natural light versus heating
Hi All:
We have an industrial building which costs us about $10,000/yr to heat (natural gas unit heaters) and about $30,000/yr for electricity: about $2,000/yr of that is for cooling, the balance being principally for LIGHTING. And that’s at $0.05/kWh, which is only going to get WORSE…
Most of the energy goes into lighting our manufacturing/assembly facility: we build multi-storey modular chemical plants, so we need good lighting intensities with decent colour temperature on the shop floor and above. Our main bay is lit principally from the ceiling via high intensity metal halide lamps, and the ceiling is HIGH- the lights are more than 50′ above the shop floor.
We’ve got one string of 2′ high windows in every 2nd column bay between about 6′ and 8′ above grade, mostly to give us a little natural light at floor level, and they’re paired with a string of fluorescents mounted on the walls.
Construction is basic pre-engineered building: R-12 fibreglass batts w/continous interior air/vapour barrier inside the metal cladding, and R-24 or so under the flat roof. The cladding is non-structural so windows can go in at will. Climate is southern Ontario, Canada: hot, humid summers and mild (for Canada) snowy winters.
We’re doing a major addition of high bay production facility space and the thought springs to mind: can we add more windows in the south, east and west walls and trade a little heatloss to save a bit on lighting, at least during the summer months? I can calculate the heat loss, but I can’t seem to find ANY data on how much visible light you get per sq ft of glazing. The site is completely unshaded on four sides.
BTW, the archy has been of no help on this…
Replies
bumpity bump!
How about checking out universities in the area that have engineering students that study HVAC? Bring them on board through the university to do a semester project at evaluating and proposing remedies to your situation.
I am no HVAC pro but I would look to increased roof insulation, I would design more windows on south and west sides of the building, I would engineer and design shutters for the windows that seal tightly and would open and close automatically bases on availability of outside light and temperature and would be controlled by computer programs to determine the best livetime economics whether to open or close the shutters. I would install heat recovery ventilation in the heating system. Just some thoughts that I have.
You must have a lot of air exchange with welding of components, painting and such. You could recover at least 80 percent of your heat from the required ventilation of the building.
Another thought, there is a lot of natural gas in southern Ontario. You might be setting on enough gas to heat your building. Another thought, the ground source geo heating available on your large scale would give you good return on investment. A synergy of the above options could help make the oil traders and OPEC just a little poorer and you much greener.
Good Luck!
Virginbuild
OK, here's the short version ...
Many times buildings such as your are made with some of the sheet metal siding replaced by translucent fiberglass panels. These panels do help with the lighting quite a bit - but there is that heating loss. On the plus side, you don't have the solar gain that glass windows have.
As nice as adding windows my be, I think you're moving in the wrong direction. Those Metal halide fixtures have got to go.
I have installed many of the new T-5 fluorescent fixtures, as replacements for metal halide high-bay lights. Here are the advantages:
-1/3 the energy cost;
-An even better quality of light;
-Very little heat is generated by the fixture;
-Excellent operation in cold temperatures;
-No ballast hum; and,
-Instant "on" (though there is about 5 minutes to full bright.
I have found the 5-bulb fixtures to be equivalent to a 400W metal halide fixture.
Thanks a lot! I was under the impression that metal halide doped high pressure mercury lamps were pretty efficient, but I'll have to look into the figures to be sure. I'd be shocked if you got 3x the lumens out of T5s that you got out of a high pressure mercury lamp. Where'd you get that figure?
Turns out we've got an electricity "hole" that we don't understand at the moment. The lighting is less of the total electrical demand than we figured, once we counted all the fixtures we've got. It's not cooling, and our tooling power uses are modest, so we're scratching our heads and searching for the hidden grow-op at the moment.
The corrugated translucent panels would trade way too much heating/cooling loss for the light they give. They're fine for an unconditioned space.
