Greetings,
The issue is how to model Dwelling units, having in mind that they are not regulated by ASHRAE 90.1. More specifically it refers to the energy model, which is to be provided at Design review stage. The only available LPD in Table 9.6.1 of ASHRAE Standard is for Dormitory, which however is close but different to Dwelling unit.
As recommended by reviewers, I went through the Simulation guidelines of MFHRP and also through LEED Interpretation 5253.
The conclusion I’ve resumed and I’m planning to apply are:
1. Taking credits based on interior lighting savings in dwelling units must be claimed using an Exceptional calculation method
2. This kind of lighting power appears to be considered as process load.
3. The LPD for dwelling units should be entered identical in Baseline and Proposed Design, unless Exceptional Calculation Methodology is provided as described in the reference documents mentioned above.
4. The LPD is to be 1.1 W/sf as stated in the Simulation guidelines of MFHRP, Version 1.0, Revision 02, September 2013.
5. Baseline and Proposed Design lighting inside dwelling units shall be modeled as lit for 2.34 hours per day as per item 3.6.2.5 of the Simulation guideline.
6. This kind of lighting power shall be entered in the Process tab of MEP Calculator as Non-Receptacle Process Equipment
Please provide some comments and/or confirmation of the assumptions I’ve summarized above, so that to be able to comply correctly to the LEED and ASHRAE requirements.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
November 5, 2020 - 2:09 pm
Sounds right. You will also need to provide illuminance calculations demonstrating that the required light levels are achieved by the proposed interior lighting design.
Vassil Vassilev
ManagerTermoservice
13 thumbs up
November 6, 2020 - 2:21 am
Hi Marcus,
Thanks for he reply. One small clarification though. When mentioned 2.34 hours per day, does it mean 2.34 of 14 hours or 9.75%.
Vassil Vassilev
ManagerTermoservice
13 thumbs up
November 6, 2020 - 2:22 am
Sorry for the mistake - 2.24 of 24 - 9.75%
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
November 6, 2020 - 10:51 am
Yes the lighting schedule should reflect that the lights are on 2.24 hours within a 24 hour period, each day of the week.
Francesco Passerini
engineer90 thumbs up
February 11, 2021 - 4:03 am
In the page of Interpretation 5253 the Rating System v. 4 is not mentioned: https://www.usgbc.org/leedaddenda/5253
And as "International Applicable" the answer is no.
But shall I apply that in Europe for Rating System v. 4? Otherwise, I don't know which other method I shall apply.
Best Regards
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
February 11, 2021 - 10:31 am
Here are the guidelines for modeling multi-family projects. https://www.usgbc.org/credits/multifamily-energy-model-simulation-guidel...
Francesco Passerini
engineer90 thumbs up
February 12, 2021 - 4:47 am
Thank you very much!
The guidelines state: "Lighting energy savings credit may be claimed for reduced power density only if the fixtures are capable of meeting the recommended light levels for the given space type, per the IESNA Lighting Handbook."
Are the light levels available? I have found this online: https://www.superbrightleds.com/blog/residential-recommended-lighting-levels/6548/
Best Regards
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
February 12, 2021 - 11:28 am
Yes the lighting design must meet the illumination requirements and you have to demonstrate that they do meet those requirements. In the past I know the document contained the light levels required. The IES values in the first table at the link you provided look too low to me.