragraph also contrasts LED lighting with fluorescent lighting, noting the reduced need for maintenance with LEDs and their more efficient light output despite a potentially harsher appearance.
📏 Calculating Luminous Flux for Lighting Design
The second paragraph delves into the process of calculating the required luminous flux to achieve a desired illuminance level in a given area. It provides a step-by-step guide on rearranging the formula to solve for the light output per fixture (F), taking into account the area, illuminance level, utilization factor, and light loss factor. An example calculation is presented for a room measuring 8 meters by 5 meters with a target illuminance of 200 lux. The paragraph also discusses the selection of appropriate light fixtures based on their lumen output and power consumption, using an LED panel light as an example.
🛠️ Applying Lighting Calculations in Different Settings
The final paragraph extends the discussion to practical applications, illustrating how to determine the number of lights needed for different environments, such as offices, retail spaces, and engineering workshops. It provides an example calculation for illuminating a workshop area with a high illuminance requirement of 1000 lux, using a 25-watt LED tube. The paragraph also touches on the importance of balancing the electrical load across multiple phases and considers factors such as power factor and breaker capacity to ensure a safe and efficient lighting installation.
Mindmap
Keywords
💡Illuminance
💡Luminous Flux
💡Utilization Factor
💡Light Loss Factor
💡LED Lighting
💡Fluorescent Lighting
💡Lumens per Watt
💡Color Temperature
💡Efficacy
💡Circuit Breaker
💡Power Factor
Highlights
The video explains how to calculate the number of lights needed to achieve a specific illuminance level on a surface within a room.
The formula for calculating the number of lights includes illuminance, floor area, luminous flux, utilization factor, and light loss factor.
Utilization factor accounts for the reflection and absorption of light by room surfaces and colors.
Light loss factor, also known as maintenance factor, considers the deterioration of light output over time due to dust and cleaning frequency.
LED lighting is more efficient and has less light loss compared to fluorescent lighting, especially when fittings are cleaned regularly.
Example calculation provided to determine the luminous flux required to illuminate a room measuring 8 meters by 5 meters with an illuminance level of 200 lux.
Rearranging the formula to find the luminous flux (F) needed for a given illuminance level, area, utilization factor, and light loss factor.
The importance of understanding transposition in mathematical formulas for electrical students to simplify calculations.
A practical example of calculating the number of LED panel lights needed for an office area with a specific illuminance level.
Different recommended illuminance levels for various environments, such as offices, retail spaces, and engineering workshops.
The impact of color temperature on the perception of light intensity and the preference for a cool white light in certain settings.
A step-by-step guide on how to calculate the total current required to illuminate a workshop area with a specific number of lights.
Considerations for electrical safety, such as the number of devices per circuit breaker and the use of three-phase power distribution.
The use of inrush current and power factor in calculating the total current draw for a lighting installation.
Strategies for balancing lighting across multiple phases to ensure continuity in case of a phase loss.
The video concludes with a summary of the importance of accurate lighting calculations for various environments and applications.
