Retrofit Pathways for HVAC Decarbonization: A sustainable solution for harnessing ultra-low-grade waste heat for energy efficiency and net-zero buildings
冷暖房脱炭素化のためのレトロフィット経路：超低温廃熱を活用したエネルギー効率とネットゼロビルへの持続可能なソリューション (AI 翻訳)
Asim Muhammad, Muhammad Furqan Siddiqui, F. Siddiqui
🤖 gxceed AI 要約
日本語
本研究は、既存の冷暖房システムに有機ランキンサイクルを組み込むレトロフィット手法を提案。冷媒R1234ze(E)とORC用混合冷媒R365mfc/R152aの組み合わせで、総合COPが3.76%向上し、発電コスト0.061USD/kWh、投資回収期間3.8年、年間7000万トンのCO2削減が可能と示した。
English
This study proposes a retrofit strategy integrating an organic Rankine cycle with conventional HVAC systems for waste heat recovery. The optimal working fluid pair (R1234ze(E) in VCC, R365mfc/R152a in ORC) achieves a 3.76% COP improvement, levelized electricity cost of $0.061/kWh, discounted payback of 3.8 years, and annual CO2 reduction of 70×10⁶ kg/year.
Unofficial AI-generated summary based on the public title and abstract. Not an official translation.
📝 gxceed 編集解説 — Why this matters
日本のGX文脈において
日本の建築物はZEB（ネット・ゼロ・エネルギー・ビル）化が進むが、既存ストックの改修が課題。本手法は超低温廃熱を活用し、エネルギー効率向上と都市ヒートアイランド緩和に貢献する。経済性も示されており、国交省の建築物省エネ基準や補助金制度との親和性が高い。
In the global GX context
Globally, buildings account for a quarter of energy use, with HVAC as a major consumer. This retrofit offers a scalable solution for decarbonizing existing building stock, reducing both operational carbon and urban heat island effects. The clear economic payback (3.8 years) strengthens the business case for retrofits under tightening energy performance standards (e.g., EU EPBD, US building codes).
👥 読者別の含意
🔬研究者:Provides a detailed 4E analysis of ORC-integrated HVAC retrofit, offering a reference for working fluid selection and system optimization.
🏢実務担当者:Demonstrates a technically and economically viable retrofit for building owners to reduce energy costs and carbon footprint, with a clear payback period.
🏛政策担当者:Supports the design of retrofit incentive programs by quantifying both energy savings and emission reductions.
📄 Abstract（原文）
Buildings are responsible for nearly one quarter of global energy consumption, with 30-50% of this demand arising from Heating, Ventilation and Air-Conditioning (HVAC) systems. While essential for ensuring indoor comfort, conventional vapor compression cycle (VCC) units reject a substantial share of ultra-low-grade heat (<80°C) to the urban environment. This not only represents a significant loss of useful energy but also contributes to local temperature rise and intensifies urban heat island effects, thereby driving further cooling demand. In this work, a retrofit-based strategy is proposed to integrate a single-stage organic Rankine cycle (SS-ORC) with the condenser of a conventional VCC system. A novel desuperheating-driven waste heat recovery approach, combined with an Adaptive Pinch Point (APP) method, is used to maximize the recoverable work potential under varying operating conditions. Multiple working fluid (WF) combinations are assessed, including low-GWP fluids (R1233zd (E), R1234ze (E), R1336mzz (Z)) for the VCC and zeotropic mixtures (R600/R600a and R365mfc/R152a) for the ORC. A comprehensive energy, exergy, economic and environmental (4E) analysis is conducted to evaluate the performance and sustainability of the proposed system. Among the tested configurations, coupling R1234ze (E) in the VCC with R365mfc/R152a (0.1/0.9) in the ORC delivered the most favourable outcomes. This pair achieved a 3.76% enhancement in overall COP, and ORC exergy efficiency of 52.5%. From the economic standpoint, the system yielded the lowest levelized cost of electricity (0.061 US$/kWh) with a discounted payback period of only 3.8 years. Environmentally, the retrofit achieved an annual emission reduction of 70×10 6 kg of CO 2 / yr. Beyond technical and economic viability, the integration reduces heat rejection into the urban canopy, indirectly lowering surrounding cooling loads and improving the sustainability of indoor environments. The findings establish the proposed system as an effective and economically feasible retrofit method for enhancing energy efficiency and minimizing the carbon footprint of HVAC systems to support the energy conservation, net-zero transition and the sustainable built environment.
🔗 Provenance — このレコードを発見したソース
- semanticscholar https://doi.org/10.1051/e3sconf/202671604027first seen 2026-06-13 04:57:52
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