Targeting Complex-to-Decarbonise Homes in Social Housing.
Achieving net-zero emissions by 2050 is a formidable challenge for the UK, especially given the high contribution of the housing sector to greenhouse gas emissions. Reports estimate that heat in buildings accounts for 37% of the UK’s annual greenhouse gas emissions. With the oldest housing stock in Europe, and likely the world, the transition to decarbonisation presents unique challenges. Among the various segments of the housing market, social housing stands out due to its unique challenges in decarbonisation.
A significant subset of these homes is classified as hard-to-decarbonise (HTD) or hard-to-treat (HTT). However, research commissioned by the Department for Energy Security and Net Zero (DESNZ) in 2023 aimed to develop new terminology for these homes to improve existing terminology. This terminology is referred to as complex-to-decarbonise (CTD).
Retrofitting the UK’s housing stock is critical to reaching net-zero emissions by 2050, with approximately 29 million homes needing updates. A significant portion of these homes are particularly challenging to decarbonise due to higher costs and complex barriers. These CTD homes contribute over 25% of direct residential sector emissions. Addressing this issue is crucial as the UK’s Fifth Carbon Budget and the Climate Change Committee’s ‘Net Zero 2019’ report highlight CTD homes as a priority. Many occupants of these homes face fuel poverty and climate vulnerability, necessitating targeted efforts to improve their energy efficiency and reduce emissions.
Despite increased policy interest, substantial knowledge gaps persist regarding the physical, locational, socio-economic, and behavioural characteristics that render homes CTD. Current building stock models and datasets inadequately represent these homes, posing risks to effective policy implementation and retrofit success.
Why the New Terminology?
The term HTT has been used extensively in the past to describe homes that are difficult to improve using standard retrofit solutions. However, this term has been criticised for its binary nature and narrow focus on fabric issues, neglecting other important factors such as occupant behaviour and financial constraints. Similarly, hard to heat homes (HTH) emphasise the challenge of maintaining adequate thermal comfort but do not fully capture the complexity of decarbonising these dwellings.
CTD homes, as defined in recent research commissioned by DESNZ, incorporate a broader spectrum of attributes and move away from binary categorisation. This definition includes primary attributes like non-fillable cavity walls and infeasible loft insulation, and secondary system-level factors such as financial feasibility and supply chain limitations. This comprehensive approach helps in understanding the multifaceted challenges of decarbonising social housing.
Defining Complex-to-Decarbonise Dwellings
Complex-to-decarbonise homes exhibit physical, locational, demographic, or behavioural attributes that complicate the process of improving energy efficiency and reducing carbon emissions. These attributes can include:
- Physical: Solid wall construction, insufficient space for heat pump installation.
- Locational: Exposure to severe weather conditions.
- Demographic: Socio-economic challenges of the occupants.
- Behavioural: Occupant resistance to disruption.
For example, homes in seaside towns face significant challenges due to exposure to high levels of salt and moisture, which can impact materials and reduce the lifespan of installed improvements. Air source heat pumps and electrical forms of heating are considered key solutions for decarbonisation. However, because air source heat pumps are positioned outside, they are exposed to high salt levels in coastal areas. This can lead to electrolytic corrosion, reducing their efficiency and overall lifespan.
How to Identify CTD Dwellings
The CTD Identification Framework developed by DESNZ aims to systematically identify and categorise CTD dwellings. This sophisticated tool integrates a range of physical, locational, demographic, and behavioural attributes into the analysis process. It is intended to provide a nuanced understanding of the multifaceted challenges these homes present, which are not fully captured by previous terms like hard-to-treat (HTT) or hard-to-heat (HTH).
Utilising the CTD Identification Framework involves conducting detailed surveys to gather data on various attributes of homes, such as structural issues (e.g., non-fillable cavity walls), environmental factors (e.g., coastal exposure to salt and moisture), socio-economic conditions (e.g., low affordability), and behavioural patterns (e.g., occupant resistance to disruption). This comprehensive data collection enables a thorough assessment of each home’s unique challenges.
