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Published on September 12th, 2023

A to Z of Retrofit

Home retrofit is the process of upgrading and modifying a number of aspects of the home in order to make it more energy efficient, lower its bills, and make the house warmer in winter and cooler in summer all while reducing its carbon emissions.

10 mins Retrofit Guides How to be more energy efficient Reduce my energy bills Handy Guides

Home retrofit is the process of upgrading and modifying a number of aspects of the home in order to make it more energy efficient, lower its bills, and make the house warmer in winter and cooler in summer all while reducing its carbon emissions.

These changes are wide ranging and sometimes complicated. Changes can include the home’s structure and insulation; its heating, ventilation and cooling systems; or appliances around the house such as energy saving lighting or washing machines and fridges.

In order to help you understand what your home needs and help you with the contractor lingo we’ve created an A-Z of home retrofit measures so you know your underfloor heating from your energy efficient landscaping.

A is for

Air Source Heat Pump

An air-source pump uses the air outside the house as the source for collecting heat, and as the ‘sink’ to replace the heat indoors if they’re being used to cool the internal climate. Air-source heat pumps come in two forms - Air to Air Heat Pumps and Air to Water heat-pumps. In the UK, you’re likely to find more Air to Water heat pumps as our existing heating systems are water based.

The benefits of Air-Source Heat Pumps is that they are more environmentally friendly than boilers as they don’t require fuel to burn to create heat. They can also be more cost effective as they generate more energy than they use.


Is the process we use at Furbnow to monitor the effectiveness of your retrofit changes to show your return on investment and the energy and emissions you’ve reduced. We use smart meter data and air quality and temperature sensors to track improvements in your home.

B is for

Battery Storage

Home battery storage enables you to actively store excess electricity that you generate throughout the day from home generation (like solar panels). That energy can then be used later when the panels aren’t generating enough power - such as in the evenings or on cloudy days.

Battery storage is great if you want to be more self-sufficient and, especially if you use more electricity in the evening than in the day, you’ll be able to use the energy stored in the battery, rather than relying on the national grid.

There are several types of solar storage batteries, including lithium-ion, lead-acid and flow batteries. Lithium-ion batteries are the most commonly used type of solar storage battery due to their high energy density, long lifespan, and low maintenance requirements.

The capacity of a solar storage battery is typically measured in kilowatt-hours (kWh) and varies depending on the size of the solar power system and the energy needs of the user. The larger the battery, the more energy it can store, and the longer it can provide energy for.

The average battery currently holds 10 kWh, which is pretty good going when you consider that the average hourly use in the UK is 0.43 kWh. Theoretically from a full charge you’ll be able to power your house for approximately 20 hours - although energy usage does tend to be higher in the evening.

Boiler Upgrade Scheme (BUS)

The Boiler Upgrade Scheme is aimed at reducing the upfront cost of installing a low carbon heating system such as heat pumps or more energy efficient boilers. You can get:

£5,000 off the cost of installing an air source heat pump

You’re eligible for the grant if you live in England or Wales and you own your property.

C is for

Cavity Wall Insulation

Cavity Wall insulation is a layer of insulation material inserted between an exterior and interior wall to help keep the house warm by preventing heat loss.

It exists in houses built post-1990 as a more effective way of keeping heat in - compared to previous buildings which were built with a thicker exterior wall to help keep it warm

The insulation material is usually mineral wool (the stuff you’ll find in your attic) but it can also be made up of beads and granules, or foam.

It’s installed by drilling a small hole in your wall and then blowing it in.

Cavity Wall Insulation isn’t suitable for properties in especially rainy areas as the chances of it getting wet are hugely increased.

D is for

Demand Controlled Ventilation

Demand Controlled Ventilation manually or automatically manages the airflow in a property to meet the exact need at a given time. If one room is empty and another is full, or if one room isn’t used much throughout the year then the ventilation system will channel the airflow to this part of the property.

