The fastest pathway to reducing CO₂ emissions lies in scaling retrofit strategies while ensuring all new construction meets low-energy or Net Zero standards, according to Dr Ashak Nathwani.
A celebrated engineer with a career spanning over 50 years advocating for energy efficient buildings, Nathwani participated in an ARBS panel entitled: Embodied vs Operational Energy in Buildings: Where Should We Focus?
As industry accelerates the net zero transition, industry continues to debate whether to focus on reducing embodied energy or operational energy.
Nathwani pointed to research “Embodied versus Operational Energies in Residential and Commercial Buildings: Where Should We Focus?” (Dilsiz et al., 2019) which covered 100 case studies across 23 countries.
The buildings ranged from 25 to 100 years old and included a range of buildings from retrofitted to conventional buildings, low energy, passive and net zero.
“Using Life Cycle Analysis (LCA), both embodied and operational energy values were evaluated and the results were striking,” Nathwani said.
“Operational energy dominated life-cycle energy use.”
The average operational energy was 419 MJ/m² per year.
Nathwani said operational energy accounted for an average 72% of total life-cycle energy.
“In simple terms most of a building’s lifetime energy use— and therefore emissions — comes from how it operates, not how it was built,” he said.
Nathwani then went on to talk about what the findings mean for climate strategy.
He said for existing buildings, which make up the vast majority of global building stock, there should be six priorities.
They are: improving energy efficiency; electrifying heating and hot water; optimising HVAC systems; upgrading lights to LED; installing rooftop solar and batteries (where feasible); as well as improving controls and user behaviour.
“Retrofitting conventional buildings provides the most immediate and scalable carbon reduction pathway,” Nathwani said.
Embodied energy reductions, on the other hand, are typically achieved through new low-energy construction, passive house design, net zero buildings and deep retrofit strategies.
“If retrofit is not feasible, then new buildings must be designed to low-energy or Net Zero Energy standards to avoid locking in decades of operational emissions,” he said.