Your Building Is Already Built. Now Make It Work Harder.

Most conversations about sustainable buildings focus on new construction. Yet the buildings that will house businesses, families, and communities over the next two decades are already standing. They were designed under different standards, built with different materials, and operated without today's energy and carbon targets in mind.

The numbers make the case plainly. Buildings and construction currently consume 32% of global energy demand and account for 34% of global CO2 emissions. Operational emissions alone represent 26% of global energy-related CO2. And current annual retrofit rates sit at less than 1% in most major markets, well below what is required to meet Paris Agreement targets. The sector is not on track. And the existing building stock is the primary reason why.

In South East Asia, where cooling loads are high, building stock is aging, and floor area continues to grow rapidly, the performance of existing buildings is not a peripheral concern. It is one of the most consequential decisions building owners and operators will make this decade.

Why existing buildings are the priority

New buildings represent a fraction of total stock at any given moment. In some markets, existing buildings are expected to account for up to 80% of the building stock still in use by 2030. Every year that passes without improving their performance locks in higher energy consumption, higher operational costs, and higher carbon emissions for decades to come.

Retrofitting also carries a strong financial case. Energy and water efficiency upgrades reduce utility costs within measurable payback periods. Better indoor environmental quality reduces occupant health impacts and increases productivity. Green certification of existing assets sends a verified market signal to tenants, lenders, and investors who are increasingly applying ESG criteria to their decisions.

The IEA estimates that in China, the United States, and the European Union combined, spending on building retrofits exceeded USD 120 billion in 2024, more than 20% higher than 2019 levels. Private investors and households account for more than 90% of that investment. The financial logic is already driving action in mature markets. In South East Asia, the opportunity is significant and largely untapped.

Where to start: the performance audit

The first step in improving any existing building is understanding what it actually does, not what it was designed to do. A performance audit examines real consumption data across energy, water, and indoor environmental quality. It identifies the gap between current performance and what is technically and financially achievable.

Without this diagnostic step, interventions risk targeting the wrong systems or missing the highest-impact opportunities. At GBCE, the performance audit is the foundation of every existing building project.

Key areas for improvement

Energy systems

HVAC systems are typically the largest single source of energy consumption in commercial and industrial buildings in South East Asia. Older systems are often oversized, poorly maintained, or operating on outdated controls. Upgrading HVAC equipment, improving building envelope insulation, installing smarter building management systems, and switching to LED lighting consistently deliver the highest financial returns on investment.

Rooftop solar photovoltaic systems are increasingly viable across the region. Where roof area and structural capacity allow, renewable energy integration can significantly offset grid consumption and reduce exposure to rising electricity tariffs.

Water efficiency

Water consumption in existing buildings is frequently higher than necessary due to ageing fixtures, absence of sub-metering, and no systematic leak detection programme. Low-flow fittings, sub-metering, and greywater or rainwater harvesting systems produce measurable reductions in consumption and utility costs with relatively short payback periods.

Materials and embodied carbon

Renovation projects present an opportunity to introduce lower-embodied-carbon materials and to establish construction waste management protocols. Embodied carbon, which includes emissions from materials such as cement and steel, accounts for approximately 18% of global building-related emissions according to the UNEP 2024/2025 Global Status Report. Specifying responsibly sourced materials and tracking embodied carbon during refurbishment aligns with both EDGE and LEED certification requirements.

Indoor environmental quality

Occupant health and comfort are directly shaped by air quality, thermal comfort, natural light, and acoustic performance. These factors also influence productivity and retention. Improvements to ventilation systems, envelope performance, and lighting design can transform how a building performs for the people inside it, and certification frameworks such as WELL provide a structure for measuring and verifying those improvements.

Certification as a performance framework

Green building certifications apply equally to existing buildings. LEED for Existing Buildings: Operations and Maintenance (LEED O+M) provides a structured framework for improving and verifying the ongoing performance of an existing asset. EDGE certification is applicable to renovation projects and offers a clear route to demonstrating 20% or greater improvements in energy, water, and embodied carbon.

Achieving certification on an existing building is a market signal. It demonstrates to tenants, investors, and lenders that the asset has been independently verified against internationally recognised standards. In a building sector where financing conditions and occupier decisions are increasingly tied to ESG performance, that signal carries direct commercial value.

A phased approach works

Not every building owner is in a position to undertake a full retrofit in a single programme. A phased approach, prioritising the interventions with the strongest financial and environmental returns first, allows owners to improve performance progressively while managing capital expenditure. Each phase can be designed to build toward a certification target, so that incremental improvements accumulate into a verified outcome.

GBCE works with building owners and operators to develop phased sustainability roadmaps that are financially realistic, technically sound, and aligned with certification pathways from the outset.

The bottom line

Existing buildings are not a problem to be deferred to the next development cycle. The technologies, frameworks, and expertise to improve their performance exist. The financial case is strong. The regulatory direction, including Thailand's Climate Change Act approved by Cabinet in December 2025, is clear.

The question for building owners and operators is not whether to act, but where to start. 

Learn more on how we can support your existing facilities and assets: https://www.greendesignconsulting.com/operation-renovation

GBCE specialises in existing building retrofits and sustainability optimisation, alongside green building certifications including LEED, EDGE, and WELL. To discuss your building's performance potential, contact us at contact.greenbuilding@gmail.com or visit www.greendesignconsulting.com/operation-renovation

Sources

UNEP and Global Alliance for Buildings and Construction. Global Status Report for Buildings and Construction 2024/2025. United Nations Environment Programme, 2024. https://www.unep.org/resources/report/global-status-report-buildings-and-construction-20242025

IEA. Buildings: Tracking Clean Energy Progress. International Energy Agency, 2024. https://www.iea.org/energy-system/buildings

IEA. Energy Efficiency 2025. International Energy Agency, 2025. https://www.iea.org/reports/energy-efficiency-2025/buildings

IEA. Renovation of Near 20% of Existing Building Stock to Zero-Carbon-Ready by 2030. International Energy Agency. https://www.iea.org/reports/renovation-of-near-20-of-existing-building-stock-to-zero-carbon-ready-by-2030-is-ambitious-but-necessary

IEA. Sustainable Recovery: Buildings. International Energy Agency. https://www.iea.org/reports/sustainable-recovery/buildings