Case Study: Counterfactual Impact of a Lighting Retrofit

In this fictional use case, the owner of a supermarket in Fayetteville, Arkansas, is interested in reducing his building’s energy costs. In addition, he is also concerned about the impact of his building’s energy use on climate change. In the United States, food sales buildings have the greatest amount of lit floor space of all building types. His building is lit almost entirely with compact fluorescent lighting, while LEDs can be almost twice as efficacious as compact fluorescent lights. Thus, the supermarket owner decides to investigate the effects of retrofitting his building with LED lights and new fixtures.

He researches lighting retrofits and learns that based on the particular lights and fixtures he will use, he should expect each new light to be twice as energy efficient as the light that it replaces. However, for various reasons, it is only feasible to replace about 90% of the lights across the building. Thus, because lighting currently accounts for 10% of his building’s total annual energy use, he estimates that after the change, lighting will account for only 5.5% of his building’s energy use. Furthermore, because LEDs emit less heat than fluorescent lights, the new lights will also reduce his building’s refrigeration energy use by 10%. Refrigeration currently accounts for 51% of his building’s energy use but will account for only about 43.9% after the retrofit.

To better understand the effects on his building’s energy use and greenhouse gas emissions, he enters his building’s current energy data and predicted post-retrofit data to the Co-Benefits of the Built Environment (CoBE) v.2 tool for the year 2024. Because the retrofit will not affect his building’s onsite energy use, he only enters electricity use data. As a result, the tool predicts a counterfactual decrease in his building’s 2024 energy use by 794 MMBtu, through the change in lighting. Moreover, this will decrease the building’s 2024 greenhouse gas emissions and climate change impact by 102 metric tons and $5,707, respectively. Additionally, he is surprised to learn that the retrofit will decrease his building’s 2024 air pollutant emissions footprint by 0.1 metric tons and its concomitant health impacts by $439.

You can upload the data used in this case study to the CoBE tool and assess the results yourself. Filter by building to see the electricity-related performance for 2024 without the retrofit (No Retrofit) or with the retrofit (Post-Retrofit).

Download the data here.