Wall Insulation

[Oldfart]

I have noticed that if I ventilate my present home at night by using a fan to suck in the cool night air and another fan to expell warmer air from inside the house, I’m able to stay quite cool from about 6pm every evening to about 10am the next day. After 10am, the ambient external temperature rises rapidly and I must stop sucking this warm air in so I just use one fan circulating the air within the living area, but I have all windows and doors open. Eventually of course the inside temperature will rise and equate to ambient external air temperature, often quite rapidly.

I’m wondering, if I insulate all the house walls externally, for example, by fitting polystyrene sheeting and wire mesh with cement render, or some other external insulation to the outer face of the walls, would this be sufficient to keep the block walls cool?

What I’m thinking is that, by doing this, the cooler night air that has cooled down the blocks overnight will have this coolness stored in the high-mass blocks. Sort of like a heat-sink, but a cool-sink! So then, instead of ventilating the house in the morning, I close all doors and windows before the sun rises, this stored cool night air will be able to keep the house cooler for longer, until the coolness in the blocks eventually reaches ambient air temperature. All the walls are 100% in the shade, and the roof/ceiling is insulated with foil and fibreglass.

Is anyone already doing this? Or, is this just not going to work in the tropics?

[Naam]

Is anyone already doing this? Or, is this just not going to work in the tropics?

it would partly work but not exactly as you think (walls = cool sink). insulating the outside walls AND the ceilings is the basis for having a cooler home. and yes, i am doing this already since five years and save a bundle in energy cost. 4 months a year early morning ambient temperatures are below the inside temperature of my airconditioned home and three months considerably below. i am running a huge exhaust fan which sucks fresh air from the outside and used/warm air from the inside. timing generally 03.30 till 06.00 hrs in rare cases (real cool days) an hour or two longer. before the sun is up i run all my aircons full blast because their capacity increases with every degree centigrade ambient temperature below their rated capacity (32ºC).

of course i air the house also during the hot months as used up stale inside air has to be replaced with fresh outside air.

[tpthai2]

I have been checking this out:

http://www.sprayfoamthailand.com/index.php

Any members have experience with this method and company?

[Naam]

I have been checking this out:

http://www.sprayfoamthailand.com/index.php

Any members have experience with this method and company?

the method spraying the foam on the inside of roof tiles is rubbish² inefficient and a waste of money. the attic will still heat up (takes slightly longer) and heat transfer will happen from attic through gypsum ceilings. the proper way to use spray foam is to apply the foam on the gypsum boards. best ceiling insulation available! for real efficiency thickness should be 5cm (2"), cost depending on company between 400 and 550 Baht per m².

[fredlk]

the method spraying the foam on the inside of roof tiles is rubbish² inefficient and a waste of money. the attic will still heat up (takes slightly longer) and heat transfer will happen from attic through gypsum ceilings. the proper way to use spray foam is to apply the foam on the gypsum boards. best ceiling insulation available! for real efficiency thickness should be 5cm (2"), cost depending on company between 400 and 550 Baht per m².

I have the foam on the underneath of my white Colorbond roof and it's great. I think I paid 300 Baht per square metre.