Zero Net Energy Retrofits for Small Commercial Offices: Zero Net Energy Package and Tubular Daylighting Device FLEXLAB Test Results Report

This report is a part of the California Energy Commission Electric Program Investment Charge program study “Zero Net Energy Retrofits for Small Commercial Offices”. The four-year research study launched in January 2017 and it involves lab testing, field demonstration, performance measurement and verification, and occupant engagement efforts to move an integrated set of emerging commercial retrofit technologies into wider adoption in order for small commercial offices to achieve zero net energy (ZNE) performance. This document provides the results of the FLEXLAB testing of a ZNE retrofit package applicable to both Southern and Northern California climates. The retrofit package consisted of modulating supply diffusers, LED lighting and daylight dimming, reduced plug load power and tubular daylighting devices (TDDs) for providing daylighting into core spaces. This document also provides the daylighting availability and lighting energy reduction potential specifically for the TDDs. Tests were conducted at LBNL’s FLEXLAB® facility, a customizable and configurable whole building integrated systems test facility. Results show that packages of ZNE measures resulting in substantial energy savings relative to standard practice. During cooling-dominated periods, total energy savings were 65% for south orientation and 68% for west orientation; during heating-dominated periods total energy savings were 22% for south orientation and 25% for west orientation. The introduction of the ZNE measures did not cause any measurable changes in visual comfort. Thermal comfort measurements results showed variations in thermal comfort between the two configurations, but within an acceptable range. TDD-specific tests showed potential annual lighting energy savings of 27% to 69% (annualized EUI of 0.61 to 1.42 kWh/ft2, assuming an installed LPD of 0.75 W/ft2) for 22” TDDs and 22% to 32% (annualized EUI of 1.52 to 1.53 kWh/ft2, assuming an installed LPD of 0.75 W/ft2) for 14” TDDs, with no negative impacts on visual comfort.