[Equest-users] Would like to hear from you guys

Yazan Abukhait yazan142us at gmail.com
Wed Sep 12 11:52:47 PDT 2012


Thanks for the response, the total building load is 304 tons, and we will
be dealing with chilled water as purchased, taking credit of the chiller
plant is hard because you will need to satisfy the LEED "points floor"
which is 6 points, this is equivalent to 22% of cost savings. So given that
the chilled water is purchased, only the secondary pumps following the heat
exchanger will be dealt with as downstream equipments and regardless of the
load (i.e. even if the load is below 300 tons) these pumps must be variable
for the base line, right?. the AHUs of the baseline are of the variable
speed type, and by the way the climate of the project doesn't allow for the
use of economizers, so no economizers are installed, also the building
fabric for the proposed building will only save 1% energy 0.8% cost
compared to the baseline fabric, the last factor of effect is lighting, say
you can save 5 or 6% by daylight harvesting and more efficient fixtures,
given all these data, achieving 10% cost savings will be extremely hard if
not impossible I believe. please correct me if there is any factor I didn't
consider.

On Wed, Sep 12, 2012 at 9:37 PM, Hall, Brendan <BHall at karpinskieng.com>wrote:

>  If you are a system 8 (Electric Heat), then the only pumps would be for
> chilled water. If your total cooling capacity is greater than 300 tons then
> the baseline must have variable speed drives. Even if you are less than 300
> tons it is a primary/secondary loop with pumps riding their curves so it’s
> less efficient but not straight constant volume. Also, with heat recovery
> it is important to look at how many hours you would expect that it would
> run in your climate. For example, you would not want to run a ERU when a
> economizer would be available. There are obliviously other ways to get to
> 10% but it can be hard with district systems because by not being able to
> take credit for having a chiller you are losing out on opportunity to gain
> efficiency. Good luck.****
>
> ** **
>
> Brendan Hall****
>
> ** **
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Yazan Abukhait
> *Sent:* Wednesday, September 12, 2012 2:26 PM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] Would like to hear from you guys****
>
> ** **
>
> Dear all,****
>
>  ****
>
> I'm involved in a LEED project where my company have hired a LEED
> consultant, among the buildings is an office building consisting of 6
> stories, being fed from a central utility plant located within the project,
> the base line is the same that of the proposed building ( system 8) except
> that the VAV boxes are fan powered in the baseline. The mechanical engineer
> modeling the project is insisting that he can show a minimum of 10% energy
> savings by using variable speed pumps and AHUs and heat recovery, I believe
> the heat recovery part, but using variable speed pumps and fans should also
> being modeled for the baseline as well, isn't it the case? ASHRAE 90.1-2007
> will not allow you to use constant speed pumps for pumps and fans even when
> you use the LEED supplemental document for district cooling plants
> treatment, would like to hear from you guys, and thanks in advance.****
>
>  ****
>
> Regards****
>
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