When historic buildings are adaptively reused, their operational energy typically rises sharply — in the source case study, a Gaziantep residence converted to a hotel roughly doubled its energy use, dominated by heating, while summer discomfort hours persisted. The open problem is to develop and validate intervention strategies that measurably reduce heating, cooling, and domestic hot water energy, associated carbon emissions, and summer discomfort hours in adaptively reused historic buildings while preserving in-situ historic materials, construction techniques, and tangible and intangible heritage values; and to convert such validated evidence into generalisable retrofit decision guidance that integrates measured occupant thermal-comfort perception alongside modelled comfort indices, replacing today's dominance of single-case simulation studies.

Background

Adaptive reuse — repurposing an existing historic building for a new function rather than demolishing or museum-freezing it — is widely promoted as a sustainability strategy, but it usually introduces mechanical heating, cooling, ventilation, and hot-water systems into envelopes that were never designed for them. The source study (Alasmar, Anaç and Karabeyeser Bakan, Heritage, 2024) documents this quantitatively for a late-Ottoman-period house in Gaziantep, Türkiye (hot climate zone): using DesignBuilder, a front-end for dynamic thermal simulation (hour-by-hour computation of building heat and energy balances under a recorded weather file), they compared the building's original ('restitution') state with its restored state as a four-block hotel. Pre-restoration comfort was assessed with CIBSE TM59, a UK design methodology for assessing overheating risk in naturally ventilated homes based on adaptive comfort models; post-restoration comfort was assessed with the Fanger PMV/PPD model (Predicted Mean Vote and Predicted Percentage Dissatisfied — steady-state comfort indices computed from air temperature, radiant temperature, humidity, air speed, clothing insulation, and metabolic rate, standardised in ASHRAE 55). The analysis found more discomfort hours in summer than winter in both phases (all zones failing TM59 criteria A and B pre-restoration), and a doubling of energy use post-restoration, predominantly for heating plus growth in cooling and DHW (domestic hot water) demand. The difficulty of reversing this is the core tension of the field: energy retrofit of heritage fabric — adding insulation, airtightness, glazing upgrades, or efficient mechanical systems — risks damaging historic materials (e.g., moisture accumulation and interstitial condensation behind internal insulation on hygroscopic stone or brick walls), appearance, and cultural values. Reviews by Martínez-Molina et al. (2016), Webb (2017), and Lidelöw et al. (2019) all document this balancing problem and the scarcity of validated, conservation-compatible solutions; the European standard EN 16883:2017 gives a stepwise procedure for selecting such measures but not the measures themselves or their expected performance. The source paper adds two further observations: retrofit design guidance remains unclear precisely because every heritage structure is unique, and occupants' perceived thermal comfort (which their companion work in Gaziantep shows can diverge from modelled comfort and shapes acceptance of passive strategies) must become an explicit parameter in retrofit appraisal, not an afterthought.

Problem Statement

For historic buildings undergoing adaptive reuse — exemplified and quantified by the Gaziantep case of Alasmar et al. (2024), where conversion from residence to hotel roughly doubled operational energy (dominated by heating), increased cooling and domestic hot water (DHW) demand, and left summer discomfort hours high in both pre- and post-restoration phases — the objective is to develop and validate conservation-compatible intervention strategies and to convert them into generalisable retrofit decision guidance that integrates measured occupant thermal-comfort perception.

  1. Intervention strategies with quantified, substantial reductions. Strategies that deliver simultaneously: (a) reductions in heating, cooling, and DHW energy consumption and in the associated operational carbon emissions that are substantial rather than merely detectable — reported as quantified changes against the pre-retrofit baseline over a stated assessment period, of a magnitude that offsets a meaningful share of the near-doubling of operational energy documented for the source case, and statistically significant where the assessment supports it; (b) reduced summer discomfort hours, assessed with a single, explicit, and justified comfort methodology applied consistently across the pre- and post-intervention cases; and (c) preservation of in-situ historic materials, construction techniques, and tangible and intangible heritage values, documented by a heritage-impact assessment.

