Evaluation of acoustic, visual and thermal comfort perception of students in the Educational Building at KTH Campus : A study case in a university building in Stockholm

Abstract: In recent years the focus and application of sustainability in buildings has risen. Both for environmental and human well-being reasons. The quality of the indoor environment affects the well-being, productivity and work performance, but it can also affect the occupants negatively, like increasing risks of different diseases and health issues. A good indoor environment alongside with sustainable materials, proper HVAC (Heating, ventilation, and air conditioning) installations and building code regulations contribute to a sustainable solution with low environmental impact and reduced energy consumption. Since buildings alone are responsible for 38% of all human GHG (Greenhouse gas) emissions (Wikipedia, 2017), most countries recommend new more sustainable solutions to reduce that percentage. For example, in the EU, the 2020 climate and energy package targets to: cut 20% in greenhouse gas emissions, 20% of EU energy from renewables and 20% improvement in energy efficiency (European Comission, n.d.). In addition to the positive aspect of low environmental impact new constructions have, they also create a good living or working environment for the users. Studies have shown that a better indoor quality increases the productivity and work performance, but most of all the occupants feel comfortable and satisfied with their environment. A great number of papers have reviewed the acoustic, visual, thermal comfort and indoor air quality, which are main aspects of the indoor climate. Most papers focus on the users’ perception of these four aspects as well as other parameters that influence the indoor environment (architectural geometry, materials, etc.). Similarly, in this study case I focus on two different methods of obtaining the results, the objective method that contains the indoor environment measurements and the subjective method which includes a questionnaire created specifically for this research project. By obtaining these two sets of data, key focus points are developed, such as if the building’s certification meets the recommendations of Miljöbyggnad, what aspects influence the students’ perception the most, and whether there are any distinct connections between measured and calculated data. This study case was developed in a university building in Stockholm, where the four main aspects of the indoor environment were evaluated. The physical parameters such as temperature, air velocity, relative humidity, CO2 concentration and acoustics were measured in five different classrooms. In addition, a survey was developed for this study which included perception questions of the thermal, visual, acoustic comfort and indoor air quality. As found in other studies, gender and climate zone origin affected the overall indoor environmental perception. Even though the majority of both genders voted for “no change”, the remaining females answered that they preferred the conditions warmer. Also, the majority of answers from all climate zones were “no change”. However, the second highest opinion for students from warmer climate zones was “warmer”, which has also been found in other studies. Significant negative correlations were found between the acoustics and the satisfaction level of the acoustic comfort. Similarly, high correlations were observed between the visual comfort satisfaction level and the three aspects influencing it. Furthermore, the results showed that all physical measurements influenced the students’ thermal comfort and indoor air quality perception. All measurements obtained indicated a good indoor environment in all classrooms, and all values were between the Swedish Standards recommendations. Low correlation was found between the measured PVM and the AMV from the questionnaires even though all the values were among the limitations. Lastly, this study reviews methods that could be applied to similar future studies and, discusses what kind of errors to avoid in the future. There is still a lot of research that can be developed in order to gain a deeper understanding of the indoor environment and how humans perceive it.