Outdoor Thermal Research Articles

The ANN Architecture Analysis: A Case Study on Daylight, Visual, and Outdoor Thermal Metrics of Residential Buildings in China

Selecting an appropriate ANN model is crucial for speeding up the process of building performance simulation during the design phase of residential building layouts, particularly when evaluating three or more green performance metrics simultaneously. In this study, daylight, visual, and outdoor thermal metrics were selected as main green performance. To find the suitable ANN model, sensitivity analysis was used to obtain a set of proper parameters applied to the ANN structure. To train the ANN model with a higher predicting accuracy, this paper tested four different scenarios of ANN parameter setups to find some general guidelines about how to set up an ANN model to predict DF, sunlight hours, QuVue and UTCI. The results showed that an ANN model with a combined output variable demonstrated better average prediction accuracy than ANN models with a separated output variable. Having two times the number of training samplings compared to the number of input variables can lead to a high accuracy of prediction. The ideal number of neurons in the hidden layer was approximately 1.5 times the number of input variables. These findings of how to improve the ANN model may provide guidance for modeling an ANN for building performance.

Outdoor Thermal and Acoustic Comfort in Autumn for Senior Citizens in Public Spaces in Newcastle Upon Tyne, United Kingdom

Adapting to the ageing population is one of the biggest challenges for 21st-century cities. This research was focused on the thermal and acoustic comfort perception of older adults in two outdoor public spaces in the city of Newcastle Upon Tyne in the United Kingdom, through a mixed methodology including environmental measurements and questionnaire surveys to 73 people over 60 years old during the autumn of 2019. Results about thermal comfort showed that the range of the temperature where at least 80% of the older people felt the environment acceptable, was between 11.27 and 19.93 C°. While concerning acoustic comfort, although measured sound levels exceed the limits considered harmful to health (> 65 dB) 86.3% of the interviewees perceived the level of sound as Pleasant and 83.6% were not annoyed. Decreased thermal and auditory sensitivity makes older people vulnerable to climate and noise effects on health. It is important to consider those findings to achieve healthier spaces adapted to the needs of older adults, which encourage greater use and participation and improve their quality of life.

Outdoor Thermal and Visual Perception of Natural Cool Materials for Roof and Urban Paving

Given the acknowledged thermal performance of natural light color gravels applied as cool roof and cool urban paving, this work is aimed at investigating if such behavior is perceivable by pedestrians, who are questioned in this paper about their visual and thermal comfort perception. In fact, there are still related aspects to analyze, in order to optimize their application and provide a comfortable space for users, both on the thermal and the visual point of view. Therefore, the question that this work wants to answer is: given their intrinsic characteristics, do these materials create a sensitive thermally and visually more comfortable environment for pedestrians? In order to address this uninvestigated issue, users’ judgment about visual and thermal comfort of these surfaces is considered, also by comparing them with grassland and asphalt. Also, the statistical correspondence between physical properties of such materials and possible correspondence with respect to human perception with varying weather conditions is analyzed. Given the relatively high reflectance of these materials, it appears particularly important to evaluate these aspects, to consciously apply them as urban paving or roof covering by optimizing their natural passive cooling potential. In this preliminary study, users’ response to these surfaces is evaluated by mean of field surveys, both on the thermal and the visual evaluation, and contemporary in-field measurements of surface parameters. Also, human perception with respect to these high-reflectance surfaces’ is compared with the one related to grassland and asphalt, with varying weather conditions. Then, a statistical analysis is performed to investigate the differences among different gravels, grassland and asphalt, based on surveys’ results. The results show how pedestrians, questioned during summer days, prefer grassland, while asphalt is the less favorite surface both visually and thermally; there is a small difference between gravels’ types evaluation, while weather variability affect the preferences.