Effects of Indoor Climate on Occupants’ Perception and Work Performance in Office Environment

Henna Maula

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

This thesis examines the effects of indoor climate on occupants' comfort, perception and workperformance, and whether local cooling with cooling jet can improve the indoor environment inwarm office conditions. The focus is on the effects of room air temperature, indoor air qualityand airflow on occupants' subjective reactions and performance. Four publications are included, in which one describes a series of laboratory experiments which study the room air flow pattern,and three are based on human subject experiments. The results show that the mean air speed seems to increase with cooling load and badly implemented layout in office can cause draught (Publication I). The flow pattern in the room is not stable and the position of draught risk areas can change in time and also due to changes in room heat sources (Publication I). On the other hand, insufficient air conditioning seems to have a negative effect especially on subjective measures (Publication II and III). Providing