This case study investigates the effects of ventilation intervention on measured and perceived indoor air quality (IAQ) in a repaired school where occupants reported IAQ problems. Occupants’ symptoms were suspected to be related to the impurities leaked indoors through the building envelope. The study’s aim was to determine whether a positive pressure of 5–7 Pa prevents the infiltration of harmful chemical and microbiological agents from structures, thus decreasing symptoms and discomfort. Ventilation intervention was conducted in a building section comprising 12 classrooms and was completed with IAQ measurements and occupants’ questionnaires. After intervention, the concentration of total volatile organic compounds (TVOC) and fine particulate matter (PM2.5) decreased, and occupants’ negative perceptions became more moderate compared to those for other parts of the building. The indoor mycobiota differed in species composition from the outdoor mycobiota, and changed remarkably with the intervention, indicating that some species may have emanated from an indoor source before the intervention.

This study presents extensive experimental measurements in a modern Finnish ice rink arena including temperature, relative humidity, carbon dioxide, air speed, air flow and pressure difference measurements in addition to smoke tests. Furthermore, the air exchange rate (ACH), air-exchange efficiency, and mixing factor were calculated. The main aim was to determine ventilation effectiveness, vertical stratification of the air and how commonly recirculation can be used in a modern ice rink arena representing common practice. Results show that re-circulation of return air was virtually continuous and in normal operating conditions the outdoor air fraction of the supply air was only 3.7 % corresponding to ACH of 0.03 1/h. The ceiling distributed mixing ventilation was not able to mix the whole volume sufficiently, leading to two imperfectly mixed zones with an average air-exchange efficiency of 39 % in the lower zone, corresponding to a mixing factor of 1.7.

Indoor ice rink arenas are among the foremost consumers of energy within building sector due to their exclusive indoor conditions. A single ice rink arena may consume energy of up to 3500 MWh annually, indicating the potential for energy saving. The cooling effect of the ice pad, which is the main source for heat loss, causes a vertical indoor air temperature gradient. The objective of the present study is twofold: (i) to study vertical temperature stratification of indoor air, and how it impacts on heat load toward the ice pad; (ii) to investigate the energy performance of air handling units (AHU), as well as the effects of various AHU layouts on ice rinks’ energy consumption. To this end, six AHU configurations with different air-distribution solutions are presented, based on existing arenas in Finland. The results of the study verify that cooling energy demand can significantly be reduced by 38 percent if indoor temperature gradient approaches 1 °C/m. This is implemented through air distribution solutions. Moreover, the cooling energy demand for dehumidification is decreased to 59.5 percent through precisely planning the AHU layout, particularly at the cooling coil and heat recovery sections. The study reveals that a more customized air distribution results in less stratified indoor air temperature.

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This case study investigates the effects of ventilation intervention on measured and 12 perceived indoor air quality (IAQ) in a repaired school where occupants reported IAQ problems. 13Occupants´ symptoms were suspected to be related to the impurities leaked indoors through the