Hi equesters
recently,I have trouble in equest ,my heating unmet load hours is too high,but i think my setting is no problem.attached is my model, i hope someone can solve this problem for me .and any suggestion is appreciated.

I have a question about unmet load hours that I have not seen before.
In the attached project, when I run the sim, the BEPS report says that
there are 542 unmet heating hours and 117 unmet cooling hours.

To find what systems and zones are having issues, I look at the SS-R
reports and usually find that there are more hours reported at the
individual zone level than at the BEPS level due to concurrent unmet
hours.

This project is the opposite for heating. If I sum the SS-R unmet
heating hours, I get 6. If you look at the BEPS, there are 543!

Cooling is understandable with 171 hours from the SS-R reports and 117
from BEPS.

Has anyone seen this behavior before? This is a building with Heat Pump
PVVT systems (really VRF systems, but that is handled later) and a
Makeup air unit providing OA to the PVVT systems. None of the unmet
hours are from the MAU system.

I am running into a similar issue on my model too. I wrote to the mailing
list regd. it a week or 2 back. The sum of hours outside the throttle range
reported in the SS-R does not match that in the BEPS. Neither does the % of
hours (outside throttle range) called out in the BEPS match with the total
number of hours(outside throttle range) in the BEPS.

1) appendix a, section 6.1, references that "For the purpose of Section
A1.2, the base assembly is a slab floor of 6 in. concrete poured
directly on to the earth ..." meets the requirement for an unheated slab
f-factor of 0.73, and
2) section a6.3, f-factors for slab-on-grade floors, a.6.3.1 states:
"/F-factors/ for slab-on-grade floors shall be taken from Table A6.3", and
3) section a6.3.2 states: "These /F-factors/ are acceptable for all
/slab-on-grade floors/."

does the "all slab-on-grade floors" really mean any thickness of
slab-on-grade? i.e. section 6.1 references a 6-inch uninsulated slab
meeting the 0.73 f-factor requirement, but per sections a6.3.2 and table
a6.3 a 4-inch uninsulated slab (or an 8-inch uninsulated slab) would
also meet the 0.73 f-factor requirement. so why would section a6.1
specify a 6-inch slab when any slab thickness will suffice? the user's
manuals (both years) just refer to table a6.3 for f-factor values.

the state of washington has a similar section in its energy code (see
link below), page 41, table 4-2. section 1003.2 (also page 41) lists
"All on-grade slab floors as assumed to be 6 inch concrete poured
directly onto the earth." note that on page 40, table 10.1, the
f-factors decrease the deeper the below grade the slab-on-grade floor is.
http://ftp.resource.org/codes.gov/wa_energy.pdf

Hi All,

I have a question about unmet load hours that I have not seen before.

In the attached project, when I run the sim, the BEPS report says that

there are 542 unmet heating hours and 117 unmet cooling hours.

To find what systems and zones are having issues, I look at the SS-R

reports and usually find that there are more hours reported at the

individual zone level than at the BEPS level due to concurrent unmet

hours.

This project is the opposite for heating. If I sum the SS-R unmet

heating hours, I get 6. If you look at the BEPS, there are 543!

Cooling is understandable with 171 hours from the SS-R reports and 117

from BEPS.

Has anyone seen this behavior before? This is a building with Heat Pump

PVVT systems (really VRF systems, but that is handled later) and a

Makeup air unit providing OA to the PVVT systems. None of the unmet

hours are from the MAU system.

Thanks for your help,

Bryce Munger

Bryce,

I am running into a similar issue on my model too. I wrote to the mailing

list regd. it a week or 2 back. The sum of hours outside the throttle range

reported in the SS-R does not match that in the BEPS. Neither does the % of

hours (outside throttle range) called out in the BEPS match with the total

number of hours(outside throttle range) in the BEPS.

-Sangeetha

knowing that

1) appendix a, section 6.1, references that "For the purpose of Section

A1.2, the base assembly is a slab floor of 6 in. concrete poured

directly on to the earth ..." meets the requirement for an unheated slab

f-factor of 0.73, and

2) section a6.3, f-factors for slab-on-grade floors, a.6.3.1 states:

"/F-factors/ for slab-on-grade floors shall be taken from Table A6.3", and

3) section a6.3.2 states: "These /F-factors/ are acceptable for all

/slab-on-grade floors/."

does the "all slab-on-grade floors" really mean any thickness of

slab-on-grade? i.e. section 6.1 references a 6-inch uninsulated slab

meeting the 0.73 f-factor requirement, but per sections a6.3.2 and table

a6.3 a 4-inch uninsulated slab (or an 8-inch uninsulated slab) would

also meet the 0.73 f-factor requirement. so why would section a6.1

specify a 6-inch slab when any slab thickness will suffice? the user's

manuals (both years) just refer to table a6.3 for f-factor values.

the state of washington has a similar section in its energy code (see

link below), page 41, table 4-2. section 1003.2 (also page 41) lists

"All on-grade slab floors as assumed to be 6 inch concrete poured

directly onto the earth." note that on page 40, table 10.1, the

f-factors decrease the deeper the below grade the slab-on-grade floor is.

http://ftp.resource.org/codes.gov/wa_energy.pdf