代写 ACULTY OF ARCHITECTURE

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代写 ACULTY OF ARCHITECTURE
ACULTY OF ARCHITECTURE, DESIGN AND PLANNING

Thermal Comfort Experiment

In recent history the practice of utilising air movement through natural ventilation or personal fans to improve occupant satisfaction in warm temperatures has been overshadowed by energy-intensive HVAC systems employed to condition the indoor environments of hermetically sealed buildings. This reliance on compressor-based cooling can be partly attributed to the empirical assessments of air movement and thermal comfort by Fanger (1970), and later the development of the draft risk model by Fanger & Christensen (1986), being enshrined in dominant international standards such as ASHRAE Standard 55 and ISO 7730 for decades.

Thermal comfort standards practically preclude air movement as a means of achieving occupant comfort in centrally-conditioned buildings due to the potential for air movement to be negatively perceived as draft. In the years following the excellent contribution of Fanger and colleagues, however, there has been a general refocus of research attention away from the negative effects of draft (defined as unwanted cooling), towards the positive benefits of air movement. It is now recognised that the perceptual process of classifying air movement as a draft or breeze is more than just a heat-balance assessment.

This lab session will look at the perceptual effects of air movement on thermal sensation and pleasure in different ambient temperatures. This ties in with the aim of the unit to provide students with a solid grounding in the principles and practice of instrumental and questionnaire measurement approaches in laboratory settings using state-of-the-art instrumentation.

Methods:

Both chambers of the IEQ Lab will be used, with participants divided into two groups of 12. Participants will experience a warm exposure and a cool exposure, each with two (2) air movement patterns: constant and sinusoidal. Participants will spend 30-minutes seated in the ambient conditions - ranging from 26-28°C in the warm exposure and 21-23°C in the cool exposure - before experiencing each air movement profile for 10-minutes in a randomised sequence. Participants will then swap rooms and undergo the same procedure, giving a total experiment duration of 100-minutes.

FACULTY OF ARCHITECTURE, DESIGN AND PLANNING

Instruments:

Air temperature will be measured at 0.1m, 0.6m and 1.1m above floor in compliance with the measurement protocols in international standards. Relative humidity and globe temperature will be monitored in the occupied zone the chamber. All sensors will be logged continuously by the IEQ Lab Building Monitoring and Control System (BMCS).

Low-powered personal fans will create air movement at the back of each subject’s neck and at ankle height, and a programmable switched-mode power supply will be used to regulate the voltage supplied to the fans to create the different air movement profiles.

Fast-response omnidirectional Dantec anemometers will measure local back-of-the-neck air speed at a rate of 2Hz (2 times a second) in order to properly characterise airflow patterns.

FACULTY OF ARCHITECTURE, DESIGN AND PLANNING

A simple questionnaire consisting of three Likert scales for thermal sensation (7-point), local thermal sensation (7-point), thermal pleasure (7-point) and air movement preference (7-point) will be administered on paper.