P. Wahi
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Preparing for lower-temperature heating
A multi-criteria decision-making framework for energy renovations of existing Dutch dwellings
Journal article
(2026)
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Prateek Wahi, Vera Koster, Martin J. Tenpierik, Henk Visscher, Thaleia Konstantinou
Transitioning existing dwellings to lower temperature heating (LTH) is crucial for achieving the Dutch goal of making 1.5 million homes gas-free (i.e., independent of natural gas-based heating) by 2030. This transition often necessitates energy renovations, which present significant decision-making challenges in selecting appropriate solutions. Consequently, this study introduces a systematic framework based on multi-criteria decision-making (MCDM) approach to support selecting suitable renovation options for preparing Dutch dwellings for LTH supplied by sustainable heating systems. The framework is methodically developed by generalising typical steps from existing literature and identifying essential decision-making aspects for framework development. It was then theoretically tailored to the specific context of LTH-ready renovations. The framework involves six steps: data collection and benchmarking, evaluating LTH readiness, establishing decision-making preferences and generating renovation solutions, filtering LTH feasible options, quantifying their performance, and ranking them using the TOPSIS method. Furthermore, the theoretical framework was applied to a case study of a multi-family social house (MFH) in the Netherlands to demonstrate its practical usability and to incorporate real-world context in decision-making. While the framework's applicability has been validated for this specific case, further application across different contexts is necessary to generalise its usability. The proposed framework comprehensively evaluates renovation solutions needed to transition to LTH based on environmental, economic, and social criteria, thereby addressing energy poverty and occupant comfort concerns. This supports stakeholders in making informed decisions and accelerating energy renovations for a decarbonised built environment.
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Transitioning existing dwellings to lower temperature heating (LTH) is crucial for achieving the Dutch goal of making 1.5 million homes gas-free (i.e., independent of natural gas-based heating) by 2030. This transition often necessitates energy renovations, which present significant decision-making challenges in selecting appropriate solutions. Consequently, this study introduces a systematic framework based on multi-criteria decision-making (MCDM) approach to support selecting suitable renovation options for preparing Dutch dwellings for LTH supplied by sustainable heating systems. The framework is methodically developed by generalising typical steps from existing literature and identifying essential decision-making aspects for framework development. It was then theoretically tailored to the specific context of LTH-ready renovations. The framework involves six steps: data collection and benchmarking, evaluating LTH readiness, establishing decision-making preferences and generating renovation solutions, filtering LTH feasible options, quantifying their performance, and ranking them using the TOPSIS method. Furthermore, the theoretical framework was applied to a case study of a multi-family social house (MFH) in the Netherlands to demonstrate its practical usability and to incorporate real-world context in decision-making. While the framework's applicability has been validated for this specific case, further application across different contexts is necessary to generalise its usability. The proposed framework comprehensively evaluates renovation solutions needed to transition to LTH based on environmental, economic, and social criteria, thereby addressing energy poverty and occupant comfort concerns. This supports stakeholders in making informed decisions and accelerating energy renovations for a decarbonised built environment.
Preparing Dutch Homes for Energy Transition
A Decision Support Framework for Renovating Existing Dutch Dwellings for Lower Temperature District Heating
Recent geopolitical events have driven a sharp rise in gas prices, making it increasingly difficult for households to heat their homes affordably and comfortably. Additionally, the environmental consequences of fossil fuel-based heating underscore the urgency of transitioning to more sustainable alternatives. In response, the Dutch government has set an ambitious target to eliminate natural gas heating in 1.5 million homes by 2030, emphasising the need for viable solutions. District heating (DH) systems, particularly those providing lower-temperature heating (LTH), offer a promising alternative—delivering sustainable and cost-effective heating, especially in densely populated areas. However, with their high heating demands, many existing homes require significant renovations before efficiently transitioning to LTH-based systems. The selection of appropriate renovation strategies is complex, often leading to uncertainty and delays. This research tackles the challenge of preparing Dutch homes for LTH by developing a systematic decision-support framework using a mixed-methods research approach. It is structured around four key research activities. First, it identifies and analyses the critical factors influencing building characteristics, available renovation options and performance indicators. Second, it defines LTH readiness, prioritises thermal comfort and energy efficiency at reduced supply temperatures, and uses a two-step evaluation method to assess a dwelling's readiness and identify necessary interventions. Third, recognising the diversity within the Dutch housing stock, probabilistic sampling and machine learning analyses were employed to quantify the relative significance of building features affecting LTH readiness, accounting for variations across dwelling types. Finally, a structured six-step decision support framework based on multi-criteria decision-making (MCDM) methods was developed and validated through real-world case studies and stakeholder workshops. By providing a clear and actionable decision-support framework, this thesis facilitates energy renovation planning, accelerates the transition to gas-free heating, and contributes to the Netherlands' broader sustainable energy goals.
