Projects

KEEPING COOL IN THE CAPITAL: AES DELIVERS OVERHEATING ASSESSMENT FOR LONDON TOWER BLOCKS

Leading sustainability consultancy AES Sustainability has delivered an in-depth overheating assessment for two residential blocks in London, helping to support planned improvement measures aimed at enhancing resident comfort and resilience in a warming climate.

The company was commissioned by a major social housing provider to assess two residential blocks built in the early 2000s. While compliant with Building Regulations and design standards at the time of construction, the buildings have experienced significant overheating issues during warmer periods, resulting in resident complaints and concerns regarding thermal comfort.

The project highlights a growing challenge across the UK housing sector, where relatively modern buildings are struggling to cope with rising temperatures and changing climate conditions. Excess heat has been added under HHSRS (Housing Health and Safety Rating System) Guidance (version 2) legislation. It will also be phased into Awaab's Law which requires social housing landlords in England to investigate and fix severe hazards, such as dangerous damp, mould, and emergency repairs, within strict legal timeframes. This means that social landlords will now need to manage overheating risks across their housing stock.

The development is located adjacent to a major railway corridor, creating several design constraints that have contributed to the overheating problem. To mitigate noise from the railway, apartments overlooking the tracks are fitted with enhanced acoustic glazing, with windows that cannot be opened and no trickle ventilation provided. The buildings also feature highly glazed south and west facing façades, exposing apartments to significant levels of solar gain throughout the day.

Many of the dwellings are single aspect apartments with limited opportunities for natural cross ventilation, while the upper floors have little or no surrounding shade. Combined with the thermal characteristics of the masonry construction, these factors have created conditions in which heat accumulates within apartments, particularly during prolonged periods of warm weather, leading to elevated internal temperatures and uncomfortable living conditions for residents.

AES Sustainability carried out a detailed overheating assessment to identify the causes of overheating and determine the most effective mitigation measures. The study included an analysis of building orientation, glazing performance, ventilation provision, apartment layouts and solar exposure, alongside dynamic thermal modelling to evaluate internal temperatures under both current and future climate scenarios. This enabled the team to quantify overheating risk and develop recommendations tailored to the specific constraints of the buildings.

The assessment confirmed that overheating was the result of multiple interconnected factors rather than a single design flaw. It highlights the fact that changing environmental conditions are creating new challenges for many residential developments of a similar age and design.

AES Sustainability provided a range of practical recommendations to help reduce overheating risk while recognising the limitations associated with occupied high-rise residential buildings. Potential measures included optimising existing ventilation systems, increasing ventilation capacity where feasible, introducing targeted cooling solutions and improving solar control strategies. The team also considered the practical realities of implementing changes to the blocks, acknowledging that large-scale façade modifications or external shading systems may be constrained by cost, planning requirements and the complexity of retrofitting occupied buildings.

This project demonstrates the increasing importance of overheating assessments across the residential sector. Many developments constructed in the early 2000s share similar characteristics, including extensive glazing, single-aspect apartments and urban locations where noise, planning and operational constraints limit the range of available mitigation options.

Through detailed analysis and evidence-based recommendations, AES Sustainability has helped the client gain a clear understanding of the overheating challenges affecting the buildings and identify realistic strategies for improving resident comfort, resilience and long-term building performance.