[Equest-users] Can't find the source of space heat elec use

[Chris Baker]

This is how I was able to get cooling down to baseline level in proposed.

Control setpoints were probably part of it.  I did go back in the DX cooling controls and change it to “warmest” with 70F max reset.

Just thought I would share this in case others in the future have similar problems.

The issue was definitely the supply flow, however.

The system has 5,000 CFM design capacity but only when the exhaust fan is blowing air out at the kitchen hood (Zone GNE5).  I had to set up a Min Flow Schedule so that scheduled flow was about 154 CFM for the kitchen.  The schedule corresponds with the exhaust fan schedule for the kitchen now.  So when the exhaust fan kicks on there is an ample source of makeup air from the duct.

This cut 4,000 KWH from my proposed model just in cooling energy and lowered heating energy by another 400 MBTU (an inadvertent  but added benefit).

But big thanks to RB and Brian Fountain for assisting!

-Chris

From: Chris Baker
Sent: Sunday, June 28, 2015 5:03 PM
To: 'R B'; Brian Fountain (bfountain at greensim.com)
Subject: RE: [Equest-users] Can't find the source of space heat elec use

RB,

Good news!

I think I was able to resolve this - at least for the most part.

I went back and realized I showed 2600 CFM in the kitchen (on system AHU1) but no fraction of design flow or MIN flow schedule (so it was pumping 2600 CFM into 332 square foot area on a regular basis).  My hunch is that because of the reheat temp being so warm the system would have to occasionally cool, then it would heat up, then it would cool again, etc…  At least that’s my theory.

I was right in setting 2600 CFM design flow but it should only be at design flow when the Range hood is exhausting 2500 CFM (which is on a schedule and only operates on certain hours during weekends and holidays).

I went back and showed the normal flow as a fraction of the 2600 CFM design flow (154 CFM) and Min Flow Ratio that corresponds with this flow.  This means the only time the supply air comes in at 2600 CFM design flow is when the exhaust fan is on – blowing out 2500 CFM out of the other end of the system if that makes sense (both schedules correspond).

So I think this is pretty much fixed.

Baseline Cooling is 1257 KWH
Proposed Cooling (now) 1365 KWH – it was originally 5002 KWH.

Which is at least comparable.

Also my heating energy went down from 4400 MBTU to about 4000 MBTU in the process (though I didn’t change any heating controls just yet).

-Chris

From: R B [mailto:slv3sat at gmail.com]
Sent: Sunday, June 28, 2015 3:39 PM
To: Chris Baker
Subject: Re: [Equest-users] Can't find the source of space heat elec use

If you set the cooling control strategy to warmest, and the max reset to 70F; and in heating mode the control strategy to coldest with the hot-deck-supply temp to also whatever is the zone max supply temp, then the supply air temp during winter will not be as low as 55F.
-Rohini

On Sun, Jun 28, 2015 at 3:57 PM, Chris Baker <CBaker at cci-alliance.com<mailto:CBaker at cci-alliance.com>> wrote:
Thanks I will tweak the schedule in a separately saved proposed model and see the result.

Attached is what I mean.  Look at the cooling loads for Baseline.  Then compare that to cooling loads to Proposed.

Wow!

But I’m going to try your idea.

Thanks!

Chris Baker
CCI CAD Drafter

From: R B [mailto:slv3sat at gmail.com<mailto:slv3sat at gmail.com>]
Sent: Saturday, June 27, 2015 6:14 PM
To: Chris Baker
Subject: Re: [Equest-users] Can't find the source of space heat elec use

If cooling is not installed, but needs to be modelled, then most people put the thermostat schedule at a high number like 95F, so cooling does not turn up - I think you can find this on the list.
PVAV default sends the supply temp at 55F and then the reheat heats it up to whatever is needed. That might be causing the high cooling. See if it reduces if you set the cooling control to warmest instead of constant.

On Sat, Jun 27, 2015 at 8:03 PM, Chris Baker <CBaker at cci-alliance.com<mailto:CBaker at cci-alliance.com>> wrote:
Thanks!  It was indeed more than zero.  Correcting it fixed the issue.

The next hurdle is figuring out why my system in proposed has four times more cooling than my baseline system (PSZ-AC System 3).

But part of it is that I only have four PVAV systems in proposed.  The baseline has 38 PSZ systems.

Have you run into this before?

The actual proposed building is much better insulated but doesn't have an actual cooling system because we're in Alaska.

Appendix g said if no cooking is installed to model cooking the same as the baseline.

Even with higher cooling in proposed the annual cost savings is 50-60,000.

So I'm not sure I should address it at this point.im<http://point.im> nearing the end of the modeling process.

-Chris.

Sent from Outlook<http://taps.io/outlookmobile>


On Sat, Jun 27, 2015 at 4:01 PM -0700, "R B" <slv3sat at gmail.com<mailto:slv3sat at gmail.com>> wrote:
Havn't looked at your file - but see if the electric input ratio for boiler is non-zero (EIR).
-Rohini

On Thu, Jun 25, 2015 at 1:25 PM, Chris Baker <CBaker at cci-alliance.com<mailto:CBaker at cci-alliance.com>> wrote:
So my proposed model is attached if anyone can help me narrow this down?
The bin file is TMY2 weather file for Fairbanks Alaska.

I can’t figure out what is causing electrical usage for space heating.  All space heating energy should be fuel-oil (for the boiler) unless I’m overlooking something.

In my BEPS report you will see 19 MBTU of space heating under “electrical” but I can’t find the source (5567 KWH for elec space heating in BEPU).

My PS-A Report (also attached) shows electrical use throughout the year for space heating with a max of 1.1 MWH in January.

Has anyone seen this before?  It isn’t pilot light related because that’s zeroed out.

The only other possibility I can think of is it being boiler related.

Chris Baker
CCI CAD Drafter


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