Assessments of whole body experience and local discomfort
Assessing the perception of the thermal environment is essential in order to increase the added value and certify the design quality. While informing the envelope design, key points include setting the right performance requirements, using proper assessment methods and tools and accounting for the necessary factors that impact on the perception of comfort.
Accounting for parameters such as temperature stratification, direct solar radiation that falls onto the occupants, as well as, local discomfort indices can be essential when aiming to provide a sound thermal environment. The need to account for those parameters is increased in tall spaces (such as atria), spaces with increased glazed areas (where cold drafts and other local discomfort is likely to occur) and in spaces where the uniformity of thermal environment is essential for the function of the building and the well-being of the occupants (e.g. schools, hospitals etc.).
The selection of appropriate thermal comfort models is necessary when setting performance requirements and striving towards meeting agreed upon goals. Comfort models such as Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) are most often used for conditioned spaces; adaptive comfort models are more appropriate for transitory spaces and the Universal Thermal Climate Index (UTCI) better describes semi-external spaces. Including the direct solar component is also an important factor especially when the effect of highly glazed facades on thermal comfort is questioned.
The proper use of Dynamic Thermal Modelling (DTM) tools and Computational Fluid Dynamics (CFD) tools can inform design and ensure a well perceived, uniform thermal environment, while minimizing energy demand.