Building A Cellar, Why Or Why Not

[tracker]

Since this is such a hot and humid country, would it make sense to build cellars in houses?

I understand that in flood prone areas it would be trouble, but still, with good standards, like building on a slight elevation with good drainage, sinking the cellar about 7/8 of its height into the ground, would keep it rather cool.

Anyone did this here? would like to hear someone talking from experience as I might plan one in my own future house...

[taxexile]

i think building on stilts would be a better idea , not only keep things dry , but the airflow would keep things cooler too.

the humidity in underground rooms without proper and natural ventilation would be unbearable , so you would need air con and extractors , which defeats the purpose of the exercise.

underground car parks here never seem to be any cooler than anywhere else.

i think you have to follow local practice. i cant see the advantage of having a cellar.

i have no experience of cellars here so maybe i'm wrong.

[tracker]

i think building on stilts would be a better idea , not only keep things dry , but the airflow would keep things cooler too.

the humidity in underground rooms without proper and natural ventilation would be unbearable , so you would need air con and extractors , which defeats the purpose of the exercise.

underground car parks here never seem to be any cooler than anywhere else.

i think you have to follow local practice. i cant see the advantage of having a cellar.

i have no experience of cellars here so maybe i'm wrong.

As most cellars are build, they have windows in their upper-part, the 1/8 which sticks out of the ground and takes care of moisture.

Carparks are indeed often not cool, but then again, cars are huge heaters, and because of the poisonous gasses, carparks are heavy ventilated with outside air to keep us from dying on the spot, which would explain why they are never cool.

[raro]

A friend of mine built a cellar in his house in Pattaya. Took him a while to convince the Thais that he's not joking and finally it was an extra 100,000. Not much considering the overall costs of about 6 Mio...

Unfortunately his company has sent him to another country just monts after the completion of the house (expat fate...), so I have no reports how efficient it was and moisture problems etc.

[fxm88]

My understanding is that the sub-surface temperature reflects the average surface temperature. If the average yearly surface temperature is hot, it won't be any cooler than that underground (and could even be warmer).

See also http://answers.google.com/answers/threadview?id=747431

[chownah]

I have thought about building a cellar but since the water table is near the surface during the rainy season I thought I would build up from the natural ground and then bring in dirt to bring ground level up about 2 metres all round the first floor (build it strong enough to withstand the pressure from the dirt) and out a distance of several metres. This would be a "cellar" build above the water table and thus would stay dry.

My concern with this is that in the rainy season, air entering the cellar at 95% relative humidity would by cooled by 4 or 5 degrees C and thus go beyond 100% relative humidity and then water would condense on the wall and floor surfaces. It might be possible to draw the air in through a system of baffles so that the condensation would happen there before the air entered the room but I'm not sure of the effectiveness of this sort of thing and I've never heard of anyone building something like this....another possibility would be to use an air dehumidifier system but I don't know how much it would cost to power a dehumidifier...I've heard that air con units can be run as dehumidifiers but I have no experience with this.....I wish there was someone on board here who specialized in thermodynamics or environmental engineering.

Chownah

[dvk1951]

i think building on stilts would be a better idea , not only keep things dry , but the airflow would keep things cooler too.

which is why the Thai's do it that way

the humidity in underground rooms without proper and natural ventilation would be unbearable , so you would need air con and extractors , which defeats the purpose of the exercise.

You hit the nail on the head

i think you have to follow local practice. i cant see the advantage of having a cellar.

A degree from the School of Hardknocks is well respected.

i have no experience of cellars here so maybe i'm wrong.

Me thinks you are not.

There are several reasons why you don't see cellars in Thailand, the main reason being the large amount of rain fall which would turn most cellars into an indoor swimming pool not to mention the high water table. Keeping in mind the quality of construction here, it would be near impossible to construct a waterproof basement and a comprehensive drainage system would need to be installed to remove the deluge of rain. The efforts to keep the water at bay would be never ending in my estimation and cost prohibitive.

[Nawtilus]

FXM, really, I think you are a tad wrong.