My "1/3 the electricity use" comment was based upon my actual measurements .... the T-5 fixtures wound up using less power than the markings on the ballast would indicate. While the bulbs get uncomfortable warm when lit, there is no heat from the ballast .... as compared to the egg-frying temps of the MH fixtures. Electricity "hole?" First stop: check the water heater(s). It's quite possible for a cracked element to constantly leak $50 of power/month through the water, to ground. Otherwise, there are two details that will confuse individual circuit measurements. Both are particular issues if your power is "three phase." The first is that the amps drawn by the individual legs will not simply add up. This is because the three legs are not "in time" with each other. You'll need to divide the total by 1.73 (the square root of 3). The second is an issue caused primarily by electronic components, such as those in MH lamp ballasts and frequency controllers: harmonics. For accurate measurements, your meter will need to be a "true RMS" measuring type. Do you have a 'harmonics problem?' While beyond the scope of this thread, there are two things you can check for:
-Shared neutral wires may discolor - a sign of overheating, which my be caused by excessive current going through them; and,
-Measure your amps drawn two ways: first with a 'true RMS' meter, then with a cheap meter. The figures should be within 15% of each other, or you may have something that ought to be corrected.
Our power is metered with a power factor, so unless something is phreaking the meter, I'm going to take our metered kWh as reliable. It's pretty tough to phreak a standard kWh power meter, but it's easy to phreak digital voltmeters or ammeters. Lots of scams are built around this fact.
We heat water and air with gas, so it's not the hot water. But we do have lots of other "parasitic loads"- time to add those up and do some accounting!
The metal halide doped high pressure mercury lamps are in the neighbourhood of 80-100 lumens per watt, compared with 100 lumens per watt for the 35W T5s. So the metal halides are only modesly less efficient than the T5s are. Remember that the envelope on a metal halide lamp runs red to orange hot and the ballasts are above the lamps, so of course the ballasts are hot. The ballast efficiencies are tabulated and they're not that bad.
I'm not challenging the PoCo meter .... You mentioned a problem; I naturally deduced that each circuit was being independently evaluated. That's where the different meters come into play.
Harmonics are a different thing than power factor. Different causes, different solutions. I will agree that there is more BS floating around regarding 'saving power' and 'harmonics' than can be measured! As for the T-5's vs. the MH .... forget the handbook data. There's an enormous difference. While the difference is in an area that is very hard to quantify - the quality of the light - it's a very real improvement. My experience has also been that they use quite a bit less power than you would expect.
Supply houses are pretty eager to sell these new lights; it's very possible that they would be willing to let you try one for free. There's no need to commit yourself to a major risk.
Oddly enough, these fluorescents were developed specifically for high bay applications - also a break from the usual lighting doctrine. Finally, since you've mentioned power losses ... perhaps it's time to break out the megger, and start checking things. Transformers, for instance. Check current on your ground wires; that current has to come from somewhere. Phantom load measurements, megger testing, etc., are best checked while the plant is shut down. Still, there is plenty of data to collect during operating hours. I'd start by measuring the draw on every panel, every circuit ... and identifying what loads they serve. Well, I'm off to work right now .... Happy Monday!
We're not quite ready to break out the megger or do a circuit by circuit power draw analysis- yet- we've first got to get together a list of devices and their power draws and do the arithmetic. This is early days- nobody's bothered to analyze this stuff here before, we've more or less just paid the bills.
As to the T-5s: we'd need a whole lot of them to be doing us any good from 60' up. Our "low bay" is 20'... Then there's the mean time between failures issues associated with hundreds of lower wattage bulbs versus a smaller number of more powerful ones. They last a long time, but not forever, and somebody's got to change them. No problem in our addition because our crane's got a catwalk with handrail, but in our existing high bay it's a real PITA to change a bulb. We get good life out of both the bulbs and the ballasts for the metal halide doped HP mercury vapour lamps. And compared with the light I see in most local mfg shops (ie. HP sodium etc.), I wouldn't trade our light quality or quantity for theirs any day.
An archy friend of mine pointed me to this idea which looks pretty cool: http://www.solarwall.com . Looks like a nice alternative to HRV for our addition.
Solarwall, huh? Typical architect. You probably need to find yourself a real architect with real experience doing real industrial high-bay spaces. Sounds to me like you have REAL operational issues that affect the success of your business and you are most definitely NOT going to get the advice you need here.Time to hire a professional.
