Best passive cooling strategies to cater for hot humid days 40-45C without wind?

[Acharn]

12 hours ago, bbudd said:

Plant shade trees NOW=something fast growing like tagop.

Choose a method of shading the south walls,like bigger eaves or an outer wall,Even shade cloth will help

Be sure theres adequate roof ventilation and attic insulation

A water sprinkler on the roof for those real hot days will reduce inside temp by 5" or more.Helps to wet the walls as well

An evaporator fan cools but adds water vapor-sort of a trade off to my mind

 

These methods got us thru all but 2 days of the last hot season

In Thailand you need to plant on both the North and South sides. If you haven't noticed, on 21 April every year the sun's path passes through the zenith, and after that is to the North of the zenith until 16 August. Lot's of shade trees are a help. I like to have one or more trees on the East to block early morning sun, but an alternative is to have your bedroom on the West side of the house. High ceilings seem to help. I think, but am not sure, that the old practice of extremely steeply pitched roofs help.

[ourmanflint]

1 hour ago, Acharn said:

In Thailand you need to plant on both the North and South sides. If you haven't noticed, on 21 April every year the sun's path passes through the zenith, and after that is to the North of the zenith until 16 August. Lot's of shade trees are a help. I like to have one or more trees on the East to block early morning sun, but an alternative is to have your bedroom on the West side of the house. High ceilings seem to help. I think, but am not sure, that the old practice of extremely steeply pitched roofs help.

I hadn't realised that! Although Phrae is approx May 10th to August 1st, I will have to adapt my plans somewhat. Thanks

[bankruatsteve]

Suggest anyone that wants to see if they can be comfortable in passive conditions for "cooling" to visit their local wat and hang out for a while.  Most wats have tall trees for shade, high ceilings, good ventilation, and many on "stilts".  If you can feel OK on a hot afternoon there, you are probably good for implementing suggestions in this thread.

[tracker]

most of the solutions are already mentioned. A hot and humid climate has 2 friends for us: wind and shade. By placing your house east-west so that windows never have direct sun, long awnings, and indeed a lot plants to create your own microclimate are the best options. One, I might add, is to carefully research your use of materials. Example: a roof with ceramic tiles will take a long time to cool down after the sun goes down. a metal roof, takes less than half an hour. (metal is noisy, cheaper, up to you).

 

So, if your house cools down a lot in the night because you've used materials which do not retain the heat long, you can keep your house closed most of the day and keep it cool(er).

[RocketDog]

On 10/7/2020 at 5:31 PM, phetphet said:

Going to You might also want to consider either tinted, or spectrally selective film installed on windows to reduce solar gain.

 

There was a poster that build a passive house house here with a system where air was drawn through underground pipes to cool using lower temp of soil, then passed over a heat exchange to cool the inside air. I have looked, but can't find the thread.

 

Have a look at this. A long read:   https://ecohousethailand.com

There is going to be electricity cost associated with moving and exchanging air. That cost amortized may pay for several years of running an efficient aircon. The negative btu gains from the cooling pipes must be greater than the positive heat gains from the environment to help any. Unless that margin is significant its likely not worth the initial cost, which could be significant, and maintenance issues. Many of your ideas are better suited to drier environments. 

 

Insulation is the most cost effective of all cooling methods and requires no maintenance. Super-insulate the house, plant shade trees, invest in solar electric energy, and buy an aircon. 

 

The humidity here is a real bear. Pumping even cool moist air around your house will breed mildew, cause condensation, and will leave you feeling soggy. Unless you can reduce the humidity you're fighting a losing battle. 

[Bandersnatch]

On 10/7/2020 at 5:31 PM, phetphet said:

There was a poster that build a passive house house here with a system where air was drawn through underground pipes to cool using lower temp of soil, then passed over a heat exchange to cool the inside air. I have looked, but can't find the thread.

 

Have a look at this. A long read:   https://ecohousethailand.com

https://EcoHouseThailand.com is my blog.

 

At the time of my build I was not able find a company in Thailand that would install domestic geothermal, so I decided to invest a small amount of money in a DIY approach. I was already planning to install an Energy Recovery Ventilator with ducting of filtered dried, cooled air into each room. So the geothermal would supplement this.

 

 

The problem is finding pipework in Thailand that is flexible enough to be bent, but strong enough to support a few meters of soil.

 

 

 

After installation we tested the the air temperature and it was noticeable cooler, but unfortunately when we tested it again a few months later we found that the pipe had collapsed.  

[Bandersnatch]

On 10/7/2020 at 4:27 PM, 4myr said:

1) use the high thermal mass of the colder soil conducted thru the cement/concrete slab. Have a cold floor like granito or tiles. 

2) lower the base floor of some rooms to increase the surface with the cold soil thermal mass [applicable only on elevated land]

3) create cold air inlet thru earthship design principle like air tubes buried under the soil under some slight elevation, with a condensation collection point where the warm outside air is coming into the tube thru a cylindrical chimney post. The tubes are coming inside the house and colder air spread to rooms frequently habited

4) create an air draft in the house thru a long glass trombe wall chimney [see pic] or a simple black solar cylinder chimney, whereby along the chimney surface the air is heated by the sun to create the air draft. 

 

The problem with passive cooling strategies is they can work against you when you want to lock the house down and run air-con. So whatever you will do will be a compromise.

 

(not my home)

 

1)+2)  We decided to minimize thermal bridging so that we would not be wicking aircon into the ground by installing 3 inches of foam insulation under the house.

 

 

3) - see my post above.

 

4) When no aircon is being used, the doors in the stairwells are opened to aid with natural cooling, using a principal called Stack Effect Ventilation: having an opening at the top of the building, draws heat up and out like a chimney. The effect is magnified by the higher wind speed on the third floor caused by the The Venturi Effect which creates a partial vacuum in the stairwell. It is like adding an extractor fan to the chimney. 

 

[Don Chance]

Air con very cheap in Thailand. Why you so complicated?

[Bandersnatch]

2 hours ago, Don Chance said:

Air con very cheap in Thailand. Why you so complicated?

It's a fair point and that's why most people go that way.

 

Personally I wanted to design a house that was comfortable to live in and cheap to run. I added solar and batteries to a super insulated house to minimise my electric bills.

 

[ourmanflint]

On 10/10/2020 at 5:12 AM, Bandersnatch said:

https://EcoHouseThailand.com is my blog.

The best DIY house blog there is. Thanks

[bodga]

build  underground