Dynamic Façade

The dynamic façade covering the south elevation of the prototype house is designed to be a programmable and responsive architectural element. It adapts to the changing weather conditions and to the preferences of the inhabitants.

The façade is a matrix of 4 x 9 digitally controlled dynamic windows each with three degrees of freedom allowing it to function as a filter between exterior and interior controlling air, daylight and heat flow.

The management of the technologies that are deployed on the dynamic façade is equally addressing performance and aesthetic factors.The façade attains autonomous, responsive and interactive modes of operation.

In the autonomous mode façade adapts to the weather conditions in order to maintain the desirable levels of comfort and to secure long-term optimization of performance without requiring input by the users. In the responsive mode façade adjusts its state to counterbalance any activity may interfere with the long-term optimization plan. In the interactive mode the façade engages with explicit input by the users.

Twenty seven of the windows on the façade contain an electronic actuator enabling automated operation so that the permeability to airflow can be adjusted with precision. Cross-ventilation becomes possible when house windows facing north and windows of the dynamic façade, oriented towards south are simultaneously open.

The remaining two features of the dynamic façade concern the regulation of visibility, and sun-light and heat penetration. Each windowpane integrates two electronically switchable materials: a polymer-dispersed liquid crystal film [PDLC] that renders the window transparent or opaque to visible light, securing privacy and a Sage electrochromic layer that controls the degree of solar penetration.

The autonomous control system of the house based on an Iterative Risk Allocation (IRA) algorithm manages all the active parameters of the dynamic façade in a concerted manner to maintain maximum comfort at minimum energy expense. Hence, the façade attains various states, impacting the ventilation, the solar radiation and the illuminance at the house interior.

For example, on a hot summer day the control sets the electrochromic material of a number of windows to its minimum solar transmittance to protect the house interior from direct sun exposure, while on a cold winter day it sets it to maximum solar transmittance in order to expose the interior to the winter sun. Since there is no standard class of patterns satisfying all weather conditions, the adjustment of the façade remains dynamic.

The dynamic adjustment of the number and distribution of the active electrochromic windows on the façade causes the formation of visual patterns and transforms the aesthetic presence of the prototype, since it affects how the house is perceived from the public street and from its interior.

For example, the patterns produced by the activation of the electro-active materials on the windowpanes affect the visual symmetry of the façade, while a strong kinetic effect is produced by the repositioning of the windows animating the mechanical components of the façade. In this way the dynamic façade functions as a programmable, responsive skin between exterior and interior.

Façade patterns produced randomly based only on performance would supply adequate daylight while disregarding the aesthetic potential of electrochromic technology. Our approach both takes full advantage of this potential and is computationally elegant. A façade pattern grammar is applied dynamically by the intelligent control system of the house to produce façade patterns by linking principles of 2D pattern generation to constraints of daylight adjustment.

Kotsopoulos, SD, Cara, G, Graybill, W, Casalegno, F, 2014, “The dynamic façade pattern grammar”, Environment and Planning B: Planning and Design, vol. 41, Pion Ltd, London UK.

Connected Sustainable Home 2012