Low-Carbon Design: How Green Roofs Add Performance and Value
As the construction industry continues to focus on reducing carbon emissions, roofing design is playing an increasingly important role in meeting performance and sustainability targets.
Green roofs, when paired with high-performing warm roof systems, offer a practical and technically robust solution for improving thermal efficiency, managing stormwater, and enhancing urban environments.
Environmental and Thermal Performance
Green roofs provide a number of advantages beyond their visual appeal. By reinstating greenery at roof level, they help offset the ecological impact of a building’s footprint while improving biodiversity and reducing the urban heat island effect. Their ability to absorb and slow stormwater runoff helps ease pressure on infrastructure during heavy rainfall events.
When paired with a warm roof system, green roofs also contribute to improved thermal stability, reducing heating and cooling demand. This directly supports operational carbon reduction targets and helps buildings perform more efficiently throughout their lifecycle.
Green Roof Design Options
Equus specialises in delivering durable, watertight green roof systems using the SOPREMA DUO root-resistant membrane, a proven solution for New Zealand conditions. Depending on the structural capacity and planting requirements, three primary system types are available:
- > Extensive Green Roofs – Lightweight, low-maintenance systems designed for mosses, grasses, and groundcover. These are the most economical solution, suitable for timber, metal, or concrete roofs.
- > Simple Intensive Green Roofs – Accommodates light planting and small shrubs, providing aesthetic and environmental benefits with moderate structural requirements.
- > Full Intensive Green Roofs – Comparable to a traditional garden, supporting everything from large shrubs to mature trees and water features. These require deeper soil profiles and robust structural support but offer significant design and amenity potential.
Duotherm Warm Roofs for Low-Carbon Design
The performance of a green roof is maximised when installed over a DUOTHERM Warm Roof system. The Equus SOPREMA DUOTHERM Warm Roof combines continuous thermal insulation with robust waterproofing, resulting in improved energy efficiency, extended service life, and reduced lifecycle carbon impacts.
DUOTHERM consists of the SOPREMA DUO two-layer membrane applied over rigid PIR or SOPRAROCK mineral wool insulation and a vapour barrier. This configuration provides consistent thermal resistance (R-values) that meet or exceed the New Zealand Building Code, helping reduce heating and cooling loads.
The system is lightweight, CodeMark certified, BRANZ-appraised, and available in a root-retardant version specifically designed for green roof applications. DUOTHERM can be installed on new builds or refurbishments, and offers multiple installation options (torch-applied, self-adhered, mechanically fastened, or adhesive systems) to suit different substrates and project conditions.
Supporting Low-Carbon Outcomes
By integrating green roof systems with Duotherm warm roof technology, designers can achieve multiple performance outcomes within a single roofing build-up: improved thermal efficiency, reduced operational energy, enhanced stormwater management, and increased biodiversity.
With around 20% of flat commercial roofs delivered by Equus now incorporating green roofs, these systems are becoming a mainstream solution for both environmental performance and architectural expression.
If you’re after some inspiration and a new way of looking at what a roof can offer in regards to design, contact your local Equus Representative to see what can be achieved.
