How To Cool Rooms At Night

[RubbaJohnny]

Cost is a factor but loft insulation ,trap door you can open whirlygig(spinners on roof) and refectiingfoil are good investments

[Naam]

Sorry gentlemen if this is a bit off topic, but I'm having a small house built and there is absolutely no attic ventilation. The builder has not put any sofit vents or roof vents to allow any air circulation in the attic. I built 2 house in Canada and proper attic ventilation was critical.

Why is this not done here? The temps in the attic must be astronomical

ask your builder what kind of work he did before he decided to become a builder. and don't be surprised if you find out that he was a shoe salesman or the owner of a small restaurant or ran a landscaping company. i could write a book about the year my house was built. luckily i found out the truth only a few days after start of construction and luckily my builder was intelligent and flexible enough to let me guide him through the building period. but even though i was the first one to arrive and the last one to leave the construction site unbelievable mistakes happened which had to be rectified not once but several times till the result was "acceptable". even after moving in i spent 1½ years correcting BS. unfortunately a number of shortcomings cannot be corrected.

[jfchandler]

Naam, I'm glad to see your contracting and construction management skills are as formidable as your financial ones...

[cloudhopper]

That fan is an eco friendly roof extract unit which draws the warm air from the area below it and relies on a negative pressure to replace that air with fresh air from outside.Ideal for an open plan area like a roof loft and swimming pool but not for providing ventilation to individual rooms in a house with a false ceiling.Quite impressive air volume figures but what would happen if you added a plenum chamber and ductwork to the fan?Those air volumes would come tumbling down due to the resistance.I'm making this point here in case people think that this fan would 'cool their rooms at night'

The room ceiling in this design is a shallow pyramid with a duct at the apex drawing off the warm air to a central chimney with this fan at the top. Sure the volume will be reduced but not much is really required in this application. Outside replacement air is introduced at floor level which is a water cooled slab. Exhaust water is sprayed out at the top of the chimney (cooling tower) just below the fan and the cooled water droplets are collected in a sub floor sump and recirculated through the floor slab. This probably won't work in the significantly more humid coastal environments though...

[perhamus]

Sorry gentlemen if this is a bit off topic, but I'm having a small house built and there is absolutely no attic ventilation. The builder has not put any sofit vents or roof vents to allow any air circulation in the attic. I built 2 house in Canada and proper attic ventilation was critical.

Why is this not done here? The temps in the attic must be astronomical

Hi- I wish I had found this forum earlier, as it would have been helpful. I just had a nice 3BR, 3Bath, kitchen, large living room house with front and back porch. It has a 5' tall crawl space. A/C in each BR. Cement house, with black windows, screens, etc. I am retired, living in Sukhothai. I had worked at money things and built 10 houses in New York State, doing all the work. Sukhothai is not as modern as many places, so I had to do things a little differently.

I quickly learned that I must hire good people and let them do their best. The builder did not want to insulate the ceiling, but insisted on Aluminum paper just under roof tile. A good Idea. He would not put in rotating roof vents. Instead of fighting with him, I retrofitted. I had 2 rotating roof ventillators added, after he was done. I put insulation in the ceiling later. I suspended a 24" fan under one of the ventillators and wired it to a switch that also ran an bathroom fan. I turn it on at night. A 30" ceiling access door is left open and the air is pulled up and out. Can I get closed cell foam insulation in bags? Where? How much? The way they suspend gypsum made insulating difficult and the ceiling needs much more insulation- Any ideas welcomed- John

[CDNinKS]

ask your builder what kind of work he did before he decided to become a builder. and don't be surprised if you find out that he was a shoe salesman or the owner of a small restaurant or ran a landscaping company. i could write a book about the year my house was built. luckily i found out the truth only a few days after start of construction and luckily my builder was intelligent and flexible enough to let me guide him through the building period. but even though i was the first one to arrive and the last one to leave the construction site unbelievable mistakes happened which had to be rectified not once but several times till the result was "acceptable". even after moving in i spent 1½ years correcting BS. unfortunately a number of shortcomings cannot be corrected.

Yes, I have many of the same problems. The builder (and I use that term loosely) is complaining he is not making any money on the house and I told him that if he would do things right the first time instead of having to remove/replace stuff 3 times that would not be the case. Unfortunately I cannot be on site 7 days a week, but even when I am there he stills screws stuff up.

Anyway, I have looked around at quite a few new house builds and don't see any venting on them as well, so this seems to be a new concept here. I think I will go with Perhamus suggestion and wait till the builder is gone and retrofit a roof vent.

