Abstract
Under-floor air distribution (UFAD) systems are occupied-area-based air conditioning systems that generally offer advantages over ceiling-based air distribution (CBAD) systems in terms of energy efficiency and thermal comfort; accordingly, UFAD systems have become more popular lately. The purpose of this study is to provide reasonable UFAD application conditions by comparing and analyzing the influences of cooling loads when UFAD and CBAD are applied to thermally control indoor environments. A chamber experiment was conducted to allow comparisons of the indoor thermal environment under CBAD and UFAD, with the experimental variables of the thermal load of the occupied area and the supply airflow rate. In conclusion, the lower the supply airflow and the higher the lighting power density, the more the thermal comfort of the indoor environment could be improved by using UFAD instead of CBAD. In the lighting power density range of 0–30 W/m2, correlations were calculated whereby the lighting power density levels could be predicted that would ensure thermal comfort at a desired level.
Highlights
In response to the climate change crisis, and keeping pace with international trends, South Korea passed and amended in 2013 the Low Carbon Green Growth Basic Act and its subordinate acts, specifying the goal of reducing national greenhouse gas by 30% from the 2020 business-as-usual (BAU)level
Under-floor air distribution (UFAD) have relatively smaller heating and cooling loads compared with ceiling-based air distribution (CBAD), and have less load for air supply flow or air supply temperature, saving energy and providing comfort; UFADs are known to be advantageous in terms of flexible space use [2,3,4]
The purpose of this study is to provide quantitative and foundational resource to refer to when appointing air handling systems, allowing a determination of whether UFAD or CBAD is more appropriate given expected load characteristics
Summary
In response to the climate change crisis, and keeping pace with international trends, South Korea passed and amended in 2013 the Low Carbon Green Growth Basic Act and its subordinate acts, specifying the goal of reducing national greenhouse gas by 30% from the 2020 business-as-usual (BAU). Through a study on the diverse factors that influence the indoor thermal environment, that the ventilation efficiency increases with floor-supply displacement ventilation in the occupied area, compared with mixing systems, but that it might cause discomfort around the diffuser area due to temperature stratification [7]. Chenvidyakarn et al divided the internal heating load conditions into localized heat sources and distributed heat sources in the occupied areas This supplied the optimum air flow according to such load ratios, thereby providing the potential to ensure the correct indoor ventilation amount and keep thermal comfort [9]. In this study we compare and analyze CBAD and UFAD systems, studying the effects of supply air flow changes and of heat emission from lighting equipment in the unoccupied area upon indoor thermal comfort
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