Evaluating Energy Loss through Recessed Lighting Fixtures (RLF) in Residential Buildings through a Case Study Ri Na 1 , Shengmao Lin 2 , Zhigang Shen 1 and Linxia Gu 2 1 The Durham School of Architecture Engineering and Construction; 2 Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, ABSTRACT Unintended air leakage through building envelope is a major source of energy loss of residential buildings. Air leakage through improperly installed recessed lighting fixtures (RLF) has been identified as one source of unintended air leakage. However, little quantitative study was found on the energy loss through improperly-installed RLF. In this paper, the authors conducted preliminary evaluation of the magnitude of such energy loss by numerical simulations using 3D transient CFD model. One case was studied using boundary conditions of four seasons, which were obtained from historical experimental data from Mississippi. The results of the simulations indicate RLF can be a very significant source of energy loss in both summer and winter conditions. The study suggests that systematic approach is needed to improve the RLF design and construction practice to reduce or remove the RLF’s negative impact on energy loss of residential buildings. INTRODUCTION Unintended air leakage through buildings’ envelopes is one of the common issues which affect energy performance of single-family residential buildings in the U.S. Air leakage through improperly installed recessed lighting fixtures (RLF) has been identified as one source of unintended air leakage. In response to its impacts, Washington State revised its codes and started to require all recessed lighting to be strictly air tight. The code demand that air leakage rate of RLF could not exceed 2 cfm (cubic feet per minute) at 75 Pascals pressure difference, which firstly provided the manufacturers with valuable references (Meer, 2002). Later on, IECC also enacted a series of corresponding provisions to regulate the industry standards. However, even under the above guidance when the lighting trim is properly sealed, the perforations on the recessed lighting cans are still found to be a cause of air leakage (McCarthy, 2000). Though employing the physical methods, such as the blower door test and infrared camera techniques, the leaking areas can 1691 COMPUTING IN CIVIL AND BUILDING ENGINEERING ©ASCE 2014