ePrivacy and GPDR Cookie Consent by Cookie Consent Energy Efficient Upgrades To Your House

Resi’s Retrofit Hub

There are a lot of ways you can make energy efficient upgrades to your home. These upgrades save money on energy bills, keep your home warm and comfortable, and help the environment. In this article we will help you decide how to retrofit your home

11 min read

1. Introduction from Mark Hood, our Head of Architecture

Benefits of retrofit

2. What does retrofitting mean?

Retrofitting, in essence, upgrades your home's performance and helps decarbonise your home.

It encompasses both enhancing the fabric of the building—walls, floors, ceilings, windows—and upgrading your heating and energy systems, by installing solar panels, home batteries, or heat pumps.

Check out this explanation on decarbonisation

3. Free retrofit advice at Resi

How do we provide retrofit advice?

  • This document contains loads of helpful information to get started
  • Our designers are trained to offer professional advice and support
  • We can integrate retrofit technology into the architectural drawings
  • We introduce you to vetted, market-leading suppliers of retrofit tech
  • We’ll help you get planning permission if needed (e.g. for solar panels)

What don’t we provide?

  • Detailed heat loss surveys
  • Guaranteed predictions of how much you’ll save on energy bills (though we can estimate)
  • Adopting retrofit measures into your scheme may require additional fees to cover the work required. Please ask to see our pricing scheme to see the full extent of costs.

Why retrofit whilst extending

You might be wondering if there are benefits of retrofitting while planning an extension. At Resi, we're advocating for it passionately in our webinars.

4. Mechanical vs fabric upgrades

Retrofitting can be divided into two main categories: mechanical and fabric upgrades.

Fabric Upgrades

These enhance the building's exterior, including walls, roofs, and windows, focusing on insulation and air tightness to minimize heat loss. This means keeping the warmth in during winter and out during summer, and making your home more energy-efficient.

Mechanical Upgrades

These update home systems for heating, cooling, and power, prioritising efficiency and renewable energy. This includes adopting heat pumps, solar panels, or efficient boilers to reduce energy use and embrace sustainable sources, ensuring your home’s systems are both modern and eco-friendly.

Fabric and mechanical upgrades

Fabric, mechanical, or both?

When to Only Consider Mechanical Upgrades

Your windows are in good conditions, there are no signs of air leakage or mould and your boiler is over 5 years old.
You want to invest to recognise the savings of solar + batteries

When to Only Consider Fabric Upgrades

If your windows are in extremely poor condition and there are signs of air leakage and mould.
If the existing boiler is less than 5 years old

When to Consider Both Mechanical and Fabric Upgrades

Consider both when long term investment, home comfort & environment are priority.

5. Fabric upgrades deep-dive

Watch the videos below with our Head of Architecture Mark and Studio Manager Oli as they go through the positives (and negatives):

Mechanical upgrades deep-dive

heat pump

6. Heat Pumps

Consider a heat pump for its efficiency in heating and cooling your home, lower running costs in your bills, reduced carbon footprint, and ability to provide a consistent and comfortable indoor climate using renewable energy sources.

How do they work?

Heat pumps transfer heat from outside to inside a building, or vice versa, to provide heating or cooling.

What are the typical costs?

The installation of a heat pump system typically ranges between £6,000 and £18,000, depending on the type and size of the system.

When is the best time to install during construction?

The optimal time to install a heat pump is during the early stages of construction

Should I install a battery too?

Incorporating a battery system with a heat pump can maximize energy savings, especially if paired with renewable energy sources like solar panels, by storing excess energy for use when demand is high.

Do they work with External/Internal Wall Insulation?

Yes, heat pumps are compatible with both external and internal wall insulation, improving overall energy efficiency and performance - but a lot of the time a Heat Pump will be sufficient without any other upgrades

Are there any Grants Available?

Yes the BUS grant from the UK Gov is worth £7,500 to each install (subject to conditions)

Where can I learn more about heat pumps?

Check out this overview of heat pumps with VitoEnergy or watch the videos below from Resi and our partners.

Who do Resi work with to deliver Heat Pumps?


Heat Geek is the largest network of the most highly trained renewable heating engineers, installing the highest efficiency systems in the UK, backed by a market leading guarantee.

With over 500 engineers across the country having installed over 1,000 systems, there’s likely a Heat Geek in your local community able to save you money and cut carbon.

With full accreditation for all Heat Geek installs through MCS, Trustmark and RECC, and the Heat Geek Guarantee going even further, their installs are built to last, delivering comfort and efficiency well into the future.

Check out the Heat Geek Knowledge Base


VitoEnergy is a multi-skill engineering company so they won’t steer you in one direction, they consider all solutions to suit your home.

They have an in-house team of 10 engineers and dozens of installation partners across the UK who have delivered over 200 heat pump installations in the last year alone.

VitoEnergy's focus is on the user experience and overall efficiency, whether it is a gas boiler, heat pump or Hydrogen fuel cell, they are dedicated to the long term performance and cost.

VitoEnergy proudly have hundreds of 5-star reviews!

As well as installing and supporting engineers, they offer an online heat loss service so designers can provide expert advice on the right radiators, pipe sizing, heat pump or boiler.

solar panels

7. Solar panels

How do they work?

Solar panels convert sunlight into electricity using photovoltaic cells

What are the typical costs?

The typical costs for installing solar panels range from £4,000 to £18,000, depending on the size and type of system installed.

When is the best time to install during construction?

The best time to install solar panels is during roof construction or replacement or at the end of your build.

Can you sell back to the grid?

Yes, you can sell surplus electricity generated by your solar panels back to the grid.

Should I install a battery too?

We always recommend installing a battery with solar panels allows you to store excess energy for later use, maximising your self-consumption and providing backup power.

