huge energy savings for DOAS FC/CB system compared to VAV

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zhou zarah ????? OneDrive ???????????????????


[https://r1.res.office365.com/owa/prem/images/dc-generic_20.png]

20170429 baseline done.pd2


[https://r1.res.office365.com/owa/prem/images/dc-generic_20.png]

20170429 baseline done.inp


[https://r1.res.office365.com/owa/prem/images/dc-generic_20.png]

20170429 propose done.inp


[https://r1.res.office365.com/owa/prem/images/dc-generic_20.png]

20170429 propose done.pd2

Dear eQuester,

Sorry for disturbing at weekend, but this is an urgent project for me, please help...

I am modeling an office building with first floor as a canteen with kitchen. Proposed case has DOAS with fan coil/chilled beam (induction ratio of 4), energy source is natural gas boiler and chilled water meter. Baseline has VAV with reheat systems for office, and packaged single zone systems for kitchen, basement, canteen, gym, and several printing rooms. My problem is baseline model energy use for space heating and cooling is much higher than proposed case (5 times for heating, 2 times for cooling), I know chilled beam could save energy for 20% ~30% by reduced supply air flow rate, and intermediate CHW/HW temperature, but I really did not expect such a huge saving. Since this is a LEED project, the reviewer proposed this issue. I am trying to debug for several days, but still no answers. If anyone could take a look at my model and give any comments, I am really grateful with that!

Zarah

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

Hi Zarah,

I think that it is quite obvious to get savings in cooling, heating and Fan
for these kind of systems especially when there is VAV with reheat in the
Baseline Case.

The reasons for getting savings in these cases are as follows:

1. As there is separate outside air system so it will take more energy to
cool the space in proposed case. Might be there is heat recovery system.

2. Just try to configure out your building envelope and glasses U value and
SHGC w.r.t. the base case. If the U value and the SC factors are quite low
in the case of Proposed Case then you might get savings in cooling and
heating consumption.

3. You might get huge savings in Fan as the fan power of the Baseline Case
is quite huge enough in terms of kW/cfm or TSP in order to bring huge
savings in fan in case of VAV with reheat.

4. You will again have to reconsider the fact that the Baseline Case is
having reheat system in the zone so there might be huge fuel consumption to
cause the huge energy being consumed in the Base case in the reheat.

5. You might get savings in heat rejection as the Baseline Case has huge
water cooled cooling tower.

6. I have not been able to open your linked model but yes the major reason
behind the savings can be building envelope U values and glazing factors
but yes indeed the savings are quite on higher side.

7. You have mentioned that there is CHW meter in the proposed case. I think
that it can affect your cooling consumption denoted.

This has been the help from my side.

*Thanks,*

*Sharad.Kumar*

*India.*

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From: zhou zarah via Equest-users
To: eQuest User
Cc:
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Date: Sat, 29 Apr 2017 09:49:06 +0000
Subject: [Equest-users] huge energy savings for DOAS FC/CB system compared
to VAV
zhou zarah ????? OneDrive ???????????????????

Dear eQuester,

Sorry for disturbing at weekend, but this is an urgent project for me,
please help...

I am modeling an office building with first floor as a canteen with
kitchen. Proposed case has DOAS with fan coil/chilled beam (induction ratio
of 4), energy source is natural gas boiler and chilled water meter.
Baseline has VAV with reheat systems for office, and packaged single zone
systems for kitchen, basement, canteen, gym, and several printing rooms. My
problem is baseline model energy use for space heating and cooling is much
higher than proposed case (5 times for heating, 2 times for cooling), I
know chilled beam could save energy for 20% ~30% by reduced supply air flow
rate, and intermediate CHW/HW temperature, but I really did not expect such
a huge saving. Since this is a LEED project, the reviewer proposed this
issue. I am trying to debug for several days, but still no answers. If
anyone could take a look at my model and give any comments, I am really
grateful with that!

Zarah

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200