Dear forum users, I have modelled a project following Appendix G. and have received a review regarding my interpretation of % glazed area on the baseline. The project is a mayor renovations + Additions (existing conditioned warehouse + New office building attached). There were no modification on % area of vertical and horizontal glazing on the existing bit of the building. My approach was to model existing envelope, shape and fenestration, exactly the same in both proposed and baseline. The addition was modelled following the "maximum 40% for vertical fenestration and 5% for skylight" rule. The result of the whole building for baseline is, 28% vertically glazed and 12% of skylights (the existing bit was very different than 40%, and 5% respectively) The reviewer states that the end result for the baseline should still be 40% and 5%. It is not very clear to me how would I get there.. Do I have to make the existing fenestration proportionally smaller, just like I would do for the baseline of a completely new building? Thanks in advance. Santiago.

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Marcus Sheffer

LEED Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Tue, 11/05/2013 - 14:45

Table G3.1-5 Baseline (f) says to model the baseline envelope with the existing conditions prior to the renovation. Table G3.1-5 Baseline (c) says to model the glazing area the same as the proposed or use the limits if the proposed is over those values. It clearly says that this applies only to new building and additions. Table G3.1-5 Baseline (d) related to the skylights does not say it only applies to new construction and additions. I would think the vertical glazing and skylights would be treated the same but that is not the case based on a literal interpretation. So I think you are correct to model the existing vertical glazing the same. Apply the 40% rule to the addition only. The skylight area is not so clear. Our interpretation is that (f) would allow you to model the skylight area the same in the existing and apply the 5% rule to the addition only. This does require some interpretation so the application of the skylight 5% rule is not as clear cut as the vertical glazing.

Zonda E. Team

Zonda Engineering

LEEDuser Basic Member

3 thumbs up

Tue, 11/05/2013 - 17:37

Marcus, again Thanks. I will reach out to the reviewer to see if we can clarify our approach or need to do the changes they suggested. I posted the same thread on bldg-sim email group and had contradicting opinions about the interpretation on this particular matter, which means there must be room for interpretation. I hope discussions like this one will build into future standards (or whitepapers, and 'how to' guides) so that is less and less dependent on interpretation.

Shaun Wang

Dr.

LEEDuser Basic Member

0 thumbs up

Mon, 02/24/2014 - 11:28

Marcus is absolutely right especially on interpretation on vertical fenestration for additions. So that your "The addition was modelled following the 'maximum 40% for vertical fenestration and 5% for skylight' rule" is right with a not 100 percent certainty on 5% skylights rule (but actually Marcus suggests this 5% rule and LEED reviewer's reply implies this rule as well). But your next statement "The result of the whole building for baseline is, 28% vertically glazed and 12% of skylights (the existing bit was very different than 40%, and 5% respectively) The reviewer states that the end result for the baseline should still be 40% and 5%." seems not clear to me. So in your model, if proposed case for this office addition is 28% vertical fenestration and 12% skylights, the baseline (for just this office addition) should be 28% vertical (minimum of proposed case or 40%) and skylights 5% (minimum of proposed case or 5%). In this case, I don't think you need to model baseline (for this office addition) with 40% vertical fenestration.

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