The framework is used throughout the retrofit project lifecycle, from initial engagement and planning to delivery and post-intervention. This ensures that all relevant factors are considered at each stage, leading to more effective and targeted retrofit solutions. The CTD Identification Framework not only aids in better understanding and mapping of CTD homes but also highlights gaps in current datasets, encouraging the development of more robust data sources. This tool is invaluable for policymakers, housing providers, and retrofit professionals, enabling them to design and implement interventions that are tailored to the specific needs and constraints of CTD homes, thereby improving energy efficiency and addressing issues such as fuel poverty.
Strategies for Targeting CTD Homes
Addressing CTD homes in social housing requires a multifaceted approach that includes policy interventions, innovative technologies, and stakeholder engagement. Here are some strategies that can be employed:
- Comprehensive Assessment and Identification:
A critical first step in targeting CTD homes is a thorough assessment and identification process. The use of frameworks like the CTD Identification Framework can help systematically identify homes with complex decarbonisation needs. This involves detailed surveys to capture the physical, locational, and socio-economic attributes of the dwellings. - Policy and Regulatory Support:
Government policies and regulations play a crucial role in facilitating the decarbonisation of social housing. Policies should focus on providing clear guidelines and standards for retrofitting CTD homes, as well as ensuring consistent enforcement of these standards. Regulatory frameworks should also address the unique challenges of conservation areas and listed buildings, which often require bespoke solutions. - Financial Incentives and Support:
Decarbonising CTD homes can be more costly than standard retrofits, therefore financial incentives and support mechanisms are essential. These can include grants, low-interest loans, and subsidies for both social housing providers and occupants. Funding streams such as the Social Housing Decarbonisation Fund (SHDF) and the Optimised Retrofit Programme (ORP) provide substantial financial support for retrofitting projects, promoting innovative approaches and targeting homes that are particularly challenging to decarbonise. Additionally, funding for pre-retrofit assessments and remedial works can help address the upfront costs and uncertainties associated with CTD homes. - Technological Innovations:
Innovative technologies and materials are vital for overcoming the physical constraints of CTD homes. There could be advancements in insulation materials that can be applied to solid walls, high-efficiency heat pumps suitable for spatially constrained homes, and smart ventilation systems to address moisture and air quality issues. The use of such technologies would therefore be tailored to the specific needs of each CTD home. - Skills Development and Supply Chain Enhancements:
A skilled workforce is essential for delivering high-quality retrofits. Training programmes and certifications for retrofit assessors, coordinators, and installers should be expanded to include the specific challenges of CTD homes. Moreover, developing a resilient supply chain that can provide the necessary materials and technologies is crucial for the timely and effective implementation of retrofits. - Occupant Engagement and Support:
Engaging occupants in the retrofit process is vital for its success. This involves providing clear and accessible information about the benefits of retrofitting, addressing any concerns or misconceptions, and ensuring minimal disruption during the works where possible. Post-retrofit support, including advice on the use and maintenance of new systems, can help maximise the benefits and ensure long-term success. An understanding of occupant behaviour will allow retrofit activity to be more successful by ensuring that the needs of occupants are met whilst also delivering lower carbon dwellings.
Targeting complex-to-decarbonise homes in social housing is essential for achieving the UK’s net-zero goals. By adopting a comprehensive and multifaceted approach that includes policy support, financial incentives, technological innovation, and stakeholder engagement, it is possible to overcome the unique challenges of these homes. With continued effort and collaboration, the decarbonisation of social housing can be accelerated, ensuring that no homes are left behind in the transition to a low-carbon future.
References
- Defining and identifying complex-to-decarbonise homes and retrofit solutions: research report. (2023). Department for Energy Security and Net Zero (DESNZ). Retrieved from Complex-to-Decarbonise Homes Report.
- Hard to Decarbonise Social Homes. (2022). National Housing Federation. Retrieved from NHF Report.
- Analysis: One in Four Homes Hard to Decarbonise. (2022). UCL News. Retrieved from UCL News.
- Hard to Decarbonise Social Homes. (2022). Local Government Association. Retrieved from LGA Report.
- BEIS. Clean Growth: Transforming Heating. Department for Business, Energy & Industrial Strategy; 2018.
- CCC. Net Zero: Technical Report. Committee on Climate Change; 2019.
- breTRUST. The Housing Stock of The United Kingdom; 2020.