COVER STORY


How smarter Cat A FCU design reduces carbon, cost and future disruption


Why Cat A decisions matter


As the construction industry pushes toward lower-carbon targets, HVAC specification is under fresh scrutiny. Troy Chambers, head of national sales at Ability by Dimplex, shares how the right Cat A fan coil strategy can reduce both operational and embodied carbon and make fit outs more sustainable long term


M&E decisions at Cat A stage have long-term consequences when it comes to carbon impact in commercial buildings. Fan coil units (FCUs), often designed and installed for Cat A fit outs, are major contributors to both embodied and operational carbon.


But what happens when a new tenant moves in? Space is reconfigured. FCUs get repositioned. Many end up uninstalled and partially recycled before they’ve ever been used. This waste cycle is common and costly. That’s why rethinking FCU design at the Cat A stage is crucial for decarbonisation, whole-life carbon reduction and project budgets.


Reducing embodied carbon: the Cat A–Cat B link


The Royal Institution of Chartered Surveyors (RICS) estimates that fit outs can contribute up to a third of a building’s total emissions over its lifetime . In fact, Cat B changes happen as many as 30–40 times. According to the Aecom GPU HUBS Specification Guide, commissioned by the Government, using adaptable FCUs at Cat A stage is a key strategy for reducing this waste. Fan coil units such as Multiroom by Ability use multiple fan decks and independent control zones, allowing FCUs to serve more flexible layouts. It also avoids rip-and-replace costs.


Operational carbon: the valve and flow rate factor


Operational carbon is another target area. It accounts for around 23% of the UK’s building- related emissions, with 17% from direct energy use, such as heating and cooling. Here, control valve selection makes a big difference.


Most systems use pressure independent control valves (PICVs), which rely on differential pressure across the valve to control flow. But newer electronic pressure independent valves (EPIVs) offer precise flow measurement and modulation. This reduces pressure requirements from around 30kPa to as low as 5kPa. This not only cuts pump energy use but


provides real-time data to the building’s BMS. This supports smarter control and better long- term efficiency.


Why heat pump-ready coils make sense now


Futureproofing doesn’t stop at layout flexibility. With heat pumps (and heat pump-fed district heating networks) becoming the norm, FCUs


must also handle lower-grade heat efficiently. That’s where Ability’s heat pump-ready coil design, developed as part of their Matrix and EVO ranges, comes in. It was built for chilled water cooling today and low-temperature heating tomorrow, without the need to resize units, add coils or increase air volume. Rather than bolt on secondary coils or oversize units, Ability re-engineered the coil block itself:


• Increased surface area improves thermal output at lower flow temps


• Re-circuiting reduces pressure drop and pump demand


• A single coil handles both heating and cooling modes


• No airflow increase means acoustic performance is preserved


Case study: One Glass Wharf At the One Glass Wharf project in Bristol, Ability supplied fan coils for a commercial fit out. This fit out had to support 46/36°C heat pump heating without losing cooling performance — all within the original Matrix unit footprint.


Testing showed strong performance:


• 24% lower electrical consumption • 6.2% reduction in embodied carbon (verified via TM65)


• 18% reduction in air volume with no cooling output loss


This proves that a single-coil, HP-ready solution can perform under live conditions. It can also reduce both emissions and long-term disruption.


The specifier’s opportunity


Whether designing a high-performing Cat A fit out or planning for net zero compliance, smarter FCU selection gives M&E consultants a real opportunity to add value.


By choosing:


• Durable, adaptable units • EPIV control valves • Heat pump-ready coils


…consultants can help reduce future rework, cut costs and ensure the building’s HVAC system is built to last. All of this without compromising performance today.


Want to know more?


Download our white paper Reducing Waste in Cat A to Cat B FCU Fit Outs. For any project specific questions or queries on application and technical details, contact the Ability design and technical team.


10 BUILDING SERVICES & ENVIRONMENTAL ENGINEER AUGUST 2025 Read the latest at: www.bsee.co.uk


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38