Position and movement of sun in the Thailand

[Smithson]

The first image below shows my land and the area the house may occupy. The second image shows the elevation of the house. How does the positioning look heat wise? There's a view and breeze I'd like to take advantage of.

 

 

Edited August 22, 2022 by Smithson
Change image

[unheard]

13 hours ago, Smithson said:

With skylights I think it depend on their height and the amount of ventilation. Our place was dark, we added some 1m polycarbonate sheets improved light and without a noticeable increase in heat.

A pair of op-enable (manual or motorized) skylights on the inverted V type of ceiling work the best.

Energy efficient skylights are made with two panes of hardened (tempered) glass, with UV, heat reflective and light scattering coatings.

They are super expensive - rarely seen in Thailand.

I can only dream about getting one in my own house.

I haven't seen that kind of skylights in private houses in Thailand yet but I don't have friends living in mansions.

[unheard]

1 hour ago, Smithson said:

The first image below shows my land and the area the house may occupy.

In general the west facing side(s) is the one needing most protection from late afternoon sun. Do you have a possibility of changing the house orientation to make it more aligned with E-W axis?

There are many ways to minimize heat.

Fewer windows on that site, insulated house walls, roof overhangs, shade trees, high fences, walk-in closets on the inside, awnings etc, etc.

Plus insulative qualities of the roof and ceiling.

There are also many other things to consider like local climate (night temperatures and strength/direction of prevalent winds).

[Smithson]

^ The house could be adjusted, but it would no longer line up with the block. As it is it's pretty close to the east-west axis.

 

For the past ten years I've lived in place with no air con, worst part is afternoons in the hot season. Sleeping is OK because I'm upstairs with a breeze. The roof is colorbond/metal sheet with thin insulation, it's high and there are few walls.

 

I'll do similar again, except with air con for a office/bedroom downstairs. Rather than adding walls and insulation, I'll try and keep it as open as possible and use roll down blinds to keep the sun out.

 

There's a view and breeze that comes from the east, hence the higher roof facing that direction.

Edited August 22, 2022 by Smithson

[unheard]

24 minutes ago, Smithson said:

The roof is colorbond/metal sheet with thin insulation, it's high and there are few walls.

There's a view and breeze that comes from the east, hence the higher roof facing that direction.

Thin 2.5mm insulation?

It would help but not nearly as much as the 25mm (thicker available) PU insulation.

It works wonders - allows virtually no heat to be transferred on the inside.

Is the attic area vented?

A specific roof color can also reduce roof surface temperatures.

Edited August 22, 2022 by unheard

[Smithson]

6 minutes ago, unheard said:

Thin 2.5mm insulation?

It would help but not nearly as much as the 25mm (thicker available) PU insulation.

It works wonders - allows virtually no heat to be transferred on the inside.

Is the attic area vented?

Being in my house is like being under a tree, I couldn't see how it could get cooler (without air con). Heat rises, if the roof is high enough then the heat will not reach the lower sections - provided there is adequate (a lot) of ventilation. I've noticed this from large warehouses, many of which have no insulation.

 

There is no attic, upstairs will be large open area, as well as a bedroom, with large doors and louvered vents. I would probably add something to shade. Most of downstairs will also be open.

[mistral53]

Couple of things, maybe they were mentioned and I missed them with my cursory read diagonally across the thread:

 

1. In a hot climate, ceiling fans are about as bad an idea as adding......

 

2. window shadings/curtains inside the window

 

to add to the first point - we have a couple of ceiling mounted AC units, very bad idea, too - especially in our living room which has a 13 ft ceiling.

 

Good ideas: solar panels on the roof! not just for the production of free electricity, but the added benefit of shading over the roof comes for free.

[unheard]

1 hour ago, mistral53 said:

2. window shadings/curtains inside the window

Good ideas: solar panels on the roof! not just for the production of free electricity, but the added benefit of shading over the roof comes for free.

Inside the window curtains sandwiched between glass pains?

Those are great if the budget allows for expensive double pane windows

 

Solar panels do shade the roof but can also create additional weak spots for leaking.

[mistral53]

14 minutes ago, unheard said:

Inside the window curtains sandwiched between glass pains?

Those are great if the budget allows for expensive double pane windows

 

Solar panels do shade the roof but can also create additional weak spots for leaking.

mmmhhh........yes - that was bad wording: I was referring to shades and curtains on the inner side of the window - vs. European style shades/shutters on the outer side of the window, the latter will keep the heat on the outside of the room/house, conversely, regular curtains will let the sun pass through the window, heat up the window and the curtain and of course the room. Most houses in Thailand (like ours) use the below useless setup:

[KhunLA]

1 hour ago, mistral53 said:

 Most houses in Thailand (like ours) use the below useless setup:

Not sure about useless, as curtains will block sun from heating up a few meters, and restrict it to a few cms.

