Daylight & Sunlight Assessments

The TM59 Overheating Assessment is a specialized evaluation developed by the Chartered Institution of Building Services Engineers (CIBSE) to address the growing concern of overheating in homes. Unlike typical overheating assessments governed by Part L of the Building Regulations, TM59 is more comprehensive, focusing on a detailed analysis of various factors that contribute to overheating. Its primary goal is to assess the assessment of overheating risk in homes and ensure that occupants remain comfortable throughout the year.

TM59 was established to create standardized specific industry criteria for assessing overheating in residential properties, making it an essential tool for both new constructions and refurbishments. The methodology outlined in TM59 involves Dynamic Simulation Modelling software, which allows for a thorough evaluation of potential overheating risks by simulating real-world conditions. This standardized approach ensures consistency and reliability in assessments, providing a clear framework for energy assessors and consultants to follow.

In addition to considering heat gain intensity and building orientation, TM59 also factors in occupant behavior and internal heat gains, as well as occupancy patterns. TM59 sets specific guidelines for compliance, including input data like occupancy hours and internal heat gains, to ensure a comprehensive assessment of likely internal temperatures.

Dynamic thermal modelling method is a pivotal tool in the TM59 assessment process. This method involves using sophisticated software to predict internal temperature conditions and identify potential discomfort thresholds within a building. By simulating real-world conditions, dynamic thermal analysis provides a detailed picture of how a building will perform under various temperature scenarios, making it an essential part of the TM59 methodology.

The ability to forecast potential overheating issues accurately allows designers and engineers to implement effective mitigation strategies early in the design process. This not only ensures compliance with TM59 but also enhances the overall thermal comfort of the building’s occupants.

Dynamic thermal modelling allows energy assessors to pinpoint specific areas at risk of overheating and propose targeted solutions using a simplified method that considers thermal mass.

Natural and mechanical ventilation strategies play crucial roles in managing indoor temperatures and reducing overheating risks. Natural ventilation, which relies on passive air movement through open windows, is the primary ventilation method for most naturally ventilated homes in the UK. It can be highly effective in reducing indoor temperatures, though its effectiveness can vary based on building design, orientation, and external factors like noise and pollution.

Mechanical ventilation, increasingly common in modern buildings, provides a constant fresh air flow and improve ventilation air quality in mechanically ventilated homes. These systems can enhance energy efficiency by incorporating heat recovery units and can be designed to prevent overheating. Fans, as a low-energy solution, also play a role in managing indoor temperatures by enhancing airflow and promoting heat loss.

Both natural and mechanical ventilation strategies are essential in mitigating overheating risks, especially in the context of changing climate conditions. To provide sufficient ventilation, whether through naturally ventilated means or mechanical systems, ensures that indoor environments remain comfortable and healthy for occupants.

Performing TM59 assessments during the design phase is crucial for making necessary changes before construction begins. Conducting these assessments early allows for modifications such as changing window specifications and room configurations, which can significantly reduce the risk of overheating. This proactive approach not only ensures compliance with TM59 but also prevents costly modifications later in the construction process.

Integrating early-stage assessments of overheating risks with engineering expertise can lead to more effective design solutions. Collaborating with engineers from the outset helps designers better prepare for upcoming regulations and enhance the quality of overheating evaluations. This integration of expertise and early assessment is key to creating buildings that guarantee thermal comfort and adhere to the latest standards.

Accurate weather data is a critical component of TM59 assessments, as it directly affects simulations of internal temperatures and heat gains. Using climate-specific weather files can significantly improve the reliability of overheating risk assessments in residential properties. These files incorporate real historical weather patterns, providing a more accurate representation of potential overheating scenarios.

Local microclimates must also be accounted for, as they can lead to significant differences in indoor thermal conditions. Incorporating detailed weather data into assessments allows designers and engineers to better predict and mitigate overheating risks, ensuring that buildings remain comfortable even in changing climate conditions.