Do they work with Heat Pumps?

Yes, solar panels can work in conjunction with heat pumps, providing clean electricity to run the heat pump and further reducing your carbon footprint and energy bills.

Who do Resi work with to deliver Solar Panels?


Founded by two brothers in 2017, Heatable are already the 3rd largest installer of energy savings across the UK. After taking the boiler market by storm, they decided to take on solar, presenting a unique solution and an offering that makes greener technology more accessible.

Fast forward to today and Heatable have thousands of installs under their belt and have saved their customers a lot of money on their energy bills.

Along with over 9,000 'Excellent' reviews on Trustpilot, Heatable hold the European rights to the Fusion2 panels from REA. These bi-facial panels are designed for the UK market and outperform a traditional DC system by 20%.

They are also the largest Enphase installer in the UK. The beauty behind microinverters is they work on their own individual systems. Traditionally, if one panel breaks, the whole system goes down. With the Enphase Microinverter, the rest of the system still continues to perform.

Click below to hear from Ben with intro to Heatable and how they work with Resi

Or watch Ben discuss Heatable in one of our webinars together below


8. Batteries

When you are sleeping you can be storing energy on site for cheaper rates.

Consider a home battery storage system to store surplus renewable energy for later use, enhance energy independence, reduce electricity bills, provide backup power during outages, and support a more sustainable energy consumption model.

How do they work?

Home battery storage systems store electrical energy from the grid or renewable energy sources, like solar panels, for later use when demand is higher or during power outages.

What are the typical costs?

The costs for home battery storage systems vary widely but typically range from £1,200 to £10,000, depending on capacity, technology, and installation complexities.

When is the best time to install during construction?

The optimal time to install a home battery storage system is during the electrical installation phase of construction or when integrating renewable energy systems, ensuring seamless integration with the home's energy infrastructure.

Do they work with Heat Pumps, Solar?

Yes, home battery storage systems work well with both heat pumps and solar panels, allowing for efficient energy use and savings by storing excess energy generated or low tariff energy from the grid.

Where can I store a battery in my house?

Home batteries can be stored in utility rooms, garages, basements, or against an external wall indoors, depending on space and ventilation requirements. It's crucial to choose a dry, well-ventilated location away from direct sunlight to optimize the battery's efficiency and lifespan.

Can I install a battery without solar panels?

Yes, you can install a home battery storage system without solar panels. Batteries can store electricity from the grid during off-peak hours when rates are lower and supply it during peak times to reduce energy costs

Who do Resi work with to deliver Batteries?


Click below to watch that intro to Heatable again, and check out Resi and Heatable's webinar - all about Batteries.

9. Property Performance Surveys

You may not know your property very well yet, know which areas need retrofitting, or maybe you just want some extra information in your pocket to help understand where to start and what will have the most impact. If this is the case, you may consider having some form of retrofit or heat loss survey conducted.

The more information that your designer has about the current performance of your property, the better they can diagnose how to remedy issues and specify upgrades to allow it to perform better.

There are a few types of survey you could choose to have done, and Resi works with several companies we can introduce you to.

Thermographic survey

To assess where heat is being lost. This is where a surveyor goes round your home with a thermal camera, mapping out where there is heat escaping.

Air tightness survey

To assess where air is escaping. This is often called a 'blower door test' as a surveyor basically blows lots of air into your home, and maps out where it is most leaky.

SAP calculations

To understand the energy performance of the existing building and the proposed fabric upgrades. This assessment takes into account existing fabrics, heating systems and any renewable energy considered in reference to the building’s form, size and orientation.

Retrofit survey

A full check-up for your home. This is a full assessment of the buildings fabric alongside heat loss. This usually includes a thermographic survey, air tightness survey, and a cavity wall inspection where a camera is used to identify issues like moisture build-up, insulation problems, and potential mould growth.

Resi will also ensure to take images of some vital things like your boiler, fuse box, and radiators during the measured survey visit, to ensure the suppliers you work with have all the information they need to avoid uneccessary site visits where possible. Our 3D tours are so detailed that suppliers such as solar panel installers are able to use them to assess of your home and provide a quote.

Build Green

With all this talk of the current home, you may also be wondering how you could build your extension to be as energy efficient/envrionmentally friendly as possible. If so, speak to your designer about building using SIPs - Structurally Insulated Panels.

SIPs are strong, energy efficient, and cost-effective. The panels consist of an insulating foam core sandwiched between two structural facings. SIPs are manufactured under factory conditions and can be fabricated to fit nearly any building design, so they are a great option to consider for an eco-friendly build.

Potential Additional Resi Fees

Solar panels/batteries
£0 to incorporate into design and planning drawings*
£210 during the building regulations stage for coordination

Heat pumps
£0 to incorporate into design and planning drawings*
£210 during the building regulations stage for coordination

External insulation
£0 to incorporate into design and planning drawings*
£315 for building regulation compliance detailing (option 1)
£1,260 for 4 x bespoke details for PAS 2035 compliance (option 2)

Internal insulation
£0 to incorporate into design and planning drawings*
£315 for building regulation compliance detailing (option 1)
£1,260 for 4 x bespoke details for PAS 2035 compliance (option 2)

Please note, all of the above works may require an additional planning application. If this is the case, there will be a further charge of £512 for Resi to prepare an additional set of drawings, all necessary documents and oversee as the agent of the application (this does not include the cost of the application to the council). This will need to be paid prior to work commencing.

Retrofit next steps

11. A summary from Mark

Looking to improve your home?

Which part of your property would you like to extend?

Ground Floor
First Floor

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Track record in getting planning approval


Projects undertaken across the UK

34 days

Average time from survey to planning