TM59 Overheating Assessments

With changing weather patterns and an increase in hot summers in the UK, it’s essential to address the issue of overheating in homes. The advancement in building insulation and architectural design has resulted in homes retaining more heat, which can become problematic during hot weather. To tackle this issue, CIBSE, the Chartered Institution of Building Services Engineers, developed and published TM59 Design Methodology for the Assessment of Overheating Risk in Homes in 2017.

Before TM59, there were no specific industry criteria for assessing overheating in homes, leading to inconsistent results from energy assessors and consultants. TM59 provides a comprehensive approach to assess the internal temperatures of residential properties and prevent overheating, ensuring the comfort of occupants and reducing energy consumption from heating appliances.

Components of TM59 for Homes 

TM59 sets out clear guidelines for energy assessors and consultants to assess overheating risks in homes. The guide includes input data such as hours of occupancy, internal heat gains from equipment and occupants, and air temperatures. It also provides criteria to demonstrate compliance with regards to overheating and ensure the comfort of occupants during both daytime and night-time hours.

The guide takes into consideration the design and construction of homes, including the glazing specifications, air permeability rates, and the provision of mechanical ventilation. It also provides guidance on the assessment of mechanically ventilated properties to ensure that the ventilation system is appropriately sized to prevent overheating.

Conducting a TM59 Assessment at the Design Stage 

It is crucial to conduct a TM59 assessment at the design stage of a project. If the initial design falls short of the requirements, changes can be made before construction begins, saving time and money in the long run. This may include modifications to windows, glass specifications, room layouts, and more.

Carrying out a TM59 assessment and report at the design stage can ensure compliance with the latest standards and prevent overheating in residential properties. It also provides a benchmark for energy assessors and consultants, ensuring consistent results and improving the overall quality of overheating assessments in the industry.

Overheating in Naturally Ventilated Homes 

The majority of homes in the UK are naturally ventilated, which means opening windows to provide sufficient ventilation and help keep temperatures down in hotter weather. However, with modern buildings becoming more airtight, natural ventilation may not be sufficient to prevent overheating.

TM59 takes into consideration the ventilation requirements of naturally ventilated homes and provides guidance on how to improve ventilation and reduce overheating. This may include modifications to windows, doors, and the layout of rooms to improve air flow and reduce the internal temperature of the home.

Overheating in Mechanically Ventilated Homes 

Mechanical ventilation is becoming increasingly common in modern homes, especially with the advancement in building insulation and airtight construction. TM59 provides guidance on mechanically ventilated properties to ensure that the ventilation system is appropriately sized to prevent overheating.

Mechanical ventilation systems can provide a constant flow of fresh air into the home, reducing the internal temperature and improving air quality. TM59 provides guidelines on the design and sizing of mechanical ventilation systems to ensure that they are adequate to prevent overheating in homes.

Overheating in Apartments 

Apartments present unique challenges when it comes to overheating. With a high density of homes in a small area, the internal temperature of one apartment can affect the internal temperature of adjacent apartments.

Conclusion

TM59 takes into consideration the unique challenges of apartments and provides guidelines on how to prevent overheating. This may include modifications to windows, doors, and communal circulation areas, such as corridors, to improve air flow and reduce the internal temperature of the apartments. Additionally, TM59 provides guidelines on the design and sizing of mechanical ventilation systems in apartments to ensure that they are adequate to prevent overheating.

With changing weather patterns and an increase in hot summers in the UK, it’s essential to address the issue of overheating in homes. TM59 provides a comprehensive approach to assess the internal temperatures of residential properties and prevent overheating, ensuring the comfort of occupants and reducing energy consumption from heating appliances. Whether you live in a naturally ventilated home or a mechanically ventilated apartment, TM59 provides guidelines to ensure that your home is comfortable and energy efficient, even in the hottest of summers.