Energy efficient hospital patient room design: Effect of room shape on window-to-wall ratio in a desert climate

This paper reports on a research that utilized simulation techniques for identifying the most efficient hospital patient room designs and their associated window-to-wall ratios. Simulation of the energy consumption and daylighting performance of common patient room designs were conducted using a range of Window-to-Wall Ratios (WWRs). The paper focuses on arriving at solutions that balance between the reduction of energy consumption and the achievement of proper daylight distribution in the desert climate of Cairo, Egypt. Simulations were conducted using the Diva-for-Rhino, a plug-in for Rhinoceros modelling software to interface with the Energy Plus, Radiance and Daysim software. Results demonstrated that solar penetration is a critical concern affecting patient room design and window configuration in desert locations. Use of the outboard bathroom patient room design was found to be the least efficient among the tested alternatives. Although it has a smaller external wall size, it failed to provide energy consumption that is lower than that of the other options. Its best energy performance was 20% higher than that of the nested bathroom patient room design. However, the outboard bathroom design allowed for larger WWRs (70%-90%), which might prove useful for external view exposure purposes. The nested and inboard bathroom patient room designs provided better energy performance. However, this was on the expense of window size. The acceptable cases of these designs had smaller WWRs, (30%-40%). The results of this paper demonstrated the need for the careful consideration of the size of windows and openings in relation to different patient room designs. Simulation techniques can prove useful in this regard.