Efficient Grow For A 6x7x9' Room Cheapo T-5 Ho Vs. Bad Bay T-5 Ho Vs. Hps

[DGP]

When I started looking for thermal data on T-5 HO (54W) bulbs I could not find anything that described the thermal characteristics of T-5's. In other words, for a given power rating (54W) how much heat was added to the room from natural convection, from radiation and the inefficiencies of the electrical system (ballasts). I have read a number of articles and read some grow logs that seem to indicate high quality T-5 HO's can keep up with HPS with a lower overall heat load. I don't know, I am just experimenting.

I have seen so many arguments about how hot each type of lampo runs how efficient each one is but I just wanted to gather some real data and just see what they do one against the other in the same room with the same boundery conditions.

So, I have a room that is in a garage and is insulated top and sides to R11. The floor is concrete. It has a mini-split A/C unit in it. I used a 600W HPS on a light mover for the last grow but my A/C costs were real painful. So when SUmmer came I moved a group of girls outside in an enclosed locked area.

So, I ran an experiement running one fixture in the room and seeing how much that volume of air would heat up with no supplementary cooling. I used a commercial T-5 for my first run and it came out that with ballast inefficiencies etc there temperature rise was 2.5 to 3 degrees F per bulb.

Now I am re-running the test with Bad Boy T-5 fixtures to see if their claim of 30% efficiency gains are true.

I will also be running the same experiment with my 600 w HPS. I wanted to know for each watt consumed how much does a given lamp tecnology give you in heat increase per per cubic foot. The idea is to compare similar power levels. My 600 watt HPS is being compared to two 8 bulb T-5 fixtures which is more like 900 watts total.

The one good thing I see about T-5's is the light is distributed much more evenly over the 4 foot space and the reflectors on the bad boys seem very high quality. The HPS seems alot more point source and varies more over the area being lit.

I will post the graphs once they are done.

So far the rough data is:
Cheapo T-5 fixture: Raised the room temperature 3 degrees F per bulb or about .008 degees per cubic foot

The Bad Boys are running about: 1.25 to 1.5 Degrees F per bulb or about .004 degrees per cubic foot

The goal is to run the Fall, Winter and Spring grows during the cold weather and see if we can do it without any A/C or mybe rarely used A/C. My other hope is the heat from the bad Boys will be useful in the cooler months instead of having to run heaters as well.

This is with no A/C and no active venting.

DP

 

[rmoltis]

When I started looking for thermal data on T-5 HO (54W) bulbs I could not find anything that described the thermal characteristics of T-5's. In other words, for a given power rating (54W) how much heat was added to the room from natural convection, from radiation and the inefficiencies of the electrical system (ballasts). I have read a number of articles and read some grow logs that seem to indicate high quality T-5 HO's can keep up with HPS with a lower overall heat load. I don't know, I am just experimenting.

I have seen so many arguments about how hot each type of lampo runs how efficient each one is but I just wanted to gather some real data and just see what they do one against the other in the same room with the same boundery conditions.

So, I have a room that is in a garage and is insulated top and sides to R11. The floor is concrete. It has a mini-split A/C unit in it. I used a 600W HPS on a light mover for the last grow but my A/C costs were real painful. So when SUmmer came I moved a group of girls outside in an enclosed locked area.

So, I ran an experiement running one fixture in the room and seeing how much that volume of air would heat up with no supplementary cooling. I used a commercial T-5 for my first run and it came out that with ballast inefficiencies etc there temperature rise was 2.5 to 3 degrees F per bulb.

Now I am re-running the test with Bad Boy T-5 fixtures to see if their claim of 30% efficiency gains are true.

I will also be running the same experiment with my 600 w HPS. I wanted to know for each watt consumed how much does a given lamp tecnology give you in heat increase per per cubic foot. The idea is to compare similar power levels. My 600 watt HPS is being compared to two 8 bulb T-5 fixtures which is more like 900 watts total.

The one good thing I see about T-5's is the light is distributed much more evenly over the 4 foot space and the reflectors on the bad boys seem very high quality. The HPS seems alot more point source and varies more over the area being lit.

I will post the graphs once they are done.

