Baseline HVAC system type question

15 posts / 0 new
Last post

Standard 90.1-2007. The building is a high rise residential with the ground floor mainly retail. 90.1-2007 says to use the predominant condition to select the baseline system. In this case residential is the predominant condition therefore I am assuming the retail spaces would also have System 1, PTAC? Heating is fossil fuel.

[Title: RWDI - Description: RWDI logo]

Christopher Jones, P.Eng. | Senior Energy Analyst
RWDI
901 King Street West, Suite 400, Toronto, ON M5V 3H5 Canada
Tel: (519) 823-1311 ext 2052
rwdi.com

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

I believe that if the retail gross floor area is less than 1900 m2 you can
use system 1, otherwise you can use exception a of section G3.1.1.

2017-02-16 17:12 GMT-02:00 Chris Jones via Bldg-sim <
bldg-sim at lists.onebuilding.org>:

--
Att.,

*Eng. Anderson Letti*

ASHRAE BEMP Certified - Building Energy Modeling Professional

Rua 3700, 249. CEP 88330-203

Bal. Cambori? - SC - Brasil
Tell: +55 47 99632 3912 <+55%2047%2099632-3912>
Skype: anderson.letti

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

The retail spaces are a section 3.1 "exception" and should be modeled as
System 3 or 4

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Opps. I missed Anderson's response, which is more complete than mine :)

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Thank you Anderson,
In this case, the retail is more than 20,000 ft2 so I need to select a different baseline system.

My follow-up question: the building is more than 5 floors (majority is residential) but the retail only occupies the ground floor. Would I select System 7, VAV reheat as the building is more than 5 floors.

Or would I select System 3 for the retail because the that space only occupies 1 floor?

[Title: RWDI - Description: RWDI logo]

Christopher Jones, P.Eng. | Senior Energy Analyst
RWDI
901 King Street West, Suite 400, Toronto, ON M5V 3H5 Canada
Tel: (519) 823-1311 ext 2052
rwdi.com

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Chris,
Residential is ALWAYS System 1 or 2, never one of the others.

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Jim,
My question is about the retail spaces on the main floor. I agree, the residential tower has System 1 but I am still not entirely sure about the retail spaces. They make up more than 20,000 ft2 so Exception G3.1.1.(a) applies but I am not sure if I use the area/number of floors of the entire building when selecting the retail baseline system. Or do I use the area/number of floors of the retail spaces when selecting the retail baseline System?

[Title: RWDI - Description: RWDI logo]

Christopher Jones, P.Eng. | Senior Energy Analyst
RWDI
901 King Street West, Suite 400, Toronto, ON M5V 3H5 Canada
Tel: (519) 823-1311 ext 2052
rwdi.com

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Dear Chris,

The ASHRAE INTERPRETATION IC 90.1-2007

might
help you. It states

*Exception a to G3.1.1 should be utilized first to determine if multiple
baseline HVAC system types from Table G3.1.1A are appropriate. However,
exception a to G3.1.1 only applies if the separate area is greater than
20,000 ft2 and that area must qualify for a different baseline HVAC system
type based on a different building type, heating source, number of floors,
or residential vs non-residential classification. For example, if the
office area and the warehouse area of a building are both greater than
20,000 ft2 and the office uses electric heat while the warehouse uses gas
heat, then two separate baseline systems types could be utilized. If
exception b to G3.1.1 applies to portions of the areas served by one of the
baseline HVAC systems, then separate single-zone systems conforming with
the requirements of System 3 or System 4 (depending on building heating
source) can be utilized. *

Hope this helps you!!

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Thanks very much for all the responses.

[Title: RWDI - Description: RWDI logo]

Christopher Jones, P.Eng. | Senior Energy Analyst
RWDI
901 King Street West, Suite 400, Toronto, ON M5V 3H5 Canada
Tel: (519) 823-1311 ext 2052
rwdi.com

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Right.

My framework is typically to piece this out in two steps:

1. Ignoring the possibility of G31.1.1A exceptions to start, determine the baseline system type for the whole building using the other prescriptions in play. In this case it would have to be system type 1 / 2 due to the predominantly residential situation.

2. Consider whether ANY singular or combined areas of the facility meet the 2 consistent requirements of G3.1.1A:

a. Total sum area > 20,000ft2 (aside: I?ve deliberately put forward alternative baseline systems where I haven?t met this threshold, but it totally makes sense to have a distinct/different baseline system)

b. ?nonpredominant conditions? - this isn?t a glossary term and is subject to interpretation. My successful interpretations (as measured by non-rejected LEED submissions) have included:

i. non-residential vs. residential occupancies (this is pretty clear cut as a listed example in the standard)

ii. very different load profiles (i.e. large greenhouse attached to a school, or where in the proposed design you?re excluding cooling for a warehouse)

iii. very different occupancy/usage profiles (i.e. a chunk of the facility requires 24/7 ventilation or process loads resulting in very different system operations)

The interpretation below would look to agree and clash with my usual interpretation depending on circumstance. At the end of the day I feel the presence of non-predominant conditions should not substantially help nor hinder the baseline case in an artificial manner relative to the proposed case. So long as you?re holding to that ?spirit? of the standard, you should be fine specifying alternative baseline systems.

