Driven by an increasing demand for high thermal and acoustic performance, transparency, and low maintenance costs, a number of facade innovations have been developed over the past 50 years. These advancements, collectively part of the emerging market of dynamic, adaptive facades, give designers the freedom to control energy loads and glare through the building envelope using building management software. Integrated, intelligent control systems are being developed to optimize energy performance and meet sustainability goals with minimal compromise to aesthetics and transparency.
Double skin facades, which feature two distinct glazed wall assemblies separated by an air cavity and typically include a shading device in the cavity, have been successfully used on a number of projects in Europe for the past 20 years, as well as a few in the US. More recently, the compact double skin facade known as MFreeS, which is a unitized cavity wall with integral blinds, has been developed by Permasteelisa Group and its research partners. To date, there are fewer applications of these double skin facades in the US market, due primarily to the lower cost of energy and less-stringent building codes.
This study uses whole-building simulation software to compare annual energy consumption of conventional, double-skin, and MFreeS facades in various US cities in a hypothetical south-facing office room, for the purpose of quantifying performance of the various systems.
The results show that overall building energy consumption can be significantly reduced by the use of double-skin and mfree-SCCF facades - by as much as 20% in most climates – relative to the baseline single skin façade. It is also seen that the conventional steady-state measures of thermal attributes, such as U-value and solar heat gain coefficient, are poor predictors of actual energy use for buildings with dynamic facades. The use of whole-building simulation tools has the potential to save more energy on a yearly basis in the US market.
Facade design in the last 50 years has seen tremendous innovation in the area of thermal performance. Some notable developments include insulated glazing units, which became commercially viable in the
In this study, the thermal performance parameters of the following five facade types are evaluated and compared in several cities in the US market (Fig. 3):Figure 3: Typologies studied. Image
In order to obtain reliable predicted energy performance for office buildings with dynamic DSF systems and cavity ventilation, it is necessary to use whole building simulation tools. For this purpose
Figures 6 through 15 show the thermal and energy results of the subject room for each city. In these graphs, the five facade types are shown on the top as
The results from the dynamic whole building simulation show that:In all climates, the use of DSF and mfree-SCCF results in lower total energy consumption than SSF (most notably in
From the standpoint of energy consumption in this study, Facade 4 (Interactive Wall) performs the best in all climates. Some notable examples of this DSF system in use include the
The authors would like to thank their software and university research partners for their contributions during the developments of the innovative façade solutions.
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