So far the rough data is:
Cheapo T-5 fixture: Raised the room temperature 3 degrees F per bulb or about .008 degees per cubic foot

The Bad Boys are running about: 1.25 to 1.5 Degrees F per bulb or about .004 degrees per cubic foot

The goal is to run the Fall, Winter and Spring grows during the cold weather and see if we can do it without any A/C or mybe rarely used A/C. My other hope is the heat from the bad Boys will be useful in the cooler months instead of having to run heaters as well.

This is with no A/C and no active venting.

DP

Some factors to consider when data logging your info.

1.) You will want an outlet meter that tells you the actual draw at the outlet so you have a better comparison. (For example my 2ft 8 bulb t5) runs 24 watt/bulb which should be close to 200 watts. But my actual draw is 160 watts. So just make sure when comparing you try to use a close match via electrical draw or your comparison will be off ;).

2nd. You will want to calculate your light per cubic ft as well. If your trying to create enough light for quality flower. My 2ft 8bulb ho t5 is in a 4 cubic ft space claiming 2000 lumens per bulb or 16000 lumens divided by 4cu ft. That equates to 4k lumens per square ft in my seedling/veg chamber.

Once the light density has been focused you will really be testing the temps. Because with a small ventilation fan that 4 cubic ft space hits 80°-85°. And with no fan I hit °90-°95.

So heat can get hot once light density is focused.

My 400w light (430watt draw at the wall) heats up my 2x2x5 (20cu ft) flowering chamber with ventilation fan to (80° mh) and around (°85-°87 HPS) house temp going In is a steady °70-°72.

I honestly feel that since t5s are less efficient at converting electricity into lumens/light when compared to hps. But can be higher when compared to mh.

That building a similar output system would create the same amount of heat in my book.

For example my 400 watt hps puts off 55,000 lumens at a 430 watt outlet draw that's 137.5 lumens per watt.
My hot5 is rated for 16000 lumens at 160 watt wall draw that's 100 lumens/watt(unless the cheap fixture doesn't supply full power to the bulbs). If that were the case let's use 16000 lumens divided by the rated 200watts that's still 80 lumens per watt.

The 400 watt mh of mine is rated for 29k lumens @ 430watt wall draw. That is 67.44lumens per watt (but of rich full spectrum).

I'm not bashing any of your ideas, goals or tests. Just adding input and variables to consider in your testing.
Can't wait to see what you decide on.

 

[DGP]

Thanks for the response and information. Yes, I have a kill-a-watt meter on the fixtures. Each is drawing 430 watts. My point of comparison is heat per tube right now between the 2 T5 systems. then when I compare HPS to T-5 it will be more challenging because the light sources are so physically different. Also, my next step is to turn on some ventilation. The first test was without vents just to calculate the true heat load. The first question was just how much heat is created since I know the lumen output of an HO T5 system. Of course the light values are at different distances. However, what I like about the T5's like I said before is their more even distribution of light vs. a more point source type of bulb.

One o fthe experts I have advising me has pointed out that often people try to use too much light. An example would be blasting small plants with a 1000 watt HPS when they don't need that much light til much later in their life. I think this is due to everyone thinking they need that next great 1,000 watt double ended bulb. His theory is if you give a plant more than 100% of the light they need they stop growing. so why burn a ton of electricity during phases of development that don't require it?

BTW, I have experience in lighting design and thermal analysis but I am only on my 3rd grow and have a lot to learn. In the cannabis equipment world hype seems to be king but I like data. If t5's are useful for more than just vegging (and I think they are) then I want to understand them as another tool in the grow. Are the Quantum Bad Boys really great? A lot of reading I have done say they are better than many other T5 systems but I want the real data in my real situation.

I have also studied LED's and the jury still seems to be out. Many of them are very small and because of the way LED's distribute light the footprint is very samll on many of them. The onlt system I see out there right now that attempts to solve this is Spydr and spydrX models. However, they start at $900 and go into the thousands.