In a place called 'white cliffs' and 'cooper pedy' and probably many others, they build there homes underground because of the natural coolness. Temps outside and based on your average ground temp, are anywhere around 35 to 45 degrees. Average in the underground homes naturally are around 20 to 25 degrees.

I also went into a house some time ago that was for sale upcountry, they had a cellar/basement. The difference in temperature naturally was staggering and would be a great spot for an afternoon nap away from the heat upstairs.

I do not know for sure, but always told they do not build basements because of the flooding and high water tables. Waterproofing it is just to much a problem for them, or possibly more likely they are just not experienced or good at it and give up before they start.

But, as an example, there is a shop on sukhumvit which has a semi basement, it is between soi 5 and 7 from memory and is a glasses/optician shop. Check it out, no leaking problems by the looks of it and can be done if done properly.

[dvk1951]

I have thought about building a cellar but since the water table is near the surface during the rainy season I thought I would build up from the natural ground and then bring in dirt to bring ground level up about 2 metres all round the first floor (build it strong enough to withstand the pressure from the dirt) and out a distance of several metres. This would be a "cellar" build above the water table and thus would stay dry.

My concern with this is that in the rainy season, air entering the cellar at 95% relative humidity would by cooled by 4 or 5 degrees C and thus go beyond 100% relative humidity and then water would condense on the wall and floor surfaces. It might be possible to draw the air in through a system of baffles so that the condensation would happen there before the air entered the room but I'm not sure of the effectiveness of this sort of thing and I've never heard of anyone building something like this....another possibility would be to use an air dehumidifier system but I don't know how much it would cost to power a dehumidifier...I've heard that air con units can be run as dehumidifiers but I have no experience with this.....I wish there was someone on board here who specialized in thermodynamics or environmental engineering.

Chownah

Here is 1 site to visit which may help:

http://www.greenhouse.gov.au/yourhome/technical/fs15.htm

or Google 'passive house cooling' for more

edited for 'speling' errors

[tracker]

Thanks for all the replies folks! Much appreciated.

indeed, a good preperation and construction would prevent flooding all normal natural cases (ofcourse a tsunami cannot be coped with).. That the Thais don't have any cellar, does not mean that it is stupid to build one. It is just a trigger for me to find out why.

[chownah]

I have thought about building a cellar but since the water table is near the surface during the rainy season I thought I would build up from the natural ground and then bring in dirt to bring ground level up about 2 metres all round the first floor (build it strong enough to withstand the pressure from the dirt) and out a distance of several metres. This would be a "cellar" build above the water table and thus would stay dry.

My concern with this is that in the rainy season, air entering the cellar at 95% relative humidity would by cooled by 4 or 5 degrees C and thus go beyond 100% relative humidity and then water would condense on the wall and floor surfaces. It might be possible to draw the air in through a system of baffles so that the condensation would happen there before the air entered the room but I'm not sure of the effectiveness of this sort of thing and I've never heard of anyone building something like this....another possibility would be to use an air dehumidifier system but I don't know how much it would cost to power a dehumidifier...I've heard that air con units can be run as dehumidifiers but I have no experience with this.....I wish there was someone on board here who specialized in thermodynamics or environmental engineering.

Chownah

Here is 1 site to visit which may help:

http://www.greenhouse.gov.au/yourhome/technical/fs15.htm

or Google 'passive house cooling' for more

edited for 'speling' errors

Thanks for the link....but....I couldn't really find anything about the problem of high humidity in "cellars" and methods for passively (or actively) removing excess moisture from the air. If you know of a link that address these types of issues I'd appreciate a post.

Chownah

P.S. Many of the posts so far talk about the problem of ground water seeping into the basement....I'd like to point out that my design completely eliminates this possibility....leaving just the problem of humid air.

Chownah

[astral]

I'd like to point out that my design completely eliminates this possibility....leaving just the problem of humid air.

Chownah

Design is one thing, getting it constructed to the plans is quite another.

[chownah]

I'd like to point out that my design completely eliminates this possibility....leaving just the problem of humid air.

Chownah

Design is one thing, getting it constructed to the plans is quite another.

Actually the design is fairly simple....the first floor walls are built of reinforced concrete 20 cm thick although 15cm would probably be adequate...its not very exotic really. After the walls have cured you coat with asphalt and then back fill...including adequate drainage at the base and face of the walls.

