Original Article Journal of Building Physics 2016, Vol. 40(2) 125–143 Ó The Author(s) 2016 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1744259115624179 jen.sagepub.com Effects of built-in balcony on thermal performance in residential buildings: A case study Lutfu Namli Abstract In this study, effects of built-in balcony on thermal performance in residential buildings were investigated numerically by means of open-ended structure approach. For this pur- pose, the parametric study has been carried out for various ratios of balcony depth/bal- cony height (L/H), closed barrier height/balcony height (h/H) and Rayleigh numbers (Ra) using a computer program in case of no wind for laminar flow. Analyses were con- ducted for Rayleigh numbers ranging from 10 3 to 10 6 . The calculations were carried out for the ratios of L/H, namely, 0.0, 0.24 and 0.6, and the ratios of h/H, namely, 0.0, 0.18 and 0.35. The working fluid was assumed to be air (Pr = 0.71). According to the findings, for Ra < 10 4 , Nusselt number (Nu) decreases with the increasing ratio of L/H for the constant h/H = 0.35. However, for Ra ˜ 10 5 , Nu sharply decreases with the increasing ratio of L/H, while Nu again sharply increases after L/H ffi 0.25 and almost remains con- stant after L/H ffi 0.5. For the constant L/H = 0.54, Nu decreases with the increasing ratio of h/H for the whole Ra. It is suggested that the ratio of L/H should not be over 0.35 and the ratio of h/H should be at least 0.35. Keywords Thermal performance in buildings, balcony, open-ended structure, extended boundaries, laminar natural convection in enclosure Introduction The heat transfer occurring in enclosures with the effect of buoyancy and the fluid flow have found large application fields recently. Among some studies Department of Mechanical Engineering, Ondokuz Mayıs University, Samsun, Turkey Corresponding author: Lutfu Namli, Department of Mechanical Engineering, Ondokuz Mayıs University, 55139 Samsun, Turkey. Email: lnamli@omu.edu.tr at Ondokuz Mayis Universitesi on October 27, 2016 jen.sagepub.com Downloaded from