Cost- and climate-optimal levels in a multi-objective building energy optimization: The case of a Danish Single-Family House renovation in line with the EPBD
Author
Orsaria, Tomas Emiliano
Term
4. Term
Education
Publication year
2025
Submitted on
2025-01-09
Pages
101
Abstract
The EU Energy Performance of Buildings Directive (EPBD) calls for existing buildings to reach zero emissions by 2050, with Denmark aiming for 2045. Yet many studies focus on reducing primary energy consumption (PEC) and overlook carbon emissions. This thesis introduces a method that evaluates retrofit options by combining three dimensions: energy use, climate impact, and costs. The focus is the building’s thermal envelope—the roof, walls, and windows that keep heat in or out—and the study compares commonly used industry materials with bio-based alternatives. The method is applied to a Danish reference single-family house, calculating energy performance, climate impact, and costs for 10,000 variants of energy-saving measures (ESMs). The aim is to identify cost-optimal and climate-optimal levels and to see whether one solution can perform well on both. The approach makes trade-offs between sometimes conflicting goals explicit and helps reduce them. Results show that retrofits can be both cost- and climate-effective. The best combined cost–climate option achieves 115.5 kWh/m2/year; roof insulation and targeted window upgrades are critical. This solution delivers the largest cost reduction (15%) and cuts carbon emissions by 13%, but the reduction in primary energy consumption is insufficient to meet minimum performance requirements, challenging compliance with nearly Zero-Energy Building (nZEB) standards.
EU’s direktiv om bygningers energimæssige ydeevne (EPBD) kræver, at eksisterende bygninger når nuludledning senest i 2050, mens Danmark sigter mod 2045. Mange studier har dog primært fokuseret på at sænke det primære energiforbrug (PEC) og har ikke vurderet CO2-udledninger. Dette speciale præsenterer en metode, der vurderer renoveringstiltag ved at kombinere tre dimensioner: energiforbrug, klimaaftryk og omkostninger. Fokus er på bygningens klimaskærm – tag, vægge og vinduer – og undersøgelsen sammenligner almindeligt anvendte industrimaterialer og biobaserede alternativer. Metoden afprøves på et dansk reference-enfamiliehus gennem beregninger af energiydelse, klimaeffekt og omkostninger for 10.000 varianter af energisparetiltag (ESMs). Målet er at finde omkostnings- og klimaoptimale niveauer og undersøge, om der findes en løsning, der er god for begge dele. Tilgangen gør afvejninger mellem ofte modstridende mål tydelige og hjælper med at reducere dem. Resultaterne viser, at renoveringer kan være både omkostnings- og klimaeffektive. Den bedste kombinerede omkostnings- og klimaløsning når 115,5 kWh/m2/år, hvor investeringer i tagisolering og målrettede vinduesrenoveringer er afgørende. Løsningen giver den største omkostningsreduktion (15 %) og reducerer CO2-udledningen med 13 %, men faldet i primært energiforbrug er ikke tilstrækkeligt til at opfylde minimumskravene, hvilket udfordrer opnåelsen af nearly Zero Energy Building (nZEB).
[This apstract has been rewritten with the help of AI based on the project's original abstract]
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