My goals are to:
1. Find a way to cool the room with less energy and still get decent yields. Can I use HPS during the cold months especially for the last part of flower when more light power may be the most useful? Maybe that would be more efficient.....
2. Compare the two T5 systems to find out if the 30% more efficient claim Quantum makes is measurable and real
3. Learn about growing with T5's in flower

If I know exactly how much each light source makes in wasted heat (at least it isn't wasted in the Winter if it is fairly cold outside) I can do an actual thermal simulation and change various varibles like location of inlets vs. outlets for vents, various vent inlet temperatures and what the limits are (when to vent from the outside and when not to etc.).

Thanks,

DP

 

[rmoltis]

Thanks for the response and information. Yes, I have a kill-a-watt meter on the fixtures. Each is drawing 430 watts. My point of comparison is heat per tube right now between the 2 T5 systems. then when I compare HPS to T-5 it will be more challenging because the light sources are so physically different. Also, my next step is to turn on some ventilation. The first test was without vents just to calculate the true heat load. The first question was just how much heat is created since I know the lumen output of an HO T5 system. Of course the light values are at different distances. However, what I like about the T5's like I said before is their more even distribution of light vs. a more point source type of bulb.

One o fthe experts I have advising me has pointed out that often people try to use too much light. An example would be blasting small plants with a 1000 watt HPS when they don't need that much light til much later in their life. I think this is due to everyone thinking they need that next great 1,000 watt double ended bulb. His theory is if you give a plant more than 100% of the light they need they stop growing. so why burn a ton of electricity during phases of development that don't require it?

BTW, I have experience in lighting design and thermal analysis but I am only on my 3rd grow and have a lot to learn. In the cannabis equipment world hype seems to be king but I like data. If t5's are useful for more than just vegging (and I think they are) then I want to understand them as another tool in the grow. Are the Quantum Bad Boys really great? A lot of reading I have done say they are better than many other T5 systems but I want the real data in my real situation.

I have also studied LED's and the jury still seems to be out. Many of them are very small and because of the way LED's distribute light the footprint is very samll on many of them. The onlt system I see out there right now that attempts to solve this is Spydr and spydrX models. However, they start at $900 and go into the thousands.

My goals are to:
1. Find a way to cool the room with less energy and still get decent yields. Can I use HPS during the cold months especially for the last part of flower when more light power may be the most useful? Maybe that would be more efficient.....
2. Compare the two T5 systems to find out if the 30% more efficient claim Quantum makes is measurable and real
3. Learn about growing with T5's in flower

If I know exactly how much each light source makes in wasted heat (at least it isn't wasted in the Winter if it is fairly cold outside) I can do an actual thermal simulation and change various varibles like location of inlets vs. outlets for vents, various vent inlet temperatures and what the limits are (when to vent from the outside and when not to etc.).

Thanks,

DP

This will be a fun thread to read. I like data and it seems you will be providing some. Good luck on your endeavors.

 

[DGP]

So, I re-measured all my equipment from fans to AC to lights and all. The most power I would be using at any given time is a little over 2 kw. So, at our electric prices (off peak and mid-peak) we could only spend about $40 per month and $80 if every peice of equipment was running 24/7 including the lights and AC. I will have to talk to my wife about the reality of how much AC is being used in the house vs. my grow. The whole thing that started this experiment was the fact that my power bill (and my wife) were the biggest threat to my grow. This month with all the plants outside and no major grow room activity I will have to see what my power bill is even though the weather is colder....ahhh nothing like some confounding boundary conditions.

Our power here is between 6 cents and 13 cents per kwh depending on time of day use.

I am about to sneak the house A/C programming up to 78 instead of where everyone likes it to be (around 72).

DP

 

[outnin]

I have a couple of thoughts
they now make led t5 tubes that output about 90% of a t5 florescent and use 2 less watts less watts = less heat.
these tubes reguire a different ballast than a florescent "smaller less power draw" and can be remotely wired.
I have found that placing your ballasts in a closet or other place separate from the grow helps enormously as well.

 

[DGP]

I have given some thought to removing the ballasts from the bad boys and wiring them outside the room. I don't know if there is an issue with long runs of wire from the ballast to the fixture though. I also thought of enclosing the ballasts and forcing air thru them and out of the room but that makes for some complications regarding where to get the air from and where to send it.

