کتاب نمای دوپوسته در طراحی بهینه انرژی - Summary of the Book: Double Skin Facades in Energy-Efficient Design
Author: Dr. Mahnaz Mahmoudi Zarandi
The construction industry significantly impacts energy conservation. The increasing use of renewable energy sources necessitates innovative architectural solutions. Modern facade designs, including double skin facades (DSF), are becoming popular due to their unique creativity and practicality. While not a new concept, DSFs are increasingly utilized in architecture for their benefits such as enhanced occupant comfort and efficient use of natural, renewable energy. Thermal analyses indicate that DSFs outperform double-glazed facades in energy efficiency by creating thermal buffer zones that can be designed with specific openings to provide passive heating or cooling. However, their complexity and climate adaptability require precise design. The impact of DSFs on various building parameters makes their design crucial for overall building performance. The classification of DSFs is essential for influencing design stages, determining other design and technical parameters that affect thermal performance. Identifying the primary objectives of DSF implementation can guide functional and design requirements.
The book aims to introduce DSFs, their functionality, and advantages, providing a foundation for their design and implementation to promote sustainable architecture.
Chapter Summaries:
Chapter 1: Generalities of Double Skin Facades This chapter discusses environmental sustainability and the architectural benefits of utilizing natural resources. The interaction between the building's exterior and nature is examined from various aspects, including aesthetics, energy savings, occupant health, psychological impacts, and financial considerations. The facade, as a boundary between the interior and exterior, plays a crucial role in enhancing visual appeal, adequate lighting, ventilation, and reducing surrounding noise pollution.
The chapter also addresses smart architecture and facades as a foundation for DSFs. With advancements in technology and bionics, building skins are envisioned as analogous to animal skins, responsive to their environment. Accordingly, building facades interact with external environment variables, user thermal comfort needs, and internal environment, incorporating terms like flexible skin, active skin, responsive skin, and high-performance advanced skin.
Chapter 2: History and Definitions of Double Skin Facades
This chapter analyzes and reviews various definitions of the DSF system provided by researchers such as Harrison and Boake, Aronson, Otto, Kampango, and Klesens and Dahr. The general consensus is that an active facade covers one or more floors and consists of multiple glass layers, which may or may not be air-insulated. The air cavity between the layers can be naturally or mechanically ventilated, and the ventilation strategy may change over time. Generally, systems and devices are integrated to improve indoor air quality using active or passive techniques, often managed semi-automatically by control systems.
Design Goals: The design goals of DSFs clarify the necessity of their design. These goals include:
- Acoustic objectives
- Natural ventilation
- Reduced use of heating and cooling equipment
- More effective use of natural light
- Regulation of the building's internal temperature
- Comfort for users
Advantages and Disadvantages: The chapter also discusses the advantages and disadvantages of DSFs:
- Advantages: Enhanced aesthetic and visual quality of the building, the facade as a supplementary sound insulator against surrounding noise, improved building ventilation and thermal performance, reduced heat transfer, improved shading systems, and enhanced environmental impacts.
- Disadvantages: Issues such as fire spread through the facade, noise reflection, increased structural weight, additional construction and maintenance costs are examined in this section.
Chapter 3: Types and Classification of Double Skin Facades
DSFs are designed in various forms, and this chapter categorizes them into three groups based on different criteria:
- Classification Based on Airflow Behavior Between Layers: This category evaluates and classifies DSFs based on how airflow behaves between the two layers.
- Classification Based on the Geometry of the Double Skin Facade and Structural Differences: This category classifies DSFs based on the geometry of the facade and the structural differences of its components.
- Combined Classification Considering Both Geometry and Airflow: This group considers the impact of both geometry and airflow, providing a combined classification of DSFs.
These classifications help in understanding the different design approaches and the impact of each type on the building's performance, aiding architects and designers in making informed decisions during the design process.
Top of Form
Chapter 4: Thermal and Cooling Performance of Double Skin Facades
Double Skin Facades (DSFs) as an architectural phenomenon enable natural ventilation, improving indoor air quality without the noise and safety limitations present in single-skin facades. The choice of DSF type significantly influences the temperature, airspeed, and quality of air entering buildings. A well-designed DSF can reduce energy consumption during usage and enhance occupant comfort. Due to significant solar radiation in warm seasons, the DSF cavity heats up considerably. The buoyancy effect causes warm air in the DSF cavity to rise, creating a natural ventilation effect by drawing air from the building floors.
Different airflow patterns and the configuration of openings in the inner and outer layers of the facade can vary. This chapter presents two open-airflow patterns and three closed-airflow patterns. Depending on the climate, weather conditions, wind speed, and pressure, different patterns can be designed. Understanding these patterns can be intriguing for architects designing DSFs.
Chapter 5: Components of Double Skin Facades
The performance of a DSF depends on several factors:
- External conditions
- Cavity dimensions (width of the cavity)
- Area of inlet and outlet openings for outside air
- Building height (number of floors)
The buffer space or cavity between the two glass layers in a DSF significantly impacts its performance. Important considerations for designing the cavity depth include:
- The cavity volume must be sufficient to allow adequate airflow through the inlet openings for proper ventilation.
- Sufficient space must be provided for shading equipment and structural elements.
- Easy access to the cavity must be ensured for maintenance and cleaning.
Each parameter of the cavity plays a significant role in the facade's performance, and the book addresses each in detail:
- Cavity Height: The cavity height can extend the entire building height or be separated by floors.
- Cavity Geometry: The physical structure of the cavity can take three forms: Shaft box window, Corridor facade, and Multi-storey Double Skin Facade, which are explained thoroughly in the book.
- Cavity Material: The choice of glass and appropriate measures (single or multi-glazed) is crucial to achieving the overall design goals of the facade.
- Cavity Openings: Understanding the principles governing openings is essential for understanding airflow behavior in the cavity and for both natural and mechanical ventilation. Hence, a section of the book is dedicated to analyzing how to design the openings and vents in both the inner and outer layers of the facade.
Chapter 6: Case Studies
This chapter presents case studies of DSFs designed in major industrial countries that are pioneers in DSF design. Examples from Germany, Finland, England, Sweden, Belgium, the United States, and Australia are provided. Each case study examines the building's location, project timeline, overall facade structure, buffer space, shading type, and airflow pattern.