Corrosion of Sealant

Another common failure of water seepage would be the failure of sealant. This is commonly seen in framed panels due to the wear and tear, as well as from the poor workmanship of the sealant application (Building and Construction Authority, 2016). Another common issue of the deterioration of the sealant would be biological growth from the moisture exposure (Chew Y. , 2016). This is just another possibility – but likely a problem is the wrong sealant is used. Such defect may be minor to some but it would cause a great damage to the BIPV panels and the whole structure due to harsh weather conditions. This would not only affect the aesthetics of the façade but also minimising the function of a building skin. Taking into consideration of the efficiency of BIPV solar modules, cleanliness would be the top priority to maintain its efficiency. Therefore, maintain and prolonging the strength of sealant would pose a challenge.

Figure 1. Typical Component of Glass

As illustrated in Figure 1, sealants are used to join the glass panels together as well as ‘filling’ the available spaces to provide water and air tightness. This acts as a building envelope which segregates the external and internal conditions.

There are many instances why sealants fail and the most common ones in this context is its poor resistance to weather and UV radiation, as well as the wrong type of sealant used. Before choosing the type of sealant, we need to correctly identify the determinants. As mentioned in the previous section of Weakening of Façade Joints, the PV panels have an approximate 2-4inch gap to allow for contraction and expansion, as well as to prevent the solar cells from overheating. As such, the sealant must be flexible to adapt to the changes in temperatures and as well as other acting forces shown in Figure 2 (Maintainability of Buildings, 2016).

Figure 2. Forces acting on Sealant

This is especially important for high-rise buildings in Singapore as they are more prone to the structural movement from the lateral load (The Editors of Encyclopædia Britannica, 2016). With high exposure to sunlight and rainfall, the sealant also requires having strong resistance towards extreme weather conditions as well as UV rays.

Air pockets will be created when sealant fails or cracked like illustrated in Figure 3. This allows for easy water penetration into the building. Moisture in buildings is a major contributor to mould growth, unhealthy buildings, and poor indoor air quality. The health of the occupants would be affected as mould in the building due to excessive moisture would lead to upper respiratory symptoms such as coughing, wheezing and asthmatic attacks (The United States Environmental Protection Agency, 2013).

Figure 3. Sealant Deterioration