An estimated 441,000 private rented homes in England failed thermal comfort standards in 2024, accounting for 40.3% of all non-decent private rental properties, according to new analysis from Inventory Base.
The findings come as major reforms to the Housing Health and Safety Rating System (HHSRS) came into force on 23rd June.
Inventory Base analysed the latest Decent Homes Standard (DHS) data published by the government, alongside details of the revised HHSRS framework, to examine the prevalence of thermal comfort failures across England's housing stock and consider the implications of the updated housing safety regime, which introduces a renewed focus on temperature-related hazards, including overheating.
The findings show that thermal comfort remains one of the most common issues affecting housing quality across England. In 2024, 441,000 private rented homes failed the thermal comfort criterion of the Decent Homes Standard, representing 40.3% of all non-decent homes within the private rental sector.
While the number of non-decent private rented homes has fallen by 16.5% over the last decade, almost 1.1 million non-decent private rental properties were still recorded in 2024.
Revised HHSRS brings overheating into focus
The updated framework reduces the number of hazard categories from 29 to 21, replaces the previous A-J rating bands with a simplified High, Medium and Low risk classification system, and introduces new baseline indicators designed to help identify potential deficiencies before a full assessment takes place.
Among the 21 hazard categories are those relating to physiological requirements, including both Excess Cold and Excess Heat. Excess Cold has historically been the dominant thermal concern within housing enforcement, but the presence of Excess Heat as a standalone hazard reflects growing awareness of overheating risks within residential properties.
Excess Heat hazards can arise from several factors:
- excessive solar heat gain
- inadequate shading
- poor ventilation
- building characteristics that make it difficult to maintain safe indoor temperatures
Local authorities will continue to have powers to intervene where overheating presents a significant risk to occupants' health under the revised framework.
Although the Decent Homes Standard thermal comfort criterion is not the same as an Excess Heat assessment under HHSRS, the scale of thermal performance issues identified across the private rented sector highlights the growing importance of temperature-related housing quality as warmer summers become more common.
Sián Hemming-Metcalfe, operations director at Inventory Base, believes the conversation around housing quality is shifting. "For many years, conversations around housing quality have rightly focused on keeping homes warm, dry and energy efficient during the winter months," she says. "But as the UK's climate changes, property professionals are increasingly having to consider how homes perform during periods of extreme summer heat as well."
"June's prolonged heatwave, which saw temperatures exceed 35°C in parts of the country, has brought that challenge into sharp focus," she continues.
"While thermal comfort deficiencies under the revised Housing Health and Safety Rating System (HHSRS) are distinct from overheating hazards, both highlight the growing importance of ensuring homes remain safe and habitable throughout the year."
"The revised HHSRS reflects a broader understanding of housing safety," Hemming-Metcalfe adds. "It is no longer enough to think only about protecting occupants from the cold. Landlords, letting agents and property professionals must now consider how properties perform across all seasons, particularly as hotter summers become more frequent.
"Housing safety doesn't stop when winter ends. Rental homes need to protect occupants in every season, and the revised HHSRS reflects that reality."
