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UK study mulls heat pumps for net-zero buildings

A feasibility study conducted by the UK Green Building Council (UKGBC) is re-evaluating building materials and exploring heat pumps as realistic design pathways to meet the UK’s decarbonisation targets. The findings are intended to improve collective understanding of the real-world implications for achieving new net zero buildings.

The “Building the case for net zero” report assessed the design of two real-life building types – a residential office block and an office building.

Studying the base design of both structures, the research team came up with two design versions for each of them, according to different target scenarios. The “intermediate” scenario is based on meeting 2025 net zero performance targets and the “stretch” scenario has 2030 targets in mind.

“We’ve known for some time that taking action to make buildings greener today will add value and save costs in the longer term,” says Chief Executive at UKGBC, Julie Hirigoyen.

“But the precise cost benefit analysis of achieving net zero carbon standards on new buildings today has remained elusive.”

To meet the 2025 targets for the residential block design, the team replaced traditional gas boilers with air source heat pumps, improved fabric insulation and reduced glazing areas to minimise heat loss.

For the office building design in the same scenario, the team replaced a conventional steel and concrete structure with hybrid steel and cross-laminated timber in the superstructure, removed some fitout finishes like suspended ceilings and introduced active chilled beams.

Based on cost analysis, the cost uplift for the residential block and office building were 3.5 per cent and 6.2 per cent, respectively. These costs are thought to be relatively marginal and likely to be recouped through associated increases in rental and capital value, plus reduced operational costs.

The design changes applied in the “stretch” scenario for both structures to achieve the 2030 targets resulted in a more significant uplift in capital expenditure – 5.3 per cent for the residential building and between 8-17 per cent for the office building.

The researchers say this highlights the need for supply chain innovation and investment early on, so as to scale the market for low-carbon solutions, thereby bringing down costs over time.

“This study provides long-awaited evidence that building today to the standards of energy and carbon efficiency required by 2025 doesn’t have to cost a fortune and is likely to be offset by enhanced value – for example, higher rents, reduced running costs, higher sale price, reduced offsetting costs, and so on – in due course,” says Hirigoyen.

“But unsurprisingly, when it comes to building to 2030 standards of efficiency, the current capital cost increase on a baseline 2020 design is more challenging to accommodate.”

“To overcome this, we need a long-term consistent regulatory trajectory that tightens standards over time so as to provide the certainty and level playing field required for the supply chain to innovate and costs to come tumbling down. Yet again, we are reminded that more visionary policy-making and bold industry leadership must go hand in hand in the quest for net zero carbon outcomes.”

The report is co-authored by the UKGBC with construction and engineering specialists JLL and Hoare Lea. The report also contains input from building specialists including Alinea, Bennetts Associates, Cast, Cundall, EPR Architects, Heyne Tillett Steel, Landsec, Legal & General and Robert Bird Group.

The report is available for download here.

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