Optimization of facade design based on the impact of interior obstructions to daylighting

Overcrowding in the perimeter zone is an inevitable issue in residential rooms with limited space. Obstructions, such as furniture and household items, may block the existing windows, and therefore affect interior daylight conditions. A facade design approach is needed that simultaneously takes into account daylighting and the volume of usable space for obstructions in the perimeter zone of such rooms. This study simulates daylight distributions in a typical small residential room with obstructions in front of windows. The simulation consists of two parts. First, the effects on horizontal illuminances caused by different positions and shapes of obstructions are examined under an overcast sky. Second, the maximum usable space volumes for obstructions of 51 optimized facade configurations are calculated in terms of four window-to-wall ratios (WWRs). The results of this study show that optimizing the forms of facade design can increase the usable interior space volume and meet the daylighting requirements of Chinese standards for small residential rooms. Additionally, by using the optimized facade forms, a facade with a WWR value of 50% provides the maximum usable space for obstructions. Based on the above results, this paper presents two matrices that can help architects in selecting the appropriate fenestration methods and confirming the size of usable space and allocation for residents

The influence of façade design on the optimum window to wall ratio and overheating rate in UK Passivhaus dwellings for current and future climates: A parametric design method

Many researches of overheating in buildings have focused on the optimisation of the window to wall ratio (WWR). However, the physical form of the building envelope has not been widely considered as a factor in optimisation investigations. This study examines if the optimum WWR might vary in response to slight geometrical changes to a façade's design. An evolutionary parametric design method was used to generate a range of inverted pyramidal shaped envelopes with different inclination angles for each façade. This was implemented for an existing UK Passivhaus. The WWR was set as the main variable along with a sub variable of different weather data (both current and future climate scenarios). This paper, in particular, focused on minimising the overheating during the summer while reducing the primary energy use of the building. These two parameters were set as the objectives to be optimised using the parametric tool in the dynamic thermal simulation software DesignBuilder. The calculation used batches of Energy Plus simulations using a genetic algorithm. The results showed that the optimised WWR varied significantly when implementing different façade arrangements. Optimum self-shading shapes could allow more glazing to be used while still achieving thermal comfort in summer climate