[mistral53]

23 minutes ago, KhunLA said:

Not sure about useless, as curtains will block sun from heating up a few meters, and restrict it to a few cms.

You have to think in terms of energy entering a room/house - a few centimeters or a few meters, the amount of energy entering is exactly the same. The only difference is the heated glass might radiate some small amount of heat back to the outside due to the positive temperature differential. In the middle of the afternoon after a couple of hours of direct sunlight exposure, touch the glass.........carefully, you might burn yourself.

A shutter like this on the outside makes a world of difference!

 

[Smithson]

An alternative to interior curtains is external roll up blinds or fixed wooden shutters. You can see these on pre air con buildings. Unfortunately the advent of air con has led to poor design in warm climates worldwide. To see what's effective take a look at houses build before air con was common.

 

There's an architect designed expensive place across from me. It has a huge balcony and windows to take advantage of the mountain views. There are no eaves and no roof over the balcony. The blinds are always drawn and I have never seen anyone on the balcony.

What do architects learn? Not functional design it seems.

[KhunBENQ]

2 minutes ago, Smithson said:

Unfortunately the advent of air con has led to poor design in warm climates worldwide.

So true for Thailand. No thoughts given as all tradition thrown overboard.
Bare glass and concrete fronts. No proper roof ventilation etc.etc.

[Smithson]

1 minute ago, KhunBENQ said:

So true for Thailand. No thoughts given as all tradition thrown overboard.
Bare glass and concrete fronts. No proper roof ventilation etc.etc.

Darwin in Australia used to be famous for it's practical architecture, not since air con...

I think Pattaya is the worst, as they are building to appeal to farang. The problem with air con rooms is they're designed to trap the air inside, rather than ventilate.

 

Traditionally all tropical countries had outside kitchens and across Southeast Asia were houses on stilts. When I lived in Chiang Mai I'd notice how cool it was riding at night when passing vacant block, the temperature would jump up as soon as there were buildings around. Really shows the heat island effect.

[Smithson]

27 minutes ago, mistral53 said:

You have to think in terms of energy entering a room/house - a few centimeters or a few meters, the amount of energy entering is exactly the same. The only difference is the heated glass might radiate some small amount of heat back to the outside due to the positive temperature differential. In the middle of the afternoon after a couple of hours of direct sunlight exposure, touch the glass.........carefully, you might burn yourself.

A shutter like this on the outside makes a world of difference!

 

Looks like a good shutter, gives security also.

[sometimewoodworker]

8 hours ago, mistral53 said:

 

1. In a hot climate, ceiling fans are about as bad an idea as adding......

 

In your opinion.

 

Our ceiling fans make the rooms comfortable and are mostly a substitute for running the AC. In the workshop my 84” ceiling fans are all there are.

The ceiling fans are mostly all that’s needed, apart from a bedroom AC for about 10 months of the year.

8 hours ago, mistral53 said:

2. window shadings/curtains inside the window

 

to add to the first point - we have a couple of ceiling mounted AC units, very bad idea, too - especially in our living room which has a 13 ft ceiling.

 

2 reflective silver roller blinds reduce the morning heat gain very significantly, until by about 9:30 the sun is off the relevant windows.

 

Our cassette AC (38,000 or 48,000 I don’t remember which) is perfect for our living room. The ceiling hight varies between 4 metres and about 7 metres and is roughly 64sq M. So you may have a poor design.

 

Neither of your choices of things to avoid are correct for our house. 
We have them both and would incorporate both in another building.

 

 

 

Edited August 24, 2022 by sometimewoodworker

[EricTh]

The sun does not stay in the same position throughout the year.

 

Generally, the windows should not face the afternoon sun as that is the hottest. Morning sun is alright.

[unheard]

4 hours ago, Smithson said:

What do architects learn? Not functional design it seems.

But it's not up to the architect to design an energy efficient house if the client has no interest in being efficient.

 

Edited August 24, 2022 by unheard

[mistral53]

15 hours ago, sometimewoodworker said:

In your opinion.

 

Our ceiling fans make the rooms comfortable and are mostly a substitute for running the AC. In the workshop my 84” ceiling fans are all there are.

The ceiling fans are mostly all that’s needed, apart from a bedroom AC for about 10 months of the year.

2 reflective silver roller blinds reduce the morning heat gain very significantly, until by about 9:30 the sun is off the relevant windows.

