Cooling a Thai home with a heat pump & "cool roof" coating

[onlycw]

I want to install a heat pump at a friend's house. The roof should get a reflective coating as well. Not sure about insulating the inside and replacing the windows with some of a good k-value like 1.1.

Can you recommend a heat pump for a 1,400 ft single floor house?

Thanks!

[happynthailand]

don't know of anybody who use's a heat pump in thailand,

but what do I know

[MRTHAIBRI]

Heat pump??? Are you Tasmanian??? You will never get to use a reverse cycle air-con in Thailand. I would definitely invest in ceiling insulation.

[bbradsby]

Assume yr talking about the typical, ubiquitous mini-split systems, correct? Definitely not a heat pump,as theres no reversing valve for the heat function for obvious reasons in Thailand.

Since youre talking about a reflective coating on the roof, it must be a low-slope concrete roof? Yes, this is a good idea, plus copious insulation. Else, painting a high slope roof over attic is a waste of money. Just do the copious insulation.

The part everyone here doesnt think about is plugging the air gap leaks in the conditioned space. So all their nice expensive cold air gets blown out the cracks in the slightest breeze and is replaced with hot, ambient temperature air.

IN THIS ORDER: Seal/weatherstrip, then externally shade all glass, then insulate, then add air conditioning, then add radiant reflective paint on East, South & West walls that you can't keep in shade from 10:00 AM to 5:00 PM when sun's rays can store lots of heat in your walls.

[Dellboy218]

Along the same lines.....Solar reflective paint. Anyone got any personal experience with this product/brands. Although we do have insulation I would prefer it not to heat the roof up in the first place!

[onlycw]

Thanks - the heat pump suggestion came from a friend in the UK who said it would be a lot more energy efficient...

Does anyone know a company specializing in this kind of energy efficiency & cool roof work? I would rather pay 15,000 Baht more and get a pro job than have the locals mess about. (I've seen "paint jobs" without any masking, with inches of wood stain of stairs ending up on the walls etc.

A bathroom with no air vents => smelling mouldy after 2-3 days. And bad concrete on government construction sites which looks like it was messed about as much as Mexican drugs in the hands of a starving dealer. Clumps, use of bad forms, ...

While I'm at it, I might as well ask for a top quality paint brand which is available here.

Someone told me, how building a shade for the air con saved him a lot of electricity.

Please share your experience. Cheers!

[Naam]

heat pumps for cooling and heating are available since at least a couple of years "up north" (Chiang Mai). but let's talk a bit about physics... every fridge, freezer, and airconditioner is in fact a heat pump. "cold" cannot be generated but heat is extracted from a medium to another medium which absorbs that heat, (e.g. air, water). an aircon usually extracts heat from the inside air of a home and "pumps" that heat to the outside or another medium like water when it's a water-cooled aircon unit.

questions?

[Naam]

Someone told me, how building a shade for the air con saved him a lot of electricity.

taht someone has "a lot" of phantasy

shading the condenser fins from direct sun rays adds (in theory) a tiny but not a measurable advantage as far as energy savings are concerned.

[Naam]

Does anyone know a company specializing in this kind of energy efficiency & cool roof work? I would rather pay 15,000 Baht more and get a pro job...

for 15,000 Baht you get 30m² (~100sqft) of 5cm (2") thick hard foam insulation. even a very small home with a footprint of 130m² has a roof tile area of ~180m² or more depending on the gradient. so you are looking at 90,000 Baht wasted money because the foam under the roof tiles only slows down the heating-up of the attic.

the optimal (roof) insulation for a home is ventilation of the attic and insulating the ceiling area between rooms and attic, preferably at the attic side. most efficient but also most expensive is spray foam insulation.

as far as wall insulation is concerned double outside walls (expensive) and "blow concrete" such as Ytong, Qcon or Superblock are the optimum.

double or triple glass windows are a pure waste in a tropical country except if installed to minimise outside noise. their "heat" insulation value is inefficient because the temperature difference between ambient temperature and inside temperature is far smaller (5 to maximum 8ºC) as opposed to "cold" countries where that difference can go to 45ºC and higher, e.g. Continental Europe, Northern U.S. and Canada.

[bbradsby]

+1 to most everything Naam said, but add:

Keep glass in shade from mid morning to late afternoon to avoid massive heat gain using the recommended single pane windows.

You're probably referring to blown-in loose-fill insulation on top of the ceiling, but just in case, I wouldn't recommend spray foam on top of a ceiling; it'll encase cabling and light fixtures, which could cause an overheat/fire danger condition and will for sure make future electrical remodel work or troubleshooting problematic.

[PeVee1st]

For what it is worth, here is what I did.

High pitched concrete tile roof, reflective paper under the tiles, rendered brick walls, roof overhangs walls for inc.shade and top quality ceiling insulation.

