[Bldg-sim] 90.1-2010 Baseline lighting power allowance calculation

[Nick Caton]

Sorry, I missed “2010” in the subject line … My previous response is with specific regard to 90.1-2007.  

 

For (my) clarity, “cg” isn’t a 90.1-2007 addenda, but specifically for 90.1-2010:  https://www.ashrae.org/standards-research--technology/standards-addenda 

 

90.1-2010 (pre-addenda) introduced table 9.6.2, but the Table G3.1 language is very similar to 90.1-2007 pre-addenda, with respect to lighting requirements.  

 

As I understand it, the procedure for 90.1-2010 (pre-addenda) is if you should choose to use the space-by-space method (for prescriptive compliance or for an Appendix G baseline model), part of coming up with your baseline LPD’s is adding the applicable controls credits in Table 9.6.2.  So if for example you have a 900ft2 classroom laboratory (Table 9.6.1 -> 1.28 W/ft2) with 522 Watts of installed lighting for which the proposed design uses Multi-level occupancy sensors (new glossary term), for all the lights, the baseline lighting power allowance for that space = 1.28*900 + 0.05*522 = 1152+26.1 = 1178.1 Watts, or 1.309 W/ft2.

 

Easy right?

 

I think the issue at hand here however is that Table G3.2, and the associated reference in Table G3.1, was not removed prior to addendum cg, so “by the book” you are instructed to BOTH reduce proposed LPD’s per Table G3.2 AND add baseline controls credits (Table 9.6.2) to the baseline model per the prescriptive space by space method.  When I first noticed this, I assumed it was intentional… with 90.1’s powers-that-be deciding to amplify savings in this “easy” fashion of just updating the prescriptive space-by-space approach rather than modifying/expanding upon Table G3.2 separately.  Seemed elegant at the time, in a way.

 

Addendum “cg” to 90.1-2010 (found at the above site, also attached) however suggests this was ultimately considered “double counting,” and there was never the intention to provide controls credit in both the baseline and proposed model.  So you now have 2 procedures involving Table 9.6.2:  for prescriptive compliance you must still add quantities determined via 9.6.2 to the allowable lighting power (the number you’re supposed to beat, on the whole), but for Appendix G you must instead subtract the same quantities from the proposed lighting power… 

 

This unfortunately means one can no longer simultaneously document prescriptive compliance while developing model documentation (but maybe I was the only one doing that)… bummer!

 

~Nick

 



NICK CATON, P.E.
Senior Engineer

 

360 Analytics
9750 3rd Ave NE, Suite 405

Seattle, WA 98115
office:  206.557.4732 ext. 205
 <http://www.360-analytics.com/> www.360-Analytics.com

 

From: Cheney [mailto:chenyu73 at gmail.com] 
Sent: Thursday, September 25, 2014 2:48 PM
To: Nick Caton
Cc: Jones, Christopher; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] 90.1-2010 Baseline lighting power allowance calculation

 

Hi Chris and Nick, 

 

Did some research and below is my observation: 

 

1. Instead of modifying the baseline, you will have to keep the same schedule (with consideration of mandatory lighting control requirement) in both proposed design and baseline. 

 

2. Meanwhile, LPD from Table 9.6.1 which is 1.23W/ft2 in your case, should remain the same in the baseline. 

 

3. For the spaces where no mandatory lighting control requirement, you can claim credit in the proposed design  by using: 

 

installed lighting power under control -  installed lighting power under control x control factor (table 9.6.2)

 

4. Without doing 3, you can also modify lighting schedule in the proposed design to claim non-mandatory control savings but you have to provide separate analysis 

 

Do you guys agree with my interpretation? Let me know your thoughts. 

 

Best Regards,

Cheney

Connect with me and view my    <http://press.linkedin.com/display-media/209/4>   <http://lnkd.in/bqQf52i> http://lnkd.in/bqQf52i

 

On Thu, Sep 25, 2014 at 1:48 PM, Cheney <chenyu73 at gmail.com <mailto:chenyu73 at gmail.com> > wrote:

​Wait a minute, guys. I suddenly recall that Table G3.2 has been removed from Appendix G by its addendum cg. In the same addendum, Table 3.1/6.lighting has also been modified. I just quote the relevant part for your consideration: 

 

Proposed design

 

"e. The lighting schedules in the proposed building design shall reflect the mandatory automatic lighting control requirements in Section 9.4.1 (e.g., programmable controls or occupancy sensors). 

