Page 117 - Designing for Zero Carbon-Volume 2_Case Studies of All-Electric Multifamily Residential Buildings

Building Envelope – Insulation and Windows
The nine-story concrete frame building uses non-combustible wall assemblies at the exterior walls, consisting of 2 x 6 metal stud framing with R-19 fiberglass batt insulation (formaldehyde- free). To prevent thermal bridging, a layer of two-inch rigid polyisocyanurate insulation is applied over the outside of the framed wall. (See detail below.)
The concrete slab is uninsulated below or at its edges. The roof, however, is well insulated us- ing a lightweight low-density insulating cellular concrete20 to provide both the slope required for drainage and an average thickness of six inches to achieve R=30.
For basic cost reasons, the windows are standard double-glazed metal frame windows, with a U-value of 0.25 and a Solar Heat Gain Coefficient (SHGC) equal to 0.25.
Building Envelope – Airtightness
No special airtightness measures were taken. Additional systems would be required, which would have incurred additional cost.
20 ElastizellTM Systems Inc., https://www.elastizell-systems.com/roof-deck.php
CASA ADELANTE AT 2060 FOLSOM
CASE STUDY NO. 5
Designing for Zero Carbon: Volume 2
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(Left) Representative wall de- tail showing the two-inch layer of rigid polyiso insulation ap- plied to the wall surface to prevent thermal bridging at the metal studs.