Oh, the joys of Thailand

[jaideeguy]

Cloudhopper.......why not use the locally made roof spinner vents that require no power[motors].....just the power from heat rising and the occasional breeze?? I have a couple on my roof and you can see them spinning.....the hotter it gets, the faster they spin. Cost of locally made is much cheaper I'm sure [3 yrs ago ...i think 2.5kthb installed and painted to match roof color] and so far the bearings seem to be holding up ok without any maintenance. I am curious about your 'water cooled slab'.

[cloudhopper]

This one also works quite well in passive mode when there is wind. I will paint the chimney black to improve convection.

Running water through tubing imbedded in the concrete floor slab will increase it's thermal mass. My present house already has quite a bit and the floor stays cool all day (and warm in the cold season too) relative to the outside air temp. If the water can be circulated and warmed/cooled so much the better - even a few degrees can make a huge difference.

[dinga]

Thanks for the suggestions - here's where I've finished up. The Vent Axia fans seemed to offer the solution but have significant downside ie. they (a) are not stocked in Thailand; ( had difficulty in pinning down information locally; and © are hellishly expensive [s$677 each for the 7" TX7WW Model, with a further S$85 for the controller - delivered to Thailand]. I looked at picking them up when I was passing through the UK on holiday, but the price was still GBP 284, so gave up on Vent Axia.

A few weeks ago I stumbled over Victor reversible fans at Global House, Rayong. Bought two of these 8" fans (at 505 baht each) and - while the true test will be in March/April - they seem to do the job (at a total cost installed of around 1,100 baht each). Photo attached.

[kpmsprtd]

ideal is a whole-house fan if you have space to install. i got one which ventilates my house in a few minutes and i do this every morning before the sun is up. it saves a bundle on electricity cost especially in the cool season when outside temperatures are lower than those in the airconditioned house.

Naam, how noisy is your whole-house fan? The house I bought for my parents in California has one mounted in the ceiling in the central hallway. It's quite effective at drawing outside air in through open windows/doors, but the vibration and noise prevents it being used more than a couple minutes. I've no experience with a whole-house fan before, so have nothing to compare it to, but have long wondered if it were a defective fan or bad installation. One time I was there, I had my mother cut strips of thick felt and lifted the fan and slid the felt under the fan as a gasket, but that helped only slightly. I've wondered if it would be worth buying a new one, or if in general, those fans are expected to be pretty noisy.

Highly likely that it's a defective fan or installation. Mine was professionally installed (in California) and has two settings, low and high. Low is extremely quiet. High is louder, but not too bad. I could sleep through it, and I'm fairly sensitive to noise when trying to sleep. (No dB measurement, sorry...)

[Will1]

The problem seems to be, the insulation around the walls and ceiling.

Walls are to thin and no insulation in the celling.

why not use air-con ?

[Pib]

Some good layman's info on cooling attics: http://www.factsfact...ventilation.htm

I expect many Thai builders don't ventilate attics because it can make a critters/insects/rain inlet, added cost, most Thai homes have few to no A/C's (think the whole country), and maybe they think a whole lot just can't be done to decrease house temperature other than opening the windows or running expensive A/C's. Thai builders will slowly improve current building techniques which need to be improved, but the change will probably be slower versus faster.

Edited December 11, 2010 by Pib

[wpcoe]

@kpmsprtd: May I ask the brand of the fan and/or where you bought it? I'm still thinking of replacing the fan, even though I'm not sure my mother would use it much even if it were quieter.

[tangcoral]

Anyone know where I can purchase a ventilation fan controlled thermostatically for my attic?

Would Homepro carry this product or will I have to piece it together?

thanks

[doglover]

Awesome info Cloudhopper and Pib! Maybe when I build my 3rd house I will get things right. Photos of your water cooled slab and black chimney would be much appreciated by everyone I sure Cloudhopper, along with a more in depth explanation. That continuous ridge vent with accompaning soffet vents has to be one of the most important aspects for natural ventilation and it looks great! Next house I will be building in that style for sure.

I also know that if the next builder cannot grasp or will not build these concepts into the house he will be replaced. Why should we have to spend more money after the fact to retrofit our homes when this should all be done during the original construction?