This creates a more energy efficient house as it reduces the amount spent on heating and cooling specific rooms and ensures there’s no build up of damp or condensation which can lead to structural issues later on.

Double Glazing

Double glazing means adding two layers of glass in a window frame. Adding another layer of glass in windows and glass doors, helps reduce noise, retain heat and improve security.

The process involves removing your existing windows before a new frame is installed in the brickwork, and then finally, the new glass will be fitted into place.

Double glazing was first introduced in the UK in the 1980s, with triple-glazing becoming increasingly popular in recent years for additional energy efficiency or noise reduction.

Draught Proofing

Draught proofing in its most basic form is simply blocking or sealing any gaps where air or heat might escape from your home. This can reduce the amount of energy you use to heat up a room as none of it escapes, this in turn keeps your heating costs down and your emissions down too.

A lot of draught proofing can be done yourself, be it fitting plastic strips around the edge of your windows or putting a draught excluder along the bottom of your external doors. Some of this can be done professionally such as having insulation fitted around your attic hatch or having your front door replaced all together.

E is for

Electric Vehicle Charging (EV)

EV home charging allows you to charge your electric car at home with miles of range to use the following day. The charger links up to your mains and powers your car through a connector cable.

If you have off street parking this can be retrofitted on the wall adjacent to where you park your car. You can also use this in tandem with a home battery and Solar PV system storing energy generated at home and using it to charge your car without it costing you from the grid.

Energy Performance Certificate (EPC)

​​Energy Performance Certificates range from A to G, with A being the most energy efficient a house can be and G being the worst. These certificates take into account insulation, the windows and fabrics of the building as well as the boiler and generation.

EPCs were brought in by the government in 2007 following a directive by the European Union on the energy performance of buildings. The aim was to make people more informed about how energy efficient their home is. It’s generally understood now that any property below C is energy inefficient.

An EPC is broken down into four sections:

You can find your property’s EPC rating here:

Energy Efficient Lighting

Energy Efficient Lighting is a retrofit measure you can do yourself and can save you money each year. By replacing older incandescent light bulbs with longer lasting ones your home should use less energy to power them, which should reduce your bills and carbon emissions.

There are two main types of energy-efficient lighting: light emitting diodes (LEDs) and compact fluorescent lamps (CFLs).

External Wall Insulation

External wall insulation is cladding that is attached to the outside wall of your home in order to better retain heat and protect against the elements, as well as upgrade the aesthetics of the house. External Insulation is most suitable for solid walls - which tend to have been built before 1920 - and involves fixing a layer of insulation material to the outside wall, before covering it in render (plasterwork), or cladding. Depending on your chosen finish, it can be tailored to your requirements - smooth, textured, painted, tiled, panelled or pebble-dashed.

Depending on your property, External insulation can take between 3 and 6 weeks. External Insulation is about £100 per sq. metre. On average, External insulation costs £12,000,According to the Energy Saving Trust - adding solid wall insulation could save you between £930 (Detached) and £240 (mid-floor flat) per year in energy costs, so as well as feeling the immediate benefits, you’re likely to have the difference paid off in about 10 years.

F is for

Fabric First

The "fabric-first" approach to retrofit is a sustainable building strategy that prioritises enhancing the thermal and structural performance of a building's existing "fabric" or envelope (i.e., walls, roofs, floors, and windows) before implementing other energy efficiency measures. This approach focuses on improving the fundamental building elements responsible for heat retention, air tightness, and moisture control.

By strengthening the building envelope first, the fabric-first approach aims to reduce energy consumption, enhance occupant comfort, and minimise environmental impact. It often involves measures such as adding insulation, sealing gaps and cracks, and upgrading windows and doors to optimise a building's energy efficiency and sustainability while preserving its architectural integrity.

Flat Roof Insulation

Flat roof insulation is used to reduce a property’s heat loss through the roof and increase the property’s energy efficiency. There are two ways of doing this:

1. Warm Flat Roof Insulation - this involves adding insulation material to the outside of the roof which is the most effective in reducing energy use.