Transcripts
so in this video we're going to explain
how to calculate the number of lumps
within a room area to provide an
illuminance on the surface so basically
what we have in this formula is we have
so n number of lights is the illuminance
times the floor area times the actual
luminous flux of the lumps that you fit
in the utilization factor and the light
loss factor so let me explain what these
two the utilization factor it's a light
loss factor so the moment we install our
light source at the moment that the
lighting installation is put into
service the light start to get dusty the
light performance deteriorates so over a
period of time the light will reduce the
output from the light will be reduced so
for that reason we put that factor into
our calculation the other type of factor
is the coefficient utilization
now this is takes into account the color
of the room the walls the type of finish
on the walls are those reflective of the
imap finish how many windows there are
in a room
so the coefficient light utilization
that is effectively what the light is
going to be reflecting from within the
room area so the light loss factor is
also known as the maintenance factor so
there was how often are the lights going
to be cleaned so typical factors if it's
a clean environment we can set a point
now but it's a very dirty environment
then we can sell at 0.7 and what that
does is that increases how many lights
we need so often is the case on a brand
new light installation if you've just
finished an installation in a workshop
area like a supermarket when you first
turn those lights on they're really
really bright and it's like wow you know
it's daylight but all the time
that will deteriorate and the like
especially old fluorescent lighting when
it starts to get all starts to
deteriorate it goes yellowy and what is
for sure is that the electrical power
consumption doesn't change but the light
output does change so often was the case
with fluorescent lighting is that you
would do what we call tube runs so you
would go six months twice a year you
would replace all the tubes in a factory
and the light would be absolutely
brilliant when you finished but that's
expensive with LED lighting that's not
the case as long as the fittings are
cleaned then they you don't get much of
a light loss you get zero light loss
with LED lighting compared to that and
fluorescent lighting the only downside
with other day like this some people
find it can be a little bit too intense
they can find that it's it's a little
bit too harsh on the eye so I still
think was ways to go with a lady like
him but it's certainly more efficient
than fluorescent lighting so let's look
at an example here so if we have a we're
going to calculate luminous flux
required to illuminate a level of 200
looks so that's one so what you see on
the surface in a room measuring 8 meters
by 5 meters so first thing we need to do
is we need to obviously get this formula
layer and then we need to rearrange the
formula R in this so any number of
lights eg luminance is the area F is the
light output in lumens
that's the utilization factor and that
is the light loss factor also known as a
valence factor so what we need to work
out well we need to work out the
luminous flux so we need to make F the
subject
okay so let's rearrange this formula to
find F so the first thing I'm going to
do is we're going to multiply both sides
by F so let's do that
so we'll write this out here
transposition is one area which a lot of
electrical students struggle with so my
advice is get on top of it early and
then that way your life is a lot easier
so now we've done that we multiply both
sides by F that gets rid of that gasket
that's gets rid of that so we are left
with now so n times F equals e a of BOF
times L F so now we need to get rid of n
so what we do is we divide that side by
n okay and obviously we put in on that
side so that will go there like so well
because obviously the bottom lines are
all times in yep see product is subset
of the quotient that will go up that
wall girl
so then we'll be left with F is
luminance times area a lot of times in
that of a utilization factor it sounds
like loss factor times number of lights
so let's look at our that way lights
we've got so the area is 85 so the area
8 by 5 so that's gonna be 40 meters okay
the illuminance level is going to be 200
looks from the question the UF and LF a
point seven point eight so UF is now
point seven and the LF is not point
eight
okay now as we don't know how many
lights we've got at the moment we're
gonna set I'm gonna set the number of
lights just to want so that's that that
will give you know what the whole light
would be then what we would do then is
we would look at divide in that level of
luminous flux into the illumise flux per
light and that will tell us movie how
many likes we need so we've put put
those calculations in so f so we have
200 times 40 of 0.7 was 8 times 1 so
we've done the math on there we get
fourteen thousand two hundred and eighty
five point seven one lumens that's the
talk about illumination
sorry lumen output required to provide a
two hundred looks within a five be eight
meter area so the question is is how
many of these what sort of lamps we're
going to fit well I have just got online
unless you say this was an office area
and you can see there that the power for
each light there is 40 watt so I've just
search for a 600 600 LED panel light
it's white and it's giving out a lumens
of 3500 so one panel light there so if I
was to do my sketch there so one power
light is gonna give out 3400 lumens
