1. Introduction

Green building is a sustainable approach to designing, constructing, operating, and maintaining the built environment. In South Africa, as in most parts of the globe, the construction industry is embracing sustainable practices to reduce environmental impact while constructing healthier, more efficient buildings.

Green building rating tools are the formal verification of a building's compliance with prescribed sustainability standards. Rating tools not only validate the environmental performance of a building but also provide a framework for integrating sustainable principles into the lifecycle of the building. For steel structures in particular, rating tools present an opportunity to showcase the inherent sustainability advantages of steel while ensuring that any likely environmental concerns are addressed.

2. Overview of Steel Structures

Benefits of Steel in Sustainable Construction

Steel has numerous advantages that align with the principles of sustainable construction:

• Resource Efficiency: Steel structures tend to require less material to structurally perform as good as other construction materials, resulting in conservation of resources.
• Reduced Construction Time: Prefabrication possibility of steel members saves construction time, which reduces site disturbance and construction waste.
• Durability: Steel buildings are very durable, reducing replacement needs and conserving resources over the long term.
• Design Flexibility: Steel allows innovative designs that can maximize natural light and ventilation, enhancing energy efficiency.
• Adaptability: Steel-framed buildings can be easily modified or extended, enhancing their useful life and reducing demolition waste.

Steel Lifecycle and Recyclability

The most significant sustainability aspect of steel is its recyclability:

• Closed-Loop Material: Steel can be recycled again and again without losing its properties, making it a partially sustainable building material.
• High Recycling Rate: Steel's recycling rate in South Africa exceeds 85%, which is significantly higher than that of most building materials.
• Energy Conservation: Steel recycling consumes approximately 60-70% less energy than producing new steel from raw materials.
• Reduced Carbon Footprint: The utilization of recycled steel in construction can reduce the carbon footprint of a building project by up to 30%.
• End of Life Value: Steel's high scrap value promotes recycling at the end of life for the material, resulting in continued resource conservation.

3. Primary Green Building Certifications

LEED (Leadership in Energy and Environmental Design)

Summary and Implications for Steel Buildings

LEED, developed by the U.S. Green Building Council, is the most widely known green building rating system globally. Although not South African in origin, LEED certification is undertaken by most multinational companies and high-profile projects in South Africa to demonstrate environmental leadership.

Within steel buildings, LEED certification recognizes the following intrinsic benefits:

• Efficiency of steel-framed designs
• Potential for high recycled content
• Potential to source materials locally (reducing transportation emissions)
• Minimal generation of construction waste

LEED Requirements and Credits for Steel Buildings

Steel building construction can contribute significantly to the achievement of LEED certification in the following credit categories:

• Materials and Resources (MR):
  • MR Credit: Building Product Disclosure and Optimization - Environmental Product Declarations
  • MR Credit: Building Product Disclosure and Optimization - Sourcing of Raw Materials
  • MR Credit: Building Product Disclosure and Optimization - Material Ingredients
  • MR Credit: Construction and Demolition Waste Management
• Energy and Atmosphere (EA):
  • EA Prerequisite: Minimum Energy Performance
  • EA Credit: Optimize Energy Performance
• Innovation (IN):
  • IN Credit: Innovation - for outstanding performance in sustainable steel practices

Projects incorporating steel with high recycled content, locally sourced steel, or responsibly certified production steel can earn additional points towards LEED certification.

Green Star

Green Star Rating System in South Africa

Green Star is an environmental rating system for buildings in South Africa and is administered by the Green Building Council of South Africa (GBCSA). The system has been adapted to the South African context, including local environmental conditions, regulations, and industry practice.

Green Star offers a number of rating tools for different kinds of buildings:

• Green Star - Design & As Built
• Green Star - Interiors
• Green Star - Existing Building Performance
• Green Star - Communities

Each tool evaluates the projects on the basis of nine categories and gives a rating between 4 Stars (Best Practice) and 6 Stars (World Leadership).

Green Star Assessment for Steel Structures

Green Star evaluates steel structures under several major categories:

• Management:
  • Commissioning and tuning
  • Building information
  • Sustainable procurement
• Indoor Environment Quality:
  • Thermal comfort
  • Indoor air quality
  • Acoustic comfort
• Energy:
  • Greenhouse gas emissions
  • Reduction of peak electricity demand
• Transport:
  • Sustainable transport options
• Water:
  • Potable water consumption
• Materials:
  • Life cycle impacts
  • Responsible building materials
  • Sustainable products
  • Construction and demolition waste
• Land Use & Ecology:
  • Ecological value
  • Sustainable sites
• Emissions:
  • Stormwater
  • Light pollution
  • Microbial control
• Innovation:
  • Innovative technology or process

Steel buildings can excel in the Materials category by demonstrating responsible sourcing, high recycled content, and low waste generation. The thermal mass properties of some steel-concrete composite systems can also contribute towards energy efficiency points.

