Stack ventilation

In subtropical southeast Queensland, a common to improving thermal comfort in existing school classrooms is to use air-conditioners. However, increasing reliance on air-conditioners in schools adds to energy costs and increases carbon emissions. Greater understanding of low energy approaches to improving thermal comfort is needed to address this problem. The purpose of this research was to firstly, evaluate the impact of four passive cooling strategies retrofitted to existing classroom buildings and their immediate surrounds in a Brisbane school. The retrofitted interventions were: 1) stack ventilation, 2) cool roof, 3) shade sails over courtyards, and 4) schoolyard greening. Secondly, the research explored the adaptive behaviour of teachers during times of perceived over-heating in classrooms. The research used a case study methodology that combined quantitative (temperature) and qualitative (perceptions of teachers) data gathering within an overarching systems framework. Classroom temperatures were collected before and after interventions from 2012 to 2015. Teachers participated in an online questionnaire and semi-structured interviews in 2015.
Results indicate that the duration of high classroom temperatures decreased following each intervention. However, the reduction in classroom temperature was not enough to be within an acceptable comfort range for summer months, particularly during hot and humid weather. Common adaptive behaviours exhibited by teachers included the use of windows and ceiling fans to increase air movement, and scheduling more intense teaching in the cooler, morning session. The research identified times in the school year when classrooms with passive, retrofitted interventions were within an acceptable comfort range. However, a significant finding was that air-conditioning some classrooms and not others was seen to be an equity issue. The research makes an important contribution to the information available to schools on low energy approaches to improving thermal comfort. These approaches include reducing heat load in existing classrooms by retrofitting passive cooling strategies and increasing awareness amongst teachers of the potential for adaptive behaviours to decrease the use of mechanical cooling and heating.

In Malaysia, terraced houses have been reported as the fast growing since 5 decades ago. However, the terrace houses consist of limited ventilation opening and only comply with
minimum percentage of window-to-floor ratio determined by Uniform Building By Law 1984. This study investigates the indoor thermal performance in single storey terrace house
in Kuching, Sarawak, Malaysia, by using field measurements to obtain the initial outdoor weather data and followed by CFD simulation to study the effect of the solar chimney material on the ventilation velocity and indoor air temperature. The results show that the effect of the copper material absorber induced higher velocity. Although the air temperature of the indoor environment is highest among all by using the copper absorber, the air velocity induced by the copper absorber to the indoor environment approximately 0.5m/s higher compared to others. Other than that, the comparison was made among the existing room without solar chimney and the room with varies absorber installed in the solar chimney. The
air velocity of the room with solar chimney applied with varies absorber could induce approximately 0.25 – 0.55m /s air velocity for the indoor environment. The study found that
copper could induce highest air velocity for indoor environment with value 0.502m /s and 1.16m ³/s airflow rate with outdoor air temperature of 35°C. From the study, solar chimney is proven to be an effective tool to induce the air velocity and reduces the air temperature of the indoor environment. The copper absorber is recommended for the solar chimney in order to induce higher air velocity to reduce the air temperature of the indoor environment.

In hot and humid country, ventilation and thermal performance could be improved
by effective natural ventilation strategies. However, the climatic conditions of the
tropical countries are mainly distinguished by high air temperature and relative
humidity as well as low wind velocity which are the main factors that reduce the
comfort level of occupants, especially in the terrace house. The use of solar chimney
in terrace house is one of alternatives to increase the thermal and ventilation
performance of the indoor environment. This study initiated with field measurement
in a selected case study house located in Kuching, Sarawak, Malaysia for software
validation. Validation study of CFD in DesignBuilder software was done by
compared with field measurement data, with the deviation ranges from 7.2% to
18%. The optimizations of solar chimney cross section were carried out. The
results of CFD were observed in order to study the optimized length and width gap
of solar chimney that could induce optimum air velocity and thermal performance in
the indoor environment. The results show that the effective width gap for 36m³ room
ranged from 0.6m to 1.0m while the length from 1.5m to 2.0m, whereby the induced
air speed ranged from 0.04m/s to 0.223m/s. Based on the findings, the study has
shown that the effective gap and length of solar chimney could increase the air
velocity of indoor environment that creates a cooling effect on human body,
especially for terrace house in Malaysia climate

In this 1992 study, nine computerized design and analysis tools were compared for their capabilities at modeling cooling loads and seven different passive cooling strategies. Also, a test house was modeled using a rule-of-thumb method, a detailed hand calculation method on a computerized spreadsheet, and a computerized hourly thermal network analysis model.

Natural ventilation solutions can provide sufficient outside air to maintain adequate indoor air quality (IAQ), which can improve occupants’ performance in classrooms and provide reductions in energy consumption for space conditioning. In this study, the effect of cool outside air and the vent opening configurations on IAQ and occupant thermal comfort in naturally ventilated classrooms during the heating season was examined. Dynamic and steady state computer simulations were performed to investigate the internal conditions of a naturally ventilated classroom, designed to meet the requirements of the Priority Schools Building Programme (PSBP) Output Specification. The modelled designs considered natural cross ventilation airflow through high-level top hung-out or bottom hung-in openings, and a stack (atrium). Dynamic thermal modelling results indicate that adequate IAQ and occupant thermal comfort could be achieved using natural ventilation. However, the CFD simulation results predic...