Selecting the proper green roofing system is vital for maximizing energy efficiency and environmental benefits in the bright and dry climate of Las Vegas. The Importance of Energy Efficiency and Environmental Effect The roof is, in essence, the final component of the building envelope. It plays a heading role in keeping the severe desert sun, wind, and rain from penetrating the indoor space. For any desert-dwelling, the goal is to minimize the energy needed to either cool or heat the indoor space. The green roof is, therefore, something of a hybrid design. Layered with plant materials and soil, it provides almost as much mass and density as a wall. But the green roof also has a component that makes it unique: the living part of the green roof (the plants and soil) should, in principle, absorb and deflect more sunlight than a standard roofing system.
An equally important factor in selecting a green roof for a Las Vegas building is roof load capacity. Even the lightest green roofs (modular systems with pre-grown plant containers) add considerable weight. The heaviest systems, which are composed of soil and mature plants, can weigh 25 pounds or more per square foot. A simple structural assessment by an architect or engineer can determine whether a building can support a green roof. For buildings that can’t support one, a lightweight modular green roofing system could be an excellent green alternative. They consist of easy-to-install and easy-to-maintain pre-grown plant modules that provide efficient “outsides” that even “inside” buildings can enjoy. However, a modular green roof system isn't a free lunch, weight-wise, for the building it's installed on. Because green roofs are “really green” once they’re nearly fully grown, they require weight (plants, soil, and water) and a bigger (higher-capacity) structural system to support them.
In Las Vegas, it is essential to consider maintenance and long-term care for green roofs. The city's unique weather requires that the roof is inspected regularly and maintained so that it remains functional and visually appealing. Roofs that use native plant species support biodiversity among the unique Las Vegas weather. The systems can use automated irrigation to manage their water use super efficiently, allowing the plants to thrive but without unnecessary over-watering. Beyond these first steps, green roofs are a much more significant step toward a sustainable Vegas. They can be substantial carbon sinks. They don't have to come with the risk of fire. They can be part of habitats in-house for local birds and pollinators. And they can drastically extend the life of the roof below them.
