Abstract
The focus on energy conservation in buildings is increasing. Despite that, the yearly building renovation rate is only at around 1 %. To increase the renovation rate, new and time-efficient methods used for screening of large building portfolios’ energy saving potential are needed. In this paper, a re-engineered take on the classical energy signature method is applied to two renovated apartments in Denmark. The energy signature model relies on time-series measurements of space heat consumption, outdoor temperature, solar irradiation, and wind speed. The estimates obtained from it consist of—among other things—heat loss coefficient and wind-induced heat loss. This paper focuses on the latter. To validate the model estimate, the airtightness has been quantified by blower door-tests in both apartments: the results showed that one apartment is reasonable airtight, while the other suffers from significant air leakages. The energy signature and two other infiltration models, based on blower door test results, were compared. Good agreement between the results obtained from the data-driven energy signature and the blower door test were found. With use of a simple linear relation between the average infiltration and the blower door test result (q50), from the Danish national building code, the energy signature was found to overestimate the blower door test result (q50) by 33 % for the leaky apartment and underestimate the same air flow by 18 % for the other apartment. Both estimates are within the standard error of the infiltration model in the Danish national building code.
Highlights
The energy efficiency directive (EED) of the European Union (EU) [1] requires all member states to install individual energy meters on all buildings to the extent that it is technically possible and economically feasible by January 1, 2027.the building stock accounts for 40 % of the total energy end-use in the EU [2], and the heating energy in households alone accounts for 16 % [3].With the combination of increasing collections of building energy consumption data and the significant energy use in buildings, it is clear that scalable and datadriven methods for building energy efficiency screenings are more relevant than ever and fundamental to understand where to act first
It is seen that the distribution of the daily air infiltration flows obtained from the AIM-2 model and the energy signature model are different in three distinct ways
The study has demonstrated the differences between three models used for estimating the building leakage on two deeply refurbished apartments in Aalborg, Denmark
Summary
With the combination of increasing collections of building energy consumption data and the significant energy use in buildings, it is clear that scalable and datadriven methods for building energy efficiency screenings are more relevant than ever and fundamental to understand where to act first. A significant part of the heat loss through the envelope is, not necessarily related to heat transfer such as conduction, convection, and radiation through the constructions, but rather air leakages in the building envelope. This is typically referred to as ex- and infiltration, or infiltration
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