Retrofit Works


Energy use, climate change and housing are urgent, connected issues we are all facing. Climate change is turning up the heat on the need to reduce the amount of energy we use and improve sustainability of our homes.  

The Government’s, Climate Change Act of 2008 sets a legal target for the UK to reduce greenhouse gas emissions by at least 80% by 2050. 80% of the homes we will use in 2050 have already been built. Retrofitting existing stock by 2050 will be a challenge. Retrofitting has never been done before and we need our tenants to work with us in achieving this goal.  We can not build our way to a low-carbon future without upgrading our existing homes to meet this legal energy saving target.  

What is Retrofit?

Retrofit’ is simply the process of making changes to existing buildings to reduce their energy usage and carbon emissions, reducing their impact on the environment. These changes mean a home will also be more comfortable and healthier for those who live there too. 

This may involve works such as additional insulation, improved ventilation, and new central heating, however, each home may involve a different approach.    To ensure homes perform to their best potential we take a “fabric first” approach, improving the Roof, Walls, Windows etc. where possible. 

Your home may significantly benefit from these works and if so, we are keen to work closely with you to make these changes. We may also ask you to help us capture the benefits of any works we have done on your home e.g. using a smart thermostat that we will install.

Why do we need to Retrofit our properties?

The main reason for climate change is the use of fossil fuels e.g. coal, gas and oil, this is responsible for most of the carbon dioxide emissions. 

Global Warming

The Earth is warming up due to the build-up of greenhouse gases in the atmosphere, through emissions caused by human activity. These gasses (largely CO2) trap heat in the atmosphere working like a greenhouse over the Earth. 

The aim is to minimise the heat increase to 1.5oC by 2050 to help the Earth Stabilise.  To do this we need to reduce emissions which are released into the atmosphere. The UK Government’s ambition is to reduce emissions with the ultimate target of ‘net zero’. 

Deforestation is the act of removing most, or all, of the trees from forests.  This causes a release of carbon dioxide (CO2), plus there are less trees to continue absorbing the CO2. 

Climate change already has a growing impact on economies, livelihoods and the health and well-being of people.  Buildings account for 23-36% of the energy -related greenhouse gas emissions. 17% of emissions is due to heating homes.  Reducing the energy consumption and improving the energy efficiency of buildings is a key component of the governments’ plans to achieve their climate goals.  

Typical breakdown in energy consumption in the home: 

Green jobs and inclusive economic growth

The extensive works needed to implement retrofit is expected to create high demand for skilled workers and generate a large amount of new jobs. 

Reducing Fuel Poverty

High energy prices and low performing homes raise living costs and cut into tight household budgets.

Low performing homes are not good at retaining heat, and need more energy to make they warm enough.  For people living in these homes, the amount, they spend to heat their home, means that their remaining income is below the official poverty line, and they are considered as being in ‘Fuel Poverty’.  Fuel poverty can impact on peoples health because this is likely to result in people living in cold, damp homes, created by turning their heating down below a level that helps control condensation. 

Retaining and reducing demand for heat is a key focus of retrofit projects.  

Cold living accommodation increases health care costs and the annual NHS costs in the UK attributed to housing are estimated at £1.4 billion for the first year treatment. Cold homes contribute at least £145 million of those costs. “Cold homes are linked to a wide range of health issues, from mental health to asthma and respiratory issues, trips and falls”. 

67% of children from families in fuel poverty haven’t had a holiday in the past year.  They were more likely to feel unsafe and fail to attend school. This is all because the family can afford to only part heat their home (most used and therefore noisiest) rooms, so there is no quiet place to do their homework. This often impacts on a child’s educational attainment and work opportunities in later life. 

Retrofitting homes can help us reduce fuel poverty, and improve people’s health and wellbeing.    

Technology based resource management and sustainable materials

Smart Homes – Digital sensors make it possible to monitor the conditions and energy usage of buildings in real time.  This gives new levels of control over home environments and energy bills.  

Sustainable materials – A mix of new and traditional materials is improving sustainability across a buildings life cycle.   

Nature based solutions – Green walls and roofs can reduce energy consumption and create healthier living environments.  

What is the Retrofit project and why is it being carried out?

Colchester City Council (CCC) is one of 107 Grant Recipients to be awarded a share of £778m to retrofit social homes, as part of Wave 2.1 of the Social Housing Decarbonisation Fund (SHDF). The SHDF is a pot of money being made available by the Government to improve the energy performance of social housing. 

The council’s successful bid, which was submitted to the SHDF in November 2022 and is worth more than £1.024m, will upgrade the energy efficiency of 105 selected properties that have an Energy Performance Certificate (EPC) rating below C. 

The Council and Colchester Borough Homes are working collaboratively to deliver the Retrofit project. 

With a fabric first approach, we will ensure that the properties are well insulated, providing our tenants with a home that can retain heat during the colder months and keep the property cooler during the summer months. Our tenants will generate less Carbon Dioxide keeping their homes at a suitable temperature, helping them manage their utility bills and live a more environmentally friendly lifestyle  

What are Retrofit works?

There is a major imbalance between heat demand and electricity demand. Although domestic demand for electricity varies through the day, it is relatively stable across the seasons. In contrast the heat demand is approximately the same as electricity demand in the height of summer, but peaks to six times the electricity demand in the depth of winter. If the heat demand stays at the same level, we will not be able to switch to solely low-carbon electric heating as the required rate. Heat demand must be reduced and this is most effectively achieved by dramatically increasing the thermal efficiency of our housing stock.  

