Closed cavity façade (CCF) is an intelligent, completely enclosed double-skin façade that is triple glazed internally and single glazed externally for an increased insulation. CCF system is a promising and innovative solution for exploring new possibilities in high-rise commercial buildings.
In the course of constructing a commercial building, numerous factors like energy consumption, carbon emissions, durability, feasibility, associated costs, and air ventilation are to be considered. The best way to protect a structure and ensure its durability is by installing façades.
Façades protect the structure from outside elements such as harsh weather conditions and dust, which could deteriorate the overall appearance of the building. An ideal façade provides thermal insulation and, as a result, reduces energy consumption. Comfortable indoor climate, fire resistance, and insulation against external noises are some of the additional benefits of a façade.
Several designs are available for constructing a façade; steel, curtain wall, brick slip, and double-skin are some of the prevalent types of façade design. Double-skin façades came into existence in the 90s as a result of the introduction to new materials and techniques, such as glued-on wall structures. Double-skin façades are characterized by two glass skins, which are divided by an intermediate cavity. Such façades offer several benefits, including thermal insulation and low energy consumption.
Closed Cavity Façades
Closed cavity façades are a step further than double-skin façades as they possess the advantages of single skin as well as double skin façades. Though categorized as double-skin façades, CCFs are not ventilated, and by being so, they prevent the accumulation of dust particles in the cavity, increasing the life of components inside the cavity.
Closed cavity façades use pressurized air supply or a ventilation system derived from the working of pressurized multi-layer ETFE foil (Ethylene Tetrafluoroethylene is a fluorine-based alternative to plastic) cushion constructions.
To manage condensation, dried, filtered, and sometimes temperated air is used but within a limited amount. However, the properties of good sound insulation and sun shading of a double-skin façade are still maintained in a CCF. To facilitate natural ventilation, an openable flap can be constructed with the CCF element.
Path to Closed Cavity Façades
There has been a development from double-skin façades to closed cavity façades. CCFs have turned some of the disadvantages of double skin façades to zero. Double skin façades required high cleaning and maintenance costs. This was because of the air flowing freely in and out of the façade through the intermediate cavity.
CCFs do not require such a high cost of cleaning as they do not require cleaning on the insides. In double-skin façades, there were reports of extreme heat-up, short-circuiting from exhaust to supply air, and limited functions. CCFs are introduced to take care of such issues. Moreover, in CCFs, it is possible to build larger glass sizes as compared to the glasses used in double-skin façades.
Advantages of Closed Cavity Façades
Closed cavity façades have plenty of advantages over other façade designs. Some of the major advantages of installing a CCF are the following:
1. Lower Cleaning Costs
With other façade designs, there is a high cost involved for cleaning purposes, whereas in CCFs, the cost is comparatively low as the area covered by glass surface is lesser than that of other double-skin façades.
As the façade cavity cannot be opened, therefore only the internal and external glass surfaces of the facade unit need to be cleaned. However, in traditional double-skin façades, cleaning may be required twice or thrice a year depending on the location of the building, but closed cavity façades don't have such requirements.
2. Sun-protected Systems
CCFs offer a broader choice of materials for sun blinds. The absence of exposure to wind or rain provides a wider range of blinds to choose from as the materials are required to be stable only to temperatures and sun exposure. The direction of the blinds' rotation axis is also not significant as the heat is mainly transported through radiation.
3. Cost-effective Technology
The construction of CCFs is very cost-effective, and the maintenance expenses are also significantly low. CCF-clad structures are found to be more durable than conventional double-skin façades. The life of the blinds used in the façades is extended in CCFs as they are used in a protected environment. The shading device used in the façade is also less prone to damages.
4. Reduced Energy Consumption
In closed cavity façades, the cavity between the outer and the inner skins is compactly sealed. Dry air is dispensed into the cavity to prevent the formation of condensation on the glazing, and the quantity of dry air is also electronically monitored and adjusted accordingly. As a result of these features, the energy consumption comes to a minimum level.
5. Comfort For End-users
The glass structure, along with triple and single glazing, provides transparency, making the area look more spacious and relaxed. It has been observed that the occupants feel more comfortable in a transparent environment like the closed cavity façades, rather than in single-skin façades, which are believed to be closed and confined. CCFs also ensure maximum natural light penetration inside the buildings, promoting a healthy environment.
Additionally, closed cavity façades with glazed glassing on the exterior look more appealing. Moreover, the CCFs do not require operable doors. This allows the interiors of any workplace to be designed with much more creativity as it provides interior designers with more open space to work with. It results in a larger lettable area as compared to the normal double-skin façades.
Some of the well-known buildings which have utilized the concept of CCFs are Power Tower Linz in Austria, Beijing Greenland Center, JTI Headquarters in Geneva, One New Burlington Place in London, Roche Building 1 in Basel, and many more.
Challenges for Closed Cavity Façades
Even with all of these advantages and user benefits, there are certain features that can be improved in a closed cavity façade model. For instance, the elements used in the façades are not easily repaired or exchanged; therefore, façade designers are working on new ways to motorize and control elements on the outside.
Nevertheless, CCFs fulfill all the physical, energy, and daylight requirements of a building while allowing sustainable construction. CCF is undoubtedly a step in the right direction and a major innovation in the design of double skin facades. However, the technology still has the potential for improvement with the incorporation of digital tools and services into the system.
Closed cavity façade (CCF) is an intelligent, completely enclosed double-skin façade that is triple glazed internally and single glazed externally for an increased insulation. It is a promising and innovative solution for exploring new possibilities in high rise commercial buildings.
Closed cavity facades are a step further than double-skin facades as they possess the advantages of single skin as well as double-skin facades. Though categorized as double-skin facades, CCFs are not ventilated, and by being so, they prevent the accumulation of dust particles in the cavity.
The advantages are:
1. Lower cleaning costs
2. Sun-protected systems
3. Cost-effective technology
4. Reduced energy consumption
5. Comfort for end-users