What is Retrofit?
Retrofit is the industry term for making energy efficiency improvements to your home, which will also reduce carbon emissions. It can involve adding insulation to your loft, walls and floors, upgrading windows and doors, and improving services such as heating, hot water and lighting. It also includes fitting renewable energy systems such as solar PV and batteries.
Improvements should lower energy bills, make your home healthier, warmer and more comfortable to live in, and support the country’s journey to Net Zero.
It can be difficult to know where to start and what to prioritise on your retrofit journey. It is important to consider your whole house as a system. Retrofitting is not just about reducing energy bills but improving the comfort and aesthetics of your home. The way you use your home, and the upgrades and adaptations that have been added to your home since it was first built, will all determine the best way to undertake your retrofit.
The Whole House Plan
There are different ways to approach your retrofit journey, but industry experts agree that the best place to start is with a holistic appraisal of your property, including an energy efficiency assessment, a condition report which can highlight any areas that need to be tackled before the retrofit begins, and an occupancy assessment to understand the way in which you live in your house.
A retrofit coordinator will produce a medium-term plan (aka Whole House Plan, or Home Energy Plan); a roadmap to making your property as energy efficient as possible over the next 20-30 years. Having a plan is the first step to a successful retrofit. If you know what needs to be done you can incorporate the retrofit of your property into other upgrades, such as fitting a new kitchen, or adding an extension, which will save you money and reduce overall disruption.
The plan will highlight all the measures that are applicable to your property, pinpointing the most cost-effective measures and ensuring that measures are installed in the right order to make sure that work does not need to be redone later down the line. It will also stipulate what type of insulation product is used, and how it should be installed, to ensure that no unintended consequences occur.
The fabric of traditionally built properties deals with moisture in a different way to modern houses. They were originally built using materials that are vapour open, commonly known as breathable (although later additions, such as cement based render or gypsum plaster, may have affected the wall’s ability to breathe). Ideally the insulation and any plaster and paint should be vapour open too. The plan will also look at whether your home is liable to overheating or flooding, and adaptations can be suggested to help reduce the consequences of these.
In general, retrofit professionals recommend a ‘fabric first’ approach which starts with the easy options: making sure your property is well maintained, adding insulation and draughtproofing and ventilation before moving on to a low carbon heating system.
Damp walls lose energy more rapidly than dry ones, so your property will cost more to heat, and insulation installed on damp walls will fail. Therefore, repairs and maintenance are a key part of pre- and post-retrofit. When one element of your home is improved, for example, insulation installed or double glazing fitted, internal air temperature increases and draughts are reduced. Warmer air holds more moisture, so a robust mechanical ventilation strategy is important to reduce the possibility of condensation and mould.
Having a lower heat demand in your home means that low carbon (electric based) heating systems, such as a heat pump, can be smaller, more efficient and cheaper to run. Solar panels could be added before or after your retrofit journey, but if you add them at the end, you will be able to size them dependent on how much power you need to generate and understand whether a storage battery would be suitable for your home.
An Energy Performance Certificate (EPC) can be a good starting point, and provide some basic recommendations, but does not consider the condition or location of your home, or highlight any inherent risk involved in upgrading the insulation and draughtproofing. It is best to consult a retrofit professional who understands building physics, condensation and damp, to ensure that all work complies with best practice.