Closing the Gap: Evaluating Performance in Non-Domestic Settings

In the pursuit of energy efficiency and user-centric design, understanding how buildings truly perform in use is essential. At the 2025 CIBSE Technical Symposium, researchers from across Europe presented empirical findings that underscore the challenges and opportunities of closing the performance gap in non-domestic environments. These papers cover pre-occupancy evaluation, real-time occupancy monitoring, energy retrofit strategies, and visitor comfort in cultural institutions. What unites them is the shared recognition that data—quantitative and qualitative—is the cornerstone of good design, effective operations, and meaningful energy savings. 

This blog distils four standout presentations and links their findings directly to actionable solutions using VEXO International’s energy-saving technologies. Whether you’re planning a retrofit, managing facilities, or enhancing indoor environmental quality, these insights show where building performance deviates from expectation—and how to address it. 

Pre-Occupancy Evaluation: Comparing Two Questionnaire Approaches 

Victoria Davalos Quevedo et al. 
Paper: “Pre-occupancy evaluation: comparison of two questionnaire approaches to inform renovation design in existing buildings” 


This study addressed a critical but underexplored phase in building design: the pre-occupancy evaluation (PrOE). Conducted in a 1,200 m² office in Dortmund, Germany, the research compared two feedback methods. A one-time survey and  a continuous micro-feedback system were compared to understand employee satisfaction with their working environment before a planned renovation. 

The one-time survey achieved a high 93% response rate and revealed broad dissatisfaction with open-plan layouts, especially regarding acoustic privacy and lack of personal control. In contrast, the continuous QR code-based feedback (16% participation) offered temporal and room-specific insights, highlighting when and where discomfort occurred.

Key Takeaways 
  • One-time surveys are effective for broad engagement but limited in temporal granularity. 
  • Continuous feedback is valuable for identifying day-to-day variations in satisfaction. 
  • Open offices were consistently rated the least satisfactory workspaces. 
  • Acoustic privacy and storage sufficiency were major pain points. 
  • Engagement strategy should match design phase and feedback goals. 

The dissatisfaction with HVAC-related comfort (acoustics, thermal conditions) in retrofit contexts highlights the value of VEXO’s Side Stream Solutions, which ensures clean, balanced heating systems, improving thermal stability across zones. Furthermore, thanks to VEXO’s S-BMS IoT devices, aspects such as individual zoning of rooms and offices in shared commercial buildings, can help landlords and estate teams tailor the tenant’s experience to individual comfort settings. Check out the testimonial from the Head of Buildings at Somerset House. 

Occupancy Monitoring Approaches: Learnings from Literature and Research 

Amr Suliman et al. (University of Oxford) 
Paper: “Occupancy Monitoring Approaches: Learnings from Literature and Current Research”

As hybrid work becomes the norm, understanding how, when, and where occupants use spaces is increasingly complex. This paper presents a comprehensive literature review and case studies on occupancy detection — including passive (e.g., PIR, CO₂) and active (e.g., Wi-Fi, smartphone) sensing approaches. 

A key insight: default occupancy assumptions used in design no longer hold. Occupancy patterns are too volatile. Real-world data, such as from Wi-Fi access points or smart thermostats, improves accuracy but also raises privacy and scalability concerns. The authors emphasised the value of socio-technical data (e.g., surveys) in complementing sensor data, especially in post-pandemic spaces where air quality and user preference shape occupancy decisions. 

Key Takeaways 
  • Occupancy prediction models must adapt to hybrid work patterns. 
  • Combining quantitative (sensors) and qualitative (surveys) methods yields better insight. 
  • Passive methods are cost-effective but limited in resolution. 
  • Office behaviour differs significantly from residential patterns. 
  • Privacy and intrusiveness are critical design considerations.

Dr Amr Suliman has previously been sponsored by VEXO in his PhD at Loughborough University, resulting in findings such as X-POT reducing pump energy consumption by an average of 19% in multiple system pressure scenarios.  

Data-Driven Retrofit: University Building Performance and Energy Potential 

Rajat Gupta and Alastair Howard (Oxford Brookes University) 
Paper: “Using a data driven approach to examine the current building performance and potential for energy retrofit of a university campus building” 


In this case study, a UK university building underwent comprehensive monitoring to guide energy retrofit strategies. Data sources included monthly energy consumption, heating degree days (HDD), CO₂ levels, and occupant satisfaction. 

Key findings: heating energy was tightly correlated to external temperatures (R=0.91), but indoor conditions were uneven — especially on Mondays after weekend system downtime. Offices regularly exceeded 1500 ppm CO₂, suggesting ventilation inadequacies. The study recommended fabric upgrades and a shift to electric heat pumps as part of a decarbonisation strategy.  

Key Takeaways 
  • Real-time data strengthens retrofit decisions and reduces reliance on static assumptions. 
  • Temperature stratification and CO₂ levels indicate poor airflow in office zones. 
  • Energy performance improves in milder seasons; peaks in winter/summer strain systems. 
  • Manual scheduling (e.g., Monday warm-up delays) hurts user comfort. 
  • Data fusion (energy + environment + occupant feedback) is essential. 

The university’s heating system inefficiencies and CO₂ hotspots signal a need for cleaner, more efficient system operation. Side Stream Filtration ensures system cleanliness in large commercial setups, while X-PO Additives optimises energy transfer in water — perfect complements for low-carbon heat pump systems. 

Museums and Comfort: Balancing Visitor Experience and Conservation 

Jessica Collins et al. (Arcadis / University of Reading) 
Paper: “The Impact of Indoor Environmental Conditions in a Museum on Visitor Thermal Comfort and Experience” 


How do you balance visitor comfort with artefact preservation in unheated or minimally conditioned spaces? This paper tackled that question using surveys and environmental monitoring at the Museum of English Rural Life (MERL). The building lacked heating during the study period, with average temperatures around 15–16°C and relative humidity often below recommended thresholds (<40%). 

Interestingly, longer visits improved comfort perception — even though visitors tolerated more cold. However, 51% of respondents still reported that discomfort impacted their experience. The authors call for HVAC strategies that balance temperature, humidity, and airflow without compromising conservation standards. 

Key Takeaways 
  • Indoor conditions were consistently below thermal comfort standards. 
  • Half of all visitors felt that discomfort affected their experience 
  • Longer exposure decreased cold tolerance but increased acclimatisation. 
  • Humidity often fell outside recommended conservation thresholds. 
  • Visitor experience and artefact safety can be co-optimised with smarter controls. 

Heritage environments need precision control to avoid over-conditioning while maintaining comfort. The X-POT Compact supports sensitive systems, and the X-POT Side Stream ensures flow stability — ideal for museums, galleries, and listed buildings. 

Ready to Close the Gap? 

The path to performance starts with better insights and ends with smarter systems. VEXO products empower facilities managers, designers, and engineers to make evidence-based decisions that enhance comfort, reduce energy use, and protect assets. 

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References: 

  • Davalos Quevedo, V. et al. (2025) Pre-occupancy evaluation: comparison of two questionnaire approaches to inform renovation design in existing buildings. 
  • Suliman, A. et al. (2025) Occupancy Monitoring Approaches: Learnings from Literature and Current Research. 
  • Gupta, R. & Howard, A. (2025) Using a data driven approach to examine the current building performance and potential for energy retrofit of a university campus building. 
  • Collins, J. et al. (2025) The Impact of Indoor Environmental Conditions in a Museum on Visitor Thermal Comfort and Experience 

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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