Integration case study: Small retail store
A remodel of a 3000-sq-ft retail building was simulated using an energy modeling program to determine the impact on the HVAC cooling loads. For the baseline design (simulating the existing lighting in the space), 75 W halogen track lighting fixtures and 74 W (input power) 2-x4-ft recessed, lay-in T12 lighting fixtures were used. This was compared to the same retail building to be remodeled using energy-efficient lighting fixtures. The energy-efficient versions used were 13 W LED track lighting and 48 W high-performance T8 lighting systems.
When comparing the two simulations for the building cooling requirements, the baseline existing design required 14.5 tons of cooling while the energy efficient remodeled design required only 10.0 tons of cooling. Effectively, the cooling load was reduced by 4.5 tons. While the cooling load was shown to be significantly different, the heating load difference was minimal. Replacing the baseline lighting fixtures with energy-efficient lighting fixtures resulted in a difference of only 0.47 MBh. A small difference such as this would not change the size of the heating option for the HVAC equipment selected.
This case study illustrates that by incorporating an energy-efficient lighting design, not only are there significant energy savings in lighting and HVAC power, but also cost savings in initial equipment purchase and installation.
Justin Schultz is lead electrical engineer at Metro CD Engineering and serves as education chairman and board member for his local Illuminating Engineering Society (IES) section. He is a 2011 Consulting-Specifying Engineer 40 Under 40 award winner and an active member of the USGBC Central Ohio Chapter. Brian Johnson is a mechanical engineer at Metro CD Engineering. He serves as a member of the USGBC Central Ohio Emerging Professionals Group and Advancement Committee as well as the Young Engineers in ASHRAE in Columbus, Ohio.