When you walk inside my home from the shade of the entry balcony you can instantly feel the temperature difference.

Good ventilation of the living areas, combined with good fans mean I never use the aircon except in the bedroom.

Sent from my GT-P7500 using Thaivisa Connect Thailand mobile app

[bbradsby]

The proper response depends on whether youre in the coastal/peninsular wet Tropics portion of Thailand, or the seasonally dry & hot up-country sections. If you are up-country, then yes, closing up the house during the day during the hot/dry season is optimal. You are using the shaded thermal mass of your interior structure & walls to slow and attenuate temperature swings inside the living space. On a more subtle level, they also literally pull heat from warm bodies via radiation, and this helps quite a bit.

Combine this with effective weatherstripping of all exterior openings, and minimizing interior heat loads such as refrigerators in your "Living Zone," and you can keep the inside air quite comfortable with a little air movement at just above the floor level. Ceiling fans can work against you on this by mixing the stratified air and bringing the hot layer near the ceiling down to your living zone.

For the wet tropics, these strategies will work against you by making for a damp interior space without serious dehumidification or a completely different design & oeration strategy such as low mass building systems, 110% shaded site and lots of ventilation and cold beer... but I'm out of time for now.

[Naam]

+1 to most everything Naam said, but add:

Keep glass in shade from mid morning to late afternoon to avoid massive heat gain using the recommended single pane windows.

You're probably referring to blown-in loose-fill insulation on top of the ceiling, but just in case, I wouldn't recommend spray foam on top of a ceiling; it'll encase cabling and light fixtures, which could cause an overheat/fire danger condition and will for sure make future electrical remodel work or troubleshooting problematic.

unfortunately blown-in insulation is not available in high-tech advanced Thailand although it provides the "best bang for the buck". the cost for R60 blown-in in our home in Florida was peanuts compared to what is available here.

spray foam done by proper companies does not encase light fixtures (they are protected before spraying, protection is later removed). no problem with wiring. i made sure that all wiring in the attic is installed at a minimum distance of 50cm above the ceiling at a cost of several hundred Baht cable ties.

protecting glass from direct sunrays provides indeed the highest efficiency. the coated reflective mirror glass i installed helps somehow but can't beat shading.

[Naam]

For what it is worth, here is what I did.

High pitched concrete tile roof, reflective paper under the tiles, rendered brick walls, roof overhangs walls for inc.shade and top quality ceiling insulation.

When you walk inside my home from the shade of the entry balcony you can instantly feel the temperature difference.

Good ventilation of the living areas, combined with good fans mean I never use the aircon except in the bedroom.

Sent from my GT-P7500 using Thaivisa Connect Thailand mobile app

Good ventilation of the living areas, combined with good fans means...

...to each his own.

personally i'd hate to ventilate my home with today's 35ºC hot air from outside but prefer a comfortable average of 26.5º in all areas of our home which of course can only be achieved by airconditioning.

[Canada]

informative thread. thanks.

[Pakaty]

Maybe this would help.

www.campbridge.com/Ceramicoat%20Insulating%20Paint%20Technical%20Info.html

Edited March 25, 2014 by Pakaty

[onlycw]

For what it is worth, here is what I did.

High pitched concrete tile roof, reflective paper under the tiles, rendered brick walls, roof overhangs walls for inc.shade and top quality ceiling insulation.

When you walk inside my home from the shade of the entry balcony you can instantly feel the temperature difference.

Good ventilation of the living areas, combined with good fans mean I never use the aircon except in the bedroom.

Sent from my GT-P7500 using Thaivisa Connect Thailand mobile app

Well, I'm not sure about what to do under the tiles as my main concern is reflecting most of the IR rays away from the roof.

Am looking at different coatings. One nano coating claims 95% reflection, a dubious claim? Ti Ox pigments are still around 87%. Just asking as I would hate to fall for some marketing ploy like in the U.S. food manufacturers are allowed to sell stuff as "sugar / fat free" which sure as hell is not!

www.greennio.com/en/product.php?productId=16

A real drop in temperature of 3 degrees Celsius would make a difference!

[Naam]

One nano coating claims 95% reflection, a dubious claim?

dubious²

A real drop in temperature of 3 degrees Celsius would make a difference!

of course it does make a difference but it is not achievable with radiation reflecting tiles and not even with the best ceiling insulation and attic ventilation. any such claims are either hallucinations or plain bragging combined with dàmn lies.

[Naam]

Well, I'm not sure about what to do under the tiles as my main concern is reflecting most of the IR rays away from the roof.

no need to do anything "under" or "above" the tiles. as mentioned before, prevention of heat built-up in the attic and insulating the attic from living area is the alpha and omega of "insulation above".