The visible part of light

[Jimes]

I see lots of talk about the low power consumption of the low power lights,
but I'm missing something...

Normally, people speak about a preference for a 100W light or a 60W light,
beacuse they are concerned with the amount of light produced. Now the Watt
rating actually refers to it's consumption, and not the amount of light
produced.

I personally think the low voltage 50W bulbs give the best light, and these
9W minature flourescents the worst, but I'm speaking about the quality of
the light produced. The low voltage lights produce a full bodied pyramid of
light, whilst these 9W low power ones produce a sickly sort half hearted
light (just an opinion). Fact is though, the 9W lamp is far more attractive
for the minimal power it consumes.

My question is, what are the terms of reference to describe the amount of
light given off, (not the power consumed)?

Thanks
Jimes

 

[Jimes]

Partial answer to my own question....

I'm looking at lumens per watt....but if the manufacturer of the light bulb
like Phillips doesn't put it on the box... can it be calculated?

Jimes

 

[William P.N. Smith]

I'm looking at lumens per watt....but if the manufacturer of the light bulb
like Phillips doesn't put it on the box... can it be calculated?

No, you want total lumens, which tells you how bright a light is. CR
(Color Rendition) is a number used with flourescents to tell you how
'good' a light is (you can somewhat determine this number from the
color temperature of the bulb).

L/W is a measure of efficiency.

 

[[email protected]]

I'm looking at lumens per watt....but if the manufacturer of the light bulb

like Phillips doesn't put it on the box... can it be calculated?

No, but you can easily compare a known with an unknown light source with
a grease-spot photometer. Put a grese or oil spot on a 3x5 card and walk
between the sources until the spot disappears, which indicates that it is
equally illuminated on both sides. The relative source luminosities are
then proportional to the inverse distances squared.

Nick

 

[Eeyore]

Partial answer to my own question....

I'm looking at lumens per watt....but if the manufacturer of the light bulb
like Phillips doesn't put it on the box... can it be calculated?

All the Philips CFs I've seen have a lumens figure. Maybe for the European
market perhaps ?

Graham

 

[Vaughn Simon]

There are some quite good 12W flourescent bulbs in a standard ES or BC
base (standard light fitting). There are "better' and "worse" ones.
I think you are looking to run 12v (rather than 110/230) - though my
experience is that the higher voltage bulbs -

I have been using 12v Edison base CFs for yard lighting for years. I find:

i) "Give more choice" True
ii) "Give better light" Disagree, I see no difference to the 120VAC
version.
iii) "Use practically no more power through a small inverter." Perhaps so,
but I find it convenient to use low voltage wiring for this application.

iv) To be honest, you could also mention that 12vdc on an Edison base
socket is a very non-standard configuration and subject to
embarrassing/moderately expensive accidents.

v) I keep a couple around for emergency lighting. They allow us to have
very normal room lighting with very reasonable battery drain without running a
generator. Someday, I will wire some in permanently and use them off of my 12v
PV system for normal everyday lighting.

Vaughn

 

[George Ghio]

I see lots of talk about the low power consumption of the low power lights,
but I'm missing something...

Part of what you are missing is light placement. My house has 56
separate lamps. 26 of which are LED lamps.

The highest wattage lamp is 1 - 20 Watt lamp.

All the other incandescent lamps are either ten Watt or five Watt lamps.

The led lamps are used for either reading lamps of back ground lighting.

All lamps are 12 volt.

Placement is everything. The old standard of a 60 or 100 watt lamp in
the middle of the ceiling is dead as far as my usage is concerned.

 

[Mary Fisher]

....

Placement is everything. The old standard of a 60 or 100 watt lamp in the
middle of the ceiling is dead as far as my usage is concerned.

A central light has its uses according to what you're doing in the room -
but even 100W isn't sufficient for me :-(

Placement IS everything. I wonder why we don't have general lighting to
shine from window areas when natural daylight goes?

Mary
just musing

 

[George Ghio]

...



