Energy Retrofitting Strategies and Economic Assessments: The Case Study of a Residential Complex Using Utility Bills

Cesare Biserni, Paolo Valdiserri, Dario D’Orazio and Massimo Garai
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Cesare Biserni: Department of Industrial Engineering (DIN), School of Engineering and Architecture, Alma Mater Studiorum—University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy
Paolo Valdiserri: Department of Industrial Engineering (DIN), School of Engineering and Architecture, Alma Mater Studiorum—University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy
Dario D’Orazio: Department of Industrial Engineering (DIN), School of Engineering and Architecture, Alma Mater Studiorum—University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy
Massimo Garai: Department of Industrial Engineering (DIN), School of Engineering and Architecture, Alma Mater Studiorum—University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy

Energies, 2018, vol. 11, issue 8, 1-15

Abstract: Promotion of retrofit actions on existing buildings is a goal in Italy, since most of them were built before the 80′s when little attention was paid to energy saving. This paper presents an integrated passive design approach to reduce the heating demand and limit the costs of a representative existing residential complex located in Bologna, in the northern part of Italy. To this purpose, we explored different scenarios upon actions taken on the building structure: (1) High efficiency windows; (2) additional insulation on the external walls; or (3) the simultaneous application of high efficiency windows and improved thermal envelope, on both external walls and roofing. The numerical optimization has been performed dynamically using TRNSYS simulation tool, to evaluate energy consumptions in different structural conditions. Then, the developed model has been calibrated by the real consumption data deduced from energy bills (years 2009–2015). Finally, the energy results obtained in the above mentioned different scenarios have been evaluated under an economic assessment of cost investment: It has been highlighted that the payback time (PBT) results to be strongly influenced by the national policies of fiscal incentives. According to the present model, the most profitable condition is obtained when additional insulation on the external walls is applied: The total amount of energy saving resulted to be equal to 930.4 MWh, with an optimal PBT of roughly six years, when tax refund was contemplated.

Keywords: building envelope; Trnsys simulations; energy consumption and saving; payback time; net present value (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (15)

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