Windows vs. Artificial Lighting
mikeysp
| Posted in General Questions on
Hi. I am in zone 4a (Nashville)
I am looking for advice on the use of windows vs artificial lighting for my shop.
I am building a 28×64 1800sq ft 12ft ceiling workshop that I will be working inside of 20+ hrs a week. Is this day of inexpensive LED lighting making the cost benefit of windows a poor idea?
Thank you for your thoughts.
-Mike
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Windows have benefits beyond just letting in light. Do you really want to be stuck in a windowless boxes for hours on end? Gazing out a window when you're stuck on a project is nice too, helps to clear the mind :-)
You don't want to rely entirely on windows though. The sun doesn't always set when you want it to, so you're going to need some light for long projects, or if you just feel like working late. I'd use some LED strip lights -- the kind that look like the standard 4 foot shoplights we all know from the pre-LED days -- and some good task lights for work benches.
In my own shop, I have strip lights arranged as area lighting, and dedicated strips directly over every work bench. Many of the LED strip lights can be "linked", which is a fancy way to say you can daisy chain them by plugging one into the end of the other. There is a limit on how many can be linked this way, but it's usually at least three or four. This is great over a work bench where the lights are all in a straight line. I used Feit Electric brand lights from Costco which seem to work fine, and I've had mine for four years now. They go on sale every few months which can save you some money if you have a lot to buy.
For task lights, I like the lights on articulated arms. I have a "circuline" fluorescent magnifier that I love for electronics work. If you're doing woodworking, you're going to want some lights with a very high CRI (90+) where you're doing your finishing so that you can get an accurate idea of how things will look in natural light.
Bill
Thanks Bill! I should have added I am definitely going to have excellent LED lighting. Your point is excellent for having some aesthetic windows for viewing and I will have that at a minimum.
However, when it comes to lighting for work, is natural lighting worthwhile in a small manufacturing facility? I am pondering that electricity is cheap for LEDs and the power lost in heating/cooling with a large bank of windows is significant. High end windows are not an option, so I will be picking up some second hand double pane windows locally for any windows I do utilize.
-Mike
I don't think natural light really helps you on the manufacturing floor. You sometimes see the "industrial" skylights (like places like Costco and Walmart have been installing), and they add some light, but you still need to supplement with artificial light. If you try for an old-school "glass roof" type of plant, you'll probably end up with some major issues trying to heat the place efficiently.
I'd use the windows for aesthetics and to minimize the "box" feeling, but not really rely on them for light.
Most modern plants (and I've been in lots of those) are lit with either LED or HID highbays. Windows are relatively rare, and usually placed near doors, or are IN the doors. What often happens in the smaller plants is that the staff will open a loading dock door for light/view/airflow, and that door is usually close to a gas-fired unit heater that is just running.... and running.... Not too efficient :-)
Bill
In my home shop I find myself drawn to work in the natural light near the large windows.
In a work situation while the windows make for a pleasant space to spend time. Having them can be a problem in that people will argue over who should get to be where as it relates to the window and the last thing management needs is another argument to settle. From a production point of view you want consistently and the natural light is one more variable you do not need. I say save the window for the break room at work.
Walta
I'd be inclined to go with fewer windows and more fixtures. A twin-tandem industrial or strip fixture fitted with four 13-watt 5000K Philips HO InstantFIT T-LEDs would supply 8,400 lumens (about the same amount of light as eight 100-watt incandescent lamps) and consume just under 70-watts including ballast overhead. These lamps come with a seven year/70,000 hour manufacturer's warranty although their service life will be much longer than this.
The advantage of this conventional fluorescent fixture and tubular LED lamp marriage is that you can easily and inexpensively replace a lamp or ballast should it fail; with an integrated LED fixture, a failed driver could be difficult to source and more costly to replace, assuming that replacement parts will be available at some future date and that the fixture is field serviceable.
I have spent a lot of time in manufacturing plants, I can tell you the overseas style with the zig-zag roof and north facing windows is WAY more pleasant to work in. No amount of artificial light can make up for the diffuse natural light those deliver.
For a shop space, I would definitely install a row of small high windows on the north wall and some smaller windows where you will be working. Fixed dual pane vinyl windows don't cost all that much. They only need to be about 1' to 1.5' tall so even in your 64' shop you are not talking about a lot of square feet. The heat lost through those will be next to nothing compared to a garage door.
If you are doing a post construction, you can get smaller windows and join them into an assembly so that you only need to flash/trim a couple of section instead of each window individually. My home has one that is a single assembly of 8 section overall 2'x45'
Akos, do you say North side for windows so no direct sunlight enters? I had thought originally if I was going to put a strip of windows to place them on south side between side storage area roof and the eve of the insulated shop as shown in pic.
Depends on what you are looking for. For work, you want indirect diffuse light, north facing is the best for that. I recently installed a set of north facing skylights on my wife's studio and it made a world of difference.
South facing clerestory is great for passive solar heating but it comes at the cost of a lot of glare in the wintertime. It makes working under it hard as the light band moves around with time of day and season. I have this problem in my home and there is a two week window where it is hard to work in the kitchen as the sun is too intense. Great for energy efficiency but not great lighting.
+1 for North facing if you go this route. South facing gets direct light, which moves throughout the day, reflecting off of random shiny things around you that always seem to blast the light right into your eye. North facing window light is dimmer, but diffuse and more constant throughout the day. With North facing windows, you get a relatively even light level that rises and falls throughout the day instead of making a super bright spot that moves around the floor throughout the day.
I have a "sunroom" with a bunch of North-facing skylights. We do get a little direct light at certain times of the year when the sun angles are higher, but most of the time it just makes the space brighter and more open-feeling.