A central light has its uses according to what you're doing in the room -
but even 100W isn't sufficient for me :-(

Not often. Most work stations are around the sides of a room so with a
central lamp in the ceiling you cast a shadow wherever you work. Could
explain why 100W is not enough.

Example: The pasta bench. Eight feet long, three QH lamps 600mm above
the surface, lamp in the middle = 10W with small metal reflector, lamps
500mm either side = 5W with small metal reflectors.

Metal reflectors are the tops of spray paint cans with the centre
drilled out, painted flat white and fitted with ceramic QH lamp holder.

 

[Mary Fisher]

Not often. Most work stations are around the sides of a room so with a
central lamp in the ceiling you cast a shadow wherever you work. Could
explain why 100W is not enough.

Um - I did say, "according to what you're doing in the room".

In our sitting room and dining room we don't have workstations, we have a
table lamp on, er, the table for winter suppers for two. When we have
company to dine we use an overhead central light. If I'm (hand) sewing in
the sitting room I have a lamp. When we have company we use the central
overhead light.

There are no workstations in the bedrooms or bathroom come to think of it.

My office has an overhead light between me and the pc. My workroom has three
spots lighting different parts of my workbench. There's an additional light
over the filing cabinets. Spouse has a lamp on his desk.

Overhead lights in the hall and on the landing work well, but we do have
three spots lighting pictures on the landing.
I repeat: I wonder why we don't have general lighting to
shine from window areas when natural daylight goes?Mary
still musing

 

[Mary Fisher]

No, you want total lumens, which tells you how bright a light is. CR
(Color Rendition) is a number used with flourescents to tell you how
'good' a light is (you can somewhat determine this number from the
color temperature of the bulb).

What does 'good' mean?

I thoroughly dislike what I call the 'quality' of light from long life
bulbs, is this the same thing? They seem to give everything a dull,
yellowish tint. It's very difficult to explain :-(

Mary

 

[Derek Broughton]

I repeat: I wonder why we don't have general lighting to
shine from window areas when natural daylight goes?

A home designer I know did exactly that - general lighting shines _through_
the windows from outside. Besides providing light in approximately the
same places as you get in daylight, it has the added facility of providing
privacy - outside viewers see reflected light not the people inside. Seems
like a waste of energy, to me, though.

 

[Mary Fisher]

A home designer I know did exactly that - general lighting shines
_through_
the windows from outside. Besides providing light in approximately the
same places as you get in daylight, it has the added facility of providing
privacy - outside viewers see reflected light not the people inside.
Seems
like a waste of energy, to me, though.

Well, not a huge amount would be lost through the glass, have I missed
another factor?

Did the designer use his system or replace it with somethinig else?

Mary

 

[Anthony Matonak]

What does 'good' mean?

Color Rendition index is a method of telling how well a light will
produce the full spectrum. Sunlight is considered the best and
everything else is compared against that standard. A low number
will mean that colors will look different than under sunlight.

I thoroughly dislike what I call the 'quality' of light from long life
bulbs, is this the same thing? They seem to give everything a dull,
yellowish tint. It's very difficult to explain :-(

Yellowish tint is a very good way to explain it. Such a light has
a low color temperature. Color temperature is based on the concept
that with an incandescent light the hotter it is, the more blue the
light it produces. Low temperature incandescent bulbs produce a
very red or orange light. Fluorescents don't work the same way but
it's possible to describe their overall light spectrum by temperature
as if they did.

Personally, the higher the color temperature, the better.

Anthony

 

[Derek Broughton]

Well, not a huge amount would be lost through the glass, have I missed
another factor?

A significant amount gets reflected off the glass.

Did the designer use his system or replace it with somethinig else?

It's in use now.

 

[Jim Baber]

Jim Baber wrote:

I see lots of talk about the low power consumption of the low power lights,
but I'm missing something...

Normally, people speak about a preference for a 100W light or a 60W light,
beacuse they are concerned with the amount of light produced. Now the Watt
rating actually refers to it's consumption, and not the amount of light
produced.

