Guidance Tool

Overheating in Retrofit and Existing Homes – Tool and Guidance

About the tool

The new tool responds to demand from designers, housing associations, environmental health officers, and other parties concerned with overheating risks in the existing housing stock, which are likely to increase further due to climate change and higher temperatures.

This tool is intended for use at the early stages of residential retrofit projects, or on existing homes, in order to identify key factors contributing to overheating risk and possible mitigation measures. It is applicable to existing homes, retrofits, and conversions of non-domestic buildings to residential accommodation.

The tool and guidance are meant to be easy to use by non-specialists to inform early-stage big impact decisions. They promote holistic consideration of overheating risk together with the site context and linked design issues such as ventilation and noise. The potential impacts of energy efficiency measures through retrofit are included, but the tool also highlights the important opportunities for retrofit to contribute not only to overheating risk mitigation, but also improvements in air quality and energy efficiency.

The tool builds upon the beta version which launched in March 2022, with new case studies and improved functionality. We would like to thank everyone who contributed with their comments and case studies.




Authors and supporters

The main author of this guidance is Julie Godefroy of Julie Godefroy Sustainability, with support from Susie Diamond of Inkling LLP.

The project has been co-funded by the National Energy Foundation, and the BEIS funded REFINE project on radical decarbonisation of social housing through whole house energy retrofits.

Thank you to everyone who contributed to the development of this tool and guidance, including Clare Murray (Levitt Bernstein), John Palmer (LETI), Jack Harvie-Clarke (Apex Acoustics), Anthony Chilton (Max Fordham), Harry Paticas (RAFT), Amad Kayani (Historic England), Lucy and Tom Pemble, and all those who provided comments in the feedback workshop or by email.

The REFINE project is one of the Social Housing Decarbonisation Fund Demonstrators led by Warwick District Council and Oxford Brookes University with Enhabit/QODA Consulting and Sarah Wigglesworth Architects.

We would like to thank the following steering group members for their input during the project:

  • Hayley Chivers, Sarah Wigglesworth Architects
  • Paul Ciniglio, National Energy Foundation
  • Prof. Rajat Gupta, Oxford Brookes University
  • Dr Sarah Price, QODA Consulting
  • Katharine Ray, Warwick District Council
  • Sarah Wigglesworth, Sarah Wigglesworth Architects
  • Tim Wilcockson, QODA Consulting

More information

For more information about the Overheating in Retrofit and Existing Homes tool, please contact Julie Godefroy – or Susie Diamond –

For more information about the Good Homes Alliance, please contact Julian Brooks, Programmes Director –, 0330 355 6274.


Future Homes – Avoiding unintended consequences (NF91)

The technology largely exists to enable this extraordinary transformation, but the knowledge, skills and practices required to deliver homes reliably and at volume, may not. With this in mind, this web-based toolkit, commissioned from Studio Partington, looks at key issues such as householder comfort, usability and resilience to climate change. 

It sets out in three clear sections – heating, ventilation and design considerations – the different unintended consequences that might arise from energy saving measures in new homes and suggests how these might be overcome.  

This resource will continue to evolve and become a forum for knowledge and a stimulus for thinking about the home in use and about design for future occupiers. It will be a resource for designers, builders, suppliers and home managers, sign-posting other guides and learning. We would like it to prompt discussion, identify the scale of the challenge and, hopefully, be a reminder of lessons from the recent past.

Author: Studio Partington for NHBC Foundation

Publication date:



How to achieve net zero carbon homes

Funded through the Local Government Association (LGA) Housing Advisers Programme, the guide has been produced by leading technical experts from Etude, the Passivhaus Trust, Levitt Bernstein and Elementa Consulting.

Who is the Toolkit for?

Pulling on latest guidance and best practice, the Net Zero Carbon Toolkit is a practical, easy to follow guide to help plan a net zero housing project.

Aimed at small or medium-sized house builders, architects, self-builders and consultants, the toolkit covers a range of steps – from pre-planning right through to construction – for delivering net-zero carbon, low-energy homes.

The toolkit also provides homeowners looking to retrofit or extend their existing property, guidance and advice on what they need to consider and how they can implement energy efficiency measures and begin the process of decarbonising their homes in a more affordable, phased approach.

Implementing the measures laid out in the new toolkit will help reduce the carbon footprint of new and existing buildings. Making significant reductions to a home’s carbon emissions also means lower energy bills for homeowners, more people out of fuel poverty and homes that are comfortable and healthier to live in.

How can others use the Toolkit?

West Oxfordshire District Council and its two partner councils share an ambition that net zero should be the standard for all new housing and retrofit projects in their districts.

Achieving the UK’s legally binding net zero target is no small task and it is acknowledged that reaching this goal requires organisations to work together, share experiences and build on best practice.

To help others reach net zero and to speed up the UK’s collective response to the climate emergency, the Net Zero Carbon Toolkit is openly available as a resource for private and public sector organisations to use and adopt. Further information about how the toolkit may be used is listed on page 2 of the document. 