SANS 10400

South African National Standards for Energy Efficiency

SANS 10400 is the South African National Building Regulations and Building Standards Act code of practice. Environmental sustainability and energy efficiency in buildings are addressed in Part XA (SANS 10400-XA) of SANS 10400.

Some of the key aspects of SANS 10400-XA include:

• Minimum energy consumption for buildings
• Thermal requirements for building envelopes
• Mechanical ventilation and air conditioning system requirements
• Hot water heating system requirements
• Artificial lighting system requirements

SANS 10400 and Steel Structures

SANS 10400-XA is not directly targeted at steel structures but sets out performance criteria that are to be met by all buildings regardless of material of construction. In steel structures, compliance typically involves:

• Thermal Performance: Reducing thermal bridging through steel members by incorporating appropriate insulation systems
• Building Envelope: Ensuring that the building envelope meets minimum R-value requirements
• Energy Efficiency: Employing energy-efficient heating, cooling, and lighting systems
• Hot Water Systems: With energy-efficient water heating solutions, perhaps with the addition of solar water heating

Not a certification in itself, but SANS 10400-XA compliance is mandatory and forms the foundation upon which to obtain voluntary certifications like Green Star.

4. Comparison of Certifications

LEED vs. Green Star for Steel Structures in South Africa

LEED and Green Star both offer useful frameworks for the certification of sustainable steel structures but have some key differences:

Strengths and Weaknesses

LEED Strengths:

• Higher international recognition
• Appropriate for multinational companies
• Well-established processes
• Strong technical resources

LEED Limitations:

• Less applicability to South African regulations
• Costlier certification
• Requires international consultants
• Some credits may not be applicable to local context

Green Star Advantages:

• Customized to South African context
• Direct applicability to local building codes
• Local technical resources and support
• Prioritizing local environmental issues

Green Star Limitations:

• Lower international recognition
• Smaller pool of certified professionals to select from
• Ongoing to build system with periodic changes

For South African steel buildings, Green Star tends to offer a more directly applicable certification path, with projects that have international stakeholders or visibility possibly benefiting from LEED certification.

5. Regulatory Environment and Compliance

South African Legislation and Regulation

Several pieces of legislation and regulation govern green building in South Africa:

• National Building Regulations and Building Standards Act (Act 103 of 1977): Specifies minimum building standards, e.g., SANS 10400-XA for energy efficiency.
• National Environmental Management Act (NEMA): Provides guiding principles for sustainable development and environmental protection in construction.
• National Energy Act (2008): Promotes energy efficiency and exploitation of renewable energy resources.
• Carbon Tax Act (2019): Implements carbon taxation, which indirectly promotes energy-efficient buildings.
• Construction Industry Development Board (CIDB) Act: Promotes sustainability in the procurement of construction.

For steel buildings specifically, compliance includes:

• Meeting SANS 10400-XA thermal performance
• Meeting SANS 10160 for structural design
• Meeting SANS 10162 for structural steel design
• Meeting SANS 204 for energy efficiency in buildings

Role of Local Authorities

The local municipalities play a critical role in the implementation of green building regulations:

• Approval of Building Plans: Municipalities verify building plans for compliance with SANS 10400-XA before granting permits.
• Inspections during Construction: Building inspectors verify compliance with approved plans during construction.
• Occupancy Certificates: Certification only occurs at the end after verifying compliance with all the requirements.
• Incentive Schemes: Some municipalities offer incentives for green buildings, i.e., expediting permitting or density bonuses.

In bigger cities like Johannesburg, Cape Town, and Durban, additional local green building policies may also apply. For example, the City of Cape Town's Resource Efficiency Criteria for Development requires new buildings to incorporate energy efficiency, water conservation, and waste management beyond national requirements.

6. Case Studies

Discovery Head Office, Sandton

Project Overview:

• 112,000 m² steel-framed commercial development
• 5-Star Green Star Office Design v1 certification
• 5-Star Green Star Office As Built v1 certification

Sustainability Features:

• High-performance building envelope with state-of-the-art thermal insulation
• Energy-efficient HVAC system with 35% reduction in energy consumption
• Grey water recycling system with 30% reduction in water consumption
• 25% recycled content in structural steel
• 75% construction waste diverted from landfill
• Roof-mounted photovoltaic system generating 10% of building energy

Certification Achievement:

The project earned its Green Star certification because of its exceptional performance in energy efficiency, material selection, and indoor environmental quality. The steel structure's design flexibility allowed for optimal orientation and natural lighting, which was crucial for energy savings.

