Open Packing for Facade-Layout Synthesis Under a General Purpose Solver

Abstract

Abstract. Facade-layout synthesis occurs when renovating buildings to improve their thermal insulation and reduce the impact of heating on the environment. This interesting problem involves to cover a facade with a set of disjoint and configurable insulating panels. Therefore, it can be seen as a constrained rectangle packing problem, but for which the number of rectangles to be used and their size are not known a priori. This paper proposes an efficient way of solving this problem using constraint programming. The model is based on an open variant of the DiffN global constraint in order to deal with an unfixed number of rectangles, as well as a simple but efficient search procedure to solve this problem. An empirical evaluation shows the practical impact of every choice in the design of our model. A prototype implemented in the general purpose solver Choco is intended to assist architect decision-making in the context of building thermal retrofit.

External buildings retrofit: Employing guillotine cuts for aesthetic envelopes

“…The algorithm has been tested on several façades to analyze the results. As well, the greedy solution [2] and the constraint-based one [3] have been executed against the same examples to compare the resulting envelopes. We have summarized the output results in Table 1.…”

“…As the table shows, the constraint-based algorithm [3] is the more robust solution for the design problem although it takes more time due to the search space exploration. However, it lacks of mechanisms to generate symmetrical solutions as the modeling of aesthetics under constraint satisfaction is intricate.…”

“…Due to manufacturing limitations, frames (windows and doors) over the façade are meant to be covered by one and only one panel. 3. No hole and no overlapping between panels are allowed in the envelopes.…”

“…In two previous works, we have already developed consistent algorithmic solutions to the problem: the first using a greedy approach [2] and the second using a constraint-based approach [3]. However, the generated envelopes solutions from these algorithms do not count with aesthetic aspects needed for the retrofit (such as symmetry).…”

“…Cutting is a technique from operations research widely used to solve different industrial problems [6,7,14] and it has been applied to problems where symmetry is relevant for the final output: for instance, arranging items in a newspaper [11], automatic mosaic generation [4] and aesthetics photo post-processing [8]. We use the guillotine approach and show that it generates aesthetic (symmetric) insulating envelopes not generated by the two other approaches [2,3], thus satisfying this crucial architectural requirement.…”