Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.2

Inquiry

The adoption of Appendix G under LEED 2.2 raises all sorts of interesting questions with respect to the energy modeling protocol. Please clarify for us and the world of LEED users out there the following: 1. Appendix G Addendum a Would USGBC for LEED 2.2 adopt the published Addendum a to 90.1-2004 Appendix G which changes a number of areas? 2. Building Orientation May we choose to not implement in our baseline model ASHRAE 90.1-2004 Appendix G Table G3.1 5. (a) orientation rotation which requires rotating the model to 4 cardinal directions, and averaging the results. For our project, orientation with the long axis of the building East-West was not optional. 3. Baseline Fenestration Area and Location Would the USGBC eliminate the provision under ASHRAE 90.1-2004 Appendix G Table G3.1 Baseline 5.(c) that requires dividing out the entire design window area, up to the 40% maximum window to wall ratio, and defining it as horizontal bands with average window to wall area on all facings and floors? This change is also proposed under Addendum a to 90.-2004. The addendum references the section numbering from an earlier version of the Standard prior to the creation of Table G3.1 in the current version of the Standard. 4. Residential Designed Lighting Baseline Will USGBC for LEED 2.2 adopt the same rules adopted under LEED 2.1 CIR rulings that established a residential lighting baseline, for designed fixed lighting? ASHRAE 90.1-2004 still treats residential living area lighting as exempt (9.1.1 Exception b), and Appendix G does not define a baseline for this lighting. The rulings defined a process of mapping from the designed lighting to baseline lighting with conventional incandescent lighting, with a maximum baseline lighting power density of 2.0 W/s.f. The rulings also established a 750 hour full load equivalent operating schedule to be the same in design and baseline. 5. Residential Receptacle Lighting Will USGBC for LEED 2.2 accept 90.1 Addendum a) change to table G3.1 Design 6 (d) so that receptable lighting energy usage is not subtracted out from the design and baseline models. This is an inconsistency the addendum corrects, and is the only case where non-regulated energy is not counted under the new standard. 6. Lighting Controls Will USGBC for LEED 2.2. allow Exceptional Calculations regarding energy savings for occupancy sensor and time-of-day controls that exceed ASHRAE 90.1 code requirements that are greater than the Appendix G Table G3.2. For example, LEED 2.1 rulings appeared to allow greater than 10% allowed by Appendix G for occupancy sensors controlling normally 24 hour interior stair lighting in a multi-family high-rise that would be occupied only a small fraction of the time. 7. Exterior Lighting Will USGBC for LEED 2.2 allow credit for exterior lighting that is more efficient than the new mandatory provision for exterior lighting in 90.1-2004 section 9.4. Appendix G does not address how exterior lighting should be modeled for the baseline, and therefore the default is that it should be modeled the same as the design and no credit for savings could be taken. 8. Residential Appliances and Exhaust Fans Will USGBC for LEED 2.2. allow for Energy Star rated appliances and exhaust fans an Exceptional Calculation approach (similar to previous LEED 2.1 rulings for an appliance ID credit) to calculate energy cost savings for EAc1? Exceptional calculation would be based on Energy Star data to define design and baseline energy usage? 9. DHW Usage Reduction Will USGBC for LEED 2.2. allow the approach to claim domestic hot water energy cost reduction based on low flow fixtures, relative to EPACT standard allowed fixture flows from earlier LEED 2.1 rulings. Another approach would be to adopt 90.1-2004 addendum a) revision to Table 3.1 Baseline 11. labeled as a revision to G4.3 under the older numbering convention. 10. Heat Recovery from Condenser Loop Will USGBC for LEED 2.2 allow the baseline adjustment for heat recovery from condenser loops to DHW as required in section 6.5.6.2 to be done with assistance of spreadsheet analysis outside of the model, or will the provision at Appendix G Table 3.1 Baseline 11 (f) exception that requires the proposed design to actually include the heat recovery equipment in the real building, if the modeling software cannot model it. The design feature cannot be modeled under DOE-2.2 and its interface eQuest, one of the most widely used and otherwise versatile programs. This provision, if enforced, requires a significant expense for the project that may not be cost effective compared to alternatives. This would be a penalty on the subset of projects that fall under the rules at 6.5.6.2. Normally, the design does not have to meet the prescriptive requirements of ASHRAE, but is allowed to make trade-offs to achieve overall energy cost savings. 11. Solar Hot Water-Clarify Eligibility for EAc1&2 Will USGBC state that solar hot water generation, that does not generate any electricity is eligible for credit under EAc1 and EAc2? Requirements language paragraph 1 for EAc2 does not state if energy generated from a renewable source is electric or thermal, although other parts of the chapter allow for solar hot water, but the second paragraph refers to a method to just estimate electricity generation. Just want to be sure there is no question that solar hot water generation is eligible for both EAc1&2.