How to Create High Performance Building Façades
A building facade can be referred to as the boundary or link between the internal and external environments of the building. It has a significant impact on the way its occupants interact with the building’s energy efficiency and surrounding environment. Building facades are also responsible for different parameters of environmental quality performance such as thermal comfort, HVAC and lighting electricity loads, and peak loads for lighting. Building high performance building façades requires a combination of the correct materials, latest technology, proper detailing, and flawless installation.
As a result of their importance in the performance of modern-day buildings, building facades have been a popular subject for research and development. These activities have resulted in the availability of a wide range of products for creating high performance systems.
Introduction: It was believed not so long ago that exterior solid walls made of building materials with high mass provide better energy performance because of peak load condition shifting. However, recent developments in thermodynamics and material science have challenged these presumptions. Right now, there are numerous systems of high performance solid wall, starting from 75 mm thick composite panels with integrated insulation materials to 150-250mm thick cavity insulated walls.
Recent developments also include special types of cool paints that are applied on building façades in hot climatic conditions to reduce heat gain. With high solar reflectivity, these paints can be used to ensure better thermal performance for the solid walls.
There is also a growing interest in glass materials and glazing systems because of their exceptional ability to restrict the loss or gain of heat while allowing maximum transmission of visible light. Technology solutions for creating glazing systems with high thermal performance include the use of insulators such as vacuum, dry air, or inert gas between panes to create a thermal break. Excellent acoustic performance is an added advantage of using triple and double glazing systems.
Many smart glazing systems are available these days, thanks to the easy availability of different types of glass and combinations. There are glazing systems capable of automatically adjusting their opacity in response to the outdoor lighting. Utilizing photochromic glass technology, these systems can optimise glare control and indoor daylight performance of a building. Recent developments also include the integration of photovoltaic films to create building facades capable of generating electricity. However, this technology is too expensive for large scale industry application.
Operational Necessities and Technological Feasibility: One of the foremost prerequisite for a high performance building facade system is being contextually appropriate. Therefore, systems must be built in accordance with the occupant requirements as well as variable exterior conditions. Mentioned below are some of the most important application requirements.
- Wall to window ratio: In high performance building façade systems, this ratio should be determined on the basis of the solar orientation and climatic conditions. Therefore, a low wall-to-window ratio is appropriate for temperate climatic regions because it will allow the daylight to enter deeper inside the internal space of the building. However, the same is not recommended for hot climatic regions with ample sunlight and natural illumination. Similarly, the thermal performance of any west facing façade can be improved by a high wall-to-window ratio because this will protect the building’s inner space from extreme sunlight and radiation in the afternoon.
- Operable air-tight design: Air-tight construction is often recommended because of concerns related to transmission of thermal energy through building facades. However, at the same time, air-tight construction doesn’t support several other building environmental performances such as electrical operations and natural ventilation. Industry experts have frequently held air-tight constructions responsible for issues such as poor indoor air quality. Therefore, it is always better for air-tight façade systems to provide some level of control to the occupants via operable window/glazed panels.
- Double-glazing systems and condensation: Double-glazing systems experience three common types of condensation viz. outdoor, indoor, and in-between. A Combination of low outdoor temperature and high internal humidity causes indoor condensation. Condensation takes places on the glass outdoor surface when the temperature of the glass is less than the dew point temperature outside. Finally, in-between condensation refers to the condensation that takes place within the air cavity between two glass panels. Use of low-emissivity glass can significantly reduce the likelihood of formation of indoor and outdoor condensation. In-between condensation is the result of damp air penetration through a leakage in the air cavity.
- Sun-shading devices: In case of glazing systems exposed to sunlight, all sun-shading systems must be integrated. These devices improve the facade’s shading co-efficiency, protect the glazing surfaces from direct sunshine, and reduce thermal transmission through the system.
- Self-cleaning systems: Application of titanium dioxide on glazing systems and solid walls results in a self-cleaning functionality that can reduce cleaning and maintenance requirement. A photo-catalyst, titanium dioxide is capable of activating its oxygen molecules under exposure to direct sunlight. This results in decomposition of organic matters, bacteria, and germs that may form on glass, wall tiles, aluminium claddings, etc.
If you are seriously considering a high performance facade system for your upcoming building project, please feel free to contact CGS Façade Group. We provide end-to-end support covering façade consultation, design, engineering and documentation. Please get in touch with our experts today for free consultation and quote.