Heschong Mahone Group, Inc.

NYSERDA Daylighting Case Studies

New York State Energy Research and Development Authority (NYSERDA) contracted with HMG to conduct three case studies of buildings in the Northeast with innovative daylighting technologies.

Two of the buildings (Genzyme and NRG office buildings) used advanced window blinds, while the third building (Stop and Shop grocery store) used skylights with splayed light wells to increase daylight uniformity.

HMG conducted on-site monitoring of light levels and energy consumption for the three buildings over a six-month period, and conducted surveys of the occupants and facilities staff.

In all three buildings the innovative daylighting technologies were improving the daylight distributions in the spaces, and occupants appreciated the enhanced daylight and the operation of the innovative technologies. However, the observed lighting energy savings were not as high as could potentially have been achieved; the three buildings saved 45%, 25% and 4% respectively. In the last two cases the photocontrol systems were configured to maintain high levels of electric light even when adequate daylighting was available. Re-commissioning of these systems would likely improve the achieved savings.

As part of the analysis methodology of these case studies, HMG used a “DA30” Daylight Autonomy metric, which quantifies the percentage of time for which daylight levels are sufficient to provide 300 lux (30fc) of uniform illuminance across a space, during an 8am-6pm working day. This analysis metric was developed as part of the PIER Daylight Metrics project, which was co-funded by NYSERDA and Southern California Edison, and is a precursor to the new spatial Daylight Autonomy (sDA) metric currently proposed by the IES Daylight Metrics Committee.