just read recently that ceiling vents for the exteriors might be necessary (see attached pic as sample). 
However, I am a bit concerned as this might "ruin" our design especially on the facade part. im however willing to attach some vents at the rear part of the house. which brings me back to the question, are these vents necessary? what are the implications if i don't attach such or only if i attach them at one side of the house? by the way my roof is the minimalist type, shed type with very minimal angle. the hollow space between ceiling and roof (technically truss height) is about 30-40 cm.
thanks!!!
Re: are exterior ceiling vents necessary
yes vents are necessary
Re: are exterior ceiling vents necessary
yes vents are necessary
Agree because jan lumalabas ang hot air sa kisame.
Re: are exterior ceiling vents necessary
I'm also curious.
Hot air goes up. The vents are at the bottom of the space between ceiling and roof. How would these vents help in cooling that space?
Re: are exterior ceiling vents necessary
Hot air rises. That's a fact. But when surrounding air moves (like when it's windy or something), the movement of colder air outside can displace the hot air inside... I can't really explain. I live in a house with an attic with, of course, a vent similar to the photo above. When it's windy outside, I can feel air moving to and from the vent.
Re: are exterior ceiling vents necessary
Oh boy, this is one of my pet peeves, architecturally, lol.
Eaves vents were originally used only as cool air INLETS, while a distinct
set of roof vents served as hot AIR OUTLETS. The former are much easier
to construct from scratch than the latter, and are much easier to service,
which is why they have remained in very common use, but as OUTLETS!
Yes, they are counter-intuitive in that role, because hot air rises.
With a two-slope roof, you can get away with that, so long as you have
eave vents near the roof ridge (and therefore higher than the other eave
vents) to serve as constant hot-air outlets. With a hip-roof, all your eave
vents are inefficiently at the same elevation.
Eave-vents-only are still better than nothing, since hot air also expands,
as much as it tends to rise. This means it pushes outwards and through
any holes it finds, even through holes below it. A pressure differential, like
when there is more wind velocity outside one eave vent than the other,
can indeed have one vent acting as inlet and another as inlet... but then
the volume of air moved is minimal, because the pressure differential can
be a very temporary situation, whereas the effect of solar heating is more
constant.
As such, an eaves-vents-only approach doesn't cool the roof/ceiling cavity
so much as keeps the air within it from reaching critically high temp, such
as can deform PVC conduits, plumbing vents, and delaminate plywood in
a ceiling.
Philippine homes would be a lot cooler, if eave and roof vents were used
in tandem. Roof vents however cost quite some money to provide, install
and maintain. The more efficient they are, the more they stand out like
a sore thumb (and I'm not even talking about active, spinning vents).
In typhoon conditions, roof vents can be an entry point for some rain to
get into the roof cavity. Any time you punch through the roof, you have
a breach that requires almost-yearly maintenance to keep a proper seal
against rain. Then there's the pest-ingress problem...
The reason our residential-design vernacular is the way it is today, is due
to a whole bunch of compromises. Higher indoor temps are the price we
pay for dodging a whole bunch of (see above) ongoing hassles and costs.
Today, one can find improved, unobtrusive roof-vent (and even eave-vent)
designs, but the construction industry prefers to do what it is accustomed
to,
JM2
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