[bldg-sim] Occupancy Sensors

[G GAO]

CTG Energetics recently prepared an example LEED-NC v2.1 EAc1 submittal
for the USGBC in November 2004. In this documentation the example
project adopted a 20% LPD credit for occupant sensor controls in private
offices, which is based on a CIR submitted 12/2/2003 and ruled upon
2/4/2004 (There are studies supporting a wide range of savings (20% to
43%) in private office.  Savings in open office environment would be
significantly less.)

So, it seems that 20% LPD adjustment for private office is acceptable by
USGBC.  Hope this helps.

Grace  

-----Original Message-----
From: postman at gard.com [mailto:postman at gard.com] On Behalf Of Molly
Curtz
Sent: Friday, January 21, 2005 1:42 PM
To: bldg-sim at gard.com
Subject: [bldg-sim] Occupancy Sensors

Hi Bill-
I do not have direct experince obtaining LEED credit for Occupancy
Sensors, but I too am currently looking into this issue for a LEED
project.

As you note, It's my understanding that USGBC has not yet formally
adopted either 90.1-2001, or addendum e to 90.1-2001. (Rumor has it that
they will update directly to 90.1-2004 when they do update.)

I interpret the table G3.8 in addendum e to 90.1-2001 to show the
suggested adjustments to proposed L.P.D levels. I agree that the
language of:
'automatic lighting controls in *addition* to those required  for
minimum code compliance.' is very confusing. However, I think that
adjustments are suggested according to the table listings based on use
type either " Non 24-hour use and Less than or equal to 5,000 sq.ft." OR
"All Other Spaces".
My reading is that even though automatic shutoff controls are listed as
a mandatory measure for "All other" spaces in 90.1 1999 section 9.2,
that the listed L.P.D. adjustments for installation of either
programmable timing control, Occupancy Sensor, or Both are allowed.
(Note that the listed adjustment under "All Other", " Programmable
timing control" is zero
adjustment.)

Still , keep in mind that addendum e is not offically adopted by USGBC
yet.

For now, I'm working from 90.1-1999 and the published USGBC CIRs. There
is a Credit Interpretation Request that you have access to on the USGBC
web site if your organization is a USGBC member. I've copied the text
below in case some list members do not have access to the CIRs.(see
below.) The ruling on Measure 1 is the pertinent one, which states
adjustment of L.P.D. may be an acceptable means of approximating
Occupancy sensors without modifying the schedules between proposed and
baseline.

I have anecdotally heard that other projects used an adjustment of 20%
in the proposed L.P.D. for an office use and received credit. I'm
planning on trying this adjustment for the model I'm working on (since
it's 5% more than the addendum e listing).

Best wishes,
Molly Curtz
Ecotope Inc.                   p: (206) 322-3753
4056 9th Avenue NE      f: (206) 325-7270
Seattle, WA  98105        www.ecotope.com


      12/2/2003 -  Credit Interpretation Request
      Four energy-efficiency measures, which are not covered under
ASHRAE
90.1-1999 or the LEED Energy Modeling Protocol, are outlined below for a
106,000 square foot chemistry research laboratory building with numerous
lab fume hoods. These four measures generate significant energy cost
savings.

      Based on the following USGBC Credit Rulings posted on 06/07/2001,
06/27/2001 and 01/20/2002:
      "To document savings for [energy reducing strategies not covered
under ASHRAE 90.1-1999 or the LEED Energy Modeling Protocol], follow the
ECB Exceptional Calculation Method. See Section 11.5 of the ASHRAE 90.1
User''s Manual. Under the ECM, schedule variations may be used as a
basis of engineering calculations for discrete measures that are
precluded by the reference standard or the LEED EMP."

      We assume each energy-efficiency measure listed below should be
modeled discreetly and "exceptional" savings must be subtracted from the
Design Energy Cost in the same fashion as renewable energy.

      Based on the USGBC''s LEED Credit Ruling posted on 11/09/2001:
      "It is acceptable to use [the same simulation tool that is used
for the base simulation] to triangulate on projected savings for
discrete measures that can ONLY be approximated through schedule
manipulations."

      We assume that these Exceptional Calculation Methods (ECM''s) are
to be performed using the same simulation tool that is used for the base
simulation.

      For the first three energy-efficiency measures listed below, a
corresponding reduction in energy use can only be approximated by
altering the Base Building schedules (based on sound engineering
judgement).
Therefore, we hereby request preliminary approval for the first three
energy saving measures listed. Hourly schedules for lighting power
density and fumehood exhaust in both the Design Building and Base
Building are available for each case for review.

      1. Lighting Occupancy Sensors
      When motion and/or infrared sensors determine a space to be
unoccupied for a period of at least 15 minutes (adjustable), lighting
within the space is automatically reduced to minimum levels.

      2. Fumehood Zone Presence Sensors
      When locally mounted infrared sensors determine the zone in front
of a particular fumehood to be unoccupied for a period of at least 15
minutes (adjustable), laboratory exhaust quantities shall be adjusted to
reduce sash velocity from 100 fpm to 70 fpm for that individual
fumehood.

