Cold air complaints 1

[Boiler1]

Hi all,
I am getting a lot of complaints about recently commissioned Centralised AHU system serving an open plan office.
There are a number of wall temperature sensors in the area and they all read the desired values (between 20.3 C & 21.8 C to a set point of 21 C). The supply air temperature is 15 C but even at the supply air temperature of 18 C the complaints were still coming through.
The ceiling in the office steps up by 1m half way through and only the people in the area with the higher ceiling complained.
As the AHU operates in cooling mode I would expect the people under the lower ceiling to complain more– if there are any problems. What’s happening is totally opposite.
The velocities through the ceiling diffusers are reasonable low ( less than 2.5) but in any case are the same across the whole office.
Can the 'coanda' effect speed the air up along the higher walls causing more draught?
The humidity is not controlled nor there is a need for that but it’s generally high.
Has anybody got similar experience?
Regards,

 

[Ziggypump]

Office spaces are tricky, especially open ones. My first thought is the thermostat locations and installation. Are they controllable? If they are on an exterior wall is there insulation between the wall and sensor? Are the thermostats in direct sunlight? Without further knowledge of the design and layout these are my first thoughts.

Also, 21.8 seems to be low per ASHRAE. ASHRAE recommends about 23.9C. Have they tried increasing the space temperature setpoint?

 

[willard3]

The coanda effect will definetely cause dumping in the high ceiling area.

 

[Compositepro]

You will never make everyone happy about temperature in an open office, where you have women in skirts, men in suits and ties, sunshine through different windows at different times, and differences in personal preferences.
Accutherm thermostatically controlled diffusers may help, but probably not.

 

[ProcessHVAC]

20 - 21 C in an office sounds a bit cold. 22-24 C range usually keeps most people happy.

 

[Drazen]

office temperature should be 26 C. 24 C is ok only if there is determined corporate practice that everyone wears long sleeves.

i am talking about thermostat setting. if you count variations of 1-2 C inevitable for open spaces, your will find that with your 20 C measured it could be found down to 18 C and some spots, and everyone will complain in such circumstances.

raising temperature setting should be first solution to attempt with. if someone would complain for feeling too hot afterwards, you should check local heat sources. you would not want freezer atmosphere in open office only because two seats are too close to concentrated location of hubs/copiers etc.

this question seemingly has to be tied to office space organisation.

 

[Boiler1]

Thank you all. I will ramp the set point temperature and see how it goes. I went by CIBSE recommendations of 21 C ( +- 2 degC).
The hunidity around here is ususally high which doesn't help either.

Regards

 

[berkshire]

Perhaps I should not say this here.
But one thing that has been useful with complaints from people in an otherwise well balanced office.
Is a dummy thermostat closest to the loudest complainants.
B.E.

You are judged not by what you know, but by what you can do.

 

[BronYrAur]

Is the complaint actually temperature or that they feel cold air blowing on them? Perhaps a diffuser relocation would end the complaints.

 

[ChasBean1]

“The velocities through the ceiling diffusers are reasonable low (less than 2.5)” Less than 2.5 What? Furlongs per Fortnight? Use units.

This sounds like a classic case of over sized DX.

 

[chicopee]

Tell people who complain about the cold air to wear sweaters

 

[ChasBean1]

And bras that can conceal perky nips...