Abstract
When considering that over 80% of buildings in Denmark were built before the 1980′s, a holistic energy retrofitting of the existing building stock is a major milestone to attain the energy and environmental targets of the country. In this work, a case study of three public schools is considered for post-retrofit process evaluation. The three schools were heavily retrofitted by September 2018 with energy conservation and improvement measures that were implemented targeting both the building envelope and various energy systems. A technical evaluation of the energy retrofit process in the schools was carried out, when considering one year of operation after the completion of the retrofitting work. Actual data from the heating and electricity meters in the schools were collected and compared with the pre-retrofit design numbers which rely majorly on static tabulated numbers for savings evaluation. It was shown that the retrofit design numbers largely overestimate the attained savings, where the average performance gap between the expected and real numbers for the three schools is around 61% and 136% for annual heating and electricity savings, respectively. On the other hand, an alternative approach was proposed where calibrated dynamic energy performance models, which were developed for the three schools in EnergyPlus, were used to simulate the impact of implementing the retrofit measures. It was shown that implementing this approach could predict much better the impacts of the retrofit process with an average gap of around 17% for heating savings and 21% for electricity savings. Based on the post-retrofit process evaluation in the three schools, it was concluded that using dynamic model simulations has the potential of lowering the performance gap between the promised and real savings when compared to static tabulated approaches, although the savings are still generally over-estimated in both approaches.
Highlights
A case study of three public schools is considered for post-retrofit process evaluation and assessment
While the tool is very effective in assessing whether the building complies with the building standards regarding building envelope and energy consumption, it fails to capture the impact of dynamic changes and boundary conditions on the building performance
Dynamic Model Simulations: These are the predictions of a dynamic building energy model reporting the results of the retrofit measures technical impacts
Summary
Huge efforts have been devoted by EU member states to improve the overall energy performance of buildings, and the 2002 and 2010. EU Energy Performance of Building Directive [4] set strict requirements for enhancing the buildings energy efficiency. It was highlighted that around 30% energy savings potential could be achieved in states to improve the overall energy performance of buildings, and the 2002 and 2010 EU Energy. Performance of Building Directive [4] set strict energy requirements for enhancing the buildings energy aiming to efficiency.energy. Directive 2018/844 [5] of the EU Parliament has set strict requirements regarding installing and building energy management and optimizing the operation of building systems, the EU Directive assessing Building. Breakdown of the worldwide final consumption by sectorby [1].sector [1]
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