  1. Cold Flat Roof Insulation - this involves fitting insulation within the joists of the roof, this is cheaper to install.

Floor Insulation

Floor Insulation involves inserting a layer of insulating material like mineral wool or natural fibres in the space between your floorboards and the ground below in order to better retain heat. If you have solid floors you can insert insulation over the top of it before adding another layer of flooring over the top.

Floor insulation stops or slows the transfer of heat out of your home through the ground.


Furbnow is a one-stop-home-retrofit shop that offers support throughout your retrofit journey. We start by assessing your home to show what it really needs, before providing you with a plan to show how it can be improved, what the costs and timelines are and what the payback is. We then carry out the work we outline and offer after care and monitoring to ensure you get the full payback and energy efficient home you need.

G is for

Generation (Home)

Home generation refers to generating electricity from either wind, sun or water via technologies such as solar, wind turbines or hydroelectric. These can be used to power appliances around the house, including electric vehicles. This reduces your dependency on the grid and lowers your bills as you import less energy.

You can also receive payments for any excess energy that you export into the grid via your energy supplier. For those who installed home generation pre-2019 you might be paid via the Feed-in-Tariff (FIT) scheme, and if you had your generation installed after 2019 you’ll be paid via the Smart Export Guarantee (SEG).

These are also clean forms of energy generation meaning you’ll reduce your home carbon emissions too.

Great British Insulation Scheme

The Great British Insulation scheme, previously known as ECO+, is a government scheme to help home’s reduce their energy usage by installing energy efficiency measures like insulation. The £1 billion scheme is expected to help around 300,000 homes in the UK and is focused on helping those on the lowest incomes or with homes with the lowest energy ratings (D and below).

The scheme works by obligating energy suppliers to help customers make their homes more energy efficient, distributing their share of the £1 billion to install things like cavity wall insulation and other retrofit measures.

Green Financing

Green home finance is money put in place by banks, lenders and financial institutions to help and facilitate investments in construction of green homes, or activities like home retrofit that lower the environmental impact of homes through reducing energy consumption and therefore carbon emissions.

A common green finance product is the ‘green mortgage’. The incentives for banks is that if you have a more energy efficient home you’ll have more money to put towards your mortgage as you’re spending less on bills. And the incentive for homeowners is that you’ll have a better mortgage as a result of the changes you make, so remortgaging to a green mortgage can free up cash initially and give you a better fixed deal on your home.

Ground Source Heat Pump

A ground source heat pump (or ground-to-water heat pump) transfers heat from the ground around your home to heat your radiators or, if you have it, underfloor heating. It also heats water for your hot taps and showers.

A network of pipes are buried underground next to your home. These pipes are then pumped full of water and antifreeze, creating a mixture called Thermal Transfer Fluid (TTF). The TTF moves around the pipes, absorbing the naturally occurring heat that is stored in the ground.

When it reaches the pump, this mixture is then compressed (similar to the air source pump) and then pushed through the heat exchanger which removes the heat and transfers it to the heat pump, where it is then pushed into the home heating system.

H is for

Healthy Home

A healthy home is one that has been made fully energy efficient and is up to date with its maintenance. It should be well ventilated, fully insulated and have the most efficient, clean generation system. There should be no need for major repairs and most importantly it should be comfortable to live in.

Heat Loss

Heat loss happens when heat that is generated inside your home is transferred through walls and windows and fabric of your property, known as fabric heat loss. Heat loss is also transferred, via draughts of air, through gaps in the fabric, which is then replaced by cooler outside air from outside, known as ventilation and infiltration losses.

These can be improved through home retrofit measures such as improving insulation in the walls of your home, and through improved windows that have at least double glazing and trickle air vents. It’s also worth looking at your external doors which are a major source of heat loss.

