Abstract

In this study, the performance of a micro-environment system was analysed and compared with diffused ceiling ventilation. In the analysed micro-environment low velocity radiant panel system, two low velocity units and radiant panels were installed above workstations to supply directly clean air to occupants and to cover the cooling power required. With diffused ceiling ventilation, all cooling demand is covered with air and thus, the airflow rate required is higher than with low velocity radiant panel system. The varied heat gain from 40 to 80 W/m2 consists of two seated dummies, laptops, monitors and simulated solar gain. The results show that with perimeter exhaust and local supply air, 8–13% reduction of the total cooling load required is possible, in comparison to the standard mixing systems. The average exhaust temperature was 0.7–1.9°C higher than average room air temperature at the workstation. Moreover, the mean air temperature with the low velocity radiant panel system at the occupied zone was 0.6°C lower than with diffused ceiling ventilation. With low velocity radiant panel system, the air velocity was less than 0.12 m/s in the occupied zone. Also, the draught rate was less than 10%. Furthermore, the air change efficiency with the low velocity radiant panel system was over 70% which is better than 44–49% efficiency with diffused ceiling ventilation.

Highlights

  • Building sector accounts for about one-third of the global greenhouse gas emissions and at the same time uses about 40% of the world’s energy.[1]

  • This smoke visualization confirmed that the airflow rate of 15 L/s could be used for local micro-environment control without increasing significantly the draught risk

  • The main objective of this paper was to compare the performance of the concept of a local low velocity radiant panel system (LVRP) with a diffuse ceiling ventilation system (DCV) by experimental studies

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Summary

Introduction

Building sector accounts for about one-third of the global greenhouse gas emissions and at the same time uses about 40% of the world’s energy.[1] A considerable fraction of this energy use is utilized for achieving desirable indoor climate in buildings.[2] According to the European Commission, improved energy efficiency of buildings means maintaining good indoor air quality and thermal comfort levels with less energy use than before.[3] In the European Union, policies have been stricter according to the EU 2030 goals on energy efficiency demands in buildings to meet EU’s longterm 2050 greenhouse gas reductions target, which is. Good indoor environment and energy efficiency are often seen as conflicting requirements. Novel Heating, Ventilating, AirConditioning (HVAC) systems are required to achieve simultaneously indoor climate and energy efficiency requirements. More concerns have been focused on micro-environment of occupants to optimize energy usage and trade off energy conservation and indoor comfort, where the main challenge is to supply clean air to the breathing zone and maintain thermal conditions

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