If you use my earlier example, you'll see that those skylights in the box stores are made from a kind of frosted glass to avoid direct light. Same basic concept to what Akos and myself are talking about.
Bill
How many square feet of glass would be wise if I were going with glass on north side? The only data I could find online was for naturally lighting a room in a house and it called for 10% of floor space. That would mean a 180 square feet of window; or, a 3foot tall x 60ft long section of glass.
That overhang in pic above is on the south side; therefore; "IF" I use windows, I will be able to use them on the north side and be able to raise the raise roof several inches. I think it will also add some character to the large bare north side of building.
-Mike
There are some pretty detailed guidelines for daylighting here:
http://www.tboake.com/powerpoint/daylighting_canada.pdf
It is always a compromise between heating energy use, window cost and lighting operating costs. It is impossible to give a simple % of floor area number.
Don't let sun glare be your main deciding factor. You can always filter the strong light or deflect it upwards so it washes the ceiling. Diffuse even light is the objective, for sure.
I've worked in a variety of spaces with artificial light, and personally I vastly prefer natural light. You will sometimes need task lighting either way, but I notice the connection to the changing light helps make my work more relaxed. Perhaps it's the industrial drive for production inherent in an artificial space that I find tiring. There is no natural stopping point except a clock.
Friends. I am trying to figure how much window to use on this?
My big dilemma comes from the fact I do not want to do much violence to heating/cooling efficiency and I just do not know what square footage of glass means to this.
I found a guy with many 30" wide sliding glass door panels, so I thought with about 80"x30" of glass between all the 8ft O.C. posts on the north side of building, I would have lots of good light with approximately 133 sq. ft. of glass and little or no direct sunlight entering building.
However, I do not want to regret it because I am making wild guesses What kind of expert do I need to help me figure this out.
I am recycling double pane glass. zone 4a, bldg oriented east/west, 28ftx64ft 1792 sq. ft. Walls 12ft 9in.
I can place 12" or perhaps a max of 18" tall glass on south side between eve and porch roof. I would reflect it up toward ceiling and being right under the 24" soffit, it may not get much direct sunlight in summer with the sun more overhead.
I can place 12" or much taller glass on north side under eve. I will place a few small windows at working height, so I can see outdoors. But, wall space at ground level is at a premium, so I will not do much glass there.
-Mike
There is no "normal" or "average" answer to that question. Buildings vary tremendously in their energy usage, depending on how they're built, how they're used and where they are.
On new construction, best practice is to create an energy model called a "Manual J." The inputs into a Manual J include:
* How hot does it get in the summer where you are?
* How cold does it get in the winter where you are?
* How warm will the house be in the winter?
* How cool will the house be in the summer?
* How well insulated are the exterior surfaces -- walls, ceilings, floors, windows and doors?
* How air-tight is the house?
* How much sunshine will come into the house in the summer?
* How many occupants will the house have?
From this you calculate how much energy it takes to heat the house in the winter and cool it in the summer. You can also see the incremental impact of changing different aspects of the construction.
In general, windows have three energy penalties compared to walls: They provide less insulation, they leak more air, and they let in more sunlight in the summer. How significant those penalties are depends on the type of window, the type of wall, and the placement of the window, along with the climate. The overall penalty depends on how the building is constructed. For example, in a building with no insulation the penalty of a window is unlikely to be significant.
Now, the short answer: in almost every climate, with almost every window type, the energy value of the light provided by a window doesn't come close to making up for the energy penalty of a window. If your goal is to have the most efficient possible building, you would make a windowless cube and light the interior with LED's. However, there is more to life than efficiency, and as several other posters have pointed out, natural light is qualitatively more pleasant than even the best artificial light.
My guess your outdoor design temperature is between 15F to 20F. Assuming clear glass double pane (R2) and shop at 70F, you would loose:
(70F-20F)*133sqft/R2 =3300BTU.
If those free IGUs happen to be lowE, you that number would be 40% less which would definitely put it into the "don't worry about it" category. With site built windows, make sure you air seal them properly, you'll get much more energy loss through air leaks than through glazing.
If you’re getting free glass, or at least very cheap glass, you could use some to make a sort of storm window to essentially give you a triple-pane like assembly. This would help your energy efficiency. Something to think about.
Bill
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Think about adjusting the more modern lighting system by using smart light bulbs instead of regular ones. The good thing about them is that they consume less energy and don't depend on the wires so you can place them in the proper places to sort the lighting inside your shop more effectively, so you will economize on windows and on electricity, that means double profit, need to mention that at least one window needs to be due to psychological factor, the customers will feel more comfortable inside. https://www.vont.com/product/vont-bulb-color-smart-light-bulbs-smart-bulbs/
You don't need "smart" bulbs, you get the same efficiency with regular LED bulbs -- its the "LED" part that is where the energy savings are coming from, the "smart" part is just marketing and really doesn't add anything in a typical workshop where you just want to light an area evenly.
I would never use the battery operated lights in any permanently installed system. Battery powered lights may be OK in seldom used closets, but never in an area where they can be expected to be on for long periods. The batteries will run down, and need replacing, and that's a lot less green than just running on grid power.
Bill
I built a 30X50 shop w/12' ceilings last year in Central NY, Zone 5, and placed windows on the North and west walls in the areas where I do hand work. In the machine area, there is one window on the southwall mainly for ventilation in the summer with an overhead door and man door on the north wall which also have windows.
The natural light in the hand work area is really nice. I just used generic builders grade windows and with insulated walls and ceiling kept the building at 50F or warmer all winter using just tw0 1500W oil filled radiator heaters. I'm currently installing two 18,000 btu minisplits and expect that these will do a good job for both heating and cooling.