yeah okay so how many likes do we need
we'll all we do is we divide three
thousand four hundred lumens into 14
thousand two hundred and eighty five
point seven so number of lamps is to
talk lumens required divided by the
lumen per lamps or our LED light three
thousand four hundred lumens per lamp
divide the two we get four point two
well obviously you can get four point
two lamps so that's five lumps so if we
look at the actual
flower area then we just need to equally
divide the lumps into five now you might
ask yourself that's not a lot of lumps
for that solve area but remember we are
only asked to provide 200 looks so 200
looks isn't really a lot of light to
work in so if we wanted to increase the
amount of illuminance at the floor then
we would put more lights in so basically
if we look at the recommended light
levels
so for sabzi the Chartered Institute of
building service engineer's guides they
say the following level so offices
general work areas 500 Lux drawing
boards 750 looks so it depends on the
activity that's going on so if it's a
computer room offices work sessions and
it's quite a low looks area because you
don't want a lot of glare off the lights
because obviously people are tuned into
the toilet at the monitors retailing
though is very high so thousand looks
for your superstars you hypermarkets
supermarkets so that's why when you walk
in to these places they're really bright
you know and obviously the light in the
high bare lighting produces quite a lot
of lumens your engineering workshops
well it depends on the activity so if
you are quelled in 300 looks right the
way up to 2,000 looks so this depends
very much on inspection and testing so
if you are building engines or
assembling electronic circuits and so on
then you're going to need a very very
high level of looks you know for the
detail so this is a good guide to give
you an idea you know where to start and
how many lights you would need so let's
look at an example then and we're going
to simulate a workshop area and we're
going to work out how many lights we
actually need to illuminate a
engineering workshop up to a value of a
thousand looks that's the next example
then we have a factory floor or workshop
floor of 20 meters be 10 meters
and we're going to use a 1500 mil 25
watt LED tube and I've gone online and
you can see just literally searching
online for LED data you can see that
this is a 24 input power and the lumens
is obviously to 2600 and the efficacy
lumens per watt is 109 what we're gonna
do here also tell you about the color
temperature so it's nice and cool so
6500 that's gonna be a nice white clear
light so first thing we need to do is
we're gonna work out how many lumps are
required and we're gonna work out the
total current taking to illuminate the
area okay so the day when the thousand
looks in this area okay Michael's back
to his point eight that is a little bit
state but I'm setting up point eight
anywhere and the utilization factor is
not 0.7 so first thing we do is we write
our formula down and we do the maths
we've got our formula so the illuminance
required is a thousand the area is 10
meters by 20 meters okay and the lumen
output per light is 2600 the utilization
factor is not 0.7 and the light loss
factor is 0.8 so the total number of
lights we do the maths so that's one
hundred and thirty-seven point three six
lumps or 138 lamps so that means is we
would need to divide this floor area
basically we would need to 1500 each so
you would space out that floor area to
put multiple rows of lights now if it
was myself obviously I would put those
over three phases so you put them with
three phases so they're nice and
balanced there there's no risk Astral's
copic effect well obviously we need to
keep our face is balanced so how much
current is that going to take them well
if there's a hundred and thirty-eight
lamps so we've got one hundred and
thirty-eight lamps yeah times and the
input power is twenty four twenty four
what some not a lot really if you think
about it so so we get
total power of 3.31 kilowatts which is
that's quite a bit okay but obviously we
do that over three phases but we'll stay
with one phase for now now if you look
at the electrical data you can see there
that the there is an inrush there but
basically ignoring the inrush for now
power factor is greater than 0.9 and it
says there the number of devices per 16
the second trick is 72 so see 16 so you
or not you can only put 72 fittings on
the C 16 breaker so let's have a little
look and see we can work out the the
current on this now okay one second so
we've got so we know we've got 3.3
kilowatts the total power I times V
times power factor I'm going to set the
power factor at nine point nine so we
rearrange the formula for I power is V
times power divided by bolts times power
factor so there's point nine worst case
scenario and we get a total current of
16 amps now that's total obviously we've
got one hundred and thirty-eight
fittings so we're going to need to
divide it up so my advice to keep it
over three phases 16 over three gives us
five point three three amps per phase
and that's so that's obviously 46 lamps
per face or forty-six tubes and the talk
to allow for a total in rush I would
probably go for a c10 circuit breaker on
there so over three phases and the
beauty we're doing it over three-phase
is it should you lose a phase in
emergency you don't lose you've got
another two phases to keep you going
okay I hope you found that useful any
questions please let me know thanks for
watching
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