Unlocking Net Zero Benchmarks and Strategies

The 2025 CIBSE Technical Symposium showcased hard data—and practical pathways—towards genuine net zero performance. Three contributions in particular stand out for consultants, estates teams and asset owners who need results rather than rhetoric: a systematic review of whole-life carbon (WLC) strategies for stadia (Pack), a quantified office case study demonstrating how decentralised ventilation can trim both upfront and operational carbon (Sumner & Berry), and a net-zero methodology that distils robust, typology-agnostic operational metrics using a calibrated hotel model (Shinku, König & Dehouche). 

Together they sharpen the industry’s benchmarks and reveal where design and operations can deliver measurable gains today. For VEXO’s audience, the implications are immediate: early-stage choices define whole-life outcomes; leaner building services help hit UKNZCBS targets without gold-plating; and real-world metrics (EUI, CEI, ECI) give teams something defendable to design and contract against. This blog extracts the engineering signal, then maps each insight to practical hydronic filtration, water treatment and smart controls that VEXO deploys across estates. 

A Systematic Literature Review Approach to reveal strategies towards decarbonisation for Stadia buildings 

Valeska Pack’s systematic review is a rare, holistic look at stadium WLC. It confirms stadia are among the most carbon-intensive building types, with earlier benchmarks in the 3,000–5,000 kgCO₂e/m² range and operational carbon potentially matching embodied impacts over a 60-year life in efficient new stadia (context that partly explains why “net zero stadium” claims often disappoint). It also spotlights a major methodological shift: the IOC’s 2018 Carbon Footprint Method for Games infrastructure brings LCA discipline to the sector, yet comparable WLC datasets remain sparse; Japan’s National Stadium (Tokyo 2020) reports 1,600 kgCO₂e/m² WLC—suggesting progress but underscoring the need for more transparent, standardised reporting. (Pack, 2025) 

 

The review codes strategies against RICS WLC modules and aligns them to RIBA stages. The pattern is clear: plenty of ideas at RIBA 0–4 (especially operational energy/water concepts and circular economy intentions for D-modules), but thin pickings where carbon is actually locked in—A-stage materials and construction—and almost nothing for B3-B5 (repair/refurbishment). In other words, the industry is strong on concept and end-of-life aspiration, weak on construction execution and long-term in-use stewardship. Pack also flags gaps in arid-climate water strategies and the outsized footprint from spectators’ travel (B8). (Pack, 2025) 

Key Takeaways 
  • Stadium WLC is exceptionally high; credible modern data points are still scarce and must be expanded under consistent methods.  
  • Strategy density clusters at RIBA 0–4 and end-of-life; construction (A4–A5) and in-use repair/refurb (B3–B5) are under-served but critical.  
  • Water strategies and hot-climate guidance are under-represented—important for Gulf or desert venues.  
  • Audience/user emissions (B8) dominate event footprints; operational design must anticipate crowd-driven load spikes. 

For large venues with volatile loads, resilient basics matter. X-POT side-stream filtration keeps primary and secondary circuits clean so pumps and coils run at design ΔT with lower specific fan power and fewer callouts; X-PO treatment maintains water quality and heat transfer; and S-BMS gives event-driven, demand-led heating control without the cost or complexity of a full BMS refit — ideal when early-stage intent must survive construction and long-term operations. 

Lean Building Systems: Understanding the opportunities for carbon reduction with decentralised ventilation for a UK Office Case Study 

This office case study tests three service strategies: (A) centralised AHUs with 4-pipe heating/cooling, (B) decentralised floor-by-floor MVHR with 4-pipe, and (C) decentralised MVHR with 2-pipe distribution. Against the base case, decentralising ventilation delivers a 27% reduction in upfront carbon and a 5–7% reduction in basebuild EUI—small on the meter, big on Cat A–B churn, cost and embodied carbon. The authors also remind us that building services typically contribute 15–30% of upfront carbon for UK offices, second only to structure—meaning leaner services punch well above their weight for UKNZCBS trajectories. (Sumner & Berry, 2025)  

Modelled results show Case B (MVHR + 4-pipe) trims basebuild annual energy ~6.8% versus centralised, with ventilation energy ~19% lower. Case C’s 2-pipe variant saves slightly less due to reversible heat-pump efficiency penalties (SCOP/SEER). Upfront-carbon breakdowns show riser ductwork, central AHUs and dampers disappearing in the decentralised options, offset partly by on-floor MVHRs; the net effect favours MVHR in both A1–A5 carbon and whole-life flexibility (easier access, replacement and circularity). (Sumner & Berry, 2025) 

Key Takeaways 
  • Decentralised MVHR can cut upfront carbon by ~27% vs centralised and reduce base build EUI by ~5–7%.  
  • Removing big risers/plant reduces materials, labour and Cat-B churn, aiding UKNZCBS limits that include Cat-B impacts.  
  • 2-pipe distribution is not automatically lower energy—heat-pump SCOP/SEER and control philosophy matter.  
  • Lean services are as much about right-sizing and responsiveness as they are about technology choice.  