Chownah

P.S. I've started looking into the possible humidity problem and so far I have found that I need to learn about using a Psychrometric Chart. They are available on the internet and I've downloaded one along with instructions on how to use it. If anyone has experience in using them I'd like to hear from them.

Chownah

[Pink Mist]

FXM, really, I think you are a tad wrong.

In a place called 'white cliffs' and 'cooper pedy' and probably many others, they build there homes underground because of the natural coolness. Temps outside and based on your average ground temp, are anywhere around 35 to 45 degrees. Average in the underground homes naturally are around 20 to 25 degrees.

I also went into a house some time ago that was for sale upcountry, they had a cellar/basement. The difference in temperature naturally was staggering and would be a great spot for an afternoon nap away from the heat upstairs.

I do not know for sure, but always told they do not build basements because of the flooding and high water tables. Waterproofing it is just to much a problem for them, or possibly more likely they are just not experienced or good at it and give up before they start.

But, as an example, there is a shop on sukhumvit which has a semi basement, it is between soi 5 and 7 from memory and is a glasses/optician shop. Check it out, no leaking problems by the looks of it and can be done if done properly.

look at the rainfall in coober pedy, it's almost zero, having said that with carefull design anything is possible

[Nawtilus]

Thanks for that, but I was refering to his post about ground temperatures, not rainfall.

[chownah]

Nawtilus,

Was the "house some time ago that was for sale upcountry, they had a cellar/basement" in Thailand? Were you there in the dry season or wet season. I know the basement was probably cool but do you think it was clammy? It seems to me that if the outside air was 35 degrees C and 95% humidity it would be difficult to get your basement to be 26 degrees C and 60 percent humitidy(which is considered to be a sort of upper range of the comfort zone according to what I've read so far).

Chownah

[meadish_sweetball]

Wifey's dad built a cellar in their house, which floods every rainy season and smells of mould the rest of the year.

I'd trust that Thais have learned through trial and error (excepting wifey's father) why cellars are generally not a good thing in this area.

Chownah, your idea about elevating the ground above the water table might work, but going below standard ground level I think is just inviting trouble.

[Pink Mist]

Thanks for that, but I was refering to his post about ground temperatures, not rainfall.

was really referring to the fact that it gets really hot there, but it doesnt rain much, so flooding isnt an issue.

[Swelters]

I have thought about building a cellar but since the water table is near the surface during the rainy season I thought I would build up from the natural ground and then bring in dirt to bring ground level ...........another possibility would be to use an air dehumidifier system but I don't know how much it would cost to power a dehumidifier...I've heard that air con units can be run as dehumidifiers but I have no experience with this.....I wish there was someone on board here who specialized in thermodynamics or environmental engineering.

Chownah

Basements can be waterproofed wherever they are.

Lets put aside the question of humidity for now. The first question relates to the notion of a cellar being "cool". So it might be, but in what country? Not Thailand.

The deep earth temperature is close to the mean annual air temperature, actually somewhat higher because of geothermal heat (negligable) and where present solar heating of the ground (which may be large.) But even assuming it's equal to mean annual temperature, do you think this is cool? I think not.

The underlying "heat" problem in the tropics is the absense of nocturnal radiant heat loss to the sky. The sky temperature remains warm all night (unlike the desert). Hence large "thermal masses" just refuse to cool off at night. This includes mother earth.

In re: psychometric charts, they are a complicated business, I've tried to give an example of use at our blog at

http://www.thaivisa.com/forum/blog/swelter....php?&st=10

http://www.thaivisa.com/forum/blog/swelter....php?&st=10

[pete_r]

I understand that in flood prone areas it would be trouble, but still, with good standards, like building on a slight elevation with good drainage, sinking the cellar about 7/8 of its height into the ground, would keep it rather cool.

Anyone did this here? would like to hear someone talking from experience as I might plan one in my own future house...

I've played with the idea a bit too for a house in Bangkok, but after research it didn't seem to be worth it.

