Study of Residential Thermal Transfer Values (RTTV) and vertical daylight factors (VDF) for Heavily Obstructed Public Housing Flats

Hong Kong, one of the most densely populated cities in the world, consumes more than a quarter of its total energy in residential buildings. The high urban density leaves many residential flats in a heavily obstructed environment, seriously affecting indoor lighting performance. In response, the Hong Kong government issued requirements for residential thermal transfer values (RTTV) and vertical daylight factors (VDF). The control of RTTV and VDF is considered to be effective in improving the energy efficiency and daylighting performance of residential buildings. However, achieving the required RTTV and VDF at the same time can be conflicting in terms of building façade design. This paper studies the daylight performance and energy use of public housing flats facing large sky obstructions through computer simulations. General correlations between RTTV, energy consumption, and daylighting performance are investigated. © The Authors, published by EDP Sciences, 2023.