Authors: Etude, Passivhaus TrustLevitt Bernstein and Elementa Consulting.

Publication date: July 2021



Social Value Toolkit for Architecture

The Social Value Toolkit for Architecture has been developed to make it simple to evaluate and demonstrate the social impact of design on people and communities.

Social value outcomes are increasingly being considered necessary benefits in public and private procurement through quality scores of bids and tenders. To provide evidence that meets these key performance targets and metrics, practices need to demonstrate value quantitatively and this toolkit provides a post occupancy evaluation survey and methodology for reporting social value as a financial return on investment.

The Social Value Toolkit was developed through a research project led by the University of Reading and included representatives from the RIBA and research leaders in architectural practice. Download the guidance below to hear from some of these researchers on how their practice is building social value into their projects and design processes.

Author: RIBA

Publication date: June 2020




The overarching goal of Hotmaps is the development of an open source heating/cooling mapping and planning toolbox and to provide default data for EU28 at national and local level. These data and tool allow public authorities to identify, analyse, model and map resources and solutions to supply energy needs within their territory of responsibility in a resource and cost efficient way. Those results will help authorities to develop heating and cooling strategies on local, regional and national scale which are in line with RES and CO2-Emission targets on national and EU level.

Guidance Standard Tool

Assured Performance Process (APP)

What is the Assured Performance Process (APP)?

There is often a huge difference between how buildings are supposed to perform, and how they actually do.  The assured performance process provides independent and expert input to the development process to minimise this energy, overheating, and indoor air quality performance gap.  As well as helping to reduce carbon emissions and climate change, this improves the health of people using buildings.

The Assured Performance Process TM (APP) maps to the RIBA Plan of Work and has five stages of expert, impartial review and assessment. APP assessors are accredited by The National Energy Foundation for their expertise and they offer two services:

  • APP implementation across all five key stages – supporting the client throughout the development process. This is a bespoke service.
  • One off reviews tailored to the stage of the development

Who is behind APP?

The Good Homes Alliance has secured a two year license for the Assured Performance Process (APP) from the original developer and owner, the National Energy Foundation (NEF).

NEF is a charity which has been meeting its mission of “improving the use of energy in buildings” for more than 20 years.  NEF has established other nationally recognised quality systems.

Contact Julian Brooks at to find out more.

Guidance Tool

Right to Build Toolkit

The Right to Build toolkit has been developed by the Right to Build Task Force, a professional advice service, and part community-interest company, that supports a range of organisations in their ambitions to deliver more Custom- and Self-build homes in the UK. The Task Force is supported by a team of experts able to provide advice to help unlock the growing demand from people that want to build, or commission, their own home.

Although set up by the National Custom and Self Build Association (NaCSBA), the Task Force operates completely independently, with an ethical wall between the two organisations. This is because while NaCSBA lobbies government for change, the Right to Build Task Force is solely focused on providing advice to a range of stakeholders to bring on more owner-commissioned homes, including community-led homes, working within the framework of the Right to Build legislation.

Author: National Custom and Self Build Association (NaCSBA)

Further information:

Guidance Tool

Overheating in New Homes

A new tool and accompanying guidance which aims to help planners and design teams identify and mitigate overheating risks in new homes at an early stage.

The tool and guidance were formally launched at a sold-out evening event on 16th July 2019 at Winckworth Sherwood in London, which featured short talks from the project team and steering group experts.

The work has been led by a project team of Susie Diamond (Inkling), Julie Godefroy (Julie Godefroy Sustainability) and Nicola O’Connor (Mandarin Research) with support and feedback from an expert steering group, the GHA team and stakeholder workshops.

The steering group has consisted of the following experts:

  • Lynne Sullivan OBE, Chair, Good Homes Alliance
  • Michael Swainson, BRE
  • Anastasia Mylona, CIBSE
  • Joe Baker, London Borough of Haringey
  • Guy Thompson, The Concrete Centre
  • Dr Victoria Tink, Ministry of Housing, Communities & Local Government
  • Chris Twinn, Twinn Sustainability Innovation
  • Tom Dollard, Pollard Thomas Edwards

To assist with the use and uptake of the tool, the GHA and the research project team will develop and deliver a number of training masterclasses starting in autumn 2019. If you’re interested in attending a GHA Masterclass on overheating or arranging a bespoke CPD for your organisation, please contact Julian Brooks at

Author: Good Homes Alliance

Publication date: July 2019



SCATTER (Setting City Area Targets and Trajectories for Emissions Reduction)

SCATTER (Setting City Area Targets and Trajectories for Emissions Reduction) is a local authority focussed emissions tool, built to help create low carbon local authorities. SCATTER provides local authorities and city regions with the opportunity to standardise their greenhouse gas reporting and align to international frameworks, including the setting of targets in line with the Paris Climate Agreement.

  • SCATTER generates a compliant emissions inventory

  • SCATTER can be used to develop a credible decarbonisation pathway for a local authority to implement in line with their emissions targets.

  • Outputs can then be used for engagement to create a collaborative carbon reduction approach

Author: Anthesis Group

Launch date: March 2018