One more thing:
I am not using Polycarbonate Sheets for being expensive too.
I will use thick polythene rolls that will be in direct contact with angle frame.
The apprehension is that polythene sheet over angle iron frame may get damage or get melt due to heat of summer or hot angle itself.
What do you guys recommend what should i do? What should be the minimum thickness of polythene sheet i should use?
How should this polythese sheet should be affixed with angles.
Looking for help.

Using swamp coolers can be tricky in an enclosed greenhouse because that will raise the already high humidity. Typically commercial greenhouses use cross ventilation. Running the hot dry outside air through the swamp cooler pads, blowing it across the plants to the other side of the greenhouse, and out vents on the other side. In my greenhouse the subterranean system acts as a large dehumidifier, and will circulate the entire volume of air in the greenhouse 5 times every hour through it.

If you can build your greenhouse tall enough, some commercial greenhouses create a cooling atmosphere above the plants. Basically it consist of running a shade cloth screen across the inside the greenhouse above the plants. and using a fine misting system above it to create a large cooling zone. Of coarse it would need good air circulation through your greenhouse, and to be able to get as fine of a mist as you can.

I know you plan to use the poly plastic film for greenhouse covering. I'm using that as well. I don't think they make it thicker than 6ml, and that is what I'm using. I'm not sure if your using the construction poly or greenhouse poly. But I suggest using greenhouse poly with UV inhibitors. It will last more than a year, and help reduce solar gain somewhat. This is what I got Standard Clear Greenhouse Film, 6mil. Now when it comes to poly plastic film greenhouses, you can use either a single wall, or a double wall construction. I'm using a single wall. But double wall will insulate from outside heat much better. Basically a double wall uses a air blower that forces air in-between the layers to create an air pocket between the inside and outside layers. You can even get double wall poly plastic film so you don't need to drape it over twice, or need the spacers.

In my opinion I would drop the idea of using the angle iron, it will bend and twist way too much. You would need so much of it to make a sturdy greenhouse you wouldn't be saving anything. Round tubing, or wood framing are the only two strong main framing construction methods. I'm using a combination of wood framing and 2 inch round electrical conduit. The electrical conduit is much cheaper than the 2 inch metal fence post tubing, not to mention easier to work with. Unlike PVC tubing, electrical conduit is designed to be used above ground and resist degrading from UV. I used 3 inch deck screws to attach the 2x4 framing to the electrical conduit. All in all we have already had many strong windstorms, including a good hail storm, and my greenhouse barley even moves at all in the strong wind, and the hail didn't do anything to the poly film. I also attaches the poly film to the greenhouse using Lath screws (because they have washer like heads), and polyethylene Batten Strips. I got the 1,500 foot roll and used the heck out of it, covering everything. Both before and after installing the poly film. I still have about 25% of it left. It's important to get the poly film tight, if it's loose and flaps in the wind it can tear.

You'll need to register as a forum user to be able to see the pictures, but if you do you can see all the pictures of my greenhouse construction in this thread: Greenhouse construction begins in another forum. Starting from before I even began dinging, right up until last week or so when I first ran water through all 3 levels of hydro systems. I'm in the presses of fixing some leaks right now, and hope to have everything running leak free in about a week. When I do I'll post another update. There are literally 100's and 100's of pictures of the whole construction process, and I go over all my trial and errors both good and bad.

P.S.
I almost forgot to mention, along with shade cloth to reduce solar gain, there is something called Shade Paint. It comes in a concentrate, you thin it out up to a 1 to 8 ratio, and paint it right on the poly plastic film (or any greenhouse covering). Just like shade cloth it reduces solar gain from UV inside the greenhouse. It's also biodegradable. Depending on weather conditions it typically wares off in a few months. That way during winter when you want all the light and heat you can get, it dosen't interfere. It's also relatively cheep (if you can get it locally and don't need to pay for shipping), running around $22-$28 a gallon depending where you get it. Here's a link to the stuff: Kool Ray Classic Shade

Note: RoofTop hydro plan was my first & last hydro setup until now & I have to shift this kind of hydro setup in my greenhouse too with some changes i have discussed in other post. I will continue with four setups like this in my first greenhouse experience. Thus i am new to hydro yet.

Now i am going to construct wooden structure finally that will be some what like this:

Anyhow, Fighting with Summer heat also will be the challanging issue for me to over come.

Doors at both side, three roof ventelation windows, two exhaust fans at one endwall of the greenhouse & two air inlet windows at the other endwall will be used for cross ventilation.

Shade cloth under the roof but over the plants will be used IF NEEDED.

I have planned to use Double Poly Transparent 6mil polyethyelene sheet all around the greenhouse including top. I can get construction poly easily but will give priority to find greenhouse poly. One sheet will be installed with in the inner side of the whole structure & the other will be outside of the greenhouse. The gap in between both sheet layers will be about 4-5 inches. Each sheet will be 6mil 150-160 microns thickness.

I have searched the web a lot & every where i have read that Double Poly Sheet that makes air pockets between them retain heat within the greenhouse & reduce heating costs about 50% compared to single poly coverings.
So how would i be able to use it. As i have to fight against high temperatures. Maintenance of a winter temps are not a problem at all & i am using no heating component or ant thing like that for it.

Please inform in detail how can i use double poly sheets adversely to cool down the greenhouse in high summer temps? Have you any design or so?

Since there is a 4-5 inches gap in between both poly layers I thing i wouldnot need a air blower to inflate polys. What you say? Am i right?

Have you tried or seen some plan please share with me.

I want to know the link & name of software you are using to create 3D images. I want to download it to make someone understand what i mean.

Please reply. Awaiting.

