Abstract
The objective of the paper is to demonstrate the importance of the unsteady Computational Fluid Dynamics (CFD) simulations and long-term measurements for the reliable assessment of thermal comfort indoors, for proper categorization of the indoor thermal environment and for identifying the reasons for complaints due to draught discomfort. Numerical simulations and experimental measurements were applied in combination to study ventilation in a field laboratory, a university classroom with a controlled indoor environment. Strong unsteadiness of the airflow was registered both in the unsteady RANS results and the real-scale long-term velocity data measured with thermo anemometer. Low-frequency high-amplitude velocity fluctuations observed lead to substantial time variation of the draught rate. In case of categorization of a thermal environment, the point measurements or steady-state RANS computations would lead to wrong conclusions as well as they cannot be used for identification of the reasons for people’s complaints due to draught discomfort if strong unsteadiness of the airflow exists. It is demonstrated that the length of the time interval for draught rate (DR) assessment may not be universal if low-frequency high-amplitude pulsations are present in the room airflow.
Highlights
The indoor environmental quality (IEQ) depends on both indoor air quality (IAQ) and human comfort
It was found that draught rate (DR) was below 10% in heating and transient period measurements, but the risk of draught was assessed for the intensive cooling mode
The paper presents the results of a combined numerical and experimental study of room air movement in a test university classroom with a controlled indoor environment. Both the 3D field movement in a test university classroom with a controlled indoor environment. Both the 3D field results computed with the unsteady RANS technique and the real-scale long-term point velocity data results computed with the unsteady RANS technique and the real-scale long-term point velocity data measured with the thermo anemometer report about strong unsteadiness of the airflow
Summary
The indoor environmental quality (IEQ) depends on both indoor air quality (IAQ) and human comfort (thermal, visual, acoustic). A poor IEQ could precondition different discomforts and health problems that result in short or and long-term absence from work and decreased productivity [1,2,3]. Olesen et al [4] reported that in more than 40% of enclosures people complain from the comfort or health-related issues. The situation is worsening in schools, where the occupation density is. 1.8–2.4 m2 /person, compared to 10 m2 /person in offices [5].
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