Effect of airflow direction on human perception of draught
Forty subjects, 20 women and 20 men, were exposed to airflows from five different directions: horizontally towards the front, the back, and the left side and vertically upwards and downwards. The subjects were exposed to stepwise increased air velocities ranging from less than 0.10 m/s to 0.40 m/s at three temperature levels 20, 23 and 26 o C. The results showed that airflow direction has an impact on perceived discomfort due to draught. At 20 o C and 23 o C, airflow from below was perceived as most uncomfortable followed by airflows towards the back and front. At 26 o C airflow from above and towards the back caused most dissatisfaction due to draught, but generally only a few of the subjects perceived discomfort at this temperature. Discomfort due to draught was most often felt at the body regions directly exposed to the airflow. These were the legs, the feet, and the lower back at airflow from below; the neck, the shoulders and the hands at airflow from above; the neck, the back, the shoulders and the legs at airflow from behind; the knee and the arm facing the windbox when exposed to air movements directed towards the side; and the hands and the knees when exposed to air movements towards the front.
Window performance for human thermal comfort
Anyone who has ever sat near a cold window on a winter day or in direct sunlight on a hot day recognizes that windows can cause thermal discomfort. In spite of this broad recognition there is no standard method to quantify the extent of such discomfort. The purpose of this study was to: 1. Review the literature to identify relevant work relating to windows and thermal comfort. 2. Develop an improved understanding of the impact of windows on thermal comfort and to propose an analytical method for evaluating this impact. The method could form the basis for a future NFRC window comfort rating method that could be used by both designers and consumers.
Fully Integrated Bidirectional CMOS-MEMS Flow Sensor With Low Power Pulse Operation
Leveraging More-than-Moore technology, we demonstrate an integrated CMOS MEMS flow sensor via a very compact system on chip (SoC) that can sense the bidirectional N2 gas flow. Our SoC features a very low-noise instrumentation amplifier that is implemented on a CMOS wafer and serves as a readout integrated circuit for a thermoresistive micro-calorimetric flow sensor which is fabricated on a MEMS wafer. A compact heterogeneous integration is achieved by combining the two wafers via the proprietary InvenSense AlN process. The measured sensitivity of our CMOS MEMS flow sensor is 98 mV/sccm which is three times better than the state-of-the-art counterpart. The flow range measured by our SoC is from −26 to 26 m/s (from −50 to 50 sccm). Moreover, the pulsed heater operation makes this proposed SoC flow sensor a very low power (<9 mW) and, thus, a promising candidate for the Internet-of-Things applications in smart home/green buildings.