[Equest-users] ERV in Ottawa

[Fleming, Joe]

To add to David's excellent comments, the operation and control of the ERV is also very important.
In that kind of climate there may be a lot of periods when the main AHU is trying to maintain a 74 degF interior space temperature with 55 degF supply air, and at the same time the outdoor air temp is in the range of 55degF-70degF.  In this scenario, the ERV is heating the incoming outdoor air before it has to cool it to 55degF, so the net effect is an increase in energy consumption during the moderate seasons.  An energy wheel should be shut off or idled during this time, (when OA enthalpy < RA enthalpy and the unit is in cooling mode), if it is a fixed plate ERV then there should be a way to bypass the ERV in the design.

Joe Fleming
E.I., LEED AP BD+C, BEMP
Mechanical Engineer I

TLC Engineering for Architecture
Your 2030 Challenge Partner

800 Fairway Drive, Suite 250
Deerfield Beach, FL 33441-1816

phone:

954-418-9096

fax:

954-418-9296

direct:

954-418-4591

website:

www.tlc-engineers.com<http://www.tlc-engineers.com>


[cid:image001.gif at 01CB97A4.0E3F20C0]<http://www.tlc-engineers.com/>

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of David Eldridge
Sent: Thursday, December 09, 2010 1:12 PM
To: Daniel Knapp; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] ERV in Ottawa


A couple of thoughts -- from your energy end-use breakdown the consumption in the heating season far outweighs the cooling season, so based on your particular situation, the extremes seem to be weighed towards heating.



Also your percentage of outside air in the office building is important.  If the percentage of outside air isn't very high, most of the heating for the desired MAT comes from the return air.  Try using the variable reporting to see how much load is on the preheat coil in your baseline case.



Lastly, if your building has major envelope losses, the ERV won't affect the use of your perimeter heating system if one is present, which may be carrying a lot of your heating load.



Hope this helps!



David




David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, HBDP
Project Manager

Direct: (847) 316-9224 | Fax: (847) 328-4550
http://www.grummanbutkus.com

Grumman/Butkus Associates | 820 Davis Street, Suite 300 | Evanston, IL 60201
Energy Efficiency Consultants and Sustainable Design Engineers





> -----Original Message-----

> From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-<mailto:equest-users->

> bounces at lists.onebuilding.org<mailto:bounces at lists.onebuilding.org>] On Behalf Of Daniel Knapp

> Sent: Thursday, December 09, 2010 11:56 AM

> To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>

> Subject: [Equest-users] ERV in Ottawa

>

> Hello,

>

> I've been trying to understand how ERV works because I am finding the

> energy savings to be somewhat less than I had expected.  Ottawa has a very

> cold climate in the winter and a warm, humid climate in the summer and I

> would expect enthalpy wheels to be a very good energy saving strategy.

> Instead, I am finding that in many cases the building uses more energy and

> in the best case scenario (OA exhaust DH, mixed air reset, modulate HX) on

> a VAV system saves only 0.15%.  I have built a simple box model with one

> system in a two-storey office building and tried a number of different

> control strategies (see attached tables for results).  I have tried a VAV

> and a SZ system.  The ERV is able to save marginally more energy in the SZ

> system, but in neither case are the results what I was expecting.

>

> My question is this:  are these results to be taken at face value and

> believed or is there a better way to model ERVs in a Canadian climate?  It

> seems very unlikely to me that ERVs cannot be controlled in such a way as

> to save significant energy in a climate of extremes.  (.inp file attached

> as well).

>

> With thanks and best wishes,

> Dan

>

>

> -

> Daniel Knapp, PhD, LEED(r) AP O+M

> danielk at arborus.ca<mailto:danielk at arborus.ca>

>

> Arborus Consulting

> Energy Strategies for the Built Environment www.arborus.ca<http://www.arborus.ca>

> 76 Chamberlain Avenue

> Ottawa, ON, K1S 1V9

> Phone: (613) 234-7178 ext. 113

> Fax: (613) 234-0740

>


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