[sezze]

Prsonally i think that it has to do with design more than isolation . Isolation and aircons are things to be done after the fact happened . Same like going to the hospital after you have a motorbikecrash without safety helmet and speeding . If you look at the old Thai houses , you look at roof designs which are very steep and high . The sun which will make the roof hot will create a airflow going up to the highest point where you have something which will let some air exchange ( basically a hole/gap and there were plenty of them ) . Inside you will get nearly no heat because the highest point of the roof is far away from anybody . In modern designs they did find this way impractical so they roofs where getting more flat , bringing the highest point of the roof closer to the people living the and because the roof isn't as steep , the airflow will be slower ( less airchange ) . As a 3th and very important consideration it was cheaper as the roof is a high cost and flatter roofs have smaller surface .

If you are still in design fase of your house , prefer the steep roof technique before going on the aircon units and isolation .

If after you build the house , remember the technique . Suck the air out at the highest possible point and let in fresh air from the lowest point . You can work with the simple wall fans with a hose attached to it ( to get to the highest point ) . This is very cheap and will work fine . you can feel the hot air exiting the fan and if the temp is still very high , you might consider using a 2nd one . Put on a simple timer , costs only a few 100 baht and let the fan work from 2 pm till 6 pm . If too hot , make the fan suck the air out longer ( add 1 hour each side ) . This measures are still well below the 2000 baht mark , and depending on various factors below 1000 baht , still way cheaper then any isolation , let alone aircons .

Isolation , many types available and each has it's pros and cons . Combinations of techniques can bring on huge advantages . Remeber that any dead mass in the ceiling , even isolation ,will heat up and will give out it's heat when it is colder . Steel roofs are better in the tropics for that reason ( less heat stored , so cooles down fast ) .

When you are stuck in a city , less choice , no airflow is possible and a lot of heat is stored everywhere around you . Aircons are isolation are the only options left .

[David006]

Prsonally i think that it has to do with design more than isolation . Isolation and aircons are things to be done after the fact happened . Same like going to the hospital after you have a motorbikecrash without safety helmet and speeding . If you look at the old Thai houses , you look at roof designs which are very steep and high . The sun which will make the roof hot will create a airflow going up to the highest point where you have something which will let some air exchange ( basically a hole/gap and there were plenty of them ) . Inside you will get nearly no heat because the highest point of the roof is far away from anybody . In modern designs they did find this way impractical so they roofs where getting more flat , bringing the highest point of the roof closer to the people living the and because the roof isn't as steep , the airflow will be slower ( less airchange ) . As a 3th and very important consideration it was cheaper as the roof is a high cost and flatter roofs have smaller surface .

If you are still in design fase of your house , prefer the steep roof technique before going on the aircon units and isolation .

If after you build the house , remember the technique . Suck the air out at the highest possible point and let in fresh air from the lowest point . You can work with the simple wall fans with a hose attached to it ( to get to the highest point ) . This is very cheap and will work fine . you can feel the hot air exiting the fan and if the temp is still very high , you might consider using a 2nd one . Put on a simple timer , costs only a few 100 baht and let the fan work from 2 pm till 6 pm . If too hot , make the fan suck the air out longer ( add 1 hour each side ) . This measures are still well below the 2000 baht mark , and depending on various factors below 1000 baht , still way cheaper then any isolation , let alone aircons .

Isolation , many types available and each has it's pros and cons . Combinations of techniques can bring on huge advantages . Remeber that any dead mass in the ceiling , even isolation ,will heat up and will give out it's heat when it is colder . Steel roofs are better in the tropics for that reason ( less heat stored , so cooles down fast ) .

When you are stuck in a city , less choice , no airflow is possible and a lot of heat is stored everywhere around you . Aircons are isolation are the only options left .

Good info...

...we are in the boonies on a farm...we have a hi ceiling'd, large roof spaced, concrete roof tiled house on a hill(was gonna use "zincalum" like in FNQ Oz but couldn't find it and was a bit worried about lightning up here) ..it's really a pole home but finished (half enclosed for add' bedroom laundry/ bathroom) under now......we do get good breezes ( best in NE trades as on eastern lee of hill/mountain) and lots of big windows and whole upper house is fronted with sliding doors..no aircon.

My question is: would there be any advantage to just putting venting screened openings in the highest part of the ceilings (I had 'em vaulted)...I thought I read someplace that this is one method of cooling a house. Also can you explain more about the wall fan venting method you describe? Maybe just turbo style roof vents would be the best option?

Having said all that it hardly ever gets hot since the rain we all prayed for last May has only just stopped in S Thailand, it seems ..and the night temps are cool! Maybe I am just "fixing the hole in the roof even though it ain't rainin"..

.thx for any comments suggestions

rgds d