What can we realistically do to help reduce overheating in existing homes?
For new developments, the industry has clear guidance. Approved Document O requires designers to consider overheating at the design stage through measures such as limiting solar gains, providing adequate ventilation and, where necessary, demonstrating compliance using dynamic thermal modelling.
For existing housing, however, the picture is less straightforward and landlords are increasingly dealing with resident complaints about overheating during prolonged periods of hot weather.
Designing out overheating versus managing it
Guidance such as Approved Document O, Approved Document F and CIBSE TM59 provides valuable direction, but much of it focuses on the design and assessment of new homes rather than practical interventions for existing housing stock.
One message is consistent across the guidance: ventilation plays an important role in managing overheating, but it must form part of a wider strategy.
There is no single ventilation rate that solves overheating. Research consistently shows that effective cooling depends on several factors working together, including:
- Building orientation and solar gains
- Thermal mass
- Background ventilation
- Cross-ventilation
- Purge ventilation
- Occupant behaviour
- The timing and control of ventilation
Practical steps landlords can take today
While structural alterations may not always be practical, there are several measures that can help improve resilience during periods of hot weather.
Reduce heat gains
- Encourage residents to close blinds or curtains before direct sunlight enters the property.
- Reduce unnecessary internal heat gains from lighting and appliances.
- Consider external shading where appropriate.
Maximise opportunities for cooling
- Encourage purge ventilation during cooler evening and early morning periods.
- Ensure background ventilation remains open and unobstructed.
- Promote good airflow throughout the dwelling.
Check that ventilation systems are performing as intended
Mechanical ventilation systems are often installed to improve indoor air quality, but are they operating as designed?
Questions worth asking include:
- Are systems correctly commissioned?
- Are airflow rates still compliant?
- Has routine maintenance been carried out?
- Are filters and grilles clean?
- Are residents using the systems correctly?
- Could temperature-responsive controls improve performance during periods of hot weather?
These are simple questions, but they can have a significant impact on both indoor air quality and thermal comfort.
There is no single ventilation rate that solves overheating. Success depends on using ventilation at the right time, in the right way, as part of a wider building strategy.
Could your existing ventilation system do more?
As overheating becomes a more frequent issue, there is growing interest in whether continuous mechanical ventilation systems can play a greater role in supporting thermal comfort.
For example, intelligent controls that respond to internal temperature could allow systems to increase airflow when conditions are favourable, particularly during cooler night-time periods, before returning to normal operation when temperatures stabilise.
While this is not a substitute for good building design, it demonstrates how existing systems may be able to contribute more than simply providing background ventilation.
A practical starting point
Before considering upgrades or replacement systems, it makes sense to understand how your existing ventilation is performing.
At Vortice UK, we are offering a Ventilation Health Check for social housing providers.
Our aim is simple: to help landlords assess whether existing ventilation systems are operating as intended, identify opportunities for improvement, and support a proactive approach to indoor air quality and overheating resilience.
As our summers continue to become warmer, ensuring ventilation systems are performing effectively is no longer just about compliance. It is increasingly about protecting resident comfort, wellbeing and the long-term resilience of existing homes.
If you’re reviewing your housing stock following this summer’s heatwaves, we’d be delighted to discuss how a Vortice Ventilation Health Check could help identify practical opportunities for improvement.
