Narrowing the Performance Gap

Measuring, inspecting and testing a building’s performance through all stages of development and over the duration of its lifecycle is critical to narrowing the performance gap. Interpreting data is just as important as collecting it to achieve the intended performance targets and relevant building certification. It’s important to examine the typical areas where performance gaps can occur and understand how to narrow that gap.

The Human Factor

In an ideal world, users of a new building or retrofit project would engage with the space in the most efficient ways possible, but human behavior is the hardest thing to predict. This often leads to a performance gap, reflecting the disparity between the forecasted energy use of the building and the actual energy use once it is operational. Recent studies have shown that in non-domestic buildings, energy consumption can be anywhere from 5-10 times as high as original calculations.

This can cause owners to fall short of their targets and result in loss of certification or government funding. Designers must account for and monitor the operational performance of a building using predictive software tools, intrusive inspection, and consistent testing to give owners a clear picture of their investment.

Building Envelope Commissioning 

Assessing a building’s envelope can help identify any pitfalls in air leakage, insulation and HVAC controls that often contribute to a performance gap. This quality-based process is part of a holistic approach that requires consideration through the life cycle of the building.

• Concept – Work with the owner to set expectations and requirements
• Detailed Design – Review the owner’s original plans for performance gaps
• Preconstruction – Conduct site inspection, pre-installation testing, review of construction drawings, and evaluate contractor wall mock-ups including fenestration
• Construction – Conduct systems test and performance review
• Occupancy – Training employees and users on system operations

Accounting for thermal performance, air leakage, moisture management, durability and compatibility must be conducted throughout the entire life cycle of the building. The data collected helps narrow the performance gap and provides valuable feedback for future builds. 

Interpreting Accurate Data 

Performance gaps exist due to inconsistencies in data. Employing modern methods of testing and measuring is crucial to narrowing this gap. These include:

• Thermography Scans – An inexpensive and non-intrusive way to trace thermal bridges and air leakage on existing buildings
• Blower Door Tests – Testing the tightness of a building for air leakage at various pressure levels as the building is being constructed
• Fog Test – Using glycerin to create a harmless fog in conjunction with a blower door test to help spot air leakage

These practical tests can identify problems throughout the entirety of the construction process and show building owners any inconsistencies with performance in real-world scenarios. For example, in Passive House certifications, air leakage must meet a certain minimum threshold throughout construction and that can only be verified with modern methods.

Software and automated systems can also do a lot of the heavy lifting when it comes to spotting and solving gaps in performance. Below are some additional tools that can assist in reducing the performance gap:

• COVE Tool – Software that uses climate, weather, space, building size, and occupancy to establish a baseline of operational performance
• IES Software – Globally recognized software that helps create a virtual environment to test performance
• Passive House Planning Package – A complete building model focusing on the performance of the entire structure and its individual elements
• NERVA – Automated smart controls monitoring duct and suite seals to improve air leakage

Continuous Collaboration

Educating owners, investors and managers in the process helps everyone invested in the project understand the importance of narrowing the performance gap. The building envelope is a crucial part of the construction plan, and ongoing testing is vital to calculating performance. Establishing clear targets at the outset of the project and conducting regular testing before, during and after occupancy identifies cost-saving opportunities in the present and for future buildings.