Page 31 - Designing for Zero Carbon-Volume 2_Case Studies of All-Electric Multifamily Residential Buildings

IVY SENIOR APARTMENTS
CASE STUDY NO. 1
Renewable On-Site Energy Supply
Solar Thermal System
The solar thermal system described in the previous section was actually required to be part of the DHW system at the time of this project’s building permit application (2019) by the terms of the grant from the California Solar Initiative (CSI), administered by the California Public Utilities Commission (CPUC). This requirement is no longer in effect, having been removed with the adoption of the new Title-24 energy code in 2020. It was deemed to be more efficient to simply apply electrical energy directly to the preheating elements and make better use of limited roof space for solar PV panels.
The system consists of eleven SunEarth TRB-40 solar thermal collectors (4’x10’) circulating heated water to the solar hot water storage tank. Originally designed as a 20-panel system, calculations showed that the preheated water temperature would be too high, reducing the boiler efficiency and causing the solar thermal system to be shut off approximately 40% of the operat- ing time. Reducing the system to 11 panels balanced the system and optimized performance, incidentally opening up more roof space for the solar PV panels.
PRELIMINARY DESIGN
(Left) Solar thermal panels system design and layout on northwest roof, preliminary (top) and final design (bottom).
Designing for Zero Carbon: Volume 2
17
16
FINAL DESIGN (AS BUILT)
KEY: PLAN LOCATION - SOLAR THERMAL PANELS