Heating and Hot Water Controls

Heating controls monitor the level of heat coming from your boiler that heats your home and your water. On a basic level heating controls prompt the boiler to switch on and go off though a thermostat. A thermostat is set to the desired temperature in a room and it will ensure the boiler comes on in that room until the temperature is reached. Once the room reaches that temperature the thermostat will tell the boiler to go off again. At their most sophisticated, these heating controls can be used to set different rooms to different temperatures depending on whether they’re in use, and can keep your home regulated at a specific temperature rather than turning the heating on and off again.

Heat Pump

A heat pump is a machine that can heat a home by transferring outside energy into the house as heat. It can be used in the place of a boiler or air conditioning unit.

There are three types of heat pump; ground source, air source and hybrid. A ground source heat pump takes energy from the ground, an air source heat pump from the air, and a hybrid does a combination of the two. Because heat pumps use less energy to power themselves than the energy they create in the house, and because they use pre-existing energy, it burns no fuel and therefore creates no emissions.

Heat Pump Installer

A Heat Pump Installer oversees the installation and commissioning of heat pump systems. They ensure heat pumps are fitted in line with manufacturer guidelines, and are responsible for servicing, repairs and ongoing maintenance.

Their role also includes ensuring risk assessment and safety plans are in place - and they will work closely with heat pump coordinators, customer service teams and project managers to provide a professional service.

Home Assessment

A retrofit assessment involves an assessor performing an in-depth inspection of your property to find out what changes are needed to make it more energy efficient. ‍As part of the assessment the assessor will talk to you about your plans for the home and any constraints on getting work done. They’ll then perform a Standard Assessment Procedure (SAP) inspection, a ventilation inception and may use thermal imaging to assess how energy efficient the property is, and how it can be improved. ‍

The retrofit assessor will spend the first half of the visit talking with you about your property, your aspirations for the home and what obstacles exist to getting certain jobs done (these could be financial, structural or time constraints). They’ll then conduct a Reduced Standard Assessment Procedure (RdSAP) inspection. This looks at how much energy your house is using to reach a specific level of heat. The assessor will also carry out a ventilation report, to see how you house handles damp and the like.

You can see all the changes needed rather than committing to one job and finding there’s still work to do. You get a plan that shows the return on investment in your bills and your property value. Your assessor can provide the accredited contractors to carry out the work rather than finding your own.

Home Energy Plan

Once we’ve assessed your home and analysed the information we’ve found on it, we’ll organise this information into a plan we’ll send it back to you as part of your home energy dashboard. This looks at:

Your current energy efficiency, house value, carbon emissions and what work needs to be carried out:

- The level of improvement you can achieve in terms of energy efficiency, carbon emissions and house value

You can then choose if you want to carry out the work through us or through your own contractors, or if you want to carry out the work at all. At least you’ll know where you stand.

Home Energy Storage

Home Energy Storage is the practice of storing electrical energy generated at home for later use. A typical solution is a battery attached to solar panels to store excess energy that is generated during the day. That energy can then be used later when the panels aren’t generating enough power - such as in the evenings or on cloudy days.

There are several types of batteries, including lithium-ion, lead-acid and flow batteries. Lithium-ion batteries are the most commonly used type of solar storage battery due to their high energy density, long lifespan, and low maintenance requirements.

The capacity of a battery is typically measured in kilowatt-hours (kWh) and varies depending on the size of the solar power system and the energy needs of the user. The larger the battery, the more energy it can store, and the longer it can provide energy for.

The average battery currently holds 10 kWh, which is pretty good going when you consider that the average hourly use in the UK is 0.43 kWh. Theoretically from a full charge you’ll be able to power your house for approximately 20 hours - although energy usage does tend to be higher in the evening!

I is for

Internal Wall Insulation

Internal Insulation is the process of fitting insulation material inside the walls of your house, and is one of the better ways of ensuring your house retains energy. It is different from cavity wall insulation, which puts insulation between cavity walls. Internal insulation can reduce floorspace slightly.