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Recent geopolitical events have driven a sharp rise in gas prices, making it increasingly difficult for households to heat their homes affordably and comfortably. Additionally, the environmental consequences of fossil fuel-based heating underscore the urgency of transitioning to more sustainable alternatives. In response, the Dutch government has set an ambitious target to eliminate natural gas heating in 1.5 million homes by 2030, emphasising the need for viable solutions. District heating (DH) systems, particularly those providing lower-temperature heating (LTH), offer a promising alternative—delivering sustainable and cost-effective heating, especially in densely populated areas. However, with their high heating demands, many existing homes require significant renovations before efficiently transitioning to LTH-based systems. The selection of appropriate renovation strategies is complex, often leading to uncertainty and delays. This research tackles the challenge of preparing Dutch homes for LTH by developing a systematic decision-support framework using a mixed-methods research approach. It is structured around four key research activities. First, it identifies and analyses the critical factors influencing building characteristics, available renovation options and performance indicators. Second, it defines LTH readiness, prioritises thermal comfort and energy efficiency at reduced supply temperatures, and uses a two-step evaluation method to assess a dwelling's readiness and identify necessary interventions. Third, recognising the diversity within the Dutch housing stock, probabilistic sampling and machine learning analyses were employed to quantify the relative significance of building features affecting LTH readiness, accounting for variations across dwelling types. Finally, a structured six-step decision support framework based on multi-criteria decision-making (MCDM) methods was developed and validated through real-world case studies and stakeholder workshops. By providing a clear and actionable decision-support framework, this thesis facilitates energy renovation planning, accelerates the transition to gas-free heating, and contributes to the Netherlands' broader sustainable energy goals.
Towards Lower Temperature Heating
A framework to support decision-making for energy renovations of existing Dutch dwellings
This study introduces a systematic framework to facilitate decision-making in selecting renovation options for preparing existing Dutch dwellings for utilising lower temperature heat (LTH) supplied by district heating (DH) systems. The framework was applied to an archetype terraced intermediate house built between 1945 and 1975 to identify the renovation options required for transitioning from existing High-Temperature (90/70℃) supply from gas-boilers to Medium Temperature (70/50℃) supply from DH systems. The framework's effectiveness was demonstrated by systematically assessing the readiness of the archetype dwelling for LTH use, reducing the number of viable renovation options, evaluating the financial feasibility using a life cycle costing approach and generating decision support insights through comparative analysis. The framework identified an optimised solution involving cavity wall insulation, exhaust ventilation and switching to low-temperature radiators. This solution incurs low initial investment and global costs while significantly reducing space heating and underheated hours. As a result, the framework provides tangible solutions for the specific use case and can serve as a valuable tool for dialogue among stakeholders during the decision-making process.
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This study introduces a systematic framework to facilitate decision-making in selecting renovation options for preparing existing Dutch dwellings for utilising lower temperature heat (LTH) supplied by district heating (DH) systems. The framework was applied to an archetype terraced intermediate house built between 1945 and 1975 to identify the renovation options required for transitioning from existing High-Temperature (90/70℃) supply from gas-boilers to Medium Temperature (70/50℃) supply from DH systems. The framework's effectiveness was demonstrated by systematically assessing the readiness of the archetype dwelling for LTH use, reducing the number of viable renovation options, evaluating the financial feasibility using a life cycle costing approach and generating decision support insights through comparative analysis. The framework identified an optimised solution involving cavity wall insulation, exhaust ventilation and switching to low-temperature radiators. This solution incurs low initial investment and global costs while significantly reducing space heating and underheated hours. As a result, the framework provides tangible solutions for the specific use case and can serve as a valuable tool for dialogue among stakeholders during the decision-making process.
