Seeing the whole picture
A full all-electric retrofit typically delivers the lowest operational carbon, but waiting or doing nothing can be far more damaging, potentially doubling overall emissions. For many transition risk assets, bivalent heating strategies offer a practical interim approach that cuts carbon now while avoiding premature scrappage of functioning boiler plants.
A bivalent system retains existing boilers for the coldest periods, often less than 10% of annual operation in the UK, while adding a smaller electric heat source, such as an Air Source Heat Pump (ASHP), to meet the majority of demand. In milder climates like central London, this can be more carbon-efficient in the short term than going fully electric, while also avoiding the embodied carbon waste of retiring boilers early.
These systems can be integrated more easily with existing infrastructure, often without disruptive terminal unit upgrades, and they are recognised in EPC assessments. In practice, they can lift buildings to meet anticipated 2030 MEES requirements of an EPC B or above, or even achieve an A rating, without the cost and disruption of a full electrification project, while also improving urban air quality.
Crucially, the supplementary electric heat source becomes part of any future all-electric solution. Bivalent approaches are particularly beneficial during chiller replacement projects, where considering future heating strategies helps prevent plant space constraints that could otherwise block later electrification.
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