Exploring the thermal demand response potential of English households using electric heating systems

The widespread deployment of renewable energy technologies to address the climate crisis has introduced challenges related to energy supply intermittency. To mitigate these issues, significant efforts have focused on enhancing energy system flexibility through demand-side management (DSM), which involves engaging consumers – domestic, commercial, or industrial – to adjust their demand patterns in response to grid needs. Amongst numerous domestic flexibility options, the thermal demand response (TDR) potential of dwellings remains under-explored. Due to the relatively heavyweight construction of English homes (using brick/block construction), occupants can temporarily reduce heating demand without compromising comfort, offering a valuable yet underutilised source of energy flexibility. This topic requires significant and robust exploration to better understand the role that domestic dwelling’s TDR potential can play in wider DSM services.

This research aims to identify and quantify the factors influencing TDR potential in English dwellings. To achieve this, dynamic building energy modelling was employed to simulate complex interactions between the building and energy system in response to TDR events. The first phase of the research established Spawn of EnergyPlus (Spawn) – a co-simulation platform integrating Modelica and EnergyPlus – as a suitable modelling tool. It was validated against other established simulation tools using a comparative testing method called the Building Energy Simulation Test (BESTEST). The validation demonstrated that Spawn achieves accuracy comparable to established tools, with minimal deviation from EnergyPlus. The choice of case study models highlighted the crucial role of thermal mass in moderating indoor temperatures – a key enabler of TDR.

Literature identified several key factors of energy flexibility, but with limited understanding of their relative, quantitative, significance, particularly in the context of TDR. The second phase of research used a local sensitivity analysis to provide a side-by-side comparison of the key factors by quantifying their contribution to TDR potential across multiple metrics. The analysis found that the local variation of occupant behaviours, like heating patterns and temperature setpoints, is much more dominant than other factors like building characteristics or system operation – consistently accounting for over 50% of the total sensitivity in each case study scenario.

The third and final research phase explored the natural variation of English households (building characteristics and occupant behaviours), by simulating the impacts of potential future policy direction on fabric thermal performance. The findings indicate that when considering more realistic variations of parameter inputs, building characteristics (in particular thermal resistivity and air tightness) are more dominant than occupant behaviours. The findings also present a dichotomy by improving fabric thermal performance of dwellings: lower-energy dwellings can engage in TDR for longer and shift more energy (in relative terms), but at the expense of reduced absolute energy shifting and response power – necessitating more households to participate in a service to achieve a system-level impact.

The research has identified, quantified and demonstrated the varying impacts of key factors of TDR across multiple flexibility metrics – showing that building characteristics are the key driving factor in English dwellings’ TDR potential. Therefore, concluding that a balanced and targeted policy approach should be considered for different households: Fabric upgrades should be prioritised for households who need it most (i.e., those in fuel poverty), whilst flexibility programmes may be better targeted to incentivise higher-capital households with potentially poorer fabric, but may be more likely to effectively engage in flexibility services. The rebound effects from these larger dwellings, however, still requires more study. Further, by utilising compound flexibility metrics to assess TDR potential, multiple stakeholder objectives can be balanced and aligned. These findings will be of value to all stakeholders across the energy system as it provides a better understanding of TDR potential and the role of English households in the future flexible energy system. This research, therefore, provides additional work towards better understanding the role that TDR can play in broader energy flexibility services, whilst also providing deeper insights for businesses and policymakers to comprehend the ensuing impacts of building energy policy on the English domestic built environment.