Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
I believe, the envelope performance factor is the annual cost for the whole building based on the model described in Appendix C and using the purchased energy rates described in C3.3. The proposed envelope performance factor is based on the proposed building and it is compared to the base envelope performance factor (sometimes called budget envelope performance factor) that is the proposed model modified to meet the prescriptive requirements. I was a little surprised by your question but in looking through 90.1-2013 and 90.1-2016, it is not explicitly described.
Please note that this is my personal opinion and is not an official interpretation from ASHRAE.
| | 2 | No.2 Revision |
I believe, the envelope performance factor is the annual cost for the whole building based on the model described in Appendix C and using the purchased energy rates described in C3.3. The proposed envelope performance factor is based on the proposed building and it is compared to the base envelope performance factor (sometimes called budget envelope performance factor) that is the proposed model modified to meet the prescriptive requirements. I was a little surprised by your question but in looking through 90.1-2013 and 90.1-2016, it is not explicitly described.
Please note that this is my personal opinion and is not an official interpretation from ASHRAE.ASHRAE. To request an official interpretation see this page.