Evaluating building-level parameters for lower-temperature heating readiness
A sampling-based approach to addressing the heterogeneity of Dutch housing stock
The Dutch government aims to eliminate natural gas for residential heating in 1.5 million homes by 2030. One strategy is connecting existing dwellings to lower-temperature district heating (DH) systems, although these dwellings might require energy renovations. The heterogeneous dwelling stock causes varying renovation needs that complicate the energy transition. The present study addresses this issue by assessing the building-level parameters affecting the readiness of the Dutch terraced-intermediate and apartment types for lower-temperature heating (LTH) supplied by DH systems. A sampling-based approach was employed to capture variability within these dwelling types, addressing the limitations of archetype-based methods. The findings suggest a sample size of 1300 to represent the variations in these dwelling types. Parametric simulations and machine learning methods were used to identify significant building-level parameters for medium-temperature (MT: 70/50 °C) and low-temperature (LT: 55/35 °C) supply levels. These include heating setpoints (desired indoor temperature) and ventilation-related parameters (ventilation system type and air infiltration rate), followed by fabric-related parameters (roof, glazing, wall, ground, and door insulation) and geometric properties (orientation, compactness ratio, and window-to-wall ratio). Additionally, radiator oversizing also impacts LTH readiness. These results broadly apply to the studied dwelling types, although feature importance varies by supply temperature and dwelling type. The findings can guide stakeholders in assessing current conditions and prioritising renovation measures, aiding the development of targeted renovation solutions. Encompassing the representative variations within studied dwelling types enhances the robustness of the results. However, incorporating more refined data could improve the accuracy of the findings, better supporting the energy transition of these dwellings.
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The Dutch government aims to eliminate natural gas for residential heating in 1.5 million homes by 2030. One strategy is connecting existing dwellings to lower-temperature district heating (DH) systems, although these dwellings might require energy renovations. The heterogeneous dwelling stock causes varying renovation needs that complicate the energy transition. The present study addresses this issue by assessing the building-level parameters affecting the readiness of the Dutch terraced-intermediate and apartment types for lower-temperature heating (LTH) supplied by DH systems. A sampling-based approach was employed to capture variability within these dwelling types, addressing the limitations of archetype-based methods. The findings suggest a sample size of 1300 to represent the variations in these dwelling types. Parametric simulations and machine learning methods were used to identify significant building-level parameters for medium-temperature (MT: 70/50 °C) and low-temperature (LT: 55/35 °C) supply levels. These include heating setpoints (desired indoor temperature) and ventilation-related parameters (ventilation system type and air infiltration rate), followed by fabric-related parameters (roof, glazing, wall, ground, and door insulation) and geometric properties (orientation, compactness ratio, and window-to-wall ratio). Additionally, radiator oversizing also impacts LTH readiness. These results broadly apply to the studied dwelling types, although feature importance varies by supply temperature and dwelling type. The findings can guide stakeholders in assessing current conditions and prioritising renovation measures, aiding the development of targeted renovation solutions. Encompassing the representative variations within studied dwelling types enhances the robustness of the results. However, incorporating more refined data could improve the accuracy of the findings, better supporting the energy transition of these dwellings.
Lower temperature heating integration in the residential building stock:
A review of decision-making parameters for lower-temperature-ready energy renovations
Lower temperature heating (LTH) involves using the lowest possible supply temperatures to meet residential heating demands, thus supporting the integration of sustainable heating sources and decarbonising the existing residential stock. However, choosing appropriate energy renovation options to prepare existing dwellings for LTH presents decision-making challenges due to the heterogenous dwelling stock with varying building characteristics, numerous renovation options, and various performance indicators for evaluating trade-offs. This study aims to review the scientific literature on integrating LTH into existing dwellings to identify the building characteristics for evaluating the potential of using LTH and the necessity for renovations, presents a systematic method for organising renovation options and summarises key performance indicators. The study employed the SALSA (search, appraisal, synthesis and analysis) framework for systematic review and identified 24 scientific publications. Findings show that dwelling characteristics such as compactness ratio, thermal insulation, thermal bridges, airtightness, ventilation systems, space heating system capacity and supply temperature level are essential for investigating LTH potential and the need for renovations. Most research lacks qualitative renovation criteria and product-level information for selecting renovation options. Key performance indicators related to energy efficiency, thermal comfort and quality-of-services can help indicate the possible solutions, while those related to environmental and economic performance indicate the feasibility of possible solutions. Nevertheless, there is a lack of standard set of criteria for indicating the dwelling's readiness for using LTH. These findings can help address the decision-making challenges of selecting appropriate renovation strategies to enable the use of LTH and contribute to decarbonising the built environment.
...
