Evaluation of simplified ventilation system with direct air supply through the facade in a school in a cold climate (original) (raw)
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Indoor climate of classrooms with alternative ventilation systems
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More than a well-being, providing a good Indoor Climate Quality (ICQ) in education buildings is necessary for students’ health and in order to maximize academic results. In the context of a research focusing on hybrid ventilation strategies, this paper presents the results of a first survey on thermal comfort and indoor air quality in high school classrooms; the results will be subsequently used to develop strategies on mixed mode ventilated classrooms. The objects of the study are the classrooms of ESTP, a civil engineering school located in Cachan, a suburban city in southern of Paris, France. The survey lasted one month during the mid-season. The classrooms are equipped with a mechanical ventilation system and with windows, so that various solutions can be tested based on natural, mechanical and hybrid ventilation. After a first period of monitoring and an analysis of initial conditions, ICQ was analyzed in different conditions according to the schedule and the occupancy of the i...
2007
SUMMARY Within the UK, the importance of providing adequate ventilation in schools has been recognised in a recently adopted document (Building Bulletin 101), which defines the set of performance criteria in relation to ventilation rates and indoor air quality in new school buildings. This paper describes a series of field measurements that investigated the ventilation rates and indoor air quality in three new secondary schools in England with respect to these new criteria. The study also analysed the overall performance of the integrated heating and ventilation systems with regards to comfort. All the schools satisfied the recommended ventilation performance standards during the week that the measurements were undertaken. However, this apparently reassuring message can be misleading unless one takes into account both the original design assumptions and then the actual occupancy of the classrooms and occupant behaviour in general. With regards to comfort, for many rooms the schools ...
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2016
Ventilation air may be provided in buildings by means of natural or mechanical strategies. When a HVAC system is installed, thermal comfort and indoor air quality (IAQ) may be controlled with higher precision. However, especially between the 70s and the 90s, mechanical ventilation systems have been installed on formerly naturally ventilated buildings without providing any control for natural ventilation. The two ventilation systems are therefore overlapping, without any energy or comfort oriented control strategy, and the occupants are operating windows without any consistent understanding of IAQ and comfort conditions, neither of energy consumption. It may both lead to a substantial energy waste and to low indoor climate conditions. A typical university classroom with exhaust mechanical ventilation and operable windows without switching control has been assessed, in order to understand how occupant behaviour and different ventilation scenarios may influence indoor climate conditions.
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2016
Indoor climate quality as well as energy standard of school buildings is very important subject. In this context it seems obvious that mechanical ventilation with heat recovery (HR) is better solution than natural/hybrid ventilation. However, data collected within RenewSchool Project showed that in some cases natural ventilation provides better indoor climate than mechanical ventilation with HR. At this point the question arises whether it is possible to provide required indoor climate and similar energy consumption in school classrooms with natural/hybrid ventilation as in buildings with balanced mechanical ventilation with HR? The paper presents comparison of energy performance and indoor climate in typical school classroom with two different ventilation strategies: mechanical balanced ventilation with heat recovery (HR) and natural/hybrid ventilation. For both types of ventilation the model of energy performance as well as calculation of indoor climate were carried out. The prima...
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Most of the school buildings in Italy are high energy-demanding buildings with no ad-hoc ventilation systems (i.e., naturally-ventilated buildings). Therefore, reducing the heat losses of schools represent the main aspect to be dealt with. Nonetheless, the indoor air quality of the building should be simultaneously considered. Indeed, to date, energy consumptions and air quality are considered as incompatible aspects especially in naturally-ventilated buildings. The aim of the present paper is to evaluate the effect of different ventilation and airing strategies on both indoor air quality and energy consumptions in high energy-demanding naturally-ventilated classrooms. To this purpose, an Italian test-classroom, characterized in terms of air permeability and thermophysical parameters of the envelope, was investigated by means of experimental analyses and simulations through CO2 mass balance equation during the heating season. The air quality was assessed in terms of indoor CO2 conce...
CLIMA 2016 - proceedings of the 12th REHVA World Congress: volume 5, 2016
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 predicted occupant discomfort due to draughts in the regions close to the openings. Bottom hung-in vents reduced draught impact and the study also suggests moving occupants away from the draught zones to minimise the effect of discomfort draughts on occupant comfort. The air velocity and airflow patterns in the classrooms were influenced by the shape, size, location of internal openings, and the flowrate through the openings. This could be controlled by introduction of new openings with lower airflow rates through each opening.
Energy and Buildings, 2018
This paper presents the ventilation performance of a Passive Ventilation System with Heat Recovery (PVHR) based on in-situ monitoring in a primary school in London. The study involves long-term (15month) monitoring of temperature, relative humidity and Carbon dioxide (CO 2) concentrations in both the classrooms and the outdoor environment. In addition, short term (1&2 week) observational monitoring was performed in two classrooms at ventilation system level and classroom level, during both the heating and non-heating seasons. Temperatures and air velocities were measured within the PVHR system while instances of window opening and the number of students were noted in daily diaries. Air permeability and infiltration measurements were performed to characterise the spaces. Time-varying ventilation rates were estimated through a form of continuity equation considering CO 2 generation rates by occupants. Preliminary results show that the operation of the ventilation system is more sensitive to changes in wind speed and direction than to buoyancy. When negative pressure was observed on the classrooms" facades the ventilation system was supplying two to three times more air in comparison to instances when positive pressures were observed. The assessment of the ventilation performance of such natural ventilation systems depending solely on wind and buoyancy is complicated as they are dynamic systems that constantly balancing with the surrounding conditions, and the operation is highly correlated to the airtightness of the building"s envelope.
Stack driven ventilative cooling for schools in mild climates: analysis of two case studies
This paper presents two case studies of stack driven ventilative cooling systems implemented in kindergarten schools located in the mild Subtropical-Mediterranean climate of Lisbon, Portugal. Both systems rely on stack driven natural ventilation supplemented by a larger, single-sided ventilation opening to be used in the warmer months. In both systems air enters the rooms at a low level, directly in front of the heating passive convector systems, and is exhausted in the back of the room, through a chimney. In addition to the smaller opening configuration, that is sized for the heating and mild seasons (1-3% of room floor area) both designs have larger openings to be used during the cooling season. This larger opening is fundamental to meet the minimum code requirement for total ventilation opening area (5% of floor area). The designs were developed and fine-tuned using dynamic thermal simulation (EnergyPlus). This approach allowed for straightforward statistical analysis of expected system performance, assessed in terms of thermal comfort and indoor air quality. Measurements in steady state mode show a good agreement between simulated and measured airflow rate. During the warmer months the smaller and protected heating season openings are opened for night cooling effect. The chimney exhausts were optimized to avoid opposing stack and wind effects. Both systems are user controlled. The importance of effective commissioning of passive systems is discussed and an example of a simple user manual is provided. The performance of these systems shows that a well-designed natural ventilation system can ensure adequate levels of indoor air quality in kindergartens.