Designing for Performance: Why Measurement Matters in Retrofit and Renovation

Energy efficiency is no longer a secondary consideration in building design and refurbishment. With rising energy costs, tightening regulations and changing occupier expectations, the performance of heating, ventilation and insulation strategies is now under scrutiny. Particularly in existing buildings.

Recent research shows just how quickly priorities are shifting. According to Property118, 86% of renters now prioritise energy efficiency when choosing a home, and more than half are willing to pay a premium for properties with higher EPC ratings. For architects and designers working on renovation projects, this places new emphasis on understanding how buildings perform, not just how they are specified.

Beyond the EPC snapshot

EPC ratings remain an important benchmark, but they are ultimately based on calculated models rather than real-world conditions. In practice, the thermal and energy performance of a building is influenced by far more than its fabric alone. Occupancy patterns, user behaviour, ventilation strategies and the interaction between systems all play a role.

This is particularly relevant in retrofit projects, where buildings often have a long operational history and layered upgrades. Two properties with the same EPC rating can perform very differently once occupied. Without measured data, it is difficult to know where improvements will have the greatest impact.

Understanding rest-state and occupied performance

Environmental monitoring offers a practical way to bridge this gap. By measuring temperature, relative humidity, CO₂ levels and energy consumption over time, project teams can build a clearer picture of both rest-state conditions and occupied performance.

Temperature and humidity data can highlight heat loss, cold bridging and the effectiveness of insulation upgrades. CO₂ monitoring provides insight into ventilation adequacy, helping designers balance indoor air quality with energy efficiency. Energy logging reveals how heating systems, appliances and controls behave in day-to-day use. This is information that is particularly valuable when upgrading legacy building and systems.

For architects and interior designers, this data can inform more confident decisions around materials, layouts and system selection, while also providing evidence to support clients’ investment cases.

Supporting better outcomes in retrofit

The relevance of this approach is growing as more focus is placed on upgrading existing housing stock. Research highlights that lower-rated EPC properties are becoming harder to let, especially larger and detached homes, which typically have higher heating costs and require more extensive retrofit work.

In these projects, monitoring enables a phased and targeted approach. Short-term data collection can identify quick wins, such as addressing draughts or optimising heating schedules, while longer-term monitoring helps validate the impact of deeper interventions like insulation upgrades or ventilation improvements.

Importantly, this measured approach also reduces risk. Rather than relying solely on assumptions, teams can verify performance before and after changes are made, ensuring that design intent translates into real-world results.

A time-tested approach to environmental monitoring

For over 40 years, Gemini Data Loggers has supported professionals with reliable environmental monitoring solutions. Our Tinytag data loggers are widely used to measure temperature, humidity, CO₂ and energy consumption in both domestic and commercial buildings.

What has remained consistent over decades of use is the value of accurate, independent data. As the industry continues to adapt to new standards and expectations, this evidence-led approach is becoming an essential part of delivering buildings that are comfortable, efficient and future-ready.

For architects and designers working on renovation and retrofit projects, understanding how a building performs in reality is no longer optional. Measurement provides the insight needed to design, specify and improve with confidence, turning energy efficiency from an abstract goal into a measurable outcome.

Gemini Data Loggers Ltd
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Chichester
West Sussex
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+44 (0) 1243 813000
info@geminidataloggers.com
www.geminidataloggers.com/housing