The building sector is currently responsible for approximately 40% of global energy-related CO₂ emissions. While existing literature extensively covers heat generation technologies, a significant research gap remains regarding the environmental impacts of emission and distribution networks. This research investigates the life-cycle environmental performance of three residential heating system configurations, Radiators, Radiant Floors, and Fan-coils, within a residential case study in Milan, Italy. Using a 50-year Reference Study Period, the study employs a dual-methodological approach: dynamic energy modeling via IESVE software and a comprehensive Life Cycle Assessment using SimaPro and the Ecoinvent database. The methodology follows the ISO 14040/14044 framework, utilizing a Functional Unit of 1 kWh of delivered thermal energy. The scope encompasses the full life cycle, including the product stage (A1–A3), replacement (B4), operational energy (B6), end-of-life (C3–C4), and benefits beyond the system boundary (Module D). Energy modeling results indicate that the Radiant Floor system achieves the highest seasonal boiler efficiency (95–96%) and superior thermal comfort due to lower operating temperatures (25–30°C), whereas the Fan-coil system exhibits the highest auxiliary electrical consumption. The Radiator system, operating at higher temperatures (50–60°C), shows lower efficiency (88–92%) and higher natural gas consumption, along with more intermittent operation and slightly reduced thermal comfort stability compared to the radiant floor system. The Life Cycle Impact Assessment results identify operational energy (Module B6) as the dominant environmental hotspot, contributing over 90% to Climate Change and Fossil Resource Use. However, for categories such as Mineral and Metal Resource Use and Freshwater Eutrophication, the product (A1–A3) and replacement (B4) modules are the primary drivers, collectively accounting for up to 86% of impacts in complex systems like Fan-coils. Notably, components such as brass valves can represent 36% of a system’s embodied impact despite accounting for only 2% of its total mass. The analysis of Module D highlights the critical role of the "avoided burden" approach; recycling high-value metals (steel, copper, and aluminum) offsets over 70% of mineral resource depletion across all systems. Overall, the Radiant Floor system emerged as the most sustainable configuration in nearly all categories. This research demonstrates that as buildings become more energy-efficient, the material intensity of technical systems, which can contribute up to 20% of total life-cycle impacts, can no longer be ignored. The findings provide building designers and engineers with essential data to prevent "burden shifting" and support informed decision-making in the pursuit of truly low-carbon residential architecture.
Il settore edilizio è attualmente responsabile di circa il 40% delle emissioni globali di CO2 legate all'energia. Sebbene la letteratura esistente tratti ampiamente le tecnologie di generazione del calore, permane una significativa lacuna nella ricerca riguardo agli impatti ambientali delle reti di emissione e distribuzione. La presente ricerca analizza le prestazioni ambientali nel ciclo di vita di tre configurazioni di impianti di riscaldamento residenziale, Radiatori, Pavimenti Radianti e Fan-coil, nell'ambito di un caso studio residenziale a Milano, Italia. Adottando un Periodo di Studio di Riferimento di 50 anni, lo studio applica un approccio metodologico duale: la modellazione energetica dinamica tramite il software IESVE e una Life Cycle Assessment (LCA) completa utilizzando SimaPro e il database Ecoinvent. La metodologia segue il framework ISO 14040/14044, adottando come Unità Funzionale 1 kWh di energia termica fornita. L'ambito comprende l'intero ciclo di vita, inclusa la fase di prodotto (A1–A3), la sostituzione (B4), l'energia operativa (B6), il fine vita (C3–C4) e i benefici oltre il confine del sistema (Modulo D). I risultati della modellazione energetica indicano che il sistema a Pavimento Radiante raggiunge la più alta efficienza stagionale della caldaia (95–96%) e un comfort termico superiore grazie alle basse temperature di esercizio (25–30°C), mentre il sistema a Fan-coil presenta il maggiore consumo elettrico ausiliario. Il sistema a Radiatori, operando a temperature più elevate (50–60°C), mostra un'efficienza inferiore (88–92%) e un maggiore consumo di gas naturale, unitamente a un funzionamento più intermittente e una stabilità del comfort termico leggermente ridotta rispetto al sistema a pavimento