Ventilative Cooling in a School Building: Evaluation of the Measured Performances

Hilde Breesch,Alexis Versele,Bart Merema

doi:10.3390/fluids3040068

Abstract

The test lecture rooms on Katholieke Universiteit Leuven (KU Leuven) Ghent Technology Campus (Belgium) are a demonstration case of Annex 62: Ventilative Cooling of the International Energy Agency’s Energy in Buildings and Communities programme (IEA EBC). The building is cooled by natural night ventilation and indirect evaporative cooling (IEC). Thermal comfort and the performances of ventilative cooling are evaluated. Long-term measurements of internal temperatures, occupancy, opening of windows and IEC were carried out in the cooling season of 2017. The airflow rates through the windows in cross- and single-sided ventilation mode were measured by both tracer gas concentration decay and air velocity measurements. In addition, the air flow pattern is visualized by measuring air temperatures in the room. The results show that good thermal summer comfort was measured except during heat waves and/or periods with high occupancy. Both nighttime ventilation and IEC operate very well. IEC can lower the supply temperature by day significantly compared to the outdoor temperature. The Air Changes Rates (ACR) of the night ventilation greatly depends on wind direction and velocity. The air temperature profile showed that the air is cooled down in the whole lecture but more in the upper zone. The extensive data monitoring system was important to detect malfunctions and to optimize the whole building performance.

Highlights

In the recently approved second recast of the Energy Performance of Buildings Directive (EPBD) [1], the member states of the European Union committed themselves to develop a sustainable, competitive, secure, and decarbonized energy system by 2050
Conceptual and building technical measures as well as energy efficient cooling systems are needed in these nearly zero-energy buildings (nZEB) buildings to guarantee good thermal comfort all year round
This paper aims to evaluate thermal comfort in this nZEB school building and to discuss the performances of its ventilative cooling systems

Summary

Introduction

In the recently approved second recast of the Energy Performance of Buildings Directive (EPBD) [1], the member states of the European Union committed themselves to develop a sustainable, competitive, secure, and decarbonized energy system by 2050. While the first recast of the EPBD [2] required that from 2020, all new buildings in the European Union have to be nearly zero-energy buildings (nZEB), this second recast focusses on renovation strategies. One of the major new challenges in these highly insulated and airtight buildings is the increased need for cooling and the risk on overheating during summer but all year round. This cooling demand depends less on the outdoor temperature and more on the internal and solar heat gains [3]. Ventilative cooling is an example of an energy efficient cooling method that can contribute to achieve the goal

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