Exception: Automatic daylighting controls required by Section 9.4.1 shall be modeled directly in the proposed building design or through schedule adjustments determined by a separate daylighting analysis approved by the rating authority.

f. Automatic lighting controls included in the proposed building design but not required by Section 9.4.1 may be modeled directly in the building simulation or be modeled in the building simulation through schedule adjustments determined by a separate analysis approved by the authority having jurisdiction. As an alternative to modeling such lighting controls, the proposed building design lighting power density may be reduced by the sum of all additional allowances per Section 9.6.2c and Table 9.6.2, which are calculated individually as the lighting power under control multiplied by cf, where cf is the appropriate control factor given in Table 9.6.2 corresponding to the space type and the lighting controls designed to be used." 

 

Baseline

 

"c. Mandatory automatic lighting controls required by Section 9.4.1 shall be modeled the same as the proposed building design." 

 

It looks like section 9.6.2c and Table 9.6.2 will govern the calculation rather than Table G3.2.  




Best Regards, 

Cheney

Connect with me and view my    <http://press.linkedin.com/display-media/209/4>   <http://lnkd.in/bqQf52i> http://lnkd.in/bqQf52i

 

On Thu, Sep 25, 2014 at 1:06 PM, Nick Caton <nick at 360-analytics.com <mailto:nick at 360-analytics.com> > wrote:

There are multiple ways to approach proposed vs. baseline LPD’s & scheduling which would arrive at the same annualized answer for relative lighting end-use energies, however Table G3.1 has another line that helps clarify 90.1’s intent.  (I’m paraphrasing) “The lighting schedules (which are normally identical between baseline and proposed) are understood to reflect the mandatory automatic control requirements.”  The suggestion here is to use the baseline LPD’s presented, unmodified, for the baseline model.  In turn, the proposed model may take the prescribed “credit” for occupancy sensors anywhere they are used EXCEPT for the spaces identified within the mandatory requirements (section 9.4).  As an example, if you had a proposed LPD of 0.90 installed in an office with occupancy sensors everywhere, you could model 0.81 for all spaces excepting the conference/break rooms, where you’d model the actual LPD.  

 

Incidentally, if you are performing an Appendix G model for LEED, I believe this is the approach pushed by the EAp2 workbook/footnotes.

 

Be cognizant that the inverse procedure you’ve proposed (amplifying the baseline LPD, instead of reducing the proposed LPD) may have the same net difference for lighting consumptions, but may result in a different (possibly helpful / possibly detrimental) overall Appendix G performance rating percentage, as you are now playing with distribution of the baseline’s internal loads instead of the proposed model’s.

 

Food for thought ;).

 

~Nick

 

 



NICK CATON, P.E.
Senior Engineer

 

360 Analytics
9750 3rd Ave NE, Suite 405

Seattle, WA 98115
office:  206.557.4732 ext. 205 <tel:206.557.4732%20ext.%20205> 
 <http://www.360-analytics.com/> www.360-Analytics.com

 

From: Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org <mailto:bldg-sim-bounces at lists.onebuilding.org> ] On Behalf Of Cheney
Sent: Thursday, September 25, 2014 10:49 AM
To: Jones, Christopher
Cc: bldg-sim at lists.onebuilding.org <mailto:bldg-sim at lists.onebuilding.org> 
Subject: Re: [Bldg-sim] 90.1-2010 Baseline lighting power allowance calculation

 

Yes, it is what I understand for ASHRAE appendix G baseline but not NECB baseline. 




Best Regards, 

Cheney

Connect with me and view my    <http://press.linkedin.com/display-media/209/4>   <http://lnkd.in/bqQf52i> http://lnkd.in/bqQf52i

 

On Thu, Sep 25, 2014 at 9:51 AM, Jones, Christopher <cjones at halsall.com <mailto:cjones at halsall.com> > wrote:

I am somewhat confused about calculating the baseline lighting power calculation, Space-By-Space method, with respect to lighting controls.

 

For example, Table G3.1 states “Lighting shall be modeled having the automatic and manual controls in Section 9.4.  For a Conference/Meeting/Multipurpose room the LPD is 1.23 W/ft2.  9.4.1.2.(b) states that a conference room shall have an occupancy sensor.  Does this mean that the LPD is reduced by the factor listed in Table G3.2 is 10% for occupancy sensor in buildings greater than 5000 ft2.  So would the LPD for the baseline conference room be 1.23 * 0.9 = 1.1?

 

Thanks for your assistance!

 

 

Christopher Jones, P.Eng. 
Tel: 416.644.4226 <tel:416.644.4226>  • Toll Free: 1.888.425.7255 x 527 <tel:1.888.425.7255%20x%20527> 

 


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