[Equest-users] Cambridge direct fired units in warehouse space

[Adam Barker]

Michael,

The weather file is representative of the area, and I did run an auto sized load, which calculated heating and airflow capacities much higher than what was specified (about 3x higher on average off the top of my head).

You raise a good point regarding de-stratification - reduced stratification is another claim the company boasts, as the building is pressurized. The claim to cut ACH due to infiltration in half.  I believe the team is looking into reducing the # of de-stratification fans in response to this.  I searched the forums for how to model de-stratification about 2 weeks ago and came up with a few threads basically hinting that it can't be accurately done.  Does anyone have a different opinion, or know if a way where this can at least be approximated? I want to avoid playing with the infiltration rates as I do not believe that is acceptable for a LEED model (at least here in Canada it isn't). As of now I have not modeled this effect.

The combustion problem is somehow managed through some limited venting, though I can't remember exactly what is going on, which is why I called them 'direct' fired units.

Adam Barker, C.E.T., LEED AP BD+C
Sustainability Project Manager
Provident Energy Management Inc.
T: 416-736-0630 x 1874 | abarker at pemi.com<mailto:abarker at pemi.com>

From: Busman, Michael R [mailto:MBusman at chevron.com]
Sent: Thursday, August 09, 2012 4:40 PM
To: Adam Barker; 'equest-users'
Subject: RE: Cambridge direct fired units in warehouse space

Adam,

I haven't had any experience with the Cambridge unit, nor am I able to answer your question about the unmet heating hours.  Have you tried auto-sizing just for a cfm and Btuh capacity comparison with the mech engineer's load calc?  Also, is the weather file representative of the warehouse location?

Because the building is a warehouse, it triggered a question in my mind that somebody else might be able to answer.  That is if eQUEST models thermal stratification in high bay areas such as warehouses or hangars?  If so, it may calculate unmet hours on the coldest days near floor level and a nice warm temperature at ceiling/roof level.  Just a wild thought.

Mike Busman

Michael R. Busman, CEM
Lead Project Engineer II

Chevron Energy Solutions
A Division of Chevron U.S.A., Inc.
145 S. State College Blvd.
Brea, CA  92821
Direct  714-671-3561
Fax     714-671-3438
eFax   866-420-0335 (Include my Full Name followed by "CAI:MHTZ" on Cover Sheet)
Mobile 310-387-2083
mbusman at chevron.com<mailto:mbusman at chevron.com>



From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-bounces at lists.onebuilding.org]<mailto:[mailto:equest-users-bounces at lists.onebuilding.org]> On Behalf Of Adam Barker
Sent: Thursday, August 09, 2012 1:07 PM
To: 'equest-users'
Subject: [Equest-users] Cambridge direct fired units in warehouse space

Hello everyone,

I was recently asked to model the impact of Cambridge 'direct' fried air handling units for a warehouse building compared to a conventional MUA with supply and exhaust. Has anyone had experience with these units?

They boast a very low fan power consumption (5 hp for 8565 cfm of air), 92% thermal efficiency, and a temperature rise and max discharge temp of 160 F.

Most of the inputs are straightforward however I am not sure I am modeling the 160 F temperature rise properly.  As of now I have Packaged Single Zone systems and have entered 160 F as both the 'zone entering max supply temp' and 'hot deck max leaving temp'. Would this fully capture that temperature rise?  I ask as I am getting about 150-200 unmet heating hours in these zones, even though all other inputs are as per the mechanical engineer.  Is this significant, or likely just the difference between how eQuest and the mechanical engineer size their loads?  The building is a cold climate (southern Ontario, Canada) LEED building, so I want to make sure I am modeling as much benefit as possible.

Adam Barker, C.E.T., LEED AP BD+C
Sustainability Project Manager
Provident Energy Management Inc.
T: 416-736-0630 x 1874 | abarker at pemi.com<mailto:abarker at pemi.com>

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