  2. Validation beyond the single case. The strategies and the decision guidance are derived from the exemplified case alone and are shown to transfer to at least two held-out buildings that were not used to derive either deliverable and that together span at least two vernacular types and at least two climate zones, assessed by dynamic thermal simulation, by measured performance of the intervened buildings, or by a combination of the two, with the evidence basis stated explicitly.

  3. Generalisable decision guidance. Decision guidance identifying which combinations of passive-strategy retention, selective fabric upgrade, and low-impact mechanical solutions produce robust energy and comfort improvements, asserted only for the vernacular types and climate zones for which transfer is demonstrated under part 2, and stating the limits of that transferability.

  4. Occupant perception as a parameter. Measured occupant thermal-comfort perception (which can diverge from modelled PMV/PPD results and governs acceptance of passive strategies) incorporated as an explicit parameter in the appraisal.

The four parts are jointly needed to answer the question. Evidence must come from empirical measurement or validated simulation, with its basis stated explicitly.

References

  1. Reham Alasmar; Merve Anaç; Merve Karabeyeser Bakan (2024), 'Evaluating the Effect of Adaptive Reuse in the Energy Performance of Historic Buildings: A Case Study from Türkiye', Heritage 7(11):6085–6100, DOI 10.3390/heritage7110285, https://doi.org/10.3390/heritage7110285
  2. Antonio Martínez-Molina; Isabel Tort-Ausina; Soolyeon Cho; José-Luis Vivancos (2016), 'Energy efficiency and thermal comfort in historic buildings: A review', Renewable and Sustainable Energy Reviews 61:70–85, DOI 10.1016/j.rser.2016.03.018, https://doi.org/10.1016/j.rser.2016.03.018
  3. Amanda L. Webb (2017), 'Energy retrofits in historic and traditional buildings: A review of problems and methods', Renewable and Sustainable Energy Reviews 77:748–759, DOI 10.1016/j.rser.2017.01.145, https://doi.org/10.1016/j.rser.2017.01.145
  4. Sofia Lidelöw; Tomas Örn; Andrea Luciani; Agatino Rizzo (2019), 'Energy-efficiency measures for heritage buildings: A literature review', Sustainable Cities and Society 45:231–242, DOI 10.1016/j.scs.2018.09.029, https://doi.org/10.1016/j.scs.2018.09.029
  5. Cem Doğan Şahin; Zeynep Durmuş Arsan; Selim Sarp Tunçoku; Tor Broström; Gülden Gökçen Akkurt (2015), 'A transdisciplinary approach on the energy efficient retrofitting of a historic building in the Aegean Region of Turkey', Energy and Buildings 96:128–139, DOI 10.1016/j.enbuild.2015.03.018, https://doi.org/10.1016/j.enbuild.2015.03.018
  6. Merve Karabeyeser Bakan; Kalliopi Fouseki; Hector Altamirano (2024), 'Investigating the Role of Thermal Comfort Perception on Negotiating Heritage Conservation and Energy Efficiency Decisions through System Dynamics', Buildings 14(6):1800, DOI 10.3390/buildings14061800, https://doi.org/10.3390/buildings14061800
  7. Benito Andreozzi; Mariano Nuzzo; Gianfranco De Matteis; Clementina Donisi; Giovanni Ciampi (2025), 'Energy retrofit of heritage buildings: A literature review on adopted solutions for balancing efficiency and heritage', Journal of Physics: Conference Series 3143:012057, DOI 10.1088/1742-6596/3143/1/012057, https://doi.org/10.1088/1742-6596/3143/1/012057
  8. Hao Huang; Jianfei Dong; Sheng Huang; Yunlong Jin (2026), 'Energy Retrofit in Historic Buildings: Problems, Strategies, and an Evaluation Framework', Buildings 16(10):1939, DOI 10.3390/buildings16101939, https://doi.org/10.3390/buildings16101939
  9. Filiz Karakuş; Ümit Gökhan Çiçek (2026), 'Mechanical and HVAC interventions in the adaptive reuse of historic Khan structures as hotels: a comparative study of Çukur khan and Zincirli Khan', Journal of Asian Architecture and Building Engineering, DOI 10.1080/13467581.2026.2675157, https://doi.org/10.1080/13467581.2026.2675157