See all forum discussions about NC-v4 EAp2
 Subscribe to new posts about NC-v4 EAp2 Post a new question aboutNC-v4 EAp2
See LEEDuser’s guidance on NC-v4 EAp2»
FAQs about EAp2 :

Do the required savings for this prerequisite (and credit) need to come only from building energy, or also process loads?

Our project doesn't have enough energy savings to earn the prerequisite. Can we get there by incorporating onsite renewables?

Our proposed design has insulation R-values that are below those prescribed by ASHRAE 90.1-2010. Can we still meet the prerequisite?

View answers »

Forum discussion

NC-v4 EAp2:Minimum energy performance

Existing building curtainwall reduced glazing %

I have an existing envelope that is a complete curtain wall assembly that is to be replaced.  The overall WWR for the building is over 70% currently and is being removed and redesigned to be approximately 35% glass when complete.  Two questions:

1. Should the baseline model WWR be the original 70% or be set at the new WWR of 35%?

2. Should the baseline glazing and wall assembly values be set at current conditions (single pane glass, low wall R-value) or have to meet the minimum requirements in section 5 of ASHRAE 90.1-2010?

Thank you.

1
Post a reply

You rely on LEEDuser. Can we rely on you?

LEEDuser is supported by our premium members, not by advertisers.

Go premium for $15.95  »

Profile picture for user sheffer
Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Tue, 01/16/2018 - 15:53

The standard is certainly not clear. Table G3.1-5 Baseline (f) indicates that you can model "existing conditions". It is not clear that they mean area and window performance values or just window performance values. Looking ahead in the development of Appendix G in ASHRAE 90.1-2016 it appears that they have clarified this to include the area. So I think that you can model the baseline with the original 70% WWR and the existing performance parameters.

Tue, 01/16/2018 - 16:06

Thank you Marcus.  I appreciate your expert feedback.

Add new comment

To post a comment, you need to register for a LEEDuser Basic membership (free) or login to your existing profile.