Deterioration of Façade Joints

Structural systems in building construction are extremely important, especially for tall buildings, as to effectively transmit the loads (i.e. deadweight loads, live loads and environmental loads) to the ground (Lim, 2014). This is usually done by constructing an effective system whereby the elements work together to ‘support and resist’ the loads acting on it, and joints are one of the most important aspects of structural continuity.

Table 1: Classification of Loads on Buildings

Usually, there is a combination of loads, like shown in Table 1, acting on the building structure. Engineers have to comply with building codes specified by the Building and Construction Authority (BCA) to ensure the safety of building structure under different maximum loading scenarios.

Figure 1. Joints in PV Cells

In such case, like shown in Figure 1, the 2-4 inches of space between the cells are essential to keep the panel from overheating. However, if the PV are integrated into the façade, it will pose another set of problems. In short, the façade joints are the weak points of the PV panels. Water collection can cause damage to the materials, starting from the formation of mould in the joints. As the layout of BIPV roofing is similar to fixed windows layout in building façade, the problems of collection of water and dust can be similar in some ways. This is in relation to the factor stated in the section on Dust and Stains.

Moulding is one of the most common problems of façade joints. Mould, in general, can cause problems – especially in cleaning and removing them, as it can trigger health issues for the building occupants (Group, 2009). One of the most common ones is black mould. Damp and mould are caused by excess moisture. As mould require the existence of natural matter and humidity to grow, this serves a major problem to implement this technology in Singapore as we are faced with high humidity all year round (National Climate Change Secretariat, 2016).

Figure 2: Moulds on Glass Façade

When condensation takes place where water droplets, collected on a cold surface when humid air is in contact with it, gets trapped in the joints, it does provide optimal conditions for the development of mould (The Florida Solar Energy Center (FSEC), 2014). This is undesirable especially when BIPV is implemented on the building’s façade as it weakens the structural integrity as well as compromising the aesthetic value of the building like shown in Figure 22.

In worst case scenario, water can penetrate into the interior of the building. Failure of the joints will result in structure continuity failure. If the water accumulation occurs over time and starts damaging the materials, or if the joints are not tight enough that it created holes, it can cause various problems for the building as well as the building occupants. This happens when the building envelope fails to function and thus, occupants of the building are no longer protected from the external conditions. Such cases would be rain water and the wind from outside penetrate into the building interior, which causes another set of problems in which we will explain in the next section: Water Seepage due to Sealant Failure.

Even though it is inevitable and difficult to implement a strict and completely watertight structural component, we should enforce the utmost high-quality workmanship during the installation (EFE Laboratories, Inc., 2016). This will help to reduce the maintenance cost as well as extend its life cycle to the maximum. Furthermore, BIPV is not a cheap alternative and thus, it will cost a fortune if constant maintenance is required due to poor workmanship during installation.