Early-design sensitivity of radiant cooled office buildings in the tropics for building performance

Abstract

The research community has worked on improving the design, performance, and operation of radiant system technologies; however, the interactions between architectural design decisions and radiant cooling systems design in the tropics – where radiant system design and operation represents a challenge due to high external heat gains and latent loads – have been left unexplored by existing work. This manuscript (1) addresses the holistic early-design of effective radiant cooling systems and the architectural environments that they serve in hot and humid tropical climates, (2) analyses how different design choices and their interaction affect buildings performance compared to conventional all-air systems, and (3) proposes preliminary early-design indications of the parameters values to adopt when designing radiant cooled office buildings in the tropics to achieve high multi-objective design goals. Morris sensitivity analysis is used to analyse the impact of 13 different building and system design parameters on comfort, system and energy performances for 3 radiant systems typologies applied to a parametric office building in the tropical climate of Singapore. The elementary effect (EE) of each parameter is analysed based on 8200 individual EnergyPlus simulation models being run, and the impact, interactions & (non) linear effects of different design factors are assessed. It is found that radiant cooling systems require different early-design phase considerations than conventional air-based cooling systems since different parameters prove to be dominant or significant. All three radiant system typologies, if coupled with efficient operational strategies and a complimentary set of design variables, ensure high multi-objective building performance, showing how the implementation of radiant cooling technologies could be beneficial for a tropical climate. The window solar heat gain coefficient and the façade window-to-wall ratio play a key role in this effort with respective values falling below or equal to 54% and 57%. The system set-point temperature has an increased importance for operational efficiency allowing high dry-bulb room temperatures ranging from 24.8 °C to 27 °C.