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Britain’s housing stock is old and draughty. Nearly a third of the UK’s total carbon emissions come from our homes. So, what can we do about it?

We must act now to combat climate change, say environmental campaigners from Greta Thunberg to David Attenborough and King Charles. We’re told we should invest in loft and cavity wall insulation, draught proof windows and doors, and turn down our central heating a degree or two. Moreover the UK Government wants homeowners to swap fossil fuel boilers for cleaner, greener heat pumps. And with gas and electricity prices soaring, there’s a clear financial incentive to make our homes more energy efficient.

But there are many conflicting opinions on how best to do this. The Government’s failed £2bn Green Home Grant scheme ended in chaos with companies involved in installing heat pumps and solar panels owed tens of thousands of pounds. Yet one home will need to be retrofitted every 35 seconds between 2020 and 2050 to meet the government’s net zero carbon emissions by 2050, say the Passivhaus Trust. The Federation of Master Builders (FMB) is campaigning for a national strategy to retrofit homes to make them warmer, greener and cheaper to run.

Assess your home’s energy efficiency

The first step in eco-retrofitting your home is to understand its current energy performance and identify areas for improvement. There are several different ways of doing this:-

An Energy Performance Certificate (EPC) tells you how energy efficient your property is and will give it a rating from A (very efficient) to G (inefficient). It will estimate how expensive it is to heat and light the property and what its carbon emissions are likely to be. It’s possible to access any home’s EPC through the government’s website. https://www.gov.uk/find-energy-certificate.

Currently 46% of homes in the UK have an EPC of C or above. This is up significantly from 13% in 2010, but there’s still lots of work to do to reduce carbon emissions from heating our homes, says the Energy Performance Trust. Based on its Clean Growth Strategy, the UK Government’s target is to get all homes to EPC C or above by 2035. For rented homes the target is 2030.

An EPC also includes information on what the energy efficiency could be if you made recommended improvements and highlights cheaper ways to achieve a better rating. In addition to lower energy bills, a good EPC rating can improve your property value and may make it possible to achieve lower mortgage rates through green mortgages.

Bear in mind that any figures for energy use and potential savings are for a typical household in that property – they’re not specific to you, your family or housemates or lifestyle.

Eco-retrofit assessment and plan

It’s possible to make relatively quick and cheap improvements, such as switching to LED bulbs or adding draughtproofing around windows and doors, but the biggest benefits come from what is known as “whole house” retrofits. “It may cause problems if you take energy efficiency measures one by one without attention to how they’ll interact,” says the Centre for Alternative Technology. For example, heat pumps don’t work well in poorly insulated homes because the devices work at lower temperatures and so will struggle to keep the house warm and comfortable. They work best with lower temperature systems, such as underfloor heating. This sort of pitfall can be avoided by what is called a “whole house” retrofit.

A specialist architect or qualified retrofit assessor and coordinator will draw up a structured improvement plan. Be prepared to answer questions about your household, lifestyle and energy use. They will also conduct a full house survey to look at all aspects of the insulation, draught-proofing, ventilation, heating and hot water system and provide you with expert advice on the best way to reduce your fuel bills and carbon emissions.

TrustMark is a government-endorsed quality scheme for work carried out in the home – and it now covers professionals who carry out energy efficiency work, including retrofits. It’s being linked to a new standard PAS 2035: Specification for the Energy Retrofit of Domestic Buildings. This standard is for a whole house retrofit. However, the cost of such a retrofit can be daunting – running into tens of thousands of pounds.

Retrofit step by step

If you can’t afford a whole house retrofit, it can be done step by step. With the help of an expert retrofit survey and plan, allocate your budget to where it will have the most benefit and set priorities. This will help you plan how one stage can lead to another. For example, starting with loft and cavity wall insulation which are relatively inexpensive and then planning later stages if you have the budget. Concentrate first on the building fabric, says the Centre for Alternative Technology. This means focusing on insulation, airtightness and ventilation, including risks from cold bridging. 

When improving the building fabric, think about the plumbing needed for a heat pump and underfloor heating or a biomass boiler and solar thermal energy.