Regarding humidity, the Thai builders and engineers I consulted strongly advised against the idea, because of the risks of water infiltration and flood. I still think it must be possible to waterproof a cellar, but at a relatively high cost, since one would have to find a team of builders who can do that kind of job well.

Then I found that in Bangkok, the temperature at 50cm below the surface is about 24-26 degC, and fairly constant year round. I say that based on the measurement of the temperature of the water coming out of the tap at home (the house has no water tank so the water comes straight from the underground pipe). The temperature in a cellar would probably be a bit higher, maybe 28-30 degC, because the top of the cellar would be above ground and receive more heat than the water pipe buried in the ground.

So I figured that a cellar temperature of 28-30 degC seemed a bit high to justify the extra-cost of building a water-proof cellar, and forgot about it.

In other areas of Thailand, drier and/or cooler, I would still be tempted to try.

(Edited for spelling mistake)

[Nawtilus]

Chownah, I believe from memory it was the dry season we were up there.

Walking down into the basement was very noticably cooler, like I said so much so that it would be a nice spot for an afternoon nap.

There was no real noticably humidity problem, in fact from memory it felt cool and dry.

I likened it to many stone houses in Oz in hot temperatures with big overhanging verandahs, they are naturally very cool inside and the cooler temp seems to be dry, even if it is humid outside. Why this is so I do not know, I am not a weather expert b any means.

[chownah]

I have thought about building a cellar but since the water table is near the surface during the rainy season I thought I would build up from the natural ground and then bring in dirt to bring ground level ...........another possibility would be to use an air dehumidifier system but I don't know how much it would cost to power a dehumidifier...I've heard that air con units can be run as dehumidifiers but I have no experience with this.....I wish there was someone on board here who specialized in thermodynamics or environmental engineering.

Chownah

"............

Lets put aside the question of humidity for now. The first question relates to the notion of a cellar being "cool". So it might be, but in what country? Not Thailand.

The deep earth temperature is close to the mean annual air temperature, actually somewhat higher because of geothermal heat (negligable) and where present solar heating of the ground (which may be large.) But even assuming it's equal to mean annual temperature, do you think this is cool? I think not.

The underlying "heat" problem in the tropics is the absense of nocturnal radiant heat loss to the sky. The sky temperature remains warm all night (unlike the desert). Hence large "thermal masses" just refuse to cool off at night. This includes mother earth.

..........."

Thanks for directing me to your blog with the psychrometric chart....I'm starting to get a feel for them.

Thailand stretches quite a ways from south to north and while your observations may be correct for the southern parts the data that I have for Chiangrai for instance makes a cellar seem like a more hopeful situation.

My data is all from a website called WorldClimate and I have lost the link but it is from the Chiangrai weather station at about 19.92°N 99.80°E. Height about 394m / 1292 feet above sea level. It shows April, May, and June as the three hottest months of the year (data is averaged from 1951 through 1975) and the data for average, average maximum, and average minimum is as follows:

April: average temp 27.2 : average max temp 34.9 : average min temp 19.4

May: average temp 27.6 : average max temp 33.3 : average min temp 21.9

June: average temp 27.2 : average max temp 31.6 : average min temp 22.7

The data sheet for average temp indicates that the average for the entire year is 24.6 degrees C so a cellar should passively be at about that temp.....and also notice that the night time temperatures for April, May, and June are a whopping 15, 11, and 8 degrees C below the day time highs. From what I have read this would strongly indicate that during these month using thermal mass should be a viable and effective option.....a cellar, of course being an excellant example of thermal mass.

I could present all of the data but it would be time consuming...if you googled you could probably find the sight....I think they have data from alot of places in Thailand but I can't remember....Bangkok almost for sure.

I am still concerned about the humidity in the cellar during the rainy season....maybe a cellar would be too humid for part of the year and great for the rest.....I'm still checking it out and looking for more data.

Chownah

Nawtilus,

Thanks for the response...as the data I have posted here indicates, a cellar should be really effective during the dry season at least in Chiangrai....I'm still concerned about the air humidity in the rainy season but I'm starting to think about whether a cellar would be worth is even if it was only useable during the dry season and perhaps as uninhabitable thermal mass the rest of the year.