~Nick

[cid:image002.png at 01D288F6.9F5BC690]
Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Schneider Electric

D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

[cid:image003.png at 01D288F6.9F5BC690]

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Thank you Nick,
The responses received point to using a different baseline system and I agree with those interpretations. In my specific case, high rise residential with retail on the main floor, I am going to use System 1, PTAC for the residential and System 3, PSZ for the retail.

However, it seems to me that I could also assign System 5 to the retail spaces. The non-denominate space (retail) is larger than 20,000 ft2 and the building is large enough to meet the threshold for System 5.

The standard doesn?t explicitly indicate that the non-denominate spaces are to be on System 3 or 4 therefore, I believe I could select System 5 although it would not be an apples-to-apples comparison. The proposed design has packaged single zone systems serving the retail spaces making tenant sub-metering simpler.

[Title: RWDI - Description: RWDI logo]

Christopher Jones, P.Eng. | Senior Energy Analyst
RWDI
901 King Street West, Suite 400, Toronto, ON M5V 3H5 Canada
Tel: (519) 823-1311 ext 2052
rwdi.com

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Chris,

There's a PNNL report that came out in 2016 that aims to fill this kind of gaps (though I feel there still are gaps, and sometimes I don't 100% agree with their interpretation). The openstudio-standards project which I contribute to that aims to automate baseline creation is based on this report

The title is ASHRAE 90.1-2010 Performance Rating Method Reference Manual.
The report is intended to be a reference manual for the Appendix G Performance Rating Method (PRM) of ASHRAE Standard 90.1-2010, but most holds true for 2007.

Best,
Julien

Envoy? de mon iPhone

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Here is the URL for the report:

http://www.pnnl.gov/main/publications/external/technical_reports/PNNL-25130.pdf

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Thank you Julien,
I have had the PNNL guideline since last May ? it is a great resource.

Off topic ? how far along is the openstudio-standards measure? I know a couple of people at NRCan who are working on the NECB version of that measure. It would be great to have an idea when we can start testing it.

[Title: RWDI - Description: RWDI logo]

Christopher Jones, P.Eng. | Senior Energy Analyst
RWDI
901 King Street West, Suite 400, Toronto, ON M5V 3H5 Canada
Tel: (519) 823-1311 ext 2052
rwdi.com

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400

Chris,

Well, though I contribute to the project, I only do so as a user (when I
find problems I fix them, and when I do might as well make a pull request
so that it's fixed for everyone). I'm in no way in charge of it (NREL is,
with help of Canada's NRC), *so anything below is my own opinion only*.
Also worth mentioning that* I've mostly played with (much) earlier versions*
of openstudio-standards too (v0.1.4 might be the last I used on a real-life
project, today's version is v0.1.11!)

I've successfully used openstudio-standards to generate a baseline for
several of my real-life projects. But so far I always had to modify the
code to make it work, which was slightly annoying for me but great for the
openstudio-standards project since it meant it got tested it on real,
complex projects and uncovered some new cases and bugs that got fixed (eg:
high-rise buildings that qualify for several exceptions because portions
were residential, other were commercial, and each had secondary areas
served by other type of fuel...).

Even though it required me to fiddle with the code, I found it to achieve
two things: a speed improvement anyway, and a much higher quality baseline
(for example the system exceptions based on the load difference and/or
different operating hours are very hard to do correctly and fully "by
hand", especially when you have 100 zones).

Since OpenStudio 1.13, the openstudio-standards is part of the OpenStudio
package itself, proof that it is deemed to be bug-free enough to be
released to the public. That doesn't mean you aren't going to hit a bug, or
simply get an error that you'll have to troubleshoot with an error message
that might not be crystal clear and will require you to dig a bit in the
source code - or get someone else to do it (eg this question

asked 5 hours ago). But this should happen less and less often as bugs and
new cases are uncovered as the user base grows (assuming users, who have
rights and duties, do the right thing and open issues when they find them).
The openstudio standards is still under active development (see
https://github.com/NREL/openstudio-standards/releases if you need
convincing).

Worth mentioning that even if one day it becomes "perfect" (it's getting
quite close to it), it will never mean a user can just switch their brain
off, click a button, and voil?! You'll still be responsible to ensure that
it worked correctly. Plus, the baseline determination uses inputs that are
in the proposed model: you have to properly assign space types, and
proposed HVAC systems (including fuel used, etc). If you screw that up, the
baseline will be wrong. As usual, the one rule is GIGO.

Cheers,
Julien

--
Julien Marrec, EBCP, BPI MFBA
Energy&Sustainability Engineer
T: +33 6 95 14 42 13

LinkedIn (en ) *| *(fr
) :

2017-02-22 14:52 GMT+01:00 Chris Jones :

Bldg simulation's picture
Offline
Joined: 2016-04-13
Reputation: 400