Part O Overheating
As of June 15, 2022, the implementation of the new building regulations document Part O has introduced measures to address the issue of overheating in new buildings. This development is aimed at improving the living conditions within these structures by minimizing the discomfort associated with summer overheating, which often results from excessive solar gains. The ultimate goal of these calculations is to ensure that new homes remain comfortable, eliminating the stuffy and uncomfortable conditions that can emerge during the hotter months.
Summer overheating is a widespread concern in modern building design and can have a significant impact on the well-being of occupants. Excessive solar gains are a key contributor to this issue. These calculations serve to identify potential trouble spots where excessive solar gains might occur, as well as areas where excess heat removal is hindered due to insufficient opening areas, such as windows that cannot be opened. The calculations distinguish between high and moderate-risk locations, with high-risk areas encompassing most of London and specific parts of Manchester, while all other areas are considered moderate-risk.
Overheating during the summer months can lead to a range of problems, including impaired sleep and reduced cognitive function. This is especially concerning for vulnerable populations, such as the elderly. It is crucial to take a holistic approach to building design, ensuring that it caters to the specific needs of occupants year-round. In addition to mitigating overheating, designers should consider the benefits of winter solar gains, daylight, and access to outside views. Achieving a balance between these elements ensures that the building remains comfortable, resilient, and energy-efficient.
To assess overheating in a design, two methods are commonly employed. The simplified method takes into account factors such as glazing area, opening area, and relative orientation. If this method proves insufficient, more detailed calculations using the dynamic thermal modeling method can be conducted. This approach factors in glazing area, opening area, relative orientation, as well as additional variables like openable windows, shading devices, and nearby trees. By employing these methods, designers can create buildings that maintain optimal thermal comfort throughout the year while minimizing overheating during the summer months.
Although it can seem early to be thinking about overheating in a climate like ours, it can be a real issue in the summer months and a comfortable building is one that works.
Further reading
https://goodhomes.org.uk/news/shading-for-housing
https://www.gov.uk/government/publications/overheating-approved-document-o
https://www.passivhaustrust.org.uk/guidance_detail.php?gId=62
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