Control of Energy Recovery System in the Baseline Building on ASHRAE 90.1-2010 Simulated

3 posts / 0 new
Last post

Hello to all equest -users,

I am trying to model my Baseline building based on ASHRAE 90.1-2010.

In my case:

1. In my case based on paragraph G3.1.2.11 and in accordance with
Section 6.5.6.1 due to the climate zone and the %outdoor air at full design
airflow rate ?my baseline building? require Heat Recovery System.

2. Due to the climate Zone from Table G3.1.2.6A an Economizer is not
required.

My question is about the control of the heat exchanger in the baseline
building. In paragraph 6.5.6.1 is mentioned: ?Provisions shall be made to
bypass or control the energy recovery system to permit air economizer
operation as required by 6.5.1.1?.

The tables of 6.5.1.1, Table 6.5.1.1A and B mention about control of
Economizer.

Also is in the baseline building required an economizer required or not? I
mean, Table G3.1.2.6A and tables 6.5.1.1A and B seems to be in
contradiction.

I have modeled this in equest as following: What do you think;

[image: image.png]

[image: image.png]

Thank you

Konstantina Kalliakoudi

Konstantina Kalliakoudi
Mechanical Engineer,M.Sc.,

Konstantina Kalliakoudi's picture
Joined: 2019-03-25
Reputation: 0

Konstantina,

It?s not a contradiction as your wheel is only seeing your outdoor flow whereas an economizer would see more air flow.

If you?re 30% outside air at 10,000 cfm you have 3,000 cfm bypassing the wheel. The other 7,000 cfm are being returned and never see the wheel.

If you had an economizer you might get up to twice that flow rate when it?s 65F-75F depending on your location?s economizer requirements.

Yes, it?s economizing, a little but not enough to meet the full requirements of an air-side economizer. The intent here is primarily to avoid the pressure drop of the wheel while not recovering heat.

Hope that makes sense.

Dig into the hourly flow rates and loads to determine that?s working properly as the controls can get wonky.

Good luck.

Fred

Fred Betz PhD, LEED? AP BD+C
Building Performance
AEI | AFFILIATED ENGINEERS, INC.
5802 Research Park Boulevard | Madison, WI 53719

P: 608.236.1175 | F: 608.238.2614
fbetz at aeieng.com | www.aeieng.com
Follow us: [twitter] [instagram] [linkedin]

Fred Betz's picture
Offline
Joined: 2011-09-30
Reputation: 0

Hi Fred,

thank you for your answer.

So if I understood right ,the baseline building is with bypass of the
enthalpy wheel and with no economizer. And yes, this make sense.

Thank you

Konstantina Kalliakoudi

Konstantina Kalliakoudi
Mechanical Engineer,M.Sc.,

???? ???, 6 ??? 2020 ???? 6:23 ?.?., ?/? Fred Betz
??????:

Konstantina Kalliakoudi's picture
Joined: 2019-03-25
Reputation: 0