Lower temperature heating (LTH) involves using the lowest possible supply temperatures to meet residential heating demands, thus supporting the integration of sustainable heating sources and decarbonising the existing residential stock. However, choosing appropriate energy renovation options to prepare existing dwellings for LTH presents decision-making challenges due to the heterogenous dwelling stock with varying building characteristics, numerous renovation options, and various performance indicators for evaluating trade-offs. This study aims to review the scientific literature on integrating LTH into existing dwellings to identify the building characteristics for evaluating the potential of using LTH and the necessity for renovations, presents a systematic method for organising renovation options and summarises key performance indicators. The study employed the SALSA (search, appraisal, synthesis and analysis) framework for systematic review and identified 24 scientific publications. Findings show that dwelling characteristics such as compactness ratio, thermal insulation, thermal bridges, airtightness, ventilation systems, space heating system capacity and supply temperature level are essential for investigating LTH potential and the need for renovations. Most research lacks qualitative renovation criteria and product-level information for selecting renovation options. Key performance indicators related to energy efficiency, thermal comfort and quality-of-services can help indicate the possible solutions, while those related to environmental and economic performance indicate the feasibility of possible solutions. Nevertheless, there is a lack of standard set of criteria for indicating the dwelling's readiness for using LTH. These findings can help address the decision-making challenges of selecting appropriate renovation strategies to enable the use of LTH and contribute to decarbonising the built environment.
Lower-Temperature-Ready Renovation:
An Approach to Identify the Extent of Renovation Interventions for Lower-Temperature District Heating in Existing Dutch Homes
This study presents an approach to determine the extent of renovation interventions required for existing Dutch dwellings aiming to transition to lower-temperature district heating (DH) systems. The proposed method is applied to a typical intermediate terraced house built before 1945 in the Netherlands, and it consists of two steps: first, assessing the potential of a dwelling to be heated with a lower temperature supply from DH systems and subsequently developing and evaluating alternative renovation solutions if necessary. This study defines a set of criteria for evaluating the readiness of a dwelling for lower-temperature heating (LTH), considering energy efficiency and thermal comfort as non-compensatory criteria. The application of the approach reveals that the case study dwelling is presently unsuitable for a medium-temperature (70/50 °C) and low-temperature (55/35 °C) supply compared to a high-temperature supply (90/70 °C), thus requiring energy renovations. Furthermore, this study indicates that moderate intervention levels are required for the dwelling to be lower-temperature-ready in both supply temperature goals. These interventions include strategies and measures that upgrade the building envelope to the minimum insulation levels stipulated by the Dutch Building Decree, improve airtightness, and replace existing radiators with low-temperature radiators. By systematically narrowing down renovation options, this approach aids in simplifying the decision-making process for selecting renovations for heating dwellings with LTH through DH systems, which could reduce stakeholders’ decision paralysis.
...
This study presents an approach to determine the extent of renovation interventions required for existing Dutch dwellings aiming to transition to lower-temperature district heating (DH) systems. The proposed method is applied to a typical intermediate terraced house built before 1945 in the Netherlands, and it consists of two steps: first, assessing the potential of a dwelling to be heated with a lower temperature supply from DH systems and subsequently developing and evaluating alternative renovation solutions if necessary. This study defines a set of criteria for evaluating the readiness of a dwelling for lower-temperature heating (LTH), considering energy efficiency and thermal comfort as non-compensatory criteria. The application of the approach reveals that the case study dwelling is presently unsuitable for a medium-temperature (70/50 °C) and low-temperature (55/35 °C) supply compared to a high-temperature supply (90/70 °C), thus requiring energy renovations. Furthermore, this study indicates that moderate intervention levels are required for the dwelling to be lower-temperature-ready in both supply temperature goals. These interventions include strategies and measures that upgrade the building envelope to the minimum insulation levels stipulated by the Dutch Building Decree, improve airtightness, and replace existing radiators with low-temperature radiators. By systematically narrowing down renovation options, this approach aids in simplifying the decision-making process for selecting renovations for heating dwellings with LTH through DH systems, which could reduce stakeholders’ decision paralysis.