Chownah

[tracker]

I checked some inf here and there... Indeed, the cellar takes the average temp from the air in that place.

Being a couple times in the mountains in thailand, it is always nice cool at nite, whatever the season. So the average temp would be certainly a couple of degrees lower than the biggest heat in the middle of the day. These areas would probably be ok to include a cellar.

Bangkok, as a concrete jungle, isn't a good location but as close as khao yai, would be ok.

The flooding of a cellar is really an issue of construction and, of course, of constructors. The latter being widely and randomly famous for delivering low quality as all the stories on thaivisa forum can prove. Cracking houses in almost any mooban older than 3 years is more proof.

Strangely enough, in almost any thai house the hong-nam has a non-leaking water-pool constructed, so they do know what portland means

[chownah]

The flooding of a cellar is really an issue of construction and, of course, of constructors. The latter being widely and randomly famous for delivering low quality as all the stories on thaivisa forum can prove. Cracking houses in almost any mooban older than 3 years is more proof.

I suppose it is true that it is possible to build a water proof cellar after all they do build ferro-cement boats.....but....generally speaking people are not willing to pay the cost of building a cellar that will be 100% water tight even when the water table is above the floor level of the cellar. Cellars are usually build with waterproofing which is adequate to allow a bit of rain water to trickle down the surface occasionally and to stop almost all of the water vapor from the soil....but....I have never seen a cellar that was built to be water tight against constant standing water like what would be encountered in alot/most of habitable Thailand.....even a swimming pool will develop leaks and I've never seen a cellar built to swimming pool standards (sealer covering the entire surface of the concrete on the water side of the enclosure). In areas of high rainfall a successful cellar ususually depends on being able to build trench drains around the base of the cellar which discharge the water away from the foundation...something that is not possible for alot of building sites in Thailand during the rainy season.

Chownah

[tjo o tjim]

If the objective is to have some nice "free" cooling, the easiest approach is to go with a "ground-source heat pump." Basically, you bore holes down and at angles from a central pit, and circulate water or coolant through the (lined) bores. If memory serves me correctly, a 150', 6" diameter bore can dissipate 500W of heat. This technique can take advatage of the high water table, as your heated water moves "downstream."

It is a little bit more efficient than cooling to the air, and if you are up-country and in need of heat it can provide that more economically.

As far as finding ways to keep the basement dry, the easiest way is to warm up the air (from the psych chart, you maintain constant wet-bulb temperature and increase the dry-bulb temperature... thereby reducing the relative humidity). Since you are trying to make a cool place, your options are to install a de-humidifier (which cools the air temperature to below its saturation point to condense out water, and then uses the outlet airstream as the heat rejection source, warming the air back up above saturation).

A better approach is to look more closely at passive solar design, and see if you can bring air into your house low on the north (shaded) side of the building, and exhaust it at the highest point in the building.

A cellar will eventually flood. Sump pump will stop running, sewer will back up, or water will come in through the top. Once this happens, cleaning out all the mold becomes a nightmare.

[Nawtilus]

Speaking about your cooling method above, is this how the new airport cools itself as I read it has no aircon, but done through the underground and the slab etc.

Is this method easily done and is the cost to do it an acceptible alternative in a normal home to do away with conventional airconditioning ?

[opothai]

1 dig your hole for the cellar 4ft below f/f level of cellar

2 on hard ground [ usual in los ] lay a heavy gauge visqueen on the soil. fill with 12" of medium grade stone, then 3-4" sand then compact.

3 dig out 2 channels a further 2 ft below the stone, to act as drainage away from the building and fill with medium grade stone and hardcore.

4 excavate and dig a soakaway, at least 4m away from the building and as deep as you can below the level of your cellar footings, then fill with loose hardcore.

5 line the hole for your cellar with a high grade visqueen.

6 pour a concrete raft of approx 3ft with reinforcement bars, [this will be a raft foundation for the house].

7shutter up the walls for a 20" re-enforced concrete walls.

8 inside the walls coat with a quality bitumen based water proofer. then finish with a specialist cellar type walling system.

