Data-driven process for the energy assessment of building envelope retrofits

Authors: Roberto GARAY-MARTINEZ, Beñat ARREGI, Mikel LUMBRERAS, Belén ZURRO, Jose Manuel GONZALEZ, Jose Luis HERNANDEZ.

Abstract:

In the last decades, a growing industry has been created concerning building envelope retrofits. Linked to the lack of financial capacity of many building owners, innovative instruments such as energy performance contracts have been promoted by public bodies. This kind of instrument requires detailed energy assessment processes to define the expected heat load reduction and the associated economic flows between building owners and Energy Services Companies.

When dealing with building envelopes, existing methods for building envelope heat loss characterization require substantial efforts in terms of equipment and time, which makes it difficult to apply in real practice.

In this paper, a novel method is proposed based on whole-building heat load assessment using heat meters, and analytical calculations of building envelope transmission heat load coefficients. This method, which requires minimal or no additional equipment, can be used over historical data from District Heating systems. It assigns a specific load fraction to the building envelope heat transfer and allows assessing the expected reduction due to the building envelope retrofit. Numerical and experimental data is presented based on an educational building in the city of Burgos, Spain.