So, here is a graphic of the run using a cheap fixture and with T5 HO's. The little dip at the beginning is a measurement error. The blue line represents the FLower room under test. I noted the Garage and outside temperature along with the workroom temperature which is also adjacent. one of the long walls runs inside the garage and the other is facing outside. One short wall is adjacent to a workroom which is never over 75F and the other short wall faces the garage interior.

4 lamps increased the temperature by about 12 degrees or 3 degrees/bulb.

 

[DGP]

Ok, so here is the data running 16 bulbs in 2X8 bulb T5 "Bad Boy" Quantum fixtures. They do seem more efficient as the raw data indicated earlier. The run was shut down at about 250 minutes and the total increase in temperature was 21.7 degrees which means each bulb was adding 1.4 degrees. With the standard fixture in the previous run at 2.5 to 3 degrees it appears to be about 2X more efficient thermally. The ballast enclosures seem quite cool to the touch as well. Now on to the HID lamp and then some ventilation experiments to see if I can reduce the AC to almost nothing (at least during Fall through Spring). Remember all these tests are being done with the AC shut down to just get the thermal load of the lamps, ballasts and any radiation heating of the room.

By understanding the heat load I can say for example, on a 60 degree day I can get by without AC so when the average daily high tempoeratures are below 60 my lamps will run without AC and hopefully most days I won't need a lot of supplementary heat either.

DP

 

[DGP]

Here is the thermal run for the 600W HPS. Not sure how to compare it to T5 but in this case the T5 was 900watts total vs. 600 watts for the HPS. It is hard to compare but I think the 2 banks of 8 bulb T5's will give me better coverage but will obviously have to be closer tothe plant tops.

The HPS bulb raised the temperature by a total of 18 degrees F. If I turned off 4 tubes on one of the T5 fixtures the total power would be about 600 watts and would have raised the room temp by 18 degrees F. So, I guess it comes down to a personal choice between T5 and HPS.

The experiment is not over though as my goals are to look for every way possible or practical to reduce energy costs. Ideas such as outside air ventilation when temperatures outside are favorable to cooling, bringing cool air in from the house when outside air temps are not favorable (too hot) or insulating all my ductwork. maybe even remotely mounting the T5 ballasts???

Apparently, all things being about equal (power input) a high quality T5 fixture creates almost as much heat as an HPS but a cheapo T5 fixture is not such a good idea. In this case the cost of the Bad Boy Quantum fixtures seems to have been a good choice as far as T5's go.

I am interested in other ideas that anyone may have as well as other T5 experiences people may have had.

Cheers,

 

[DGP]

Summary:

Standard T5 Fixture:
Input watts: 54/tube
Lumens: 5,000/tube (total would be 60,000 for 600watts of input (12 tubes))
Delta T per bulb: 3 degrees
Heat load: .008 degrees/cubic foot of room space (.096 degrees/ft3 for 12 tubes)

Quantum T5 Fixture
Input watts: 54/tube
lumens: 5,000/tube (total would be 60,000 for 600watts of input (12 tubes))
Delta T per Bulb: 1.5 degrees
Heat load: .004 degrees/cubic foot of room space (.048 degrees/ft3 for 12 bulbs)

600 watt HPS standard fixture (no glass, no ventilation)
input watts: 600
lumens: 80,000 initial
Delta T for bulb: 17 degrees
Heat Load: .044 degrees per cubic foot of room space

So, from my amauerish experiement I would say the HPS wins by a small margin over the best T5 system for efficiency. However, the tube life of the T5 is 20,000 hours and the light output is very consistent over the life of the bulb. Also, to get to 80,000 lumens (ignoring the distance differences) there would need to be more than 12 T5 tubes used, 16 to be exact. SInce the T5 lights would be used at 2-6" and the HPS at about 18" there are differences in grow style. Some argue about the quality (spectrum) of the light and node distance when T5's are used close to plants. SOme also argue about true light penetration. So, comparing T5 to HID/HPS is an awkward comparison at best. In doing some pretty extensive research I have seen some beautiful results with both types.

I am still considering the possibility of remote ballasts for the T5's and what impact that might have.

My next experiment will be to run the HPS with glass on and 120 CFM of outside air going through the lamp and back outside into the garage. This way I am removing some of the heat from the lamp (not radiant or the heat load from the glass temperature) to the outside without wasting inside air that would eventually be air conditioned. SOme experts have claimed the glass and hood metal are the hottest items in a grow when glass is covering the lampo but I want to see the data.

