Cooling A Room

In my house, my room is the only one that does not get its share of cool air when the AC is turned on. After having a professional look at it, he said something about the position of my window towards the sun as well as the fact that my room is the last on the line to get the cool air.

My father said that he is up for me figuring out some way to cool my room. Without buying an external AC unit [that hangs out of my window] I was wondering if anybody has any ideas or knows anything about this type of stuff so that I can mod my room? Any ideas or suggestions would be appreciated because I have no idea where to start for my research except off of others’ (who have some knowledge possibly about this field) knowledge.

EDIT: I have a ceiling fan, and some other fans in my room keeping me cool right now but all that does is circulate the warm air inside my room.

Thanks for your help,
Pavan Dave.

(PS. If you think it gets hot where you’re from, please visit Houston in the summer and I don’t think I’ll have to say a word, ;))

My room is the same way it would get like 95 degrees in the summer, with the AC on. I basically just lived with it. How hot does yours get? Mine basically felt like a car that was sitting in the sun. I would get the afternoon sun through a biigggg window.


My house has no AC, we cool the house by opening all the windows and running fans at night. I don’t know how cool it gets in Texas, but you might want to try that.

Start with the window! Cover it with a sun protecting layer, either directly on the window or as a shade that will reflect the heat back. Many shades can still let light in while reducing the heat!
This web site has some other good ideas as well!

it sounds like you have a/c, but your room is the last in line, therefore you get little or no cold air. my solution is this:
you can get fans that you install in the air ducts that literally suck the cold air into your room. almost certain you can get them at Home Depot or sotres like that. it’s basically a duct segment with a fan in it.

I live in CT, so I have nothing to talk about.

But, here is what I do:

I have a cubicle inside my room. (I need to keep the servers inside COOL… I run the robotics website off of one, my personal site off of another, plus some file servers, my gaming machine, my CD-SPY machine, my two work machines, my IM machine…just to name a few). The cubicle is sealed, including the top (it is under my loft). I have a window unit (not designed for my windows… my windows does not open vertically… it opens horizontally, so I made a cardboard cutout for it… I’m not too worried about my room getting hot). I made (out of cardboard) an adapter that is duct taped onto the front of the unit that adapts to a 7" round aluminum flexible duct. I calculated the size of the duct based on the area of the output vents on the air conditioner. The flexible duct runs across my room (at about hip height, just tall enough so you can’t possibly step over it, but just low enough that you cant go under it… how convenient) to my cubicle. I cut a hole in the side of the cubicle and duct taped it in. Inside I have a piece of printer paper (my final physics exam cheat sheet) with a piece of duct tape on one side. I can tape the paper to any side of the round duct to deflect cool air onto me regardless of where I am sitting inside. I have a thermometer (indoor/outdoor) inside so that I can see the temperature difference. I also have an electric meter inline so I can tell how much juice I am sucking.

Now this sol’n requires a window unit. My grandmother has an A/C unit that is upright, and is on wheels, so that it can be moved from room to room. The unit is about 3.5 feet tall (hip height maybe). It has a tube (looks like a dryer vent) coming out of the back with a little plate adapter to go into your window. This is so that you don’t need to lift the unit into the window, and you don’t have an ugly unit sticking out (just a small white plate with the vent).

Now for the 5 dollar solution (probably more like 20)… Take your regular oscillating fan, make a coil of copper tubing around the back, attach the tubing to a aquarium pump, and into a garbage can of ice water. Pump the freezing water through the coil so that the fan sucks the air over the cold coil and cools it. You need to keep changing the water (adding ice), but if you have an automatic ice maker, this isn’t a big deal (yeah right.)

That’s my input.


My room is small, a few inches bigger than 10’ x 10’, and on average feels about five to ten degrees hotter, if not more, than the rest of the house. So I went up to my father and made a deal with him: if I could find a way to cool my room, which is both efficient and economical, he would get me the parts and let me go from there.

Thanks for the help guys.

An engineering solution from one of my fellow students at Waterloo is to have a large container of cooler-than-air water at a high level. Get some copper pipe, run it from the water container in a spiral in front of a fan, then have it empty into a lower container (or out your window).