Internal Insulation either involves attaching rigid insulation boards to the wall inside, or building a stud wall and filling it with insulation material such as mineral wool fibre. If you opt for a stud wall, it needs to be at least 120 cm thick to be effective, so bear that in mind when considering which direction to take.

J is for


Building junctions are where walls meet roofs, floors, etc. - often these need insulation and attention to reduce heat loss and prevent thermal bridging.

K is for

Kilowatt-hour (kWh)

A unit of energy commonly used to measure electricity consumption. When retrofits involve energy-efficient measures, reductions in kWh are often reported.

K-Value (Thermal Conductance)

A measure of how easily heat can flow through a material. Lower K-values mean better insulating properties.

L is for

Loft Insulation

Loft Insulation (aka attic insulation) is the placing insulation material within the loft. Typically this material is placed between the rafters and joists.

It is placed to help reduce the amount of heat lost from the attic - thus keeping the house warmer.

Loft insulation can be made from many materials, including fibreglass, mineral wool, cellulose, foam and reflective foil. The type chosen is dependent on budget, effectiveness and climate.

Landscaping (Energy Efficient)

Energy efficient landscaping is an environmentally friendly and sustainable type of landscaping. It prioritises the optimisation of natural resources and promotes mimimizing energy consumption to create aesthetically pleasing, and functional, outdoor spaces.

It focuses on practices such as:

Appropriate plants
for the climate and soil. The practice leans towards native and drought-tolerant plants as they require less maintenance and water.

Effective irrigation. It prioritises efficient watering systems such as drip systems or smart irrigation controllers which adjust settings depending on the weather.

Using foliage as windbreaks and shade. Strategically placed trees and other vegetation can regulate temperature in buildings, reducing the need for internal climate control.

Permeable surfaces. Utilising materials such as gravel or porous asphalt allows rainwater to soak into the ground.

Green Exteriors. Installation of vertical and roof gardens can enchance insulation and improve energy efficiency.

Rainwater Harvesting. The collection of rainwater in cisterns or barrels to reuse in irrigation.

Wildlife Habitats. The creation of a wildlife-friendly environment with the addition of native species, and amenities such as bird baths and shelter.

Leadership in Energy and Design LEED Certification

LEED is the world's most widely used green building rating syste. Available for virtually all building types, LEED certification provides a framework for healthy, highly efficient, and cost-saving green buildings, which offer environmental, social and governance benefits. LEED certification is a globally recognized symbol of sustainability achievement, and it is backed by an entire industry of committed organisations and individuals paving the way for market transformation.

M is for


Furbnow monitors the effectiveness of your retrofit changes to show your return on investment and the energy and emissions you’ve reduced.

We use smart meter data and air quality and temperature sensors to track improvements in your home. Home Monitoring means we stick to our service promise of making your home more energy efficient and you get a clear picture of your home’s health.

We work to ensure everything is to the highest standard, but if something doesn’t seem right we’ll capture it through the Home Monitoring or you can report it to us directly.

N is for

Nest Thermostat

The Nest Thermostat is a ‘smart’ self-learning thermostat that learns a property’s ideal temperature and the inhabitants routines and optimises its schedule to provide the most efficient use of energy.

It is compatible with most standard central heating systems, and can be set to run automatically or controlled manually via an app.

It can help provide suggestions to reduce energy usage and therefore, bills and carbon footprint.

New Home Buyers Report

Our HomeBuyer Retrofit Plan makes sure you're in a strong position to complete your home purchase and plan renovations that will improve your new home's energy performance.

The EPC and RICS survey can give you an indication of energy performance and building condition but often comes short in understanding how to actually plan and start your renovation project.

Our HomeBuyer Retrofit Plan can help understand how energy efficiency improvements can integrate with the suggested building condition improvement measures from your RICS report. Make sure you're in a strong position to complete your new home purchase.