Hopefully, if nothing else, the heat load data will help people predict what the effect of a given fixture will have on their room or tent space.

DP

 

[DGP]

Ok, so no big surprise but running an isolated air supply through the lamps makes a huge difference. I just didn't expect such great results. I suppose there are tiny leaks but I would thin that if one filters the incoming air and it only goes through the lamp at then back outside then the room would still be considered "sealed".

Only an 8 degree rise in the room and the room stabilized very quickly.

Other interesting facts: the hood is about 95 - 100 degrees F (surface temp) so adding an insulating blanket to the reflector hood (top and sides) may help even more. The glass temperature doesn't seem to be a big problem but it is a factor. It is hard to measure with my non contact thermometer because there is so much radiation present.



DP

 

[DGP]

I went back through all my electrical data and tried to make a solid estimate of what my increased energy costs were during my first 2 grows. The hard part to figure out is what is our increased usage due to (besides the grow). We had a relative move in during part of it and that certainly will show in energy usage and this year's bills were higher by about $40/month before the grow started. Also, each year the weather patterns are different. As near as I can tell I am spending $90 - about $135 (Summer) more per month. It seems I can trace most of our energy usage to the house AC and the amount of laundry that gets run each month. The other factor is the rest of the family uses most of their energy during "peak" hours where the power is 2X as expensive while my grow is almost entirely during "off-peak".

I found a corrected a number of efficiency issues in the grow as well and am anxious to see how much that saves. My wife was all outraged about the electric bill and was over exagerating for one thing. I downloaded all the weather, daily usage etc from my power company and built a spreadsheet to show moving averages and trends related to grow room activities as well as the weather.

The upper chart is my actual usage (daily) and the second chart is just a moving average to show general trends. It is interesting that my usage moving average makes a curve that almost fits the average outside temperature curve. This is why I think the hosue AC is what was killing us. I set the thermostat to 78 and pissed everyone in the house off.......

 

[DGP]

Tonight's testing as well as the rest of this week will be doing power cunsumption measurments of each device. Some things like an HPS lamp don't take long to test because they are 100% duty cycle. However, the AC system is dependent on outside temperatures and how long the average temperatures have been trending up or down.

So I put a KWH meter on the AC on a day when I would say it is the typical weather for a Mid Summer day. Tonights run is with the lamp cooled by forced air and the glass on the hood. I will be adding filtered outside cool air at night on a thermostat. I have noticed the temperatures outside after 8pm and before 8am are almost ideal for bringing in outside air to keep the grow cool at night (maybe without AC).

I will post some results of the power study soon. I guess my goal for this test is evolving. First it was to figure out the differences between HPS and T5 but now I want to find all the inefficiencies and tune up the room befor ethe next flower cycle begins.

DP

 

[rmoltis]

Yeah I think your woman was exaggerating the power cost of your setup.

My kill-a-watt meter has my whole tent running through it. 400w mh/hps, lower chamber t5, 6" 400 cfm can fan, clip on fans, fan controller. My total electrical useage was $60 over 105 days not counting a/c costs.

I removed a/c costs because the past 4 years before growing it runs almost full tilt and electric bill was around $200/month. And that cost hasn't really changed at all.

To compensate I installed some 5000k led bulbs in the house. Existing cfl's were 25 watts each. Now I have mostly 4w Cree bulbs along with four 9 watt feit electric bulbs for certain rooms.

Total current draw was reduced %75 (if all bulbs are on which happens more than you think).

This can be a cheap way for you to reduce house costs a little.

The other tool I use is this weather history website.
https://www.wunderground.com/

Using your city and dates of the year you can see daily temp plotted on a graph over time (as well as other weather variables). And you can find the peak temp parts of the day most ideal for having your lights off relative to your location. Very useful for reducing a/c demands during peak temps. While running your grow room during the cooler parts of the day (along with I'm assuming lower power costs from off peak useage?)


Another note is that if you have an air cooled hps/mh you could drop that light directly to the canopy of your plants.

