Fresh air supply to room 1

[remp]

I have an office with normal VAv box in it to do the air conditioning. Fresh Air component is approx 10l/s/person and there is one person in the room.

They are converting the room to a 10 person meeiting room. We need an additional 90l/s to cater for an extra 9 people in the space.

This is happening in a few offices on the floor.
Is it ok to install a small fresh air air handling unit where by each meetingroom will be served by the VAV box for temp control thor an air grille(s) and by a secondary supply to a seperate air grille for fresh air. The fresh air is supplied to the room at room temperature or just bewlo it.?
IOn other words 2 different grilles in the room with different temperatures?

I know someone who did it before for a high rise/ What do you think>?

REMP

 

[DRWeig]

Remp,

It's not only acceptable, it's the best way to ventilate in my opinion, period.

Tempered, individually ducted fresh air gives you total ventilation rate control, easy control of building pressure, and the best comfort control available at minimum energy -- especially when paired with carbon dioxide demand control of ventilation volume.

I've seen this system many times, but usually only in places built with oversized budgets (US government and military facilites, headquarters of huge corporations, etc...).

Let's see the opinions fly, though! I'm just one guy...

Good on ya,

Goober Dave

 

[SAK9]

Questions rather than answers:

Is the existing air flow sufficient to meet the increase in load?

How is temperature control achieved?

 

[remp]

Yes. The existing supply is Ok re: air flow rate for the load, just about. The existing VAV supply will deal with the room load and control temp. The fresh air will be delivered into the room at a few degrees below room temp just to help out in the room load also.

R

 

[remp]

Do you put attenuaoters at the end of your VAV box? I see some manufacturers offer lined duct attenuator type. Is it worth it if you are using a low velocity system max 7m/s

Remp

 

[mikanical]

Have to agree with DRweig regarding the ventilation strategy. Decoupling of the ventilation and H&C systems simplifies controls and can increase overall energy efficiency as you don't have to supply excess fresh air to the other zones to meet the O/A requirements of the critical zone.

I recommend including an attenuator at the end of all VAV boxes. The only time I don't is on low velocity air valves used for demand control ventilation (<4-5 m/s) where the air system is purely for ventilation. Heating and cooling loads are then covered by radiant panels and/or slabs.