Yep, we hired a "real" architect/design firm, who delivered drawings for a box with a boilerplate bidspec and collected their fees. Zero innovation- no real thought given to it. Crank out the drawings and move on. We had to request insulation beyond minimum code- it wasn't even discussed. I'm not blaming him- he's just serving his market, which by and large still doesn't give a sh*t about energy consumption and is unwilling to even consider something new.
Sure, we could have retained them, or someone else, to go on an energy conservation fishing expedition on our behalf, but we prefer to be a knowledgeable consumer of our professionals' services. That implies a little homework up front on our part before we start the expensive man-hours timeclock for real. The commonsense one gets from a trip here is refreshing- though like any information source, you've got to figure out what's credible and what's ####.
Our operational considerations are pretty modest and don't care how we heat or cool- or light for that matter, as long as there's enough of it, reasonably well distributed, and it doesn't blind us or make us feel sick. If we can get some heating/cooling without additional operating costs and at the same time increase our ventilation rates in return for a modest capital investment, it's worth a little investigation. If the benefits aren't demonstrated in proper studies, then it's a fad and we'll move on. We're not after the cachet of "going green", but we're not against spending some capital now to reduce our operating costs later- even if the payback will take a while. We're in this for the long haul.
There are a few installs of this Solarwall in our local area and that's all my archy friend pointed out to me, which is a darn-sight more than the guy we hired did for us.
I'd like to blame the prevalence of CAD programs, but the responsibility is still with the architect to serve his customer. All too often, they drop the ball, cranking out minimal designs, with little care for the concerns of the customer. Indeed, it seems that 90% of the plans I see are stock designs, to which the architect does little beyond adding his stamp. Naturally, the stock designs often have their origin with the manufacturer of the pre-fab system they're selling. If the architect does anything, it's adding some cheesecake trim to the outside and choosing the paint color. I expect more. Just a rant.
Before y'all go on an architect rant, you have to understand that 90% of clients, and I'd say full well 99% of industrial clients have the bottom dollar as the highest priority. Couple of the folks I work for don't want to pay to have the drywall taped and mudded.Service takes time and costs $$$. Innovation requires research and experience which costs $$$. When it comes to proposing fees for architectural service, clients do NOT want to see what it really costs for me to come up with something creative for them.That's why I do the "churn-and-burn" projects, and I do them VERY well, VERY fast, and VERY cheap.
But good architectural services provide a cost effective benefit that should pay for itself over time. Minimizing space, maximizing efficiency and minimizing the long term costs. That IS the bottom line. Many clients don't/won't understand that and think the only goal is to secure the permit.
If you aren't looking at basic lighting, daylighting, insulation for your clients, you aren't much more than a code technician schlepping out plans for a permit. While there is a time and place for everything, I frequently see simple opportunities in design simply tossed aside because the architect doesn't care, doesn't know any better (which is NO excuse), or clients that don't care or understand what good energy efficient design even means.
You may want to check with your local utility company. Many of them these days are offering free energy audits, where someone comes out to your facility and makes recommendations on energy efficient lighting upgrades. Plus, after you make the improvements many of them have healthy rebate programs.
I was just reading in the business section of the local newspaper about a manufacturer here who replaced their light fixtures, and with the reduced utility costs and rebates their payback will be only about three years.
Ditto on the T-5s. We're just finishing up a GIANT Caterpillar equipment service shop and they put T-5s in there and it's brighter than the sun! As I understand it, there's a definite price premium over MH, but the energy savings QUICKLY offset that...
moltenmetal
The formula's are simple. R value of building of say R 18 versis say R 1
Now the the question of lighting.. how much suplimental light is required on a cloudy day? That is what you need to find out.. measure the required lumens and test a window on a cloudy day.. there are plenty of light meters out there..
Frenchy: the heatloss calcs are no problem. What I was looking for was some data on average daytime lumens per sq ft of glazing, averaged out by month over the year. The best I'd be able to do with a hand-held lightmeter is to waste a lot of my time to get enough data. Architects have modelling software which helps with this stuff, but before I spend the bucks retaining one I wanted to do some basic, order-of-magnitude calcs to see if it's even worth considering. And given the power consumption of our lights alone, the answer is simple- windows don't make sense.
