HVAC in Thailand

[drumboi68]

Hi all,

Been reading this forum for about two years and am now building a detached studio in my backyard, here
in Thailand. It’s a single room for drumming and recording, and for a set of slightly complex reasons, it
is only a single leaf construction. It will also have a minimum of one or likely two ( non-opening ) windows.
Yes, I realize what this does to “soundproofing”. Let’s assume that noise in/out is not a concern. What IS
throwing me for a loop is HVAC; at least the H is taken care of! I assume we will be installing an A/C unit,
and like all the ones I’ve seen here, the compressor etc will be outside the room.

The room measures 5m by 4m, ceiling height of 3m. Walls will be cinder blocks that are 14cm thick and will
be thicker obviously after rendering both sides. There will be a fairly airtight door, not strictly to a
Rod Gervais standard, but enough to make a sealed room; I need to design a fresh air in/stale air out system.

Main question: if the cold air blowing out of an A/C unit doesn’t count as “fresh air”, what can I do about the fact
that the fresh air fan will be sucking HOT air from outside in order to “freshen” up
my room? Must the A/C and the fresh air vent fight each other? This question of outside heat also applies in case
I forego A/C altogether and try to make do with floor fan(s). Either way, the fresh air vent will effectively be heating
my room, which thanks to drumming will already be getting warm. I can’t imagine that the stale air out fan can
reduce this problem.

I have read about A/C units that have a fresh air component to them but haven’t yet checked for availability here.
Availability in general is an ongoing issue.

Thanks for reading and extra big thanks if you can shed some light.

[gullfo]

you need an energy recovery ventilator - this will help preserve the cooler air while exchanging it with the hotter outside air. and since you're likely dealing with moisture balance as well, and ERV would be the correct unit. something around 2m3/min air flow should do it. you'll likely want to run some plenums in the room to reduce noise. something like this: https://na.panasonic.com/us/home-and-bu ... r-solution

[drumboi68]

Thanks Glenn, I'll be looking into that.

[drumboi68]

Ok, been researching ERV's and am having difficulty measuring how much ventilation I will need.

I think according to Glenn, 2m3/minute means 120m3/hour. I was under the impression that a minimum of 6 exchanges per hour (per person) is recommended, which would be 60m3 (the size of my room) every 10 minutes or 360m3/hour. That is three times Glenn's recommendation and anyway sounds wrong to me.

I'm hoping someone can point out my miscalculation.

Thanks!

[gullfo]

so 60m3 x 6 = 360m3/hr. divide by 60 min = 6m3/min total room. 35% (a decent starting point) is 2.1m3/min. so a 3m3/min unit should be enough. in US that's between 75-100cfm.

[drumboi68]

Thanks Glenn... ok so the calculating wasn't too far off but I've not yet come across this 35% or any percentage for that matter. Why is it recommended to use a fraction of the volume/minute that the formula produces?

Confused but getting there...

[gullfo]

it's 35% of the total air volume should be exchanged with fresh air. this can vary - typically from 25%-50% depending on the activity (more = more co2) etc. i like to start @ 35% as it's a good overall level. not a rule

[drumboi68]

Ah ok, thanks for that. I had no idea and could easily have invested in way too much ERV for my needs. That said, I might still aim higher within that range on account of being a drummer. There may also be the rare instance of a second person in that room. We'll watch each other for symptoms!

Really appreciate your input.

My HVAC engineer friend advised that I could put the fresh air output and the A/C close together if I'm concerned with the incoming temperature from the ERV, as I had mentioned before. So for the heck of it, here's a picture of what is to be:

appliances.jpg

[gullfo]

as a general guideline - usually the hvac unit and ERV are closely situated (and of course both decoupled from the structure), and typically all the other bits needed - VaV (if multi-zoning), balancing valves and duct bits, etc to ensure the system is operating properly, you have positive pressure in the room, etc.