Center for the Built Environment, University of California, Berkeley, CA, USA.
Department of Building, Energy and Environmental Engineering, University of Gävle, Gävle, Sweden.
Indoor Air. 2017 Jul;27(4):852-862. doi: 10.1111/ina.12364. Epub 2017 Jan 20.
Draft is unwanted local convective cooling. The draft risk model of Fanger et al. (Energy and Buildings 12, 21-39, 1988) estimates the percentage of people dissatisfied with air movement due to overcooling at the neck. There is no model for predicting draft at ankles, which is more relevant to stratified air distribution systems such as underfloor air distribution (UFAD) and displacement ventilation (DV). We developed a model for predicted percentage dissatisfied with ankle draft (PPD ) based on laboratory experiments with 110 college students. We assessed the effect on ankle draft of various combinations of air speed (nominal range: 0.1-0.6 m/s), temperature (nominal range: 16.5-22.5°C), turbulence intensity (at ankles), sex, and clothing insulation (<0.7 clo; lower legs uncovered and covered). The results show that whole-body thermal sensation and air speed at ankles are the dominant parameters affecting draft. The seated subjects accepted a vertical temperature difference of up to 8°C between ankles (0.1 m) and head (1.1 m) at neutral whole-body thermal sensation, 5°C more than the maximum difference recommended in existing standards. The developed ankle draft model can be implemented in thermal comfort and air diffuser testing standards.
草案是不需要的局部对流冷却。Fanger 等人的草案风险模型（Energy and Buildings 12, 21-39, 1988）估计了由于颈部过度冷却而对空气流动感到不满的人的百分比。目前还没有预测脚踝处气流草案的模型，而脚踝处的气流草案与分层空气分布系统（如地板下空气分布（UFAD）和置换通风（DV））更为相关。我们基于 110 名大学生的实验室实验，开发了一个预测脚踝气流不满百分比（PPD）的模型。我们评估了空气速度（名义范围：0.1-0.6 m/s）、温度（名义范围：16.5-22.5°C）、湍流强度（脚踝处）、性别和服装隔热（<0.7 clo；小腿裸露和覆盖）的各种组合对脚踝气流草案的影响。结果表明，全身热感觉和脚踝处的空气速度是影响气流草案的主要参数。在中性全身热感觉下，坐姿受试者接受脚踝（0.1 m）和头部（1.1 m）之间高达 8°C 的垂直温差，比现有标准建议的最大温差多 5°C。开发的脚踝气流草案模型可用于热舒适和空气扩散器测试标准。