 

Our cassette AC (38,000 or 48,000 I don’t remember which) is perfect for our living room. The ceiling hight varies between 4 metres and about 7 metres and is roughly 64sq M. So you may have a poor design.

 

Neither of your choices of things to avoid are correct for our house. 
We have them both and would incorporate both in another building.

 

 

 

Let me get this straight - you posit that the use of a ceiling fan to pump the hot air from the ceiling, down to where you roam around, makes the room more comfortable? Might make sense in your universe, but I prefer to use standard physics to maximize my personal comfort at the lowest possible cost. While it is true that moving hot air over your sweaty skin is more comfortable, it is still hot air, and it wont make you stop sweating.

 

Start by using one of these and be dazzled by facts:

[sometimewoodworker]

34 minutes ago, mistral53 said:

Let me get this straight - you posit that the use of a ceiling fan to pump the hot air from the ceiling, down to where you roam around, makes the room more comfortable? Might make sense in your universe, but I prefer to use standard physics to maximize my personal comfort at the lowest possible cost. While it is true that moving hot air over your sweaty skin is more comfortable, it is still hot air, and it wont make you stop sweating.

You may suggest that the air in my ceiling is significantly hotter Than the air a meter or so lower however standard physics will illustrate that that is only true if there is no air movement.

 

You should also educate yourself on the science of evaporative cooling, may be that passed you by, and how that lowers the temperature the ideal is “Cengel Thermodynamics 9Th Edition”

[KhunLA]

20 hours ago, mistral53 said:

You have to think in terms of energy entering a room/house - a few centimeters or a few meters, the amount of energy entering is exactly the same. The only difference is the heated glass might radiate some small amount of heat back to the outside due to the positive temperature differential. In the middle of the afternoon after a couple of hours of direct sunlight exposure, touch the glass.........carefully, you might burn yourself.

A shutter like this on the outside makes a world of difference!

 

Our curtains at the 2 sunny glassed areas, E & W make noticeable difference in the temp, though very slight, since tinted glass block 95 ish % anyway.

 

Curtains are more for the sun's glare, as we'll just keep the AC on, as needed for temp / humidity control.  That's what the ACs are far, just as much, if not more for humidity along with temp control.

Edited August 25, 2022 by KhunLA

[Smithson]

Regarding ceiling fans, I think some will draw air up, rather than pushing it down. In the past I haven't liked them, but I've seen a few one really high in a few shopping centers and they seem to do a good job.

 

Edited August 25, 2022 by Smithson

[sometimewoodworker]

22 hours ago, KhunLA said:

Our curtains at the 2 sunny glassed areas, E & W make noticeable difference in the temp, though very slight, since tinted glass block 95 ish % anyway.

 

Curtains are more for the sun's glare, as we'll just keep the AC on, as needed for temp / humidity control.  That's what the ACs are far, just as much, if not more for humidity along with temp control.

There are semi transparent reflective roller blinds that are almost 100% reflective, reduce glare but still allow the scenery to be viewed

silver backing 

 

white front 

[unheard]

On 8/25/2022 at 10:55 AM, sometimewoodworker said:

You should also educate yourself on the science of evaporative cooling, may be that passed you by, and how that lowers the temperature

How do you use evaporative cooling in your house?

[sometimewoodworker]

1 hour ago, unheard said:

How do you use evaporative cooling in your house?

While a dissertation on the subject of ways of evaporative is employed may be entertaining I’m not actually going to do one, however there are a number of articles so a quote is

 

Quote

To understand evaporative cooling, we also need to understand heat and evaporation. Water can hold a lot of heat without changing temperature. The heat stored in water is called latent heat. Water absorbs the heat from other surfaces, making them cooler. When water absorbs enough heat, it evaporates, or changes from a liquid to a gas. The gas leaves the surface, taking the extra heat with it. The result is a decreased amount of heat and thus, decreased temperature in the surface. This is how evaporative cooling works.

 

Quote

(1) A theoretical model that simultaneously solves heat and mass transfer in a wet skin surface and fur layer that occurs when an animal is cooled by blowing air over its wetted skin surface and hair coat is presented. (2) The model predicts evaporative and convective heat losses for different levels of wetness, air velocity, ambient temperature, relative humidity and fur properties. (3) Model predictions provide insight about evaporative and convective cooling processes of cows in stressful hot environments.

https://doi.org/10.1016/S0306-4565(00)00048-6
 

in a simple example, slightly moist skin (virtually all skin has a degree of moisture) with air movement over it loses heat by evaporative cooling, the lower the humidity the more effectively the skin is cooled, the lower the temperature the more effectively the skin is cooled.