Green Roofs Meet Smart Technology: VILPE Sense for Leak Detection and Moisture Management

VILPE Sense Green Roof

As part of the global trend towards environmentally sustainable solutions, green roofs are becoming increasingly popular. The benefits of green roofs include improved natural insulation leading to lower energy costs, reduction of urban heat islands, improved air quality, stormwater management, increased biodiversity, and aesthetically pleasing exteriors. However, green roofs also come with challenges, the most severe being moisture damage. The VILPE Sense product family with its smart technology offers several solutions to combat moisture-related risks on green roofs.

Green roofs are gaining popularity across Europe. For instance, Germany has over 86 million square meters of green roofs, and cities like Stuttgart and Berlin have implemented significant green roof initiatives. The benefits of green roofs are well-documented. The most important benefits include helping to cool urban areas by reducing rooftop temperatures and lowering the surrounding air temperature, absorbing and retaining rainwater to reduce runoff and the risk of flooding, and increasing biodiversity in cities.

Different types of green roofs

A green roof is a building roof that is partially or completely covered with vegetation, planted over a waterproof membrane, often including additional layers. The design, implementation, and regulatory requirements of green roofs vary from one country to another due to differences in climate, building practices, and local policies. In general, there are three types of green roofs.

  • Extensive green roofs are lightweight systems with a shallow growing medium (approximately 10 cm). They are designed to be relatively low-maintenance and typically support drought-tolerant plants like sedums.
  • Intensive green roofs are heavier systems with a deeper growing medium (approximately 15 cm up to 2 meters) that can support a wide variety of plants, including shrubs and small trees.
  • Semi-intensive green roofs fall between extensive and intensive systems, with a medium depth growing substrate that can support a variety of plants requiring moderate maintenance.

Layers used and their order can vary, but in general, there is:

  • a growing medium (soil) under the vegetation layer
  • a filter layer that prevents particles from clogging the drainage layer
  • a drainage layer that allows excess water to drain away from the growing medium
  • the insulation layer (e.g., PIR, XPS, EPS, or mineral wool)
  • a root barrier
  • waterproofing membrane
  • roof deck

The placement of the insulation layer can vary, with some designs positioning it above or below the waterproofing membrane depending on specific project requirements and climate considerations. For instance, in colder climates, so-called inverted green roofs are more common. In these roofs the waterproofing membrane is placed under the insulation layer (source).

Increased moisture damage risks on green roofs

Although green roofs offer many benefits, they also present challenges that must be addressed at all stages. Water and moisture pose the biggest and most severe challenge to green roofs. Green roofs are more prone to leaks and water damages than ordinary roofs, and these can be very difficult and expensive to repair. The risks can be mitigated with proper planning and building, high-quality building materials, and more careful and intensive maintenance compared to ordinary flat roofs.

There are several risk factors for moisture damage on green roofs:

  • Root growth and penetration: The roots of the plants can grow and potentially penetrate the waterproofing membrane, compromising the integrity of the waterproofing layer, leading to water infiltration and damage to the underlying roof structure.
  • Thermal fluctuations: Green roofs are exposed to significant temperature fluctuations, which can cause the waterproofing membrane to expand and contract. This thermal cycling can lead to cracks and failures in the membrane over time, which in turn can lead to leaks.
  • Heavy weight load: Compared to regular flat roofs, the additional weight of the vegetation, soil, and retained water adds significant load to the roof structure. If the roof is not adequately designed to support this weight, it can lead to structural issues and water damage. Excessive weight and poor drainage can cause water to accumulate, increasing the risk of leaks and structural damage.
  • Drainage failure: Green roofs require effective drainage systems to handle excess water. These systems can become blocked by soil, vegetation, and debris, leading to water accumulation and potential leaks. Blocked drainage systems can cause water to pool on the roof, increasing the likelihood of leaks and water damage.
VILPE Sense Roof Leak Detector
VILPE Sense offers effective moisture control on green roofs

The VILPE Sense product family offers tools to monitor and manage moisture on different types of roof structures, including green roofs. Using smart technology, the VILPE Sense products monitor the condition of structures in real-time and alert to increased moisture levels, enabling early intervention and preventing minor moisture damage from developing into larger and more expensive problems. The product family consists of two products: VILPE Sense leak detectors and VILPE Sense humidity control.

The VILPE Sense leak detectors consist of temperature and humidity measuring sensors that are placed inside the insulation layer of the roof. The sensors alert to excessive moisture and pinpoint the affected areas on the roof. The VILPE Sense humidity control tackles excess moisture with demand-based ventilation. This product is best suited to prevent moisture damage arising due to structural causes, for instance, air leakages or condensation. The VILPE Sense humidity control improves the air circulation within the roof by controlling the roof fan(s) to ventilate the structures when needed and at the most optimal time. For instance, the system does not ventilate the structures when the outdoor air is humid.

The VILPE Sense leak detectors and humidity control system can be used to monitor and/or ventilate all green roofs where the waterproofing membrane is installed over the insulation layer. Therefore, VILPE Sense is not suitable for so-called inverted green roofs, where the waterproofing membrane is installed under the insulation layer. As green roofs are sensitive to thermal fluctuations, for instance, the outer parts of the insulation on green roofs tend to be cooler, the right type of ventilation is important to avoid condensation. During the summer, moisture can start to accumulate within the cooler parts of the green roof if the roof is ventilated with underpressure vents as the temperature within the insulation material is lower than the outside air. VILPE Sense solves this by ventilating the roof at the most optimal time.

In conclusion, green roofs offer substantial environmental benefits, but they also present significant moisture management challenges. The VILPE Sense product family addresses these challenges with advanced, real-time monitoring and demand-based ventilation solutions. By ensuring effective moisture control, VILPE Sense enhances the durability and functionality of green roofs, supporting their role in sustainable urban development. This integration of smart technology and green infrastructure represents a crucial step forward in the maintenance and optimization of eco-friendly roofing systems.