Building conversations up with Olivia Guerra-Santin

BUILDING CONVERSATIONS UP WITH... Olivia Guerra-Santin, Assistant Professor in the chair of Smart Architectural Technologies in the Department of the Built Environment at Eindhoven University of Technology (TU/e).

“The specific benefits of the energy performance assessment are varied and depend on the party carrying out the evaluation”

With her research, Guerra-Santin aims to design and evaluate energy-efficient and healthy environments. Her expertise involves user-centred and data-driven research methods, building monitoring and performance evaluation, and the use of Living Labs for socio-technical research. Guerra-Santin’s topics of interest include building management and control, occupant behaviour, and building performance.

BUILD UP (BUP): Can you define building performance assessment, and describe what the benefits are?

OLIVIA GUERRA-SANTIN (OG-S): Building performance assessment could be defined as the process followed to determine whether a building has reached the energy targets anticipated during the planning and design phases. This process can start from the design stage of the building, although it is often focused on the pre- and post-occupancy phases. 

Post-Occupancy Evaluation (POE) consists of several activities carried out after the delivery of the building. These can include building monitoring (with environmental sensors and energy meters), energy audits, and thermal comfort and satisfaction assessment through the use of diverse quantitative and qualitative methods. Occupants' behaviour itself (how people interact with the building and building systems) can also be the focus of the POE. POE is necessary because the actual performance of the building can only be measured after the occupants have moved in. Energy performance assessment can be carried out before occupancy, but it then focuses only on the efficiency of the installations and the performance of the building envelope, not on energy consumption. There are many methods to assess performance before occupancy (also used during construction such as air permeability tests, tracer gas tests, co-heating tests, etc.) that can tell a lot about how the individual elements of the building perform (including the building envelope) but cannot tell us how much energy will be used since energy consumption also depends on occupants typologies, intensity of use of the systems, the needs and preferences and behaviour of the occupants and the effectiveness of the building management. In my opinion, building performance assessment must include some type of POE.

In general, the benefits of the energy performance assessment can be seen in the increased energy efficiency of buildings, higher levels of comfort for the occupants, lower energy costs, and increased trust in low-carbon technologies. However, the specific benefits are varied and depend on the party carrying out the evaluation. The assessment results can be used to 1) improve the building’ performance either through fine-tuning of the installations, or through feedback to occupants and building managers; 2) to verify the building’s performance for compliance, performance contracts or certifications (usually intended to brand buildings as ‘green’); and 3) to learn from the process to improve future projects.

It is important to make a distinction between the theoretical and actual performance of buildings. Theoretical performance (obtained from EPCs, labels, most commercial certifications) are based on design values, intentions, and assumptions regarding building occupancy. Theoretical performance should only be taken as the baseline to assess performance. This is against what we compare the actual (measured, monitored) performance. However, a difference between the theoretical and actual performance does not always indicate that there is a fault either with the building envelope and systems or with the occupant's behaviour. There can often be performance gaps that have been created by the (wrong) assumptions made about the use of the building. This is why, next to POE, it is good practice to also do a design review, but these are not normally carried out. 

Read the full interview on BUILD UP!