Use the results from your RICS HomeBuyer report or Building Survey to understand what energy efficiency measures are suitable for your new home and a high-level plan of where to start.

O is for

Occupancy Modelling Approaches

Occupancy modelling is where designers and engineers take into account how the occupier of a property behaves within their home. This allows for design around when the occupier is in the property throughout the week, when they use most energy or when they use specific features of the home or room. Occupancy patterns and occupant behaviour are even more critical to energy and thermal performance in models that include occupancy-based controls. Modelling approaches associated with occupancy can consider temporal, spatial and occupancy resolution.

P is for

Passive Home

A passive home (aka “Passive House“) is a building standard and design approach focused on high levels of energy efficiency, indoor air quality and comfort, alongside a significant reduction of energy consumption for heating and cooling.

They are designed to maintain a consistent indoor temperature without traditional systems such as boilers or air conditioners.

Instead they utilize passive design principles such as insulation, airtight construction and energy recovery systems.

Some key principles include:

Superior Insulation
- A Passive House is heavily insulated across the main structure: walls, floors and roofs - with a focus on airtight construction. This is also applied to the windows and doors, where triple-glazing is used.

All of these measures combined minimises heat loss in the winter and heat gain in the summer.

Ventilation. A mechanical ventilation system with hear recovery ensures the air is continually refreshed whilst recovering hear from the outgoing air.

Solar Design. Utilising passive solar heating (via south-facing windows) and thermal mass (materials that can store and release heat) allow effective capture of solar heat during the day.

Energy Efficient Appliances: All appliances and lighting are highly energy efficient to reduce energy consumption as much as possible.

Thermal Bridge-Free Construction. Special attention is paid to the removal of thermal bridges (as such as corners where heat can easily escape).

Quality Control. A high level of quality control is applied to all buildings constructed under the Passive House standard.

PAS 2035

PAS 2035 is a code of practice created to ensure that retrofit standards and approaches on UK housing stock are done to a consistent standard. It was created in 2015 to address a previous lack of consistency in retrofit projects.

Project Support

Once you’ve received your Home Energy Plan from us, outlining what your home needs and how it can be improved we offer project support to get your home to where it needs to be. We have two options:

Full project management: We organise the work, the deadlines and the entire installation and process and aftercare, only involving you as much as you want.


Project Support: You'll find the contractors and we'll help advise you throughout the process to make sure it all goes to plan.

Q is for

Quality Assurance

Ensuring that retrofit works are completed to the highest standard and performance.

R is for

Rainwater Harvesting

Rainwater Harvesting is the sustainable practice of collecting rainwater that falls on rooftops paved areas for later use.

The easiest way of collecting rainwater is via a roof, gutters and downpipes. It is then stored in a container such as a rainwater barrel.

Once stored, it is generally used for non-potable applications such as washing clothes, toilet flushing and watering the garden.

An additional benefit of collecting rainwater is the reduction of water into sewers and drains, reducing the risk of flooding.


Retrofit is the process of upgrading existing buildings with technology, whilst also focusing on a ‘fabric first’ approach: ensuring heat preservation is prioritised over heat creation. This increases energy efficiency, and reduces carbon impact with a reduced requirement for heating.

Retrofitting existing structures reduces the environmental footprint of our current stock and the energy efficiency improved, with the happy byproduct of lower bills.

Retrofit Assessor

A Retrofit Assessor carries out the PAS2035 required survey on properties which informs the decision making on what retrofit measures are suitable for a property.

The survey is a key part of the retrofit process as it lays the groundwork for the work that is to follow and provides an assessment of the condition, occupancy and significance of a building inline with PAS2035 standards.

They work under a Retrofit Coordinator.

Retrofit Coordinator

A retrofit coordinator holds accountability for making sure that a retrofit project runs smoothly.

They will have worked in retrofit or other energy efficiency projects for a number of years to give them the relevant experience for the job.