The type and number of works required to each property will vary depending on the individual building and current condition: 

Loft insulation

Rockwool insulation laid most typically between the joists in the loft space, forming a thermal barrier keeping the warm air from the home in, and the cooler air from outside of the property, out. Existing insulation will be either entirely replaced, or topped up, to a depth of 300mm. 

Cavity Wall insulation

Insulating material installed within the cavity formed between the inner and outer walls of the home. It traps the warm air in, reducing heat loss, energy consumption and keeps the home warmer for longer. Holes are typically drilled externally, with insulation blown in to form a complete barrier. 

External Wall Insulation (EWI)

A system, in varying forms, applied to the exterior of the property to create a thermally insulated barrier. Commonly rendered over, these also form a protective and decorative finish. 

Internal Wall Insulation (IWI)

An additional layer of insulation applied internally. Commonly involves installing specialist insulation boards to the external walls or forming secondary stud walls, with the cavity formed then insulated such as mineral wool fibre. 

Flat roof insulation

Insulation applied to flat roofs, typically of entrances or extensions. It serves to keep the area warmer in the winter and cooler in the summer. A surveyor will determine if this is best achieved as a ‘warm roof’ or ‘cold roof’, affecting where the insulation is applied and the work required. 

Air Source Heat Pump (ASHP)

A heat pump, installed externally, that absorbs the heat and provides it as space heating inside the property using the same vapour-compression method as a typical, domestic refrigerator. Commonly installed in areas off the gas network, though not exclusively. 

Solar Photovoltaics (PV)

Solar Photovoltaics (PV) are a collection of panels, formed as an array, typically to the property’s roof, converting the light generated by the sun into electricity that is directly consumed by the home it is connected to. These systems are installed without battery storage, providing electricity to supplement what a resident uses and pays for from the grid for free, during hours of daylight – but not once the sun goes down. 


Properties lose heat through all aspects of the building fabric – the roof, the floors and the openings (the windows and doors). Targeted draughtproofing aims to reduce the loses in specific areas by relatively simple measures, such as draught excluders at the base of external doors, preventing cold air entering and warm air escaping. 


Domestic properties generate a lot of moisture, primarily from bathing/showering and cooking. Without adequate ventilation, removing the moisture and vapour, the risk of damp and mould forming increases. Mechanical ventilation measures primarily concern the installation of extractor fans in kitchens and bathrooms – and are supported by windows that open adequately and feature trickle vents. 

Double Glazing

Double glazed windows are formed from two panes of glass, separated by a spacer bar that creates an air gap, filled with an insulating gap. These greatly improve the thermal insulation of the property, retaining heat whilst preventing external cold air from entering. 

Low energy lightbulbs

Energy-saving lamps that replace traditional lightbulbs. These are commonly traditionally bulb-shaped LED (Light Emitting Diodes) in living rooms and bedrooms, sealed units in kitchens and bathrooms (or any other areas where a high amount of moisture may be produced). 

Heating controls

Gas-fired boilers, or Air Source Heat Pumps, are installed with the ability to regulate the temperature of the radiators individually in each room at source (using TRVs – Thermostatic Radiator Valves or other controls) – supplemented by a portable unit to monitor and adjust and programme the overall temperature throughout the property. 

How we will work with tenants

A Retrofit Advisor will provide advice to you as the occupier of the property on how you may be able to save money through the day-to-day running of your home. They will also work with residents to find ways to make your home more comfortable and efficient, so you use less energy in your home.

The Retrofit Advisors are there to:

  • Provide excellent customer support by guiding the customer through the retrofit process, answering queries, and providing information
  • Educate customers regarding retrofit systems etc.
  • Diagnose and troubleshoot issues when they arise
  • Communicate clearly and effectively with customers, colleagues, and interested parties

To ensure we follow the correct processes and complete improvement works correctly, we follow a standard called PAS 2035 (Publicly Available Specification 2035) this covers the whole process from the start to completion of the works, and on-going monitoring of the success of the works carried out. PAS2035 ensures that when works (referred to as Energy Efficiency Measures – EEMs) are selected, designed and installed that the whole building is considered to ensure they are technically suitable. The standard also has a clear focus on occupant comfort levels to ensure a well-rounded approach is followed. The contractors we will be working with also follow PAS 2030, which is a standard used in conjunction with PAS 2035 to ensure the measures are installed correctly.

By following these standards and using Trustmark registered contractors, our tenants can have the assurance of the highest quality works being provided. The works to your home will be carefully selected and we will work with you to make sure you get the best out of your home, and avoid issues such as damp and mould in the future.

The stages of PAS2035 are:  

  • Project Inception – starting point of the project where we identify the homes, we will be working on finding a suitable contractor for the work 
  • Risk Assessment – the risk based on the type of work being carried out and the number of homes we will be working on is assessed so we can select the best way to proceed  
  • Dwelling Assessment – the homes are assessed to select the best EEMs for each home/type of home  
  • Strategy – the extent of work we will be carrying out is defined based on factors such as type of home, type of construction, condition of homes etc.  
  • Design – the required works are designed by qualified Retrofit Designers
  • Installation and Handover – the works to complete the EEMs are carried out by qualified (TrustMark registered) contractors  
  • Monitoring & Evaluation – this will involve testing the homes to ensure the work will be successful, and you will be asked about your experience with the work and your level of satisfaction with your home following the work

A Retrofit Coordinator will also be heavily involved in the project and it is their responsibility to ensure that residents receive the correct advice.  In some cases the Retrofit Coordinator may provide the required advice themselves.  Where this occurs you can expect the same service you would receive from a Retrofit Advisor. 

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