New build homes across Britain are failing to cope as temperatures soar to 34C during the country's fourth heatwave of summer 2025. Eco-friendly insulation designed to retain winter heat is now trapping residents in sweltering conditions, with indoor temperatures reaching 35C in some flats.
The UK Health Security Agency has issued amber heat health alerts across central and southern England until Wednesday. Residents in tower blocks are experiencing the most extreme conditions, with some reporting indoor temperatures above 27C for two consecutive months.
Sandra Monteiro, a 41-year-old teacher living on the 11th floor of an east London flat, hasn't seen her home temperature drop below 27C in eight weeks. She told journalists the conditions left her feeling "out of breath" and "exhausted" with frequent headaches.
Design flaws exposed
Building expert Lorraine Thomas explained that fire-resistant insulation has created additional heat-trapping layers in already energy-efficient properties. The director of property company View From My Window said: "Windows were put in these flats to provide natural daylight but what's happened is a conservatory effect where it's hotter in summer and colder in winter."
New build windows open only a few inches for safety reasons, severely limiting natural ventilation. The same insulation that allows some residents to avoid heating costs in winter becomes a liability when temperatures rise, creating what Thomas described as "sweltering boxes".
Lucian Ho, 21, who lives on a top floor of a 28-storey high-rise, struggles to sleep due to heat with minimal relief from windows that barely open. Residents at the Three Waters development in Bow have recorded indoor temperatures approaching 30C.
Urban heat challenges
London's dense population compounds the overheating problem, with high-rises positioned close to busy roads, transport links and commercial buildings. Thomas noted: "Dense population and area, there's nothing sparse and the overcrowding of blocks with too many flats - it all helps to capture the heat."
The urban environment creates additional heat through dark roads and concrete buildings, while limited green spaces offer little cooling relief. The combination of building design and city planning has created what residents describe as "unbearable" living conditions during heatwaves.
Expensive solutions
Air conditioning represents the primary solution, but installation costs range from £1,000-£2,000 per room for fixed units. Multi-room systems can reach £6,000-£9,000, placing effective cooling beyond many residents' budgets.
Thomas confirmed that expensive air conditioning units are becoming the only viable option: "More and more people will have to get air conditioning because opening windows just doesn't do enough to help." Some residents have resorted to eating cold meals outdoors rather than using ovens that would further heat their homes.
Heat pumps offer a more efficient alternative that may qualify for government renewable energy incentives. Strategic window management - closing windows during direct sunlight and opening all windows at night - provides some relief without requiring expensive technology upgrades.
Community frustration
Social media groups have become forums for desperate residents seeking cooling advice. In Greenwich, one resident posted: "Is anyone else struggling in their new build flat with the heat? I just moved into one recently and the heat is unbearable."
Responses reveal widespread frustration with new build design. One resident wrote: "It's actually starting to affect my health and the health of my pets. They build them quick, charge high rent but don't build them properly with good ventilation."
The problem has persisted for years, with 2023 social media posts showing similar complaints about flats reaching 28.5C during the day and remaining at 27C even at 3am. Many residents report chronic sleep deprivation during summer months, with some forced to seek alternative accommodation during heatwaves.
Sources used: "Daily Mail", "Metro", "Independent", "Wales Online" Note: This article has been edited with the help of Artificial Intelligence.