As the water runs in front of the fan, it will absorb heat energy from the air. The pump is powered by the height difference between the container and outside. Efficiency can be increased by adding more surface area to your copper pipe to facilitate heat exchange.

Edit: Beaten.

Another solution that I left out (practically free compared to an air conditioner) was to create the fan idea that I described above, but instead of using a bucket of cold water, was to run a hose outside and bury coils of it under ground (which is constantly 50ish degrees). Use this as your cooling source. This is a very cheap, almost no power usage solution. You may need a bigger pump than an aquarium, however.


isn’t that calles a geo-thermal exchanger or something like that? or, use the outside garden hose with cold water…

Partially close the vents that are in the rooms that do get adequate AC. That way, the remaining air is forced to go to your room. It works quite well.

Well if you wanted to go all-out-robotics-style on this, you could try building a thermocouple peltier effect cooling array out of these. The first few on the page are the same as ones used in those nifty take-with-you-in-your-car thermocouple based cooler/warmers. Just remember that these MOVE heat, they don’t just get cold, so you’ll need a cooling fan and a place to blow the heat (probably just hang a hose out your window if you have to, or put it into your attic, something like that.

Building an enclosure for this out of plywood and insulating the inside to keep the heat from reentering the room, then using some surplus kit fans from the FRC kit should work for moving the hot air out of the box down your hose. A large PC power supply should do the trick for supplying 12VDC to your thermocouple array(s). Wow now i wish this was my project! :]


p.s. each one of the first junctions shown on the page is equivalent to about a 275btu/h air conditioner, so 22 of these babies gets you up a little past a 6000 BTU/h energy transfer rate, about the average for mid size window air conditioners. its a little pricey… but man is that cool! (no pun intended :smiley: )

Living in Texas, there proably isnt a basement. So the unit would proably be in the attic or garage. Because air takes the path of least resistiance, it will be flowing to the grilles closest to the unit. There should be a damper at the takeoff of the plenum. You can slightly close off the airflow to the rooms closest to the unit. I wouldn’t close it more than 50%. This will help in two ways. It will increase airflow to your room while increasing the runtime of the unit. If this dosent work, Fantech makes a quality in-line fan that will boost the air to your room.

It sounds like you have two directions at which you can attack the problem. First, do something about the heat entering your room through the window. One of the best solutions is to use a deciduous tree to shade it, so the leaves are only blocking the heat in the summer. There are also metallized plastic films that you can put on the outside of the glass. Be wary of using shades on the inside of the window, as they’ll mostly end up trapping the heat and radiating it to the inside anyway.

Second, you want to get some air moving. A ceiling fan will help dramatically, as will “booster” fans in the ductwork. If you can force the air inside your room to mix with the air in the rest of the house, you’ll be able to keep the temperatures more consistent.

this is what I would do first, too. Also make sure there is an exhaust path for the warm air to leave your room and return to the a/c unit.

To truly solve this dilemma, you have to go back to the root of the problem. Your forced-air AC system is overstretched and the placement of the window in your room (it’s probably facing south) are the sources of the problem.

Step 1: Prioritize which rooms really need AC:

Close the central air vents in either the coldest room in your house (by the virtue of forced-air HVAC systems, this most likely will be the room closest to the heater/AC unit.), or rooms that are seldom used (like those extra bathrooms, guest rooms, etc. that aren’t really ever used) and don’t need to be cooled. If these vents aren’t adjustable, then take the vent cover off, put a piece of cardboard into the vent*, and put the vent cover back on. :yikes:

If you don’t need a room cooled/heated to perfect room temperature, then why [strike]pay for[/strike] waste the energy to do so?

  • With this method, you could always cut small holes into the cardboard to restrict airflow (as opposed to entirely stopping it), but the decrease in air entering that room should at least somewhat increase the airflow to your room.

EDIT: After just thinking about using cardboard for a moment, from a fireproof standpoint it would probably be better if you went to Home Depot or Lowes, bought a small sheet metal air duct plate, and using tin snips cut it down to size and used that behind the plate instead of cardboard.