Utilising the information provided by the retrofit assessor, they will build an appropriate plan for how the project should proceed. They need to have a deep understanding of energy efficiency measures, compliance and building codes‍.

As well as managing the budget and contractors on a retrofit installation, they will give final confirmation that the project is compliant with the PAS2035 standards. Once the project is completed, they will run a ‘
post-occupancy evaluation’ to check everything is functioning as expected, that the project ran as intended and to collate and report any learnings that would be useful for future projects

Retrofit Surveyor

See Retrofit Assessor.

Retrofit One-Stop-Shop

A Retrofit One-stop-shop is a service that makes the process of retrofit easy.

Instead of not knowing where to start, speaking to a multitude of contractors, assessors and experts, the one-stop-shop will do the leg work for you and provide you with a tailored list of options and a defined plan based upon your requirements.

Examples include Furbnow.

S is for

Smart Meter

A smart-meter is a device used to measure a property's energy usage. This can be electricity, gas or water consumption. It provides real-time data which is transmitted to your energy supplier, allowing more accurate meter readings for utility companies and ensuring that the home-dweller can see their energy usage and adapt habits accordingly if they want to reduce energy consumption for cost or environmental reasons.

Solar Panels

Solar Panels are panels of semi-conductive material (usually silicon) designed to create electricity when light shines on it. The stronger the light, the more efficient the connection, and the more electricity is created. This does still mean that you can generate electricity even on a cloudy day from solar panels.

Typically each panel creates 265 watts a day - although in bright sunlight it can go above 350 watts. Most systems commonly have between 6 and 12 panels installed. You can either utilise this electricity in your home, or sell it back to the grid. The current generated is DC, so an inverter is also installed as part of the process, to turn it into AC for use in the home. This can then be stored in a solar battery, for your system to use.

The benefits of solar panels are that they reduce your bills as you export less energy from the grid so have to pay your energy supplier less. They’re also clean sources of energy so you reduce your household carbon emissions too.

Solid Floor Insulation

Solid Floor Insulation is required if you have concrete floors. It is made of rigid insulation foam.

In an existing solid floor, the insulation will be placed on top of the existing floor and chipboard laid on top. This will raise the floor height so skirting boards and sockets will need to be assessed prior to installation.

In a new-build or floor replacement work, insulation will either be installed above or below the concrete.

If it’s below the concrete, it may store heat during the day which will help raise the temperature at night.

If it’s above the concrete, the room will heat faster in the morning.

It is usually advised to lay a damp-proof membrane beneath the insulation.

Solid Wall Insulation

Solid Wall Insulation is required for homes built before the 1920’s - therefore before cavity walls became standard in new-builds.

External insulation involves placing solid insulation boards on the external wall before covering it with render, reinforcing mesh and potentially a new render.

Internal insulation is similar with the addition of a solid insulation board or by creating a stud-wall and filling that with mineral insulation or similar.

Generally exterior insulation boards are preferred as there is less disruption to the house in installing these. Internal insulation will reduce the usable space in the room they are placed in and with a stud wall, reduce the space available for shelves. Stud walls are not suitable to hang heavy objects on.

Sound proofing

Sound proofing is an important part of home retrofit. It involves reducing the amount of sound that comes in and out of your home so that you can have a more comfortable, peaceful experience. Or you can turn your music up and party a bit more if preferred.

Things like double and triple glazing, and insulation can reduce the amount of noise coming in and your of your property, meaning you’re less likely to be disturbed by traffic outside.

Super Homes

Super Homes refers to a network of homeowners who have refurbished their houses to the highest standard of energy efficiency – meaning that little energy is being wasted in the home, and there is no reliance on fossil fuels for energy.

Originally set up in 2007 to raise awareness of how homeowners could reduce their household carbon emissions by 60-80%, and inspire others to do the same. In the first stage, 222 homes were given SuperHomes status.

The project was relaunched in 2021 with the support of the National Energy Foundation.