You said 18", but I got mine much closer with no ill effects (mine is 400w, not 600w). Same concept though. As we all know the closer the light to the canopy the more intense the lighting.

 

[DGP]

Thanks for the information from your grow. Yeah, I am going down to the hardware store to get a couple more Kill-A-Watt meters to keep them plugged into most of the feeds to the room so there will be NO argument whatsoever about our true cost to grow. I think when plants are in full flower they are more tolerant of being quite close to the lamp. That has been based on my limited experience of 3 grows. The last grow the flower spikes were very close to the lamp and I never saw any burning or symptoms of too much light.

We also replaced all our indoor lighting to LED at 8watts per bulb as opposed to 60 watts. I am about to replace all my shop ligthting to LED as well. Ace has 60W equivalent regular Edison style LED bulbs for $12 per 4 pack (a great deal).

We also:
-reuse bath/shower towels 2 times or more (hang em up to dry)
-Turned cooling thermostat in the house to 78 as opposed to 72F
-I am constantly turning off and disconnecting things that get left on in the house
-Encouraging everyone to rinse and reuse their dishes during the day so we don't have to do so many dishes
- Cleaning all house filters on a strict schedule
-Set my computer to "sleep" after 10 minutes (goes from 200 watts to 12 watts!)
-put fans in the house on timers (the typical box fan uses 100 watts!)
-Found out how to log into my electric companies web site to monitor hourly, daily weekly etc. power usage vs. outside temperatures etc.
-Dumped all the data from the elctric companies website into a comma delimited file to graph (excel) all the relavant data.

Since my current testing is being done during the hottest part of the year for Western Oregon I beleive my numbers will be absolute "worst case". Also, I was conservative on the price per KWH because we are on a three teir pricing system and 90% of my lights on time is during the cheapest rate and during the time when we have the lowest average temperatures outside.

My Ideal Air split AC burns about .9KW/hour with a total for the flower room of 1.69 KW/hour for this worst case time of the year. Also, when I bring a vent in from the outside I will leverage the evening and nighttime outside air which even in the Summer runs about 55 avg degrees. It drops to 70 by 8pm quite often and rarely exceeds 70F before 8am.

My list:
-Finish power study in the current configuration
-Add thermostatically controlled venting to the outside (filtered)
-Upgrade all 6" and 4" ductwork to R8 insulated duct (my split AC exhaust pipe which is 6 feet long gets to 92F and thius is just another heat source)
-Maybe add insulation foam sheets to my R11 walls to bring them up significantly in "R" value

On a very hot evening my total power draw for my 6'X7'X 9' flowering room
-.90 for Split AC
-.63 kw for 600 watt HPS
-.110 for 4" inline boost fan to cool lamp only
-.050 for a 16" Hurrican oscillating fan on medium

These values represent absolute worst case based on the hot weather
Total: -1.69KW/hour
Cost per KWH .06 to .09
Cost per day at Worst Case:$1.82
Cost per month: $55
Cost per flower cycle: ~$110
Cost per year: $660

Now I need to calculate/measure the veg room costs and any overhead for misc things in the work room like the computer and work area lighting.

DP

 

[DGP]

I did some planning on a calendar and I just can't wait for the outdoor plants to go into flower in mid September. This means no harvest this time around. Also, I have been looking outside at night and there is a street lamp right across the street and I think they would have never transitioned into flower because of the ambient light levels.

So, I am confident I can keep the flower room costs under control now and they will improve as I make more changes and when the weather cools back down in the Fall. Right now I have eight plants in a scrog net uder one 600 watt HPS that is being cooled with air from inside the house and is exhausting out into the garage. Currently I am using a light mover so I can get closer to the plants and cover a slightly larger area. I also like light movers because the plants see a wide variety of light coming from many angles. I have to think this helps with penetration.

Tonight I set up the timers, fans etc. and trained the plants into the scrog so the canopy is one very consistant height. I will add a second net later as more training is needed to keep all the girls at the same height.

During late flower I will switch to a 1,000 watt bulb. These plants vegged outside and they got bigger than any of my last crops in veg. Hoping for much better success on grow #3.