I personally think the low voltage 50W bulbs give the best light, and these
9W minature flourescents the worst....

There are two things related to the quality of light given off by any
source.

* The Lumen which deals with the intensity / quantity of light, and
is usually stated as either Lumens (the total of all light being
generated at this voltage and current) or as Lumens per Watt.
* The color temperature, usually stated as degrees Kelvin. This is
literally the color of the light emitted by the light in the terms
of how hot any object has to be to give off light of this color.

................................. but I'm speaking about the quality of
the light produced. The low voltage lights produce a full bodied pyramid of
light, whilst these 9W low power ones produce a sickly sort half hearted
light (just an opinion). Fact is though, the 9W lamp is far more attractive
for the minimal power it consumes.

My question is, what are the terms of reference to describe the amount of
light given off, (not the power consumed)?

Thanks
Jimes

--
Jim Baber
Email [email protected]
1350 W Mesa Ave.
Fresno CA, 93711
(559) 435-9068
(559) 905-2204 (Verizon IN cellphone (to other Verizon IN accounts))
See 10kW grid tied solar system at "http://www.baber.org/solarpanels.jpg"
See solar system production data at "http://www.baber.org/solar_status.htm"

 

[Mary Fisher]

Color Rendition index is a method of telling how well a light will
produce the full spectrum. Sunlight is considered the best and
everything else is compared against that standard. A low number
will mean that colors will look different than under sunlight.


Yellowish tint is a very good way to explain it. Such a light has
a low color temperature. Color temperature is based on the concept
that with an incandescent light the hotter it is, the more blue the
light it produces. Low temperature incandescent bulbs produce a
very red or orange light. Fluorescents don't work the same way but
it's possible to describe their overall light spectrum by temperature
as if they did.

Personally, the higher the color temperature, the better.

OK, thanks, I'd like to think I'll remember that.

Now, how does one know the colour temperature before one pays for a product?
'Daylight' seems to be the only variant we can get here (UK) and they're
VERY expensive. People seem to be satisfied with what's on offer. Perhaps
they're watching telly all the time so it doesn't matter, it matters to us.

Mary

 

[Mary Fisher]

A significant amount gets reflected off the glass.


It's in use now.

Hmm. Well, knowing a bit about designers I'd be happy with such a commitment


Mary

 

[George Ghio]

Um - I did say, "according to what you're doing in the room".

In our sitting room and dining room we don't have workstations, we have a
table lamp on, er, the table for winter suppers for two. When we have
company to dine we use an overhead central light. If I'm (hand) sewing in
the sitting room I have a lamp. When we have company we use the central
overhead light.

Table - workstation
Chair for sewing - workstation

There are no workstations in the bedrooms or bathroom come to think of it.

You never read in bed and there is no mirror or counter top in the bath.

My office has an overhead light between me and the pc. My workroom has three
spots lighting different parts of my workbench. There's an additional light
over the filing cabinets. Spouse has a lamp on his desk.

Overhead lights in the hall and on the landing work well, but we do have
three spots lighting pictures on the landing.


I repeat: I wonder why we don't have general lighting to
shine from window areas when natural daylight goes?

Because it is inefficient, wasting energy.

Mary
still musing

Well, it seems that you have, in fact, adjusted your life around the
lighting supplied. Common practice in existing homes.

I adjusted the lighting around my needs as I built. Far more satisfying
in the long run.

 

[Mary Fisher]

Table - workstation

You call eating work???

Chair for sewing - workstation

Sewing isn't work either, for me. I do it for pleasure.

You never read in bed

We do

and there is no mirror or counter top in the bath.

There are both in the bathROOM. And we read in the bath.

Well, it seems that you have, in fact, adjusted your life around the
lighting supplied. Common practice in existing homes.

LOL! Don't think that we haven't considered lighting, we have. That's why we
decided to keep the central overhead lighting as well as having spot
lighting where it's needed. But our house isn't a series of workstations!