Suspended Floor Insulation

Suspended Floor Insulation is required in the event of floorboards (suspended floors) rather than concrete.

As they are less effective at maintaining heat (due to being above a void) the space between the joists should be filled with insulation.

This usually takes the form of mineral or sheeps wool, but can also be hemp, recycled plastic bottles, rigid insulation boards or spray-foam insulation.

It is important to ensure enough ventilation is available, otherwise the floorboards will rot.

T is for

Triple Glazing

Triple Glazing is very simple, two or three layers of glass in a window frame. Adding another layer of glass in windows and glass doors, helps reduce noise, retain heat and improve security. Double glazing was first introduced in the UK in the 1980s, with triple-glazing becoming increasingly popular in recent years for additional energy efficiency or noise reduction. There is quite a cost difference between the two, and double glazing is still the standard across much of the UK.

Thermal imaging

Thermal imaging, sometimes referred to as infrared thermography, is a tool that can be used in a home energy assessment. It allows assessors to visually identify areas of a home where energy is being lost. The imaging can identify why that energy is being lost also, be it down to inadequate insulation, air leaks, or other issues that can lead to higher energy bills and discomfort for the homeowners

Thermal bridging

Thermal bridging, in the context of building and construction, refers to a situation where a pathway of significantly higher heat conductivity allows heat to bypass or "bridge" around insulation materials within a building's envelope. These pathways typically occur at structural elements such as wall studs, concrete beams, or metal framing, which conduct heat more efficiently than insulation materials like fibreglass or foam.

This means that in areas where thermal bridging occurs, heat can escape or enter a building more easily than in the insulated sections, leading to temperature variations, reduced energy efficiency, and potential issues like condensation or mould growth. Thermal bridging is a critical consideration in building design and retrofitting to ensure effective insulation and optimal energy performance.

U is for

Underfloor Heating

Underfloor heating can either be a heating system that makes your floor warm, or it can be your primary heat source, replacing your radiators. ‍Underfloor heating either comes as electric cables that generate heat, or as a water system that uses piping and a pump to push the hot water around each floor. ‍

V is for


Ventilation refers to the process of providing controlled airflow from the interior to exterior of a building to keep air quality high, remove pollutants and maintain internal comfort.

It is also required in floor, wall and attic insulation installation to allow effective moisture control and prevent rotting.

It generally takes the form of mechanical ventilation (heat, ducts or natural ventilation solutions such as windows or vents.

W is for

Whole house approach

The whole house approach is when you take into account the entire home and all its interacting parts when carrying out work to make improvements. This includes looking at the fabric of the building, the insulation, the heating system, the ventilation and airtightness.

By looking at the home in its entirety you can ensure all the components work together optimally. By making changes piecemeal you may find that there are discrepancies between the changes made or that the changes have negative impacts on each other. It’s also more cost effective to take a whole house approach as you don’t have to pay for new contractors and equipment each time. It’s also less disruptive to have builders in just the once.

X is for


Xeriscaping is the practice of designing landscapes that reduce or remove the need for irrigation. This means that the natural climate is able to provide enough water to nourish its vegetation.

In locations that experience little waterfall, it has become a viable alternative to landscapes which require much water (such as lawns).

It has become popular due to its ability to self-sustain, with water use being reduced by between 50% and 75%.

Examples of xeriscaping plants include cacti, agave and juniper.

Y is for


In the context of energy retrofits, this could refer to the amount of energy produced (as in the case of solar panels) or the return on investment for a particular retrofit measure.

Yearly Energy Consumption

A metric that homeowners or businesses might look at when determining the success of a retrofit project in terms of energy savings.

Z is for

Zero Emissions

The UK government aims to achieve Net Zero Emissions by 2050. In order to achieve this they need to decarbonise the country’s housing stock, along with all other industries.

This means that 1.8 homes will need to be retrofitted every minute between now and 2050.

Written by

Oisin Teevan