9 construct the house floor from block and beam, then construct the house of your dreams.

the amount of soil you will have to dig out will be phenominal and should be enough for you landfill to raise the ground level

you will need at least 6 air vents to allow cross airflow through the cellar, and you must be able to make these water tight for the rainy season.

this should give you a water tight cellar and prevent cracking as you are on a raft foundation that will move with the ground. access to the cellar fom within the house.

very expensive and time consuming for something that might not work in the hotter parts of los.

i'm sure a cellar could be built but to get the perfect build in the humid and rainy conditions of los might take a bit more thought than normal.

[chownah]

Tjo o tjim,

I'd hardly call a ground source heat pump as the "easiest approach" to ""free" cooling". First, it is probably the most difficult approach to cooling since it no only requires a full heat pump unit installation but it also includes having to drill circulating bores in the ground......and second, it will not produce "free" cooling since by your own admission it is "a little bit more efficient than cooling to the air" so this is obviously not even nearly "free".

Passive solar design is great and shoud be included at the design stage for every building and even retrofitting to existing buildings can have good potential but in Thailand in April and May when its really hot, if you draw air into your house even from the shadey side it will be hot air and will do little to cool the house.

I find your conjecture on the ineveitability of basements getting wet to not match with my personal experiences. I have lived in three buildings in a very wet coastal climate in the US and none of them ever leaked even a drop of water ever unless I left a window open and the floor got wet....not a disaster as you have described. Also please note in a previous post of mine in this thread that I have proposed building a basement above grade by building the first floor walls to earth retaining strength along with surface waterproofing and proper drainage trenches and then backfilling with earth.....thus the entire basement would be above the water table and top quality and reliable drainage can be constructed below foundation level easily before backfilling......flooding would never be a problem with this construction method......what I am wondering about is if it is possible in the climate in northern Thailand if moist warm air could be channeled in a particular way to dehumidify it in a way similar to your description above (cooling to condense excess moisture and then warming to 60 or 70% relative humidity....and if this can not be done by only circulating air appropriately then how much energy would be required to do it with a dehumidifier or air con unit acting as humidifier.

Chownah

[Swelters]

My data is all from a website called WorldClimate and I have lost the link but it is from the Chiangrai weather station at about 19.92°N 99.80°E. Height about 394m / 1292 feet above sea level. It shows April, May, and June as the three hottest months of the year (data is averaged from 1951 through 1975) and the data for average, average maximum, and average minimum is as follows:

April: average temp 27.2 : average max temp 34.9 : average min temp 19.4

May: average temp 27.6 : average max temp 33.3 : average min temp 21.9

June: average temp 27.2 : average max temp 31.6 : average min temp 22.7

Weather Underground is a great site for weather summaries, at:

http://www.wunderground.com/history/airpor...hlyHistory.html

I extracted Bangkok and Chiang Rai for May 2005, representative hot season months. This is the challenge for any thermal mass attempt at cooling. I am a little surprised at the results, shown in the graph, suggesting Chiang Rai is considerably worse than Bangkok (Don't just look at peak afternoon temp, look at dew point and morning/evening temps). I did this in a hurry, I'd welcome any correction to this counter-intuitive result.

[chownah]

Swelters,

I went out and found that in May 2006 for Chiangrai the dew point ranged from a high of 77 to a low of 61 with the exception of one day when the dewpoint was reported as being as low as 36 which I take to be an error. This data for May 2006 is not at all similar to what is reported for May 2005 so it seems likely that there is an error somewhere...perhaps in the May 2005 data.

I looked at Bangkok for May 2006 and found that the dew point ranged from a high of 86 to a low of 70. This is not at all similar to what is reported for May 2005 so it seems like there is an error somewhere...perhkaps in the May 2005 data.

It almost looks like they got the dew point data reversed for Chiangrai and Bangkok!!! Also if you look at your data for Bangkok closely you will see that there was probably some problem with their system because there are some flat spots in the dewpoint plot which I'm reasonably certain do not reflect real world conditions.

Chownah

P.S. Thanks for the link...I'm going to look at their data for the rainy season and see if it can give me some insight into how a basement might work(or not) in the north during those months.....although I can see that I'll have to be careful and check their data to see if it makes sense....since it seems that the data you have pointed out does not.

Chownah