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Eco-retrofit at a large Victorian Semi-detached

A large family home in North Oxford has undergone an eco-retrofit to cut carbon emissions and make the home as energy efficient as possible.

Cosy Homes Oxfordshire recently completed work on retrofitting a large Victorian semi-detached property in North Oxford, including replacing a fossil fuel boiler with an Air Source Heat Pump to improve comfort and reduce carbon emissions.

Find out how the owners made their home greener, more comfortable and cheaper to run.

The home was assessed and measured and provided with a Whole House Plan before proceeding with any work.
New double-glazed sash windows were installed throughout the house and were protected whilst internal wall insulation was installed.
Post-retrofit the home is tastefully finished and fits in well with other homes on the street. From the outside, you couldn’t tell it’s now an energy-efficient home.

About the home

The house was built in the 1880s and also had a two-floor modern extension added in 2013.

The house is a well-maintained and large multi-storey Victorian semi-detached and is used as a family home. One of the motivations the couple had in owning a house of this size was to have the option to invite lots of friends and family to stay.

Caption: Retrofit Coordinator, Mark Saunders, explained that the ceilings had been removed to install the underfloor heating ducting which sits in trays that are mounted between the joists of the floor above.

What were the motivations?


The owners were driven by the need to reduce the carbon emissions from their home.

After taking action on the climate and ecological emergency in other areas of their lives, they wanted to feel they were living in alignment with those principles.

“It’s so apparent that houses of this type and period and nature are incredibly energy inefficient. So it was always part of the dialogue in looking at houses like this one that the condition of buying it would be to make it much better than it was.”Meg, Cosy Homes Oxfordshire Client

Seeing the inefficiency and energy waste in their home they wanted to feel comfortable knowing they had made a large personal contribution to reducing carbon emissions.

They also hoped to show what can be done in larger and older homes, and support the local low carbon building industry. Through retrofitting they could play a part in driving carbon cutting change.


The home was cold in winter and changes in temperature could be felt around the house through draughts and cold spots. Not only was this uncomfortable but meant that more energy was wasted on heating.

“You could feel those colder spots, you could feel the draughts that came in, both under doors and particularly around single-glazed windows and it required a lot of energy to heat.”

What measures were installed?

A Whole House Plan from Cosy Homes Oxfordshire helped the owners work out what would be needed and how best to prioritise and order upgrades.

Measures include:

  • New double-glazed sash windows
  • Internal wall wood fibre insulation
  • Air source heat pump
  • Underfloor insulation and heating
  • Re-roofing and loft insulation
  • Centralised mechanical extract ventilation

“We needed to make it more energy efficient to feel comfortable living here for many years.”

Internal wall insulation was the largest initial measure and meant insulating three sides of the home because it’s semi-detached, taking down plaster, putting up wood fibre insulation and re-plastering those walls.

“A ground source heat pump would have meant a huge amount of work in the garden that was not very practical. An air source heat pump was the obvious choice once we discovered that it was actually compatible with a house of this size. So that was quite exciting because we weren’t sure that would be the case.”

Wood fibre insulation panels need to be applied to a smooth, flat surface so the internal walls were prepared with a coat of lime plaster to make them level. The insulation panels, which are rigid, can then be fixed in place.

The wood fibre is then ready for its top layers of finishing plaster to create a very well-insulated and cosy room.

To complete the thermal envelope, they next began insulating the loft, insulating the floor above the cellar and between the floors on each storey.

Wooden flooring relaid in the loft
Air Source Heat Pump

After reducing the heat loss from the home, they were then able to completely remove gas heating from the home and replace it with a new air source heat pump.

A large heat pump in the cellar heats the whole house through underfloor heating.

Alongside this, a sophisticated ventilation system operates on every level making sure air is circulated effectively and that the structure of the home is kept in good health.

Sustainable Materials

Like many Cosy Homes Oxfordshire clients, the owners were keen to use natural and reusable materials in their retrofit.