Step 2: Eliminate possible sources of “wasted” AC:

Tint your windows/skylights with a light-blocking product. Leave the shades/blinds/etc closed. Glass acts like a greenhouse, so if you can stop the suns rays from entering the room, then you’re less likely to have your AC wasted by the sun’s radiant energy.

For bonus points, both of these solutions have the potential to not only save you money in the long run on utility bills, but they’re also green, environmentally-friendly solutions. It’s win-win.

// Me thinks I’ve spent too much time working on houses… :stuck_out_tongue:

I have the same problem, except I’m the first in line for the air conditioner, but I run a server 24/7 that has a warm exhaust and the house is pretty well insulated, so my room keeps in the heat, and the rest of the house keeps the cold air, which means that our A/C doesn’t run very much, making my problem much worse. At times, my room gets up to 87 degrees, which really sucks. I usually take my laptop and go into the living room. I guess the easiest solution I could think of is getting a fan that blows air out of your room through a window, that way more cool air enters your room. Another idea is to partially close other vents in the house to give you more air flow. I’ve been thinking of getting our small windows A/C that is in my workshop not being used and putting it in my room’s window and leave it on low. My room is the hottest in the morning (since the A/C usually doesn’t run much at night and my server is still running). When I get it, it is usually 82 in my room. If I’m playing games on my server my room gets very warm, and my laptop also heats up my room after a long day of playing games or something.


2 main things to do.

  1. Reduce heat energy from entering
  2. Remove heat energy

Window films will cut the sun load. (And in Texas in summer, I’m guessing you are close to 1000 watts/m2.)

Powered vent fans will help pull in cold air (remove heat). OR - if you find the return vents, fans going the other way will remove hot air (remove heat).

Insulate your room to the outside. (reduce heat from entering.)

You live in Texas. It gets humid I assume. The swamp cooler (evaporative cooler) might not be a good idea, since it requires a dryer air to really work well.

The peltier effect is really awesome and fun, but probably not a good solution for this. The average store TED (thermal electric device) is about 40 watts. A human at rest, on average, gives off 100 watts. PLUS - if you remove 40 watts from one side, the hot side has to get rid of 40 watts plus the power used to run it (lets say about 80 watts), for a total of 120 watts. Now you have a HUGE problem getting rid of all that power. And don’t get me started on the tiny Delta T… (I spent about 2 years doing research on these things. They are AWESOME, for the right application.)

And before anyone says plug in a fridge and open the door, remember that will heat the room up. It’s all energy. Learn as much as as you can about energy, and you’ll come up with some cool ideas. (Pun intendent.)

Good Luck!

Thanks for the ideas. Jacob and I have been discussing this for about an hour to two hours tonight and tomorrow I will try to make a cooling fan similar to the ones suggested in the earlier posts. This of course will be a short term solution. Also I am looking into possible shades to put outside my window like some sort of tree or a large screen of some sort to put inside… For the long run I will suggest prioritizing the vents and possibly looking into some thermoelectric technology (Click Here).

The project, which is expected complete by the end of this Saturday, is to coil some copper tubing around one of my current oscillating fans and to pump cold water through it, and hopefully through the use of ice packs keep a steady supply of cool air in my room.

Thanks for the ideas guys, and keep the coming. Many of you have very good ideas. Chief Delphi’s 5000W think tank is running at full blast and the to think that the season has been over for nearly a month.


  1. Leave the door to your room open if your room does not have a dedicated A/C return vent.
  2. Adjust A/C exhaust vents in all rooms to provide appropriate airflow.
  3. Check the A/C ducting to assure that it hasn’t “collapsed” or is otherwise obstructing airflow.
  4. Are the coils in the air handler clean?
  5. Is the air filter clean?
  6. Install a ceiling fan.
  7. Install a thermal barrier on the window (reflective film, curtains, etc.)
  8. Check the insulation in the attic over your room.
  9. Install an attic fan to remove warm air from the attic.
  10. Check ducting for air leaks.