[Equest-users] PTAC vs WLHP Annual Energy Consumption

Wed May 6 09:42:41 PDT 2015

Tim and Maria

Thank you for sharing your experience on this issue.

Morteza

On Wed, May 6, 2015 at 11:49 AM, Maria Karpman <
maria.karpman at karpmanconsulting.net> wrote:

> Morteza and Tim,
>
>
>
> Attached is a nice article from ASHRAE Journal discussing HVAC system
> selection for envelope-dominated buildings. It compares modeled performance
> of VRF, GSHP, boiler+chiller, and WSHP in a generic 9-story multifamily
> building in a variety of climates, and concludes that WSHP is the worst
> option.
>
>
>
> Maria
>
>
>
> --
>
> *Maria Karpman *LEED AP, BEMP, CEM
>
> ________________
>
> Karpman Consulting
>
> www.karpmanconsulting.net
>
> Phone 860.430.1909
>
> 41C New London Turnpike
>
> Glastonbury, CT 06033
>
>
>
> *From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
> Behalf Of *Tim Johnson
> *Sent:* Wednesday, May 06, 2015 11:26 AM
> *To:* 'Morteza Kasmai'; equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] PTAC vs WLHP Annual Energy Consumption
>
>
>
> Morteza,
>
> I took a quick look at your models and the one thing that sticks out to me
> is your pump energy.  The difference between PTAC and WSHP is huge.  I
> would expect some difference since the WSHP needs to run the pumps in
> cooling mode as well as heating while the PTAC only needs pumps in heating,
> but the difference in energy seems too big.  Also keep in mind that the
> heating and cooling efficiencies of the WSHPs are only for that piece of
> equipment, they don’t include the heat rejection required in cooling mode,
> the boiler input in heating mode, or the pumps.  For those reasons, I
> wouldn’t expect the WSHP system to be a lot more efficient than the PTAC.
>
> Tim
>
>
>
> *Tim Johnson*
>
> Mechanical Engineer
>
> o 208.336.4900 | d 208.577.5645
>
> [image: CTA_email_graphic]
>
>
>
>
>
> *From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
> Behalf Of *Morteza Kasmai
> *Sent:* Wednesday, May 06, 2015 7:54 AM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] PTAC vs WLHP Annual Energy Consumption
>
>
>
> Dear eQUEST experts,
>
> I am still struggling to find out the main reason(s) for high-energy
> consumption of WLHP system comparing to PTAC system and what can be done to
> make this system more efficient that the baseline system. In other words
> for complying with EAp2 requirements, for a mid rise residential building
> what types of HVAC systems (other than split system HP) can be selected
> which consume less annual energy than the PTAC.
>
> I would appreciate it if you would share your experience on this and make
> some recommendation.
>
> Morteza
>
>
> [image: Image removed by sender.]
>
>
>
>
>
> On Mon, May 4, 2015 at 4:03 PM, <
> equest-users-request at lists.onebuilding.org> wrote:
>
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> Today's Topics:
>
>    1. PTAC vs WLHP Annual Energy Consumption (Morteza Kasmai)
>    2. Re: PTAC vs WLHP Annual Energy Consumption (David Reddy)
>
>
> ---------- Forwarded message ----------
> From: Morteza Kasmai <morteza.kasmai at gmail.com>
> To: "equest-users at lists.onebuilding.org" <
> equest-users at lists.onebuilding.org>
> Cc:
> Date: Mon, 4 May 2015 12:04:23 -0400
> Subject: [Equest-users] PTAC vs WLHP Annual Energy Consumption
>
> Dear all,
>
>
> This is a multifamily mid-rise building, 9 floors above grade. Per ASHRAE
> Table G3.1.1A the Baseline HVAC system is system 1 (PTAC with hot-water
> fossil fuel boiler) 9.3 to 11 EER.
> Selected HVAC system for the proposed design is WLHP (3 Ton High
> efficiency HP by Daikin, 15.9 EER and 4.83 COP) with 2 cell cooling tower,
> DOAS unit (9.8 EER) and 2 Boilers (0.92 Eff.).
>
>
>
> Although the efficiency of the selected HVAC systems is much higher than
> the efficiency of the baseline model, the simulation results indicate
> annual energy consumption of the proposed design is much higher than the
> baseline!
>
>
>
> Am I missing something or did something wrong in the models? Please see
> the attached files of the both models
>
> .
>
> I would greatly appreciate it if anyone kindly gives some feedback on this,
>
>  Morteza
>
>
>
>
>
>
> [image: Image removed by sender.]
>
>
>
>
>
> ---------- Forwarded message ----------
> From: David Reddy <david at 360-analytics.com>
> To: equest-users at lists.onebuilding.org
> Cc:
> Date: Mon, 04 May 2015 09:39:44 -0700
> Subject: Re: [Equest-users] PTAC vs WLHP Annual Energy Consumption
>
> Hi Morteza,
> I have not reviewed the results or detailed inputs of your model, but one
> thing to be aware is that depending on the rating conditions of your
> efficiency data, you may have to adjust the EIRs to be consistent with
> DOE-2 performance curves.  The default DOE-2 curves are normalized to the
> GSHP rating condition, so if using these and if your efficiency data is @
> the WSHP rating condition, you will need to apply these adjustments.
>
> Here is the table from the DOE-2 help provided with eQUEST.  There is a
> library of DOE-2 WSHP curves available from ClimateMaster that do not need
> these adjustments.
>
>
>
> - David
>
> On 5/4/2015 9:04 AM, Morteza Kasmai wrote:
>
> Dear all,
>
>
> This is a multifamily mid-rise building, 9 floors above grade. Per ASHRAE
> Table G3.1.1A the Baseline HVAC system is system 1 (PTAC with hot-water
> fossil fuel boiler) 9.3 to 11 EER.
> Selected HVAC system for the proposed design is WLHP (3 Ton High
> efficiency HP by Daikin, 15.9 EER and 4.83 COP) with 2 cell cooling tower,
> DOAS unit (9.8 EER) and 2 Boilers (0.92 Eff.).
>
>
>
> Although the efficiency of the selected HVAC systems is much higher than
> the efficiency of the baseline model, the simulation results indicate
> annual energy consumption of the proposed design is much higher than the
> baseline!
>
>
>
> Am I missing something or did something wrong in the models? Please see
> the attached files of the both models
>
> .
>
> I would greatly appreciate it if anyone kindly gives some feedback on this,
>
>  Morteza
>
>
>
>
>
>
> [image: Image removed by sender.]
>
>
>
>
>
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