Does anyone have experience showing code compliance via the performance path in 90.1-2013 vs 2015 IECC? I have a project that isn't meeting the 15% threshold against the 2015 IECC standard reference design (per C401.2(3)). I have always thought the 15% was to level the compliance paths, but the main difference I am finding between the 2015 IECC SRD and 90.1-2013 budget building is the mandatory plug load control requirement. What am I missing to account for the 15% difference?
Thanks,
Cory Duggin, PE, LEED AP BD+C, BEMP
Principal/Energy Modeling Wizard
TLC Engineering for Architecture
6 Cadillac Drive, Suite 200
Brentwood, TN 37027-5080
direct:
615-346-1939
website:
www.tlc-engineers.com
I just did a little seminar on this very topic for our Rocky Mountain
ASHRAE tech conference last week. There are a few other key differences in
90.1:
- Mandatory occupancy and daylighting controls in parking garages
- Bi-level occ sensors required in stairwells
- Slightly more stringent cooling efficiency requirements (full load and
part load, also slightly lower economizer thresholds). Differences in heat
pumps as well I believe.
- More stringent envelope requirements (walls and windows). Also note
limits to E/W glazing which may require that you rotate/average the
baseline.
Other important items to note:
- A90.1 has MANDATORY electrical submetering requirements (separate
monitoring for lighting, receptacles, and HVAC, plus some whole-building
requirements) -- this is a biggie. Read section 8-Power thoroughly!
- You CAN take credit for renewable energy (up to 5%)
- A90.1 does not have the same commissioning requirements
- A90.1 allows extra lighting credit for room geometry adjustments and some
extra lighting controls (see control factor table), whereas IECC does not
This is not a comprehensive list but those are the big ones that jump out.
Whichever method you choose, make sure you are using the space-by-space
method for lighting (it will almost always come out better than
whole-building).
Cheers,
Elizabeth
*Elizabeth Gillmor PE, BEMP, LC, LEED AP*
*e n e r g e t i c s **consulting engineers, llc*
energetics-eng.com | 303.619.0091
I think the reason for the 15% is that the IECC performance path has not kept pace with improvements to the prescriptive requirement in the rest of the IECC for several cycles. Things like insulation requirements, light power allowance, and HVAC equipment efficiency get updated automatically when the tables the performance path reference get updated. However, there are lots of other prescriptive requirements that have been added to the IECC that have not been captured by the performance path. A few that come to mind include:
1. 30% window to wall ratio limit C402.4.1
2. Variable speed fans on single zone systems C403.4.1.1
3. Skylights and daylighting controls for large high bay spaces
4. Heat recovery required for large service water heating systems C403.4.5
5. Boiler turndown requirements C403.4.2.5
6. Additional efficiency options C406
7. High input service water heating efficiency C404.2.1
I don?t really think it has anything to do with keeping up with ASHRAE 90.1.
__________________________
Michael Rosenberg, CEM, LEED AP
Senior Research Scientist
ENERGY & ENVIRONMENT DIRECTORATE
Pacific Northwest National Laboratory
2032 Todd Street
Eugene, OR 97405
(509) 375-1995
michael.rosenberg at pnnl.gov
www.pnnl.gov
Sorry, I should have qualified the envelope stringent-ness with an ***in MY
area*** note (CZ5). ?That isn't the case with all climate zones.
*Elizabeth Gillmor PE, BEMP, LC, LEED AP*
*e n e r g e t i c s **consulting engineers, llc*
energetics-eng.com | 303.619.0091
Elizabeth,
Don?t neglect Section 10 ? it also includes mandatory provisions for whole building metering ? all fuels. Measurements are to be taken every 60 minutes and reported hourly, daily, monthly, annually. The system shall be capable of storing the data for 36 months.
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Christopher Jones, P.Eng.
Senior Engineer
WSP Canada Inc.
2300 Yonge Street, Suite 2300
Toronto, ON M4P 1E4
T +1 416-644-4226
F +1 416-487-9766
C +1 416-697-0056
www.wspgroup.com
Good point, should have included section 10 in the must-read list! Thanks!!
*Elizabeth Gillmor PE, BEMP, LC, LEED AP*
*e n e r g e t i c s **consulting engineers, llc*
energetics-eng.com | 303.619.0091
I thought the same thing. I?m just having a hard time finding 15% worth. In my situation, the building could get the 40% exception for having 50% of the floor area in a daylight zone, so the SRD having 40% glass makes sense. None of the additional efficiency requirements are worth 15% savings from what I can tell.
Cory Duggin, PE, LEED AP BD+C, BEMP
Principal/Energy Modeling Wizard
TLC Engineering for Architecture
direct:
615-346-1939