Havering named London's least energy efficient borough as Tower Hamlets leads the capital in new research

The research, by sheet materials supplier Cut Plastic Sheeting, analysed nearly 2.5 million domestic energy performance certificates lodged across all 33 London boroughs over the last ten years.

Using data from the Energy Performance of Buildings Register, the proportion of homes rated C or above and the proportion rated below C was calculated for each borough, covering certificates issued between January 2016 and December 2025.

Tower Hamlets recorded the highest proportion of energy efficient homes in the capital at 79.75%, with 84,365 of the 105,792 certificates assessed rated C or above. The City of London ranked second (67.95%), followed by Southwark, where 54,675 of 81,807 assessed homes met the standard (66.83%), Hackney (66.78%) and Greenwich (63.06%).

Newham (62.87%), Islington (62.11%), Westminster (61.79%), Wandsworth (61.07%) and Hammersmith and Fulham (59.16%) also performed well above the London average of 56%.

At the other end of the table, Havering recorded just 43.15% of homes rated C or above, followed by Enfield (43.69%), Richmond upon Thames (44.39%), Bromley (44.46%) and Redbridge (44.77%), making them the boroughs with the lowest proportion of energy efficient homes.

Nearly half of all assessed properties in London (1,065,020 homes in total) are currently below the C rating that landlords will be legally required to meet by 2030, with the gap between London's best and worst boroughs standing at 36.6 percentage points.

Daniel Southern, Managing Director at Cut Plastic Sheeting, commenting on the study, said: "The scale of London's energy efficiency challenge is clear, and with landlords now required to bring properties up to a C rating by October 2030, there is still a significant amount of work to do across the capital.

"There are a range of improvements homeowners and landlords can make to improve a property's energy performance, from low-cost measures like draught proofing, low energy lighting and hot water cylinder insulation, as well as larger investments such as loft insulation, upgraded heating controls and solar panels.

"Windows are one of the biggest sources of heat loss in older properties, and for many homeowners and landlords, full window replacement is not always practical or affordable. Secondary glazing is worth considering as a more accessible alternative, and one that can have a meaningful impact on a home's heat retention."