Menlyn Maine Central Square, Pretoria

Project Overview:

• Mixed-use development with retail, office, and leisure spaces
• 4-Star Green Star Design certification
• First South African building to achieve both Green Star and LEED certification

Sustainability Features:

• 80% recycled content structural steel
• Composite steel-concrete floor system for energy efficiency and thermal mass
• Rainwater harvesting system that reduces potable water by 45%
• Building envelope optimized to minimize cooling loads by 30%
• Low-VOC materials utilized throughout for improved indoor air quality
• Local materials utilized extensively, including locally fabricated steel components

Certification Achievement:

The project finished both LEED and Green Star certification procedures, demonstrating that steel buildings are capable of complying with a range of green building criteria. The project team documented the lifecycle benefits of steel, from manufacture to possible future adaptability, in order to obtain points within the two systems.

V&A Waterfront Silo District, Cape Town

Project Description:

• Adaptive reuse of old grain silos into mixed-use development
• 6-Star Green Star Design certification (the highest rating achievable)
• Steel frame integration with retained concrete silos

Sustainability Features:

• Retention of structure, reducing embodied carbon
• New steel components with a minimum of 50% recycled content
• Sea water cooling system with 65% energy saving
• Blackwater treatment plant recycling 100% wastewater
• Rooftop solar PV system
• Natural ventilation strategy reducing mechanical cooling requirements

Certification Achievement:

This project illustrates how steel can be integrated with existing structures to achieve the highest sustainability ratings. Innovation points were given to the project team for recycling industrial heritage in an innovative way and integrating high-level sustainability systems within the constraints of an existing building.

7. Conclusion

Green building rating systems are of great benefit to steel buildings in South Africa, developing a framework to unlock the inherent sustainability advantages of steel while reducing its environmental shortcomings. The choice of rating systems—whether LEED, Green Star, or SANS 10400-XA compliance—needs to be project-specific, stakeholder-driven, and target market-dependent.

The following dimensions are particularly important in South African steel building construction:

• Local Relevance: Green Star typically offers the most relevant certification pathway for local projects, since it is specifically adapted to South African conditions.
• Regulatory Compliance: SANS 10400-XA compliance is the minimum for any green building project and needs to be met first before voluntary certifications are attempted.
• Material Selection: Specifying steel with high recycled content from responsible sources can go a great way towards certification credits.
• Life Cycle Approach: Considering the entire lifecycle of steel—from manufacture to potential ultimate reuse—further strengthens the sustainability case for steel buildings.
• Integrated Design: Getting architects, engineers, and sustainability consultants working together at an early stage in the process maximizes the potential for achieving high scores for certification for steel buildings.

As South Africa continues to emphasize sustainable development, green building ratings will only become increasingly important for market competitiveness, regulatory compliance, and environmental responsibility. Steel buildings, with their inherent efficiency, versatility, and recyclability, are well-positioned to thrive in this evolving landscape.

By C&H Contractors Team

The certifications detailed in this guide are the roadmap to get there, providing recognition for excellence in sustainable steel building construction.

8. References

• Green Building Council of South Africa. (2023). Green Star Rating Tools. https://gbcsa.org.za/certify/green-star/rating-tools/
• U.S. Green Building Council. (2023). LEED v4.1 Building Design and Construction. https://www.usgbc.org/leed/v41
• South African Bureau of Standards. (2021). SANS 10400-XA:2021: The application of the National Building Regulations - Part XA: Energy usage in buildings.
• South African Bureau of Standards. (2018). SANS 204:2018: Energy efficiency in buildings.
• Steel Construction Institute. (2022). Sustainability of Steel Construction. https://steel-sci.com
• World Steel Association. (2023). Steel's Contribution to a Low Carbon Future. https://worldsteel.org
• Construction Industry Development Board. (2023). Best Practice Project Assessment Scheme. http://www.cidb.org.za
• Department of Mineral Resources and Energy, South Africa. (2022). National Energy Efficiency Strategy.
• City of Cape Town. (2021). Resource Efficiency Criteria for Development. https://www.capetown.gov.za
• City of Johannesburg. (2023). Green Building Policy Framework. https://www.joburg.org.za