P.S.
I do have a lot of greenhouse designs, construction methods, typical cooling and heating system designs I can post. I've been researching the subject for about 2 years now (well over a year before I started construction on mine). I don't think I know anything about your situation (planed greenhouse location), just that it gets hot and/or windy.

Yes, my area is very hot.
Outside day time temperature reaches 45-50 maximum in summer & there are about seven & half months of summer.
Outside day time temperature lowers down upto 0-5 in winter & there are about four & half month of winter.
There is no high humidity issue in our area.
Rain fall is average.

I have to place four bitter gourd type setups of pictures i posted earlier. I found this setup ideal & convinent in my case in greenhouse. One for cucumber, 2nd for tomato, 3rd for bitter gourd & fourth will be of any other gourd crop.

If you need to know any thing else please let me know.
Best regards take care.

That greenhouse looks much nicer than the one I built. Although much more expensive too. Not including the subterranean system, and the hydro systems inside, I built my whole 10 by 20 foot greenhouse for about $800. Ya, heat will be challenging. Our outside temp today was about 92 degrees, but the temp inside the greenhouse was 108 degrees. When the temps here reach the 120 mark, greenhouse temps would likely be around 140-150 if I didn't have a multi tiered cooling plan. Cross ventilation is great in some circumstances, but it wont help much at all to blow 120 degree air on your plants when it gets hot. Given the best circumstances, swamp coolers may bring the temps down about 20 degrees. But if humidity isn't carefully controlled, they may only provide a difference of between 5 and 10 degrees at most of cooling effect by themselves.

Just to clarify, when I mention high humidity, I mean in the greenhouse. That will depend a lot on temperature inside the greenhouse, water vapor given off from the hydroponic systems inside. Not to mention the biggest factor, how many plants your growing, and how big they are. Plants breath out water vapor (called transpiration). The water vapor (relative humidity) in the greenhouse will get higher and higher unless it's ventilated. But ventilating a cooler greenhouse with the (hot) dry outside air will only heat up the inside of your greenhouse.

I have searched the web a lot & every where i have read that Double Poly Sheet that makes air pockets between them retain heat within the greenhouse & reduce heating costs about 50% compared to single poly coverings.
So how would i be able to use it. As i have to fight against high temperatures.

The air pocket in-bitween the two layers of poly is an insulation pocket. Air pockets are the best insulation there is. Insulation will protect against heat just as easy as it does against cold. If your greenhouse is cooler than it is outside, the insulation (air pocket) will help keep your expensive cool air inside the greenhouse stay cooler longer. If you have no way to cool the inside of the greenhouse, then it wont help much. The air pocket is just insulation, not a cooling or heating layer. It just helps block the heat transfer from one side to the other. Blocks heat from getting out during winter, and blocks against heat from getting in during summer.

The 4-5 inch's between both layers you describe should be plenty. Typically it's only about one inch between layers. Though I would expect that you will still get much better results with a air blower between the two layers. The reason is if you blew the cooler air in between the layers, it won't give the air pocket a chance to heat up. Thus keep the heat transfer between the inside, and outside layers to a minimum.

I want to know the link & name of software you are using to create 3D images. I want to download it to make someone understand what i mean.
I use a free program called Google SketchUp. They have a pro version you can pay for, but I've always used the free version, and like it very much. I save all my drawings into a folder so I can expand on them later without starting over. Before you post your drawings, you'll need to remember to export and save it as a 2D image. Otherwise it wont be in jpg. format, and people that don't have Google Sketchup wont be able to view it.

Before I built my greenhouse, I did a lot research online to figure out what would work the best for me, as well as my budget. Here are a bunch of the links I have got bookmarked from those searches. I know it's a lot to read over, and it's been a long time sense I looked through it myself. But a lot of it is in lists of topics. I just read through what was of interest to me.

Arched Greenhouse
PRESENTATIONS
REFERENCE SOURCES
Horticultural Engineering
Greenhouse Energy Cost Reduction Strategies
POLYTHENE GREENHOUSE FILM FACTS
Chapter 11- Greenhouse Site Selection
Chapter 12- Greenhouse Structures
Chapter 13- Greenhouse Control Systems
Chapter 14- Greenhouse Energy & Resource Alternatives "Greening" the Greenhouse
Greenhouse Glazing
Greenhouse Energy Conservation Strategies
Greenhouse Energy Conservation Strategies: Temperature and Scheduling
Managing Greenhouse Temperature

I'm not really sure what this: "My ameil id is
gejaangee at y0hu0 .c0m means for sure, but I think you mean to give your e-mail. I have many e-mail addresses, and one specific for posting when I know it will result in getting spam. You can reach me at:
rocketman1022000@yahoo.com

That's my junk e-mail, but I can reply from one of my regular e-mails later. Just title e-mail "azee_2009, Greenhouse construction" Also try to e-mail me soon. I get 50+ spam messages a day in that inbox, and just cant spend the time to go through it all looking for one message. I just deleted every message there so I won't have a lot to look through (for a few days anyway).

P.S.
If you send me drawings, send me both the 2D image, as well as the original skp. (Google program) drawing. I have the program, so I'll be able to open it.

Looking forward for your co-operation.
Azee_2009

1. Where do you live (country, state, region)?
2. Do you have a specific budget, and have you looked into the cost of the materials you plan on using?
3. Do you own the property the greenhouse is going on?
4. Is this greenhouse meant to be a long term permanent structure, or just meant to last a few years and/or removable if you move.
5. Are you aware to get the power you will need, you'll need to have someone add breakers to your breaker box, as well as run the lines to the greenhouse, and outlet boxes?
6. Is the greenhouse an investment? That is, are you looking for increased property value once it's built.