BTW, I tried starting these plants out on 16 X T5 HO's (2 BAd Bay 8 bulb fixtures) but my hourly AC usage was 1.10 KW per hour instead of .90 with the HPS and isolated lamp cooling. So, the HID HPS wins for efficiency. I think if the T5 ballasts were outside the room the heat load might be about the same as the HPS but it would be a hassle to remove the ballasts and mount them remotely. Maybe it is worth while though.....

Now I will add an outside vent to make it more efficient during the night when the temps outside a quite cool.

DP

 

[DGP]

Just for reference, I am running my HPS lights from 8pm to 8am when power is half the price and the outside temps are low. Added the nightime outside vent which comes into the room with 4" ducting to a 170cfm inline fan and the out aHEPA filter into the flower room. It is on a timer so during the Summer it will bring in average temperatures of around 55F. Since the HEPA filter probabably reduces the flow significantly I will probably get less air changes per hour which is good. At 170 CFM the air would change thirty times per hour and that is way too high. I expect I am getting a 70CFM at best which is about 10-12 air changes per hour. If the incoming temperature of the vent air is 55 - 60 deg F then the AC should not even be on at night. Maybe it will run a little at first when the room starts up the lights at 8 pm and the temps outside might still be at 70 or slightly higher. Anyway, I bought a pile of wattmeters on amazon and my hope is i can track ALL my power usage and take a reading every 24 hours. Then the numbers are the numbers and the power for the grow will be precisely tracked. Also, any efficiency changes I make will be easy to evaluate.

It will be interesting to correllate the outside weather with the indoor operation costs/energy usage over a year or so. After Summer when the average temps fall below 70F I will convert the fan bringing outside air to a thermaostat controlled switch. That way whent he temps outside are favorable it will bring in cool air and take some load off the AC. Technically my room is still sealed but I am counting on having the room at a slightly higer ambient pressure so mold spores and tiny bugs can't easily get in.

DP

 

[DGP]

Bringing outside air in at night during lights on was the right decision. For the 12 hour lights on period the flower room burned only about 5 KWH which is about half. Also the temps yesterday were quite high (in the middle 90's) so this was a good run for a worst case day.

Now the rub is the veg room which is also using too much AC. I will be adding a cool air inlet for it as well and I would expect to half the AC costs. Also, my garage (which surrounds the grow rooms on 2 sides and the ceiling is running way too hot in the Summer. I will be installing a gable or roof fan and thermostat to keep the big heat bubble somewhat under control.

 

[DGP]

So the experiment is almost complete.

Here is what I did to make the room as efficient as possible:

1. HPS lamp on a light mover (600 watts with the option to go to 1,000 watts during late flowering if needed)
2. Lamp cooling is with forced air from an outside source (adjacent room) and exhausted outside. Lamp uses cover glass so the air cooling is pretty much isolated from the room.
3. Using insulated ducting for:
-Split AC exhaust (the exhaust duct gets really hot)
-All cool air air intakes
4. Using the more efficient Quantum T5's for vegging and propagation
5. Forcing cool filtered air into the rooms at times when the outside temps are at an advantage and especially at night when lights are on
6. Setting my computer and monitors to sleep when not being used for more than 10 minutes
7. Eliminating some fans that were not needed

What I learned:
1. HPS is still very efficient when compared to T5 when cooled with forced air
2. There is a big difference in efficiency for T5 fixtures (I wish I could test more brands but Quantum appears to be a sure thing )
3. During hotter months sealed rooms may not be the most efficient way to run
4. cooling duct runs need to be a short as possible and well insulated (just common sense here)

Now that I have KWH meters on all outlets I can watch my energy use on a daily basis.

The results are an over 60% improvement and my daily energy cost for the grow (flower, veg and work rooms) is less than $2.00 per day (running about $1.65/day). That cost is for a 42 sq. foot flower room, a 21 sq. ft. veg room and a 32 sq ft office /work room. Also, these costs are during our hottest time of the year so I am very pleased with the results. It started out with the challenge of checking the myth that T5's run cooler and ended up with an ongoing energy study.

Just for reference the amount of electricity used is about 23KWH/day. Hopefully this data will help other growers who are trying to grow on a smallish scale in either a closet, tent or small rooms.

 

[DGP]