Denim Jeans

Between some floors, they were able to employ material made from recycled denim jeans. Denim is made from cotton which is a natural material. Not only does this reuse materials it provides very good thermal efficiency once deconstructed and taken through a remanufacturing process. It also provides a good level of sound insulation.

“I think one of the biggest challenges for us in doing this was accepting that there’s a certain amount of waste that goes along with any building project. There are emissions associated with new materials. And where possible, we really wanted to minimise those impacts.” – Meg – Cosy Homes Oxfordshire Client

Wood fibre insulation board was used and is made from offcuts from the wood processing industry, is renewable, reusable and composts. The original trees used in its production absorbed Carbon Dioxide throughout their growing period. It’s breathable and suits older, solid-wall houses.

Samples: Wood fibre insulation (top left), Cork insulation (bottom left), Recycled Glass (top right), Calsitherm (bottom right)

“From our point of view, we don’t have any personal expertise in these areas. And we’re really busy. We’ve got a young family and we’ve got jobs and we needed a really supportive structure to embark on something this ambitious. I honestly think we wouldn’t have had the courage to do a project like this on our own. We wouldn’t have had the time.”

Cork Insulation

They also used cork insulation in the basement and bathrooms as it is most suited to humid conditions. The cork is natural and stripped from the bark of trees, which can renew when the tree grows again.

Recycled Glass

Under the cellar floor is a new structure made from recycled glass. This forms a honeycomb structure that helps insulate and prevent moisture from coming through.

Why Cosy Homes Oxfordshire?

The owners appreciated the expertise, experience and dedication of the Cosy Homes team who were able to manage the project from start to finish. This was appreciated given the overall size and technical demands of the project.

“I think what we’ve particularly appreciated is how much technical expertise and experience he brought to the project. Geordie obviously has a long history of working with different kinds of property and he tends to understand a lot of the issues that we don’t necessarily have expertise in, and it’s been very personal as well, which always helps.”

Their Retrofit Coordinator, Geordie Stewart, provided essential expertise and experience in a bespoke approach enabling change to happen.

Retrofit Scheme Manager, Geordie Stewart
Geordie was recognised as Retrofit Coordinator of the year for his work with Cosy Homes at The Retrofit Academy Awards 2022

The impact

When a Whole House Plan was created for their home the energy and carbon savings were estimated – if they carried out the actions set out.

The retrofit can be seen to save a significant amount of carbon dioxide from entering the atmosphere through reduced energy use.

Savings are based on energy bill rates prevalent on the market at the time the Whole House Plan report was published.

Find out more

If you’re interested in retrofitting your home and you live in Oxfordshire, you can get in touch with our expert team to consider your options.

An example of a Whole House Plan with estimated savings for Fuel Bills and Carbon emissions.

Want to get started?

If you’re interested in retrofitting your home and you live in Oxfordshire, you can get in touch with our expert team to consider your options.

Our Free Plan Builder can help Oxfordshire residents build an energy efficiency plan for their homes.

Simply put in your postcode and you’ll see everything we know about the current energy efficiency and performance of your home, based on existing data. Then, choose your budget and priorities and the Plan Builder will create a draft retrofit plan for your home – which you can edit to suit your needs.

Read more retrofit stories

  • Orchard House retrofit

    Mary and Philip opted for an assessment, which led to the development of a comprehensive Whole House Plan crafted by a qualified Retrofit Coordinator. This plan outlined all the necessary recommendations, actions, quotes, and
  • Maureen Dyroff Thermal camera house

    Maureen’s Whole House Plan story

    Concerned about climate change and eager to cut both carbon emissions and fuel bills, Maureen decided to investigate her home’s energy efficiency. A thermal imaging camera had highlighted an urgent need for improved insulation, and she also was considering

Get your free draft retrofit plan

Curious about what home retrofit could do for your home’s energy bills and carbon emissions? Get started by using our Plan Builder to create a draft home retrofit plan, and then submit your plan to our team to start the Cosy Homes process.

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