Light suggestions

Are you having issues with heat in the enclosure? I would think that with the size of the enclosure, it should be able to handle a couple of T8 fluorescent lights (shop light) in there. You can move the ballast outside of the enclosure to reduce the heat inside. Alternatively, you could try some T8 LED bulbs. Here is what I tried in my blog post. This Sunritek has extremely high efficiency (means more light and less heat), but it is not easy to get if you don't want to buy a lot of them (e.g. 20 bulbs). But there are less efficient, but decent ones. Here is an example: Hyperikon Hybrid T8 LED. With Hyperikon, it would be better if you can remove the ballast of the shop light like I did in the blog post (less heat, higher efficiency). But if it is too difficult, it can be used as a direct replacement on the shop light without any modification.

HomeDepot carries Philip InstantFit T8 LED, which has moderately good efficiency.

Also in the 2nd page of this thread, Marni and Kelly talk about the LED shop light (not bulbs) from CostCo and Wallmart/Sam's Club.

When you are looking for LEDs, you have to be pretty careful because there is a HUGE variation in efficiency. Some of them are not much better than fluorescent light (i.e. it will generate similar amount of heat). Lots of them still have pretty low efficiency from the older technology. So you look at the lumen output and divide it by the actual energy consumption (wattage). Previous generation LEDs are about 90 lumen/W or less. The best one is around 150 lumen/W (e.g. Sunritek).

If you are a little handy, DIY LED is the best way to go (cheaper and higher efficiency than any of the reasonably priced commercial offerings). I can provide more info if you are interested.

If not and if you can afford, there are some high efficiency grow light (<- this link is an automatically generated link by the forum software, and I wouldn't recommend this product, other links are provided by me). If you are ok with purple, BML has very good products. Spydr 600 GrowMax will cover your area nicely. But if you are supplementing, you can go with lower amount than Spydr 600. Actually, they have announced a new model a couple weeks ago, which has even higher efficiency. But I don't know the price and details. Here is a video of the release:
http://www.bmlhorticulture.com/full-spectrum-grow-lights/
They are called Fluence (a new brand by BML) SPYDRx and VYPRx. I heard that they are taking the order already.

Alternatively, Area 51 makes a very nice one, too. It is white, and uses newer technology (so high efficiency). 4 of those will cover your area (hopefully that the heigh of your enclosure is tall enough for those).

Those may look expensive, but with LEDs, it is either you pay now (higher initial cost for the fixtures with lower cost of electricity) or you pay later (cheaper initial cost, but a lot more electricity cost). Depending on the local cost of electricity (and the mind set about environmental impact), there is a best balance for each region.

 

Your vent may work to lower the temp, but don't they suffer from low RH if your ambient RH is really low? You might not think that Alaska is dry, but the preciptation of interior alaska is basically desert. So I have to fight with the low relative humidity (<20-30% in the winter), too. I also have a thermally controlled exhaust fan to my grow tent. When it kicks in, the humidity goes down quickly, and the automatically controlled humidifier kicks in. So it is wasteful. When I was using fluorescent light, this used to happen in the summer. Now, with high efficiency LEDs, I don't need the exhaust fans nor humidifier (less wasted energy), and I can keep >70%RH (typically 80%).

I looked up, and AZ has a pretty low electricity cost ($0.098/kWh while I pay almost twice; $0.183/kWh), so from the economical point (not from the ecological view point, though), it is ok to stay with low efficiency light. For low efficiency light, I would think T8 shop light is the way to go. 32W T8 gives similar amount of light as 40W T12. Efficiency of T5HO is similar to T8, so if you don't need high density of light, there is no reason to go with T5HO.

"lumens" are not the unit to be used for the growth of Phals. It is used to assess the total output from the lamp. If you put the lamp far away, then the plants can't photosynthesis efficiently. Similarly if the beam pattern is focused (e.g. flood/spot light), plants can get much more light than a light bulb with wide beam pattern (e.g. fluorescent bulbs with no reflector). So the density of light (1 foot candle = 1 lumen / square foot, 1 lux = 1 lumen / square meter) is more relevant. There are variation among Phal species (e.g. P. amabilis, P. tetraspis, P. cochlearis etc seem to be ok with much lower light than P. cornucervi group), but 500 fc or so (of constant light) seems to be ok.

For low light orchids, 6-8 bulbs of 32W T8 or 40W T12 would be a good start for the size of your area. But since you are using it as supplement, you can be ok with less depending on how much natural light you are getting. I'm pretty sure if you put 8x T12, the vent has to be open most of the time. low efficiency means more heat for a given amount of light.

Finally, lumen may not be a good unit when you are comparing white light vs purple light. From my measurement, plant spectrum fluorescent light can have much more plant relevant light (called photosynthetically active radiation, PAR) than the lumen or fc values indicate. So your plant bulbs may have lower lm/W, but it may be ok.