Sustainable Facades

By: Ken Howder

For information on climate zones within the U.S. I was given a detailed book on the study of sustainable facades written by Ajla Aksamija titled, simply, Sustainable Facades.  According to Aksamija, building facades serve the dual-purposes of improving occupant comfort and creating the look for the building in which it serves.  When all else considered, these two functions can be determined as the central idea every building that is to be designed in the architecture profession.  

A typical basis for the design of a building’s façade is the climate zone in which it is to be built.  The author describes this process in depth and classifies the possibilities of 8 different climate zones.  These zones include: Very Hot, Hot, Warm, Mixed, Cool, Cold, Very Cold, and Subarctic.  Similarly, each zone come with an added humidity category of humid, dry, or marine.  These zones throughout the United States can be seen in the following figure.

(Map of us climates, Aksamija pg. 7)

There are several differing strategies per climate zone that a designer needs to consider when planning a building’s efficiency factors.  Aksamija explains, “In choosing design strategies, we need to consider the conditions of the climate zone to minimize their impacts and reduce energy consumption.  In Table 1-3, we see how design strategies are affected by climate types” (Aksamija, 2010, pg. 10).

Basic design strategies include: “Orienting and developing geometry and massing of the building to respond to solar position, providing solar shading to control cooling loads and improve thermal comfort, using natural ventilation to reduce cooling loads and enhance air quality, and minimizing energy used for artificial lighting and mechanical cooling and heating by optimizing exterior wall insulation and the use of daylighting”  (Aksamija, pg. 9).

The information and techniques acquired from this book gave me the idea for individual study of climate zone façade design with the control subject being the exact same building shell.  It is indeed a necessity, for efficient building skins to be present within each of the climate zones individually.  However, there is not a cookie-cutter solution that can be applied to all climate zones and be effective.  This lead to the idea of separating my designs into three different climate categories: Hot, temperate, and cold (there are several more, but these have differences relevant enough to produce an effective study).  Finally the concept of designing the same building (with the same program and requirements) for the three different climate zones individually to study the differences and relationships that will be present when creating efficient buildings in these different zones.  All of these basic design strategies are directly related to the outer envelope of a building.