We talked last time about the need for major ventilation. If we hope to cool spaces under roofs that a lightly insulated with "passive" openings, say windows or grill vents we will need very large openings to keep the temperature rise less than about one degree C. when the roof gets hot. Here you can see an example, a high roof vent that provides about a square meter of open ventitlation at the peak of both ends of a traditional Thai house.The house is oriented N-S, so it presumably does well at catching the southerly breezes characteristic to the hot season.
In addition in this view you can see that the open windows with curtain billowing into the bedroom provides cross ventilation in the other direction as well.
The result in this case is a room that does not become much hotter than the outside air (maybe a degree or two at most) even though the roof, which is only lightly insulated, gets up to about 70 degrees on the outside in mid afternoon, late march.
In this case, there is no dropped ceiling or loft/attic space. but the same principle jolds if you have such space in your house and don't want a 40-degree dropped ceiling over your head when you nap, or (if your roof is concete and retains the heat) when you sleep at night. If you are goinng to cool space by ventilateing poorly insulated areas, you've got to have strong ventilation through big openings.
No comments:
Post a Comment