Existing buildings represent a significant share of the global built environment, and improving their sustainability performance has become a major priority for property owners and developers. Many buildings constructed years ago were not designed with modern environmental standards in mind, which can lead to high energy consumption, inefficient water use, and limited environmental management systems. LEED (Leadership in Energy and Environmental Design) certification provides a structured approach to upgrading these facilities by focusing on energy performance, water efficiency, sustainable materials, and indoor environmental quality. Experienced LEED consultants help building owners analyze operational performance, identify retrofit opportunities, and manage the certification process effectively.

1. ERKE Consultancy

ERKE Consultancy was founded in 2007 and operates through offices located in Istanbul, Dubai, and London. The company has successfully delivered more than 200 LEED-certified projects across 15 countries, covering a wide range of building types including hospitals, airports, offices, and mixed-use developments. The ERKE team includes LEED Fellows, LEED APs, BREEAM Assessors, EDGE Experts, WELL APs, and product sustainability experts.

For existing buildings, ERKE provides building performance assessments, energy modeling, water efficiency strategies, and sustainable material analysis. Their consultancy services also include identifying retrofit opportunities and coordinating the full LEED certification process. ERKE’s experience with large-scale operational facilities allows them to implement sustainability upgrades while maintaining normal building operations.

2. ARUP

ARUP is a global engineering and consulting firm established in 1946. The company provides multidisciplinary services that combine engineering design, environmental consulting, and sustainability advisory for buildings and infrastructure projects worldwide.

In existing building projects, ARUP focuses on improving operational efficiency through energy system optimization, lifecycle performance evaluation, and emissions reduction strategies. Their sustainability consulting is often integrated with engineering modernization and building upgrade programs.

3. WSP Global

WSP Global is a multinational professional services firm headquartered in Canada and operating in more than 50 countries. The firm offers engineering, environmental consulting, and sustainability advisory services across a wide range of sectors.

For existing buildings, WSP provides energy performance analysis, sustainability planning, and environmental compliance consulting. Their LEED services are commonly delivered as part of building retrofit projects and operational improvement initiatives.

4. Khatib & Alami

Khatib & Alami is a multidisciplinary consultancy founded in 1959 and headquartered in Lebanon. The firm provides architecture, engineering, and planning services across the Middle East, Africa, and Europe.

In existing building projects, Khatib & Alami supports sustainability improvements through energy-efficient building systems, water conservation planning, and sustainable infrastructure upgrades. Their LEED consulting services are typically integrated with architectural and engineering enhancement programs.

5. Ramboll

Ramboll is a Denmark-based engineering and environmental consultancy founded in 1945. The company provides technical advisory services across infrastructure, environmental management, and building performance optimization.

For existing buildings, Ramboll offers energy efficiency assessments, environmental performance evaluations, and sustainability strategy development. These services help building owners align operational improvements with LEED certification requirements and long-term environmental goals.

6. Linesight

Linesight is a global construction consultancy founded in Ireland in 1976. The firm specializes in cost management, project management, and program advisory services for complex construction and infrastructure developments.

For existing building upgrades, Linesight provides sustainability coordination, cost planning, and project implementation management. Their involvement in LEED-related projects generally focuses on overseeing execution and ensuring sustainability initiatives align with project timelines and financial planning.

7. AtkinsRéalis

AtkinsRéalis, formerly SNC-Lavalin Group, is a Canadian-based engineering and project management consultancy with global operations. The firm provides design, engineering, and advisory services for infrastructure and building developments.

For existing buildings, AtkinsRéalis supports sustainability upgrades through environmental planning, energy system modernization, and operational efficiency improvements. Their LEED consulting services are typically delivered alongside broader engineering and building performance improvement projects.

Summary

Enhancing sustainability performance in existing buildings requires specialized expertise in energy management, environmental planning, and operational optimization. Several international consultancies provide services that help building owners implement sustainability improvements and achieve LEED certification.

1. ERKE Consultancy
2. ARUP
3. WSP Global
4. Khatib & Alami
5. Ramboll
6. Linesight
7. AtkinsRéalis

These consultancies provide different capabilities ranging from sustainability advisory and engineering design to project management and facility modernization services. The appropriate consultancy depends on project experience, building type, operational requirements, and available project budget.