What we've got to do yet is hunt down where the REST of our monthly power bills are going!
Daylighting design can be difficult. You can get good results using basic principles. Not every architect has the skill set ... but should have some solid insight to provide some good daylighting. State of the art in daylighting design involves creating a model of the building and testing it in a laboratory. There really is no such thing as a technical factor for how much dayligting you get from a sqft of window.
If you have hot summers ... avoid east/west windows ... is your long axis oriented east west? South and north windows will work nicely for daylighting. Protect the south windows with eaves/overhangs for the summer condition.
The solar wall thing can work to preheat the ventilation air. Nice product, but you need to take care in how you apply it. In the summer, it will still preheat the air ... unless you treat it like a window and protect it from solar loads. Or provide a secondary intake for summer.
Sounds like you might need to take stock of your loads. Do you have lots of welding loads? If you weld a lot, you likely ventilate a lot ... = lots of energy summer and winter. Spot exhaust for welding can be great ... reduces volume of air used and increases comfort.
Don't underestimate the value of comfort in a situation like this. The cost of discomfort to a business can be huge! If staff are uncomfortable even only 5% of the time, it's easy to calculate your cost for that discomfort.
I'd continue research on lighting options a little. Also consider lighting controls. If you daylight, you should have lighting controls ... but HID don't usually do well w/ on/off situations, so the T-5 might work well.
Sounds like you've got a lot of issues that deserve more than minimal design services ... and you have a desire to do things right, maybe. Put in the extra time/effort now to do it right and you will have a better project in the long run.
I FULLY advocate daylighting ... but it must be done thoughtfully and not just thrown together with a bunch of windows. A good window product might be Kalwal sandwich panels. This comopany has a LONG history. Expensive product, but VERY GOOD daylighting potential and energy efficiency (down to 0.10 U-val I believe).
You might consider a green design consultant to help pull all the components together. You've got lots of systems and they need to work together to be effective.
Thank you very much for your very thorough and well-considered reply.
We're still assessing our loads to find the hidden grow-op! It turns out that our lighting cost, while significant, isn't as large as we'd have guessed as a fraction of our electricity bills.
One thing we spotted right away was that our welders all run off the SAME pair of phases! Simply switching the wiring of their plugs so they're more balanced across the phases is going to save us some money.
We do weld a lot but we use mostly TIG and hard-wire gas shielded MIG- very clean. We do use local exhaust but we also have some lousy old louvered vent fans that blow conditioned air straight out the wall. We also have a paint booth with a huge exhaust fan, and no heat recovery on the make-up air. Fortunately, we only use the booth intermittently. It surprises me that our heating cost is as low as it is, all things considered.
Molten,
If you do a lot of welding ... it can consume lots of KWH, I think. My expertise is commercial energy, not industrial ... but I've worked w/ lots of light industrial applications.
If you have local exhaust for all your work stations, I would eliminate the general exhaust ... it actually works against the local exhaust by reducing somewhat the air being sucked out. I'd take steps to add what ever is left from any missing local exhaust 'stations' and eliminate/block off the general exhaust. (are you sure that isn't a ventilation air intake?). If welding is relatively 'clean', focus on tayloring the exhaust amount to each station ... you can fine tune local exhaust to your needs so that you don't over exhaust. You might also consider a variable speed drive on the exhaust fan if you find that not all stations are frequently exhausting simultaneously.
I assume you have shut off gates for each exhaust station? and that they are used?
Don't know if there are issues w/ e.g. heat recovery from a paint booth due to the fumes (i.e. vaporized paint). If the vaporized paint is caught in some kind of 'filter', you should be able to recover heat from the exhaust. Actually ... contacting a current paint booth distributor may answer the question ... can I recover heat from paint booth exhaust. But, if you don't use it frequently, I'd push it down on your priority list a little.
Lots of daylighting can make a very comfortable work environment ... this means productivity in more ways than one. Plus you save light energy. What is your aprox elect cost and no./size of your lamps ... I could guesstimate potential savings due to daylight for you ... if you like.
At any rate ... good luck on your endeavors
Don't forget compressed air leaks. HUGE energy costs.
That one we've got covered, given what we do for a living!