Lighting experts, interesting challenge, need some advice

[Don Kondra]

You really need to do something about insulation...

I cool a 900 sq. ft. shop AND a 700 sq. ft. house with 12,000 BTU's.

Granted it very rarely gets over 100 degrees here and then the temperature inside is creeping up to 75

An "average" heat spell is around 90 degrees.

BTW - my walls are R30 and ceiling R40.

Cheers, Don

[Joe Jensen]

I ended up ordering Sylvania High Efficiency ballasts and Sylvania Ecologic 25W bulbs.

thanks for the inputs...joe

[Leo Graywacz]

Let us know what happens.

[Chris Damm]

It sounds like you turn off your AC and turn it on in the morning when it's already 85°-90°. I've found that my mini-split system works better when I just leave it on 25/7. It doesn't work as well it catch up mode.
I do agree that changing to T8s will help reduce the load. I have been thinking about the same thing for my shop but the extra heat in our cold winters is nice!

[Joe Jensen]

Update. I measured the current on the circuit for the old system which was 9 troffers with 4 bulbs each. 36 bulbs, all were 40 watts. I was drawing 14.6 amps on a 120V circuit. I took the advice of the forum and decided to keep the fixtures and just change the ballasts and bulbs. The old ballasts must be at least 40 years old. I choose high efficiency Sylvania. Online they were $50-80 each but I got a box of 10 on ebay for $140. I choose high efficiency Sylvania 25 watt bulbs. These bulbs have almost the same lumens as my old 40 watts bulbs. I did have higher CRI bulbs in the 40 watt, if you look at specs, to get higher CRI you sacrifice efficiency. I think the old were rated around 87 or 89 CRI and 2400 lumens or so. The new bulbs are rated at 2200 lumens and a CRI of 85.

The bottom line, I'm very pleased with the savings. With the new ballasts and bulbs I am now drawing only 6.67 amps. But that doesn't make total sense as 6.67 amps which at 120V is only 800 watts and 36 bulbs at 25 watts each is 900 watts alone. Must be that the bulbs don't even draw 25 watts each.

The test method was the same in both cases, true RMS clamp meter on the single lighting circuit. overall a 950 watt savings, and more importantly, 950 watts less dumped into my shop.

As to the insulation in the shop. I installed R17 insulated doors last summer. The ceiling above is insulated with 8" of fiberglass, and the attic above that is insulated as well. We can't install more insulation as the space above is a storage room. The long wall of the garage abuts the house to that wall is not an issue. Part of one side wall abuts the house as well. The balance of the side walls are not insulated and I am looking into how to get them foamed. The front where the doors are is basically all headers and supports other than the doors.

[Jim Neeley]

Joe,

With you living in Phoenix I recommend looking at the cavity thickness of your two uninsulated outside walls. If they're not as thick you'd like I recommend considering a 2x2 or so firring strip on the inside and insulating the whole thing at once. You pay for insulation once but you pay for heating and cooling monthly.. for as long as you own the home.

Just something to consider... I've yet to hear one person tell me that they wished they would have installed *less* insulation during their last upgrade, wishing for *more* is everywhere.

Jim

[Joe Jensen]

I've considered just stripping the drywall from the two side walls, insulating and then re-drywalling. I'm not concerned with the cost, but I have a large saw station that takes up the entire west wall and moving it would require me spend maybe 6-8 hours re-leveling it. I would also have to remove a bunch of electrical in conduits and also redo several dust collection lines that are hard installed.

I only use the AC maybe 10 weekends a year so the cost isn't really a consideration. I just want the AC to be able to handle the load and insulation will help.

I did a lot of reading about retrofit foam in the cavities but it looks like to have a really reliable job you need to drill holes in the wall every 2 ft. Most companies do this on the outside of the house and with our stucco outside the house I can't imagine that repaired holes every 16" horizontally and every 2 ft vertically would be invisible.