The beauty of a fully glazed transparent façade of a building can sometimes be spoilt by the spandrel glass, which simply may not match up in terms of its colour and reflections. Rather than creating a stunning, uniform glass façade, the architect may have to compromise on an inferior solution. While spandrel glass solutions do exist that closely match the spandrel glass with the vision glass, the cost can also be prohibitive.
Spandrel glass is the opaque glass that conceals structural building components such as columns, floors, HVAC systems, vents, electrical wiring and plumbing, preventing these from being visible from the exterior of the building. Curtain wall and structurally glazed designs often require the use of spandrel glass to achieve an architect’s vision of the finished project. Typically located between vision glasses on each floor of a building, spandrel glass can be either complementary or contrasting in colour when compared to the appearance of the vision glass.
Where architects desire a uniform appearance of a glass fronted building, precisely matching the spandrel glass with the vision glass – in terms of colour, reflectivity and durability – can be a challenge. When vision glass is specified with a high light transmission or low external reflection, finding an exact colour match between spandrel and vision glass is challenging. Daylight conditions can have a dramatic effect on the perception of vision-to-spandrel appearance. For example, a clear, bright sunny day provides a higher reflective appearance, which will improve the vision-to-spandrel match. A grey, overcast day may allow more visual transmission from the exterior and produce a greater contrast between the vision and spandrel glass.
Spandrel glass can consist of an opacified uncoated or coated glass, a coated glass in a shadow box construction or can be an insulating glass unit comprising of a solar control glass as the exterior pane and an opaque uncoated interior pane.
1. The most common type of spandrel glass solution consists of a monolithic float glass with enamel applied to surface #2 (picture 1). Although this solution is relatively low cost, the problem is that the colour of the paint does not precisely match the colour and reflection of the coating on the vision glass, which makes a uniform appearance between spandrel and vision glass almost impossible to achieve.
2. An alternative is to use Insulated Glass Unit (IGU) spandrels, where coated glass can be selected that precisely matches the aesthetics of the glazed façade (picture 2). Here, the coating is applied to surface #2 and paint is applied to surface #4. Although this type of solution has the advantage of providing a good colour matching with the rest of the façade, the cost is relatively high compared to monolithic float glass solutions.
3. A selection of Guardian SunGuard® HD (High Durable) or Guardian SunGuard® Solar reflective coated glass allows for the application of enamel directly to the coated surface for a monolithic spandrel (picture 3). This provides an economical, cost effective and aesthetically matching solution that is suitable for many applications.
4. The shadow box construction using a monolithic Guardian SunGuard® HD coated glass (picture 4).
Guardian Glass offers its most durable coatings, Guardian SunGuard® HD and Guardian SunGuard® Solar RB 20, for monolithic spandrels. These can be matched closely to a range of Guardian SunGuard® coated solar control glasses, including SunGuard® eXtra Selective (SNX), SunGuard® SuperNeutral (SN), SunGuard® High Durable (HD), and SunGuard® High Performance (HP). The compatibility of SunGuard HD coatings and SunGuard Solar Royal Blue 20 with paint were approved by the IFO (Institut für Oberflächentechnik) in Germany.