Key retrofit measures:-

Insulate your home:

Insulation is a key element of any retrofit scheme. Bringing a poorly insulated home up to scratch can cost thousands of pounds but should eventually pay for itself in lower energy bills. Expect to pay around £300 to £340 to insulate a loft in a three-bedroom detached house. To add cavity wall insulation to a similar sized house could cost between £450 and £500.

 External insulation and cladding are much more expensive than cavity wall insulation. But if a qualified and TradeMark scheme certified installer has surveyed your property and says it is the best option, it’s a great way to improve your home’s thermal performance – like covering it in a tea cosy. Expect to pay £7,000-£15,000.

 To avoid cold bridging, also known as thermal bridging, it’s important to get the insulation detailing right, say experts. Cold bridging is weak spots in the insulation surrounding a house, leading to heat loss. These occur when there is a break in continuity in the building envelope, for example at roof/wall and the wall/floor junctions. Other potential cold spots include where joists penetrate a wall, holes for pipes and cables.

 Upgrade your windows:

Windows are a major source of heat loss in many homes. Upgrading your windows to double-glazed or triple-glazed units can help to reduce energy costs and improve comfort. Additionally, consider installing low-emissivity or low-E glass. According to website Greenspec: “By coating the face of the inner pane of glass with metal or metal oxide, short wave radiation from the sun enters the property while long wave radiation in the form of heat from inside is reflected back into the room.”

 Upgrading windows in historic houses or properties in conservation areas is trickier. Replacing windows to match the appearance of existing windows requires careful specification if they can’t be improved. Your architect or designer will need to consult with the local conservation officer.

 Switch to energy-efficient lighting:

As already mentioned, installing LED lights is a quick and affordable way to reduce your energy bills and reduce your carbon footprint. LED lights use much less energy than traditional incandescent bulbs and they last a lot longer, reducing the need for frequent replacements. Where possible, use natural light instead of artificial lighting to reduce your energy consumption. Skylights and larger, south-facing windows will let in more natural light.

 Water conservation:

Fixing leaks and dripping taps as well as water-saving devices, such as low-flow shower heads and dual flush toilets, can help to conserve water and reduce your energy bill.

 Choose natural building materials:

When eco-retrofitting your home, choose sustainable, natural materials. The main aim of a retrofit is to reduce energy use within a building. But embodied energy is a calculation of all the energy used to produce a material or product. Natural fibre materials, such as timber, straw and hemp, have less embodied energy and a smaller carbon footprint then synthetics ones like uPVC. They are also easier to reuse and recycle. Another important factor is the breathability of a building. Natural materials are less likely to trap moisture and create damp problems.

 Upgrade ventilation

Airtightness or reducing/eliminating air leaks is key to energy efficiency. Having a healthy home also requires good ventilation to maintain good air quality. Ventilation can either be natural, for example windows, or mechanical like fans. As airtightness improves, ventilation becomes more important. Homes built (or retrofitted) to ultra-energy Passivhaus standard will have a mechanical ventilation and heat recovery system. The air temperature is constant and there are no damp patches or mouldy corners. People who live in them often say the air quality is better.

 Install renewable energy systems:

Renewable energy systems, such as solar panels or heat pumps, can help to lower your carbon footprint and your energy costs. These systems can be expensive upfront, but the savings can be mount up, though the payback period is lengthy. However, the biggest improvement in energy efficiency will probably come from upgrading your insulation and double glazing.

Check if you are eligible for grants or funding to help with eco retrofit.

Currently there are remarkably few grants available. However, a new £1 billion ECO+ scheme will see hundreds of thousands of homes across the UK receive new home insulation and with that, lower bills, says government. The scheme, set to start in April 2023, will target the least energy efficient homes, those with an EPC rating of D or below – and in the lower council tax bands. The idea is to help households who  don’t currently receive any other government support to upgrade their homes. About a fifth of the fund will be targeted to those who are most vulnerable, including those on means tested benefits or in fuel poverty.

Eco retrofitting your home is a great way to reduce your carbon footprint, lower your energy bills and improve overall comfort levels. Getting an updated EPC certificate is a good first step to understand your home’s current energy use and identify areas for improvement. If you want a whole house eco retrofit, consider hiring a TrustMark certified energy assessor to survey your home and come up with a tailored plan for improvement. Take your time to understand the pros and cons of each measure and how they interact with each other before making any changes.