https://www.um.edu.mt/library/oar/handle/123456789/30449 2026-04-12T03:16:38Z 2026-04-12T03:16:38Z Schembri, Maurizio Micallef, Daniel https://www.um.edu.mt/library/oar/handle/123456789/30543 2018-06-05T01:23:51Z 2018-01-01T00:00:00Z

Title: The effectiveness of vernacular stack ventilation with application in modern and retrofitted buildings Authors: Schembri, Maurizio; Micallef, Daniel Abstract: Ventilation is a vital aspect in an internal environment for every room occupant to achieve basic health requirements and acceptable thermal comfort. To achieve the required ventilation rate, mechanical ventilation is generally used in modern buildings. This comes at an energy cost required in operating the necessary equipment. In some cases, it makes sense to make use of natural ventilation depending on site conditions. Vernacular stack ventilation systems use vents to try to achieve modestly ventilated spaces. At the moment, there is little to no knowledge on their effectiveness and no quantification of the ventilation rates can be found from the addressed literature. This research aims at bridging this gap in knowledge. The ventilation flow rates resulting from vents are numerically assessed using a hypothetical test room as well as a case study. On the basis of this, new modifications are proposed and analysed. The purpose of this is to enhance the ventilation flow rates and compare them with established ventilation standards. The numerical approach used here is based on Computational Fluid Dynamics (CFD). The results obtained are promising, as the studied case was found to result in an air change rate of 3.2l/s or 0.13 ACH for a typical summer condition while the enhanced natural ventilation case produced a ventilation rate of 5.8 l/s or 0.23 ACH, with a significant improvement in comfort. Upon further research, such a vernacular ventilation system using vents could be an important yet simple and relatively maintenance free approach. This can aid in reaching nearly zero energy targets for buildings.

2018-01-01T00:00:00Z Vella, Roberta Ghirlando, Robert https://www.um.edu.mt/library/oar/handle/123456789/30542 2018-05-31T01:25:36Z 2018-01-01T00:00:00Z

Title: Analysis of the operation and performance of a solar cooling system Authors: Vella, Roberta; Ghirlando, Robert Abstract: In recent years, renewable sources of energy have been increasingly sought after to shift the consumption of energy from conventional sources to clean energy sources. A myriad of applications exist to exploit solar, wind, geothermal and any other means to provide the required process. Solar energy systems can either produce electricity or hot water. Solar cooling systems are being installed to provide space cooling or process cooling in locations where sufficient thermal energy is present to operate the vapour absorption chiller to replace vapour compression systems. Thus since sufficient solar energy was incident on the building of the Oenology and Viticulture Research Centre at Buskett, it was used to generate hot water to operate a solar cooling system to supply chilled water to control the temperature of fermenting wine. Prior to the installation, process cooling was provided through a vapour compression system. Initially a control system was designed to operate the solar cooling system. The system could not operate during high solar radiation scenarios and thus significant number of experimentats were carried out to improve the operation and performance of the solar cooling system.

2018-01-01T00:00:00Z Vassallo, P. L. Yousif, Charles Abela, Alan https://www.um.edu.mt/library/oar/handle/123456789/30541 2020-03-23T14:58:26Z 2018-01-01T00:00:00Z

Title: Performance gap between asset and operational energy performance rating for non-residential buildings Authors: Vassallo, P. L.; Yousif, Charles; Abela, Alan Abstract: This paper aims at identifying anomalies that may exist when an asset rating is compared to the actual energy consumption of a non-residential building. This study is part of an on-going Ph.D. study focusing on the performance gap phenomena between energy consumption and energy modelling using standardized energy performance software. As a first stage, it is important to identify the extent of this gap by studying various local non-residential projects with EPCs, as calculated by the Simplified Building Energy Model for Malta (SBEMmt). Discrepancies have been identified for two buildings (a large hospital and a large office building). A first approach for solving such discrepancies have been made to change or enhance the status quo, so that the EPC would become more meaningful for our local situation and for developing energy efficient buildings in the future. The peculiarity of Malta as being predominately cooling will be highlighted and contrasted. Description: The research work disclosed in this publication is partially funded by the Endeavour Scholarship Scheme (Malta). Scholarships are part-financed by the European Union - European Social Fund Operational Programme II – Cohesion Policy 2014-2020 “Investing in human capital to create more opportunities and promote the well-being of society”.

2018-01-01T00:00:00Z Vella, Robert Yousif, Charles Martinez, Francisco Javier Rey https://www.um.edu.mt/library/oar/handle/123456789/30540 2022-07-18T05:38:17Z 2018-01-01T00:00:00Z

Title: Monitoring indoor temperatures of places of worship : a first step towards energy sustainability Authors: Vella, Robert; Yousif, Charles; Martinez, Francisco Javier Rey Abstract: This paper attempts to investigate the status quo of the indoor climate of some churches in Malta, ranging from large and small Baroque buildings to more contemporary buildings, during the winter season. This is carried out through an investigation of measured temperature and humidity, as a first step towards understanding and evaluating the extent of comfort issues in these buildings. It was found that the thermal mass of buildings plays a very important role in controlling indoor temperature in such free running structures. A contemporary church that was built of concrete showed extreme diurnal variations in indoor temperature during the winter season, which temperature was outside the comfort zone. On the other hand, Baroque churches had a relatively stable indoor temperature and they had fewer days where the temperature dropped below 18 °C.

2018-01-01T00:00:00Z