Energy-efficient buildings tend to cause thermal discomfort due to overheating during summers. With the advent of climate change and increasing outdoor temperatures, the risk of overheating will be exacerbated. Henceforth, the building design must be future proof or robust for climate change. Passive design strategies applied to the building envelope are crucial in reducing the energy demand and provide thermal comfort. However, it is essential to determine their performance in the presence of climate uncertainties, especially in the early design stage. Therefore, the paper illustrates an assessment method for investigating the robustness of the building envelope in curbing the risk of overheating in future climate change scenarios of 2050 and 2085. The study focused on educational buildings as thermal discomfort due to overheating affects students' productivity. The study analysed the performance of different passive design strategies applicable at building envelope in reducing overheating risk and evaluated the robustness using the statistical method of “best-case and worst-case scenario”. The robustness assessment method found fixed or dynamic shading, reduced window to wall ratios, albedo effect of the building envelope, and mixed-mode ventilation strategy with P.C.M. panels as the most robust design solutions. However, ventilative cooling would have limited application towards the latter part of the century
...
Energy-efficient buildings tend to cause thermal discomfort due to overheating during summers. With the advent of climate change and increasing outdoor temperatures, the risk of overheating will be exacerbated. Henceforth, the building design must be future proof or robust for climate change. Passive design strategies applied to the building envelope are crucial in reducing the energy demand and provide thermal comfort. However, it is essential to determine their performance in the presence of climate uncertainties, especially in the early design stage. Therefore, the paper illustrates an assessment method for investigating the robustness of the building envelope in curbing the risk of overheating in future climate change scenarios of 2050 and 2085. The study focused on educational buildings as thermal discomfort due to overheating affects students' productivity. The study analysed the performance of different passive design strategies applicable at building envelope in reducing overheating risk and evaluated the robustness using the statistical method of “best-case and worst-case scenario”. The robustness assessment method found fixed or dynamic shading, reduced window to wall ratios, albedo effect of the building envelope, and mixed-mode ventilation strategy with P.C.M. panels as the most robust design solutions. However, ventilative cooling would have limited application towards the latter part of the century
In the Netherlands, district heating with a lower temperature supply (<70°C) will play a crucial part in accomplishing the energy transition goals of delivering natural gas-free sustainable heating to dwellings. The existing dwellings often require energy renovations to make them suitable for lower temperature heating. However, choosing renovation strategies that promote the transition to lower temperature district heating while improving energy efficiency and thermal comfort is challenging. This study aims to identify minimum renovation requirements for comfortably heating homes using lower temperature heat from district heating. Identifying minimum renovation strategies to prepare existing dwellings for lower temperature district heating would be vital in addressing the European Renovation Wave's target of improving worst-performing buildings. For the same, the study uses a typical intermediate terraced house built before 1945 as a case study to investigate renovation strategies based on four levels of renovation intervention (no renovation, basic, moderate and deep). The impact of renovations on space heating demand and thermal comfort was tested with medium (70/50°C) and low supply (55/35°C) temperatures against key performance indicators (KPIs) using dynamic simulation. The study found that for the case study dwelling, moderate renovation strategy of upgrading the building envelope insulation by 0.40 W/m2K for opaque parts and 1.5 W/m2K for glazing, improving the airtightness by 0.3h-1 and replacing existing radiators with LT radiators can be considered as a no-regret solution for comfortably heating homes with both medium and lower temperature supply from district heating.
...
In the Netherlands, district heating with a lower temperature supply (<70°C) will play a crucial part in accomplishing the energy transition goals of delivering natural gas-free sustainable heating to dwellings. The existing dwellings often require energy renovations to make them suitable for lower temperature heating. However, choosing renovation strategies that promote the transition to lower temperature district heating while improving energy efficiency and thermal comfort is challenging. This study aims to identify minimum renovation requirements for comfortably heating homes using lower temperature heat from district heating. Identifying minimum renovation strategies to prepare existing dwellings for lower temperature district heating would be vital in addressing the European Renovation Wave's target of improving worst-performing buildings. For the same, the study uses a typical intermediate terraced house built before 1945 as a case study to investigate renovation strategies based on four levels of renovation intervention (no renovation, basic, moderate and deep). The impact of renovations on space heating demand and thermal comfort was tested with medium (70/50°C) and low supply (55/35°C) temperatures against key performance indicators (KPIs) using dynamic simulation. The study found that for the case study dwelling, moderate renovation strategy of upgrading the building envelope insulation by 0.40 W/m2K for opaque parts and 1.5 W/m2K for glazing, improving the airtightness by 0.3h-1 and replacing existing radiators with LT radiators can be considered as a no-regret solution for comfortably heating homes with both medium and lower temperature supply from district heating.