Rating System

LEED BD+C: New Construction, LEED BD+C: New Construction, LEED BD+C: Schools, LEED BD+C: Schools, LEED BD+C: Core and Shell

Rating System Version

v2 - LEED 2.2, v3 - LEED 2009, v2 - Schools 2007, v3 - LEED 2009, v3 - LEED 2009

Inquiry

Our project is a new-construction library building, in a northern climate, with 5-stories underground (below grade) and 1 story above ground with a dome-shaped glass wall/roof structure. The glass dome is egg-shape in design (if the egg were on its side half buried in the ground), and encompasses one floor of occupied circulation and office space. The 5-stories underground will serve as climate-controlled mechanized book storage and retrieval, with little regularly occupied space. The project is designed and located to be in good standing for LEED certification, though the glass wall/roof design creates some questions about obtaining the minimum of 2 credits under EA Credit 1. We have spoken with a USGBC representative who recommended that we consider the three following assumptions when we compare the baseline energy model to the design case model. We would like to clarify whether these assumptions are correct with regard to building compliant energy models for this project. 1) The underground 5-stories of the building will be primarily climate controlled book storage, which we feel is a very energy efficient approach to design. We assume that for the energy model, our baseline building will be an above ground building (6 stories total) with typical wall construction. 2) The glass dome structure that serves as the ground floor walls and roof has clear viewing fenestration from grade to 14 feet. The dome is a total of 35\' tall. None of the fenestration is "vertical" glazing, it is at an angle that would deem it a skylight under a strict interpretation of ASHRAE 90.1-2004, though the dome is serving as a combined roof and wall structure. We propose treating the first 14 vertical feet of glazing as wall area (with 100% glazing according to ASHRAE 90.1-2004) in the design-case energy model, and the remaining vertical feet of dome area (from 14\' to 35\') as skylight (100% skylight, according to ASHRAE 90.1-2004) in the design-case energy model. 3) If the first 14 vertical feet of glass is treated as wall area in the design-case model, it would then represent a given percentage of wall glazing in the baseline energy model (represented as an above-ground building). To achieve a 14% improvement in the performance of the designed building, the design-case energy model will still be challenged by the ASHRAE 90.1-2004 allowance of a maximum 5% skylight area on the baseline energy model -against which we will be comparing our design-case model that has 100% of the roof area as a skylight. To summarize, this project is in good standing for LEED certification but we require clarification on our assumption that the baseline-case building would be an above-ground structure, that the first 14\' vertical feet of angled dome fenestration be treated as wall area in the design-case model, and that this respective area of fenestration would be used as wall glazing on the baseline model.