      3. Fumehood Occupancy Sensors
      Similar to Lighting Occupancy Sensors, when motion and/or infrared
sensors determine a space to be unoccupied for a period of at least 15
minutes (adjustable), laboratory exhaust quantities shall be adjusted to
reduce the minimum total room air change rate from 12 ACH to 6 ACH.
      Additionally, we request preliminary approval for the following
energy saving measure, to be modeled as noted below:

      4. Laboratory Air Cascading
      A portion of the makeup air required for fumehood exhaust shall be
delivered to offices and support areas and then "cascaded" to labs via a
ducted transfer air system. Ducts shall be sized so that the external
pressure drop realized along the path of the transfer air shall be a
maximum of 0.05" w.g.

      The Exceptional Calculation Method proposed would compare two
analogous air-handling system (one for office/support areas and one for
the laboratories), by breaking the air-handling system into two discreet
pieces, to facilitate comparison of the Base and Design building models.

      2/4/2004 -  Ruling
      ENERGY EFFICIENCY MEASURE 1:
      It appears that altering the schedule to approximate energy
savings from the lighting occupancy sensors (as described) fits within
the context of the 90.1 Exceptional Calculation Method. When calculating
the energy savings associated with these measures for EAc1, it is
necessary to justify both the proposed and budget schedules for occupied
hours and provide detailed space by space usage schedules that are both
reasonable and defensible. The budget and proposed building should have
the same lighting schedules for regularly unoccupied periods.
Additionally, it may be possible to arrive at a reasonable estimate by
manipulating the lighting power density in the proposed and design case.

      ENERGY EFFICIENCY MEASURES 2 AND 3:
      Fumehoods are considered process loads, which are not applicable
to EA Prerequisite 2 and EA Credit 1. The appropriate treatment of
laboratory process loads is the subject of numerous LEED CIRs. Please
refer to the EAp2 credit ruling dated 12/15/03 and EAc1.1 credit ruling
dated 12/15/03 for a discussion of the appropriate treatment of ASHRAE
90.1 non-regulated energy loads in EAc1. To maintain consistency with
the referenced standard, optimization of non-regulated energy loads is
recognized by award of an Innovation in Design (ID) credit rather than
award of EAc1 points.
      For ID credit calculations, it appears that altering the schedule
to approximate energy savings from the fumehood zone presence sensors
and the fumehood occupancy sensors (as described) fits within the
context of the
90.1 Exceptional Calculation Method. When calculating the energy savings
associated with these measures for ID credit award, it is necessary to
justify both the proposed and budget fumehood schedules for occupied
hours and provide detailed laboratory usage schedules that are both
reasonable and defensible. The budget and proposed building should have
the same ventilation rates for regularly unoccupied periods. If any of
the zones are internally load driven, the potential energy savings from
reducing the ventilation requirements must account for the possibility
of higher ventilation rate requirements imposed by internal loads.

      ENERGY EFFICIENCY MEASURE 4:
      The ECM proposal does not contain sufficient detail from which to
make an informed determination. It is likely that it will be allowed
during LEED certification review if ASHRAE 90.1 Section 11.5 guidance is
followed (i.e., provide theoretical and empirical information verifying
accuracy). Also consider this alternative approach: the lab could be
modeled as a 100% outside air system for the baseline case but as a
recirculating system for the proposed design. The outside air quantities
and relief quantities for the office space would be modeled as
identical. The fan power and schedule would be identical for the supply
and exhaust systems for laboratory and office areas. To model the
cascading system in the proposed design, the laboratory system
recirculates the volume of relief air that would be cascaded from the
office space to the laboratory space. The total amount of outside air
drawn into the building is reduced in the proposed design by the amount
of relief air that is cascaded from the office occupancy to the
laboratory. The outside air ventilation volumes and exhaust volumes are
identical for the two cases (the outside air discrepancy is due to a
make-up air, rather than a ventilation air requirement).

----- Original Message -----
From: "Bill Talbert" <btalbert at aeieng.com>
To: <bldg-sim at gard.com>
Sent: Friday, January 21, 2005 8:56 AM
Subject: [bldg-sim] Occupancy Sensors


> Does anyone have experience obtaining LEED credit for energy savings
due
> to occupancy sensors? ASHRAE 90.1-1999 requires automatic lighting
> shutoff control (9.2.1.1) and occupancy sensors are one strategy for
> meeting this requirement. Addendum e to 90.1-2001 allows power
> adjustment percentages for the use of 'automatic lighting controls in
> addition to those required  for minimum code compliance.' If occupancy
> sensors are used for meeting the automatic shutoff control requirement
> with no additional shutoff controls provided, then my interpretation
is
> that no energy savings credit can be taken. If anyone has a different
> interpretation or has had success achieving LEED credits, please let
me
> know.  I am not aware of the USGBC adopting 90.1-2001 Addendum e yet,
> but if there is an opportunity to achieve savings through the use of
> occupancy sensors, it could be accomplished through the Exceptional
> Calculation Methods outlined in A90.1-1999 (11.5). Any assistance
would
> be appreciated.
> Thanks,
>
>
> Bill Talbert, LEED AP
> Mechanical Engineer
> Phone: (608) 441-6677
> E-mail: btalbert at aeieng.com
>
> Affiliated Engineers Inc.
> 5802 Research Park Blvd.
> Madison, WI. 53719
> Tel. (608) 238-2616
> Fax. (608) 238-2614
>
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