Decentralised ventilation pays back faster when hydronic circuits are low-loss and stable. X-POT removes magnetite and debris, protecting fan-coil and MVHR coils for lower resistance and steadier SFP. PD-Monitor flags differential-pressure anomalies (e.g., clogged strainers/plates) and integrates with BMS/S-BMS for condition-based maintenance. Paired with S-BMS, zones can trim fresh-air and heating call for real-time occupancy — delivering the lean, responsive behaviour the study seeks. 

Net-Zero Carbon Methodology and Benchmark Metrics for a Commercial Typology

Shinku and co-authors go after the thing many projects lack: clear, defendable operational benchmarks. Using a 3-star hotel, they apply Paris Proof and CIBSE’s carbon hierarchy, calibrate a dynamic thermal model (ASHRAE-14 compliant), couple it with PV and microgrid simulations, and report three concise numbers at least-cost: EUIₑₗ = 116 kWh/m², CEI = 87 kgCO₂/m² and ECI = £29.48/m². The method is typology-agnostic and explicitly intended to feed the UKNZCBS evidence base. (Shinku et al., 2025)  

Two practical insights emerge. First, real roof area, setbacks and shading often cap on-site renewables; in this case PV yields ~6 kWh/m²—well below UKNZCBS’s 40 kWh/m² on-site renewable aspiration—so efficiency and flexible demand remain the fastest route to compliance. Second, a calibrated baseline unlocks meaningful scenario testing (heat pumps, fuel-cell microgrids) with investment metrics such as NPV and IRR reported alongside energy/carbon outcomes—useful for boards who need more than kWh.

Key Takeaways 
  • Provide EUI/CEI/ECI from calibrated models; argue capex using NPV/IRR alongside carbon.  
  • Physical PV constraints mean efficiency first; on-site generation may still fall short of 40 kWh/m² target.  
  • Method is portable across typologies and jurisdictions, supporting UKNZCBS evidence gathering.  

Hotels are continuous-load buildings where hydronic inefficiency silently taxes EUI. X-POT filtration plus X-PO chemistry maintain low fouling factors (better heat transfer, reduced pump head), while S-BMS provides rapid, zone-level control for occupancy-swing spaces (function rooms, back-of-house). These measures lower the modelled EUI before the project leans on scarce roof area for PV.

How VEXO Helps 

VEXO provides a practical stack, hydronic filtration, water treatment and smart controls, that maps directly onto the gaps and opportunities highlighted above: 

  • Hydronic Filtration – The X-POT range (full side-stream filtration (magnetic + cartridge/bag) with integrated dosing and air/dirt separation. Cleaner circuits lower pump energy, protect emitters and stabilise ΔT across seasons. 
  • Smart Controls – S-BMS: pre-configured, LoRaWAN-enabled panels and wireless sensors deliver demand-led heating control without a heavy BMS retrofit — ideal for heritage or multi-block estates. Demonstrated results include ~30% reduction in gas at Somerset House and 25% total energy / 36% heating energy reduction at Portsmouth City Council over a heating season. 
  • Condition-Based Maintenance – PD-Monitor: differential-pressure monitoring with alarms and BMS integration to catch blockages across filters, plates and coils before they escalate to comfort or energy penalties. 
  • Point Filtration – Y-MAG: magnetic Y-type strainer that captures magnetite to protect pumps and seals, reducing unplanned downtime in retrofit settings.  
  • Water Treatment – X-PO range (X-PO10 inhibitor, X-PO35 non-flush cleanser, glycols): targeted chemistry to reduce corrosion/scale, speed up clean-and-protect workflows and maintain heat-transfer performance. 

Share your design brief with VEXO’s engineers for duty sizing, schematics and control sequences—or get in touch to see S-BMS and X-POT diagnostics in action. 

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References: 

  • Pack, V. (2025) A Systematic Literature Review Approach to reveal strategies towards decarbonisation for Stadia buildings. CIBSE IBPSA-England Technical Symposium.  
  • Sumner, H. & Berry, M. (2025) Lean Building Systems: Understanding the opportunities for carbon reduction with decentralised ventilation for a UK Office Case Study. CIBSE IBPSA-England Technical Symposium.  
  • Shinku, B.T., König, C.S. & Dehouche, Z. (2025) Net-Zero Carbon Methodology and Benchmark Metrics for a Commercial Typology. CIBSE IBPSA-England Technical Symposium.  

To access and download all the papers from the 2025 CIBSE IBPSA-England Technical Symposium head over to: https://www.cibse.org/knowledge-research/knowledge-resources/technical-symposium-papers/2025-technical-symposium-papers/ 

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