radiante. I risultati della Life Cycle Impact Assessment identificano l'energia operativa (Modulo B6) come il principale hotspot ambientale, contribuendo per oltre il 90% alle categorie Cambiamento Climatico e Uso delle Risorse Fossili. Tuttavia, per categorie quali l'Uso di Risorse Minerali e Metalliche e l'Eutrofizzazione delle Acque Dolci, i moduli di prodotto (A1–A3) e sostituzione (B4) sono i principali responsabili, contribuendo collettivamente fino all'86% degli impatti in sistemi complessi come i Fan-coil. In particolare, componenti come le valvole in ottone possono rappresentare il 36% dell'impatto incorporato di un sistema pur costituendo solo il 2% della sua massa totale. L'analisi del Modulo D evidenzia il ruolo fondamentale dell'approccio "avoided burden"; il riciclo di metalli ad alto valore (acciaio, rame e alluminio) compensa oltre il 70% dell'esaurimento delle risorse minerali in tutti i sistemi. Nel complesso, il sistema a Pavimento Radiante si è affermato come la configurazione più sostenibile in quasi tutte le categorie. La ricerca dimostra che, man mano che gli edifici diventano più efficienti dal punto di vista energetico, l'intensità materiale dei sistemi tecnici — che può contribuire fino al 20% degli impatti totali del ciclo di vita — non può più essere ignorata. I risultati forniscono ai progettisti e agli ingegneri edili dati essenziali per prevenire il "burden shifting" e supportare decisioni informate nel perseguimento di un'architettura residenziale realmente a basse emissioni di carbonio.
Assessing environmental burdens of heat emission and distribution systems in a residential building
NASIRIBAVILI, MAHSA
2025/2026
Abstract
The building sector is currently responsible for approximately 40% of global energy-related CO₂ emissions. While existing literature extensively covers heat generation technologies, a significant research gap remains regarding the environmental impacts of emission and distribution networks. This research investigates the life-cycle environmental performance of three residential heating system configurations, Radiators, Radiant Floors, and Fan-coils, within a residential case study in Milan, Italy. Using a 50-year Reference Study Period, the study employs a dual-methodological approach: dynamic energy modeling via IESVE software and a comprehensive Life Cycle Assessment using SimaPro and the Ecoinvent database. The methodology follows the ISO 14040/14044 framework, utilizing a Functional Unit of 1 kWh of delivered thermal energy. The scope encompasses the full life cycle, including the product stage (A1–A3), replacement (B4), operational energy (B6), end-of-life (C3–C4), and benefits beyond the system boundary (Module D). Energy modeling results indicate that the Radiant Floor system achieves the highest seasonal boiler efficiency (95–96%) and superior thermal comfort due to lower operating temperatures (25–30°C), whereas the Fan-coil system exhibits the highest auxiliary electrical consumption. The Radiator system, operating at higher temperatures (50–60°C), shows lower efficiency (88–92%) and higher natural gas consumption, along with more intermittent operation and slightly reduced thermal comfort stability compared to the radiant floor system. The Life Cycle Impact Assessment results identify operational energy (Module B6) as the dominant environmental hotspot, contributing over 90% to Climate Change and Fossil Resource Use. However, for categories such as Mineral and Metal Resource Use and Freshwater Eutrophication, the product (A1–A3) and replacement (B4) modules are the primary drivers, collectively accounting for up to 86% of impacts in complex systems like Fan-coils. Notably, components such as brass valves can represent 36% of a system’s embodied impact despite accounting for only 2% of its total mass. The analysis of Module D highlights the critical role of the "avoided burden" approach; recycling high-value metals (steel, copper, and aluminum) offsets over 70% of mineral resource depletion across all systems. Overall, the Radiant Floor system emerged as the most sustainable configuration in nearly all categories. This research demonstrates that as buildings become more energy-efficient, the material intensity of technical systems, which can contribute up to 20% of total life-cycle impacts, can no longer be ignored. The findings provide building designers and engineers with essential data to prevent "burden shifting" and support informed decision-making in the pursuit of truly low-carbon residential architecture.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/259259