21. December 2015 – Built2Spec

Energy performance gap? Interview with Eurecat

Reducing the energy performance gap between a building’s designed and as-built energy performance, that is the aim of Built2Spec! But what exactly is a performance gap and how to avoid it? Irene Ràfols, R&D project manager from Eurecat, tells us more!



What exactly is a performance gap?

The energy performance gap is the difference between the energy consumption predicted or calculated during the design stage compared to the actual energy consumption measured once the building is operational. The causes for this gap can be many and varied, and occur throughout the entire construction process.

Why is it so important to avoid the performance gap?

There are many reasons to avoid the energy performance gap. First and foremost, to reach the 20% energy efficiency target by 2020, we must ensure that buildings perform as expected. Second, and mainly of relevance to owners and investors, is the impact that a performance gap has on anticipated energy-related costs. And lastly, a building’s energy performance can have a big influence on user comfort.

How to avoid performance gaps?

In order to avoid performance gaps it is necessary to improve the quality of the entire construction process. In general, during the design stage, proper detailing of all the envelope details, defining the materials and their thermal characteristics and doing a proper simulation including all the building’s energy loads (such as elevators, servers, etc., not only the regulated ones) are essential for a good result. Keeping the design robust and simple is needed to facilitate construction. During the construction stage it is necessary to ensure that the contractor builds according to the design specifications taking special care with thermal bridges, airtightness and insulation installation. Quality checks are needed to verify the construction. Commissioning is important for proper performance of building services and training the building’s users and operators seasonal commissioning is also a good idea to ensure that the building performs well throughout the year. A good metering strategy is very useful to know how the building performs during operation. If the building doesn’t perform as expected, it is necessary that the design and construction team solves the problems and learns from this experience for future projects.

Which tools and methodologies does Built2Spec provide in order to avoid performance gaps?

As previously mentioned, proper and high-quality work is essential in avoiding the performance gap. In order to ensure this high-quality work, Built2Spec provides a series of new technologies which facilitate quality checks (e.g. quantified assessement of thermal properties done with an IR camera, innovative low pressure airtightness tool, 3-D scanning, embedded sensors, a novel lightweight sound source for acoustic testing with smartphones). Moreover, the whole construction process is under investigation in order to develop a BIM- (building infromation modelling) based tool for construction experts in order to deliver high-quality buildings. High-quality construction depends upon other factors in addition to correct design such as the fact that the materials and components are correctly delivered and installed according to the specifications, detailed and updated information and drawings are at hand on-site (e.g. drawings, specification, installation guidelines etc. ) and workers can provide proof of correctness and fulfillment e.g. by taking pictures. Taking pictures and documenting correct installation can also be used for easier communication to avoid mistakes. In order to ensure proper commissioning, Built2Spec will develop several quality checks for this purpose.



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