What is an Overheating assessment?

Overheating assessments evaluate the risk of indoor spaces becoming uncomfortably or dangerously hot during warm weather. They are a key part of building design and are required under Building Regulations (e.g., Part O in England) to ensure occupant comfort and safety. Using either a simplified method or dynamic thermal modelling, these assessments help identify whether homes and buildings are likely to overheat and recommend design improvements like shading, ventilation, or glazing adjustments.

Why are Overheating Assessments Important?

Building Regulations:Overheating assessments are now a mandatory requirement under Approved Document O (AD-O) of the Building Regulations, for new residential buildings. 

Energy Efficiency:By understanding potential overheating risks, designers can make informed decisions about building design, insulation, shading, and ventilation, leading to energy-efficient and comfortable buildings. 

How are Overheating Assessments Done? 

Dynamic Thermal Modelling (DTM):This involves using specialized software to simulate how a building’s internal temperatures respond to different weather conditions, including solar gain and heat transfer through walls and windows. This method is used when the simple method fails. 

Simplified Methods:In some cases, a simplified method of assessment can be used, focusing on limiting solar gain and removing excess heat. 

Key Factors Considered:

Building Geometry: The shape and size of the building, including its orientation. 

Fabric: Insulation levels and thermal mass of the building materials. 

Shading: External and internal shading devices like overhangs and blinds. 

Glazing: Window sizes, orientations, and type of glazing (solar control glazing). 

Internal Heat Gains: Occupants, lighting, and equipment. 

Ventilation: Natural or mechanical ventilation. 

Weather Data: Local climate data, including future heat scenarios where applicable.