For the Press

Draught Proofing Advice is a free, plain-English guide to making UK homes less draughty. This page is for journalists and broadcasters: key figures with their sources, a summary of the research behind our chimney figures, an explanation of why draughts happen, and story ideas.

The site is run by Chimney Sheep, a Workington-based company that makes chimney draught excluders. We say so on every page; About this site explains how we keep the advice fair.

Press contact

For interviews, comment, images or help checking a figure:

Sally Phillips, founder of Chimney Sheep · info@chimneysheep.co.uk

Key facts

Each figure links to its source. Savings are for a typical home in Great Britain unless stated.

Fact	Figure	Source
Typical dual-fuel bill under the price cap, 1 October to 31 December 2026	£1,723 a year	Ofgem
Saving from draught-proofing windows, doors and floors	About £55 a year (£80 in Northern Ireland)	Energy Saving Trust
Saving from blocking an unused chimney	About £45 a year (£60 in Northern Ireland)	Energy Saving Trust
Saving from turning the thermostat down from 22°C to 21°C	About £120 a year	Energy Saving Trust
Cost of professional draught-proofing for a whole house’s windows and doors	Around £250	Energy Saving Trust
Heat lost through a traditional window that escapes through gaps rather than the glass	More than three-quarters	Historic England
Reduction in window air leakage from draught-proofing	33% to 50%	Historic England
Heat lost through an uninsulated roof	About a quarter	Energy Saving Trust
Households in fuel poverty in England, 2025	2.36 million (9.4%); average shortfall £379	DESNZ
Homes in England built before 1919	About 1 in 5 owner-occupied; about 1 in 3 privately rented	English Housing Survey
Heating energy saved by a wool chimney excluder, modelled	About 4% per chimney	University of Liverpool, 2024

University of Liverpool research

In September 2024 the University of Liverpool’s School of Architecture published a study of the energy, carbon and cost savings from blocking an unused chimney with a wool draught excluder. The authors are Dr Haniyeh Mohammadpourkarbasi and Professor Steve Sharples. It updates the university’s original 2013 study, which found a saving of about 5% using 2013 energy prices, with new modelling, house types and prices. Both studies were commissioned by Chimney Sheep.

Read the full report (PDF)

How the study worked

The researchers used dynamic thermal simulation software (DesignBuilder) to model three homes: a 19th-century terraced house as it is, the same house after a deep, airtight refurbishment, and a detached house. Each was modelled with one chimney, in the climates of Aberdeen, Liverpool and London, heated for a family of four. They compared an open chimney with one fitted with a Chimney Sheep wool excluder, and with one fully sealed.

What it found

Blocking the chimney cut heating energy by about 4% in every home modelled. In cash terms the saving depended mainly on how well insulated the house was:

Home modelled	Gas saved a year	Carbon saved a year	Value at October 2026 gas prices
Older terraced house	1,140 to 1,480 kWh	210 to 270 kg CO₂	About £90 to £120
Older detached house	680 to 900 kWh	125 to 165 kg CO₂	About £54 to £72
Refurbished, airtight terraced house	110 to 175 kWh	20 to 30 kg CO₂	About £9 to £14

Ranges run from London (lowest) to Aberdeen (highest). Cash values use the October to December 2026 price cap gas rate of 7.97p per kWh; the report itself used 12.04p.

Sealing the chimney completely saved a little more than the wool excluder in the older terraced house, and about the same in the detached house. Unlike a permanent seal, the excluder can be removed and still lets a small amount of air through to keep the flue dry.
In summer, an open chimney increased the hours the refurbished house was uncomfortably warm by 63%, because warm outside air was drawn in.
Across the roughly 11 million homes in England with chimneys, the authors estimate the saving could exceed 2 million tonnes of CO₂ a year. That figure is based on 2008 housing data.

Points to bear in mind

The study was paid for by Chimney Sheep. Where older articles quote the 2013 figures, including a saving of about £75 a year, this 2024 update replaces them.
The results are computer modelled, not measured in real homes, and use 2009 weather data.
Each home was modelled with one chimney; homes with more unused chimneys would save more.
For an independent estimate, the Energy Saving Trust puts the saving from blocking an unused chimney at about £45 a year.

The stack effect: why draughts happen

Most draughts in a heated home are caused by the stack effect. Warm air is lighter than cold air, so it rises and escapes through gaps high up in a building. As it leaves, it pulls cold air in through gaps lower down, under doors, between floorboards and round windows. Somewhere in between is a level, called the neutral pressure plane, where air neither enters nor leaves.

The effect gets stronger the taller the column of warm air and the bigger the difference between indoor and outdoor temperature, which is why draughts are worst on the coldest days. Wind adds to it, pushing air in on one side of the house and drawing it out on the other.

An open chimney is the clearest example in a home: a tall, open column running from the living room to the roof. Block it, and the pull on every other gap in the house weakens too. Engineers use the same principle on purpose in passive stack ventilation, where it is designed and controlled rather than accidental.

Story ideas

The first cold snap. Simple jobs that make a home warmer the same evening, most for a few pounds.
Price cap changes. Ofgem announces the January to March 2027 cap in late November; draught-proofing is one of the cheapest ways to offset a rise.
Grant deadline. ECO4 closes on 31 December 2026. The Warm Homes: Local Grant in England can pay for draught-proofing for lower-income households.
Old windows. Most heat lost through a traditional window goes through the gaps, not the glass, so repair and draught-proofing can beat replacement.
Chimneys and EPCs. How energy certificates record chimneys, and why a blocked chimney may not show up.
Renters. What tenants can do without asking, and the 2030 deadline for privately rented homes in England to reach EPC band C.
Cold homes and health. 2.36 million households in England are in fuel poverty; cutting draughts is one of the cheapest ways to help.

From the Chimney Sheep blog

Five articles from Chimney Sheep, which runs this site, that journalists have found useful. They are written by the company and give its views.

How many homes in the UK have open chimneys?: estimates of how many homes still have an open chimney, and why the figure is so uncertain
Your EPC says your chimney is blocked. But is it really?: how energy certificates record chimneys, and the case for accepting evidence of removable blockers
Chimneys and the stack effect: how a chimney pulls warm air out of a home, explained with a Cornish tin mine
Chimney Sheep turns 14: heat, money and carbon saved: the company’s estimate of what its customers have saved since it started, and how it was worked out
Wool stress: buying around 30 tonnes of Herdwick wool a year directly from Lake District farmers, and what it becomes

Images

You’re welcome to use the sash window diagram on our window guide, credited “Draught Proofing Advice”. For other images, including thermal photographs of chimneys losing heat, please get in touch.

Our guides

Room by room: chimneys, doors, windows, floors and loft hatches
Before you start: what to leave open, and safety
Saving energy: costs, savings and current grants
For professionals: standards, ventilation and listed building consent
Questions answered: short answers to common questions