Research Report · 2026 Edition
An evidence-based review of conservatory comfort in Britain, drawing on a 2011 estimate that approximately four million English households had a conservatory—and examining what subsequent evidence shows about overheating, seasonal use and heating.
Published July 2026 · SnugRoof Thermal · Data drawn from published UK Government, Met Office and peer-reviewed sources.
Executive summary
In the 2011 Energy Follow-Up Survey, approximately four million English households were estimated to have a conservatory. This remains the most substantial national baseline available, but it must not be presented as a current 2026 UK stock estimate.
The most recent national data shows that households with a conservatory are more than twice as likely to report their home overheating, and that seven in ten conservatories are used almost every day in summer — but fewer than a quarter in winter.
At the same time, most conservatories that are used year-round have some form of heating installed, frequently electric, and are exempt from the Building Regulations that would otherwise govern their thermal performance and overheating risk. The result is a large and growing category of rooms that fall outside both energy efficiency policy and overheating assessment — precisely the rooms that a warming climate is most likely to make uncomfortable.
This report brings together the strongest available UK evidence — the DECC Energy Follow-Up Survey, the English Housing Survey, the Met Office climate record and Arup's 2022 overheating work for the Climate Change Committee — and proposes an annual Conservatory Comfort Index: a transparent, 0–100 measure of all-season comfort designed to make the problem visible and improvement measurable.
Eight key findings
In the English Housing Survey 2020–21, 17% of households with a conservatory reported that at least one part of their home became uncomfortably hot, compared with 7% of households without a conservatory.
English Housing Survey 2020–21, Subjective Overheating factsheet.
70% of conservatories were used 6–7 days a week in summer; only 23% saw the same use in winter. 59% were used less than weekly in winter versus 11% in summer.
Energy Follow-Up Survey 2011, Report 6: Conservatories.
77% of surveyed conservatories had heating installed. Of those, 55% ran off central heating and 42% used storage or direct electric heat, including portable heaters. 56% of heated conservatories were heated every day in winter.
Energy Follow-Up Survey 2011, Report 6: Conservatories.
The Met Office confirmed 2025 as the warmest year in the HadUK-Grid series and the sunniest in the Met Office sunshine series. For highly glazed rooms, these hotter and sunnier conditions increase the importance of solar control, ventilation and effective thermal design.
Met Office, State of the UK Climate 2025.
Approved Document L exempts many conservatories from Building Regulations when thermally separated from the dwelling. The same exemption removes them from Approved Document O overheating assessments — so the room most likely to overheat is the least regulated.
Approved Documents L (2021, 2023 amendments) and O (2021).
The most recent detailed evidence base — the DECC Energy Follow-Up Survey — is from 2011. There has been no equivalent national study since, despite structural changes in stock, climate and energy prices.
DECC / DESNZ statistical publications.
Arup's 2022 assessment for the Climate Change Committee found that a very high share of existing homes are at elevated overheating risk under mid-century climate projections, with roof, glazing and shading measures repeatedly identified as high-impact interventions.
Arup for the CCC (2022); CCC Climate Change Risk Assessment (2026).
Comfort in a conservatory is produced by six interacting forces: solar gain, roof transfer, ventilation, fabric loss, heating and moisture. Any credible index needs to weigh all of them across summer and winter, not just one heating-season number.
Synthesis of DECC EFUS, EHS, Met Office and Arup/CCC evidence.
Building physics
Proposed methodology
The proposed index scores each conservatory across six weighted components, from summer resilience to resident experience. Weights are illustrative and require independent review and sensitivity testing before any published score is produced.
Full report
The full 30-page report includes the underlying data, the proposed index methodology in detail, sensitivity tests, and a complete bibliography of UK Government, Met Office, ONS and peer-reviewed sources.
Download PDFJournalists and researchers: contact info@snugroofthermal.co.uk for interviews or raw data.
Selected sources
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SnugRoof Thermal installs the SnugCore™ Insulated Ceiling System — a one-day retrofit designed to address the exact comfort problems this report describes.
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