Projects

Occupant comfort, wellbeing and day-to-day operations were being affected by overheating within apartments and communal areas, raising concerns about the suitability of the building for vulnerable residents in a changing climate. To help identify the underlying causes and develop a practical strategy for improvement, AES Sustainability was commissioned to undertake a detailed overheating assessment.

Through a comprehensive review of the building's fabric, services and operational practices, AES Sustainability worked closely with the client to understand the issues, evaluate potential solutions and create a roadmap of improvements.

The three-storey care home, built in the mid-to-late 2000s, was designed and built to Building Regulations and features a highly insulated building fabric and mechanical ventilation with heat recovery (MVHR) systems. However, despite meeting the requirements of the time, increasing summer temperatures and changing climate conditions have exposed overheating risks that were not fully anticipated during the original design.

The development is home to older and potentially vulnerable residents, making thermal comfort and occupant wellbeing particularly important. Concerns were raised after temperature monitoring identified bedrooms, living areas and bathrooms regularly exceeding 30°C for extended periods during hot weather. Staff also reported challenging working conditions when assisting residents, particularly in enclosed spaces where high temperatures, combined with the need to wear personal protective equipment, created significant discomfort.

AES Sustainability carried out a detailed site survey and overheating assessment to understand the causes of the problem and identify practical solutions. The investigation found that while the building fabric performed well in retaining heat during colder months, it also contributed to heat being trapped indoors during summer. Large areas of glazing admitted significant solar gains, while the apartments were predominantly single-aspect, limiting opportunities for natural cross-ventilation.

The assessment also highlighted several operational factors that were contributing to overheating. Although MVHR systems had been installed throughout the development, many residents had switched them off due to concerns about noise levels and energy costs. As a result, ventilation rates were significantly reduced, allowing heat to build up within apartments. Window opening was also restricted by safety requirements, while many bathrooms lacked opening windows entirely. In communal areas, self-closing fire doors restricted airflow and prevented natural ventilation routes from developing throughout the building.

Rather than treating the project as a simple compliance exercise, AES Sustainability adopted a holistic building performance approach. Using recognised overheating assessment methodologies as a benchmark, the team analysed the building as it operated in reality and explored a range of both passive and active mitigation measures. This enabled the client to consider not only how the building performs today but also how it may respond to future climate conditions.

A range of potential solutions were identified. Passive measures included the introduction of external shading through landscaping and planting, the installation of brise soleil systems, and the use of solar control window films to reduce solar gains without the need for costly glazing replacement.

Operational improvements formed another important part of the strategy. AES Sustainability recommended reviewing and recommissioning the existing MVHR systems, potentially increasing ventilation capacity where appropriate and providing resident guidance on how the systems should be used. By helping occupants understand the benefits of continuous operation and the relatively low running costs, the client has an opportunity to improve performance using infrastructure that already exists within the building.

The assessment also identified a number of secondary heat sources that could be addressed. These included heat gains from uninsulated pipework serving communal heating systems and older lighting installations that generated unnecessary heat. Small interventions in these areas can often contribute to meaningful reductions in internal temperatures, particularly when combined with broader overheating mitigation measures.

Where passive and operational improvements alone may not be sufficient, AES Sustainability also evaluated the suitability of targeted active cooling solutions. These recommendations were considered within the constraints of building regulations, fire safety requirements, operational practicality and resident wellbeing.

This project demonstrates a growing challenge across the UK housing and care sectors. Many buildings constructed within the last 20 years, whilst fully compliant, are not able to cope with the frequency and intensity of today's heatwaves. As a result, overheating is increasingly being identified in buildings that are otherwise performing well from an energy efficiency perspective.

Through a detailed and evidence-based assessment, AES Sustainability has provided the client with a clear understanding of the overheating risks within the development and a practical roadmap of measures to improve comfort, protect vulnerable residents and enhance resilience to future climate conditions.

The project highlights the importance of taking a whole-building approach to overheating, particularly in environments where occupant health and wellbeing are critical considerations.