Replies

1. GBA Editor
   Martin Holladay | Oct 05, 2016 04:56am | #1

   Luke,
   If the temperature is 80°F at midnight, it's going to be hard to get much cooling from a whole-house fan. In your climate, the most effective way to get comfortable is with an air conditioner.

   If comfort requires you to operate your air conditioner for more hours per day, or to install more (or larger) air conditioners, you will have lower energy bills if you perform air sealing work and if you add more insulation to your ceiling. Adding exterior shutters to your windows may also be worth considering.

   If you don't want to run your air conditioner for more hours per day, the traditional way to improve comfort is with large, ceiling-mounted fans.

   Good luck.

2. 
   lukeleewood | Oct 06, 2016 12:31am | #2

   Dear Martin,

   Thank you so much for your advice. I can easily add insulation above the ceiling and perform air sealing work as you suggest.

   I looked into shutters but many of the windows are outward-opening casements and I have grills on the inside. I will look into suppliers who can help out.

   Can I ask if you think adding insulation under the roof tiles and/or adding vents is worth doing? I have read that adding roof vents is mandatory in the US but we have requirements here.

   Thanks so much for helping me out.

   Regards,

   Luke

3. GBA Editor
   Martin Holladay | Oct 06, 2016 05:01am | #3

   Luke,
   Q. "Can I ask if you think adding insulation under the roof tiles and/or adding vents is worth doing? I have read that adding roof vents is mandatory in the U.S."

   A. Adding vents is much less likely to help than adding thicker insulation. (There is little evidence that venting an attic in a hot climate lowers air conditioning bills. For more information on this topic, see All About Attic Venting.)

   Concerning the question of whether adding insulation is "worth doing," that's a hard question to answer. The answer depends on many factors, including:
   - Whether you are renting or you own the house.
   - How long you plan to live there.
   - How expensive electricity is.
   - Whether you can afford to pay your electric bill.
   - The price of insulation work in Kuala Lumpur.
   - Whether skilled insulation contractors exist in Kuala Lumpur.

   You might want to start by just improving your air conditioning system and paying the bills for a few months before deciding whether to investigate insulation retrofit work.

4. Expert Member
   Dana Dorsett | Oct 13, 2016 04:03pm | #4

   Awnings really aren't very useful for west facing windows in the tropics, but roll down exterior window shades are. Closing the window and rolling down fairly dark exterior shades will take a huge chunk off the PM solar gain.

   Anything over R30 in the attic will have essentially no benefit, but something more than R20 would be good (say, 6-7" of rock wool batting or 7-8" of loose fill rock wool raked smooth. & level.) The thermal mass of tile roofs already reduces the peak roof gains compared to low-mass roofing, and ~R25-ish is enough. Light colored tiles or mop-on high solar reflective index coatings on the exterior will deliver more benefit than interior side radiant barriers, once you're at R20+ at the attic floor, but may not be allowed. In Greece they know the benefit of high-mass light colored roofs and whitewashed high-mass walls- with better heat rejection than the terra cotta tiled roofs of the western Mediterranean, though terra cotta tiles are also used in Greece.

   Roof vents are not mandatory in the US, but there are code prescriptions how unvented roofs must be built. But tile roofs are inherently vented, and would not need additional venting even in the US. The primary purpose of venting the attic is to purge moisture, lowering the mold/rot potential, but in a tropical climate in an air conditioned building unvented roof assemblies end up with lower moisture content in the wood.

   Once you have air sealed and insulated a bit, try keeping the windows closed during the day and running the air conditioning at least a little. The outdoor dew point averages in Kuala Lumpur run in the mid-70sF (22-23C) year round, and the high humidity is as big or bigger factor than the raw indoor temperature. Even 28C at 60% relative humidity is a heluva lot more comfortable than 24C (the average overnight low, year round) at 90% relative humidity. When you open up the windows you're letting the humidity back in, and the air conditioning won't bring the temperature down very much until it has removed a good deal of that moisture.

5. 
   user-3106915 | Oct 13, 2016 04:32pm | #5

   In hot humid Florida, bamboo can be a help. If you have any property at all along the hot side of your house to plant bamboo, you are probably aware you will have a full sun screen before you know it. A bamboo sunscreen, 22' ft tall, along the west side of my Florida house has made a huge difference.
   And maintenance is not a big deal, not at all.

6. 
   user941025 | Oct 13, 2016 04:40pm | #6

   Whether or not you own the property you need for a vegetative screen, do be careful with invasives, bamboo certainly included, and vines (which would be my suggestion) also included. Perhaps a few very large planters with drainage would be the way to do either of these.

7. 
   Jon_R | Oct 13, 2016 04:47pm | #7

   Also consider window awnings (to shade the windows until the sun gets very low).

   http://inspectapedia.com/BestPractices/Figure3-12.jpg

8. Expert Member
   Dana Dorsett | Oct 13, 2016 06:09pm | #8

   In Florida go for the kudzu- let it crawl up and shade the roof too! :-)

   In Kuala Lumpur there are plenty of native species of bamboo, but a species that grows tall enough to really shade the second or third floor isn't something most people would want to plant in town.

   BTW: Concrete roofing tiles are usually pretty reflective unless painted with some darker paint- the amount of incremental performance gain from a mop-on coating would still be pretty small, and maybe not worth it compared to other measures. Keeping it clean and free of mold / moss / algae keeps it's solar reflectiveness reasonably high.

9. 
   user-3106915 | Nov 05, 2016 05:18pm | #9

   No vegetation too close to the structure in Florida. That's asking for trouble: insect infestations, rot, etc. Bamboo comes in two major varieties: Clumping, and running. Running is typically much taller with heavy stems over 2" thick. It 'runs'. Clumping typically has maximum 1" stems, and spreads slowly over years. Some clumping varieties grow over 20' tall. That's what I have planted. And I am in the middle of town. Bamboo requires little care, is drought resistant, grows as fast as grass -- that it is. It is hurricane resistant, and if blown over, will not do much damage. Even running bamboo new shoots can be easily tamed by tapping them over with one's foot, before they get a foot tall. Bamboo is easy, and beautiful, and safe. Way too much is made of the liabilities, it's easy to care for and control.

10. 
    lukeleewood | May 30, 2018 11:27pm | #10

    Dear All,

    Thanks very much for all your advice.

    I recently installed 4 inches of cellulose insulation across the entire attic. The results have been impressive. The temperature on the top floor of the house used to regularly reach 93.2°F. Since the insulation was added, the temperature hasn't risen above 85.1°F.

    Also, the existing airconditioners take much less time to cool the room. Previously, the rooms weren't cool until 3am; they now cool in minutes rather than hours. The electricity has also reduced although it is hard to say by how much.

    Thanks again everyone for all your help.

    Kind regards,

    Luke

11. GBA Editor
    Martin Holladay | May 31, 2018 05:53am | #11

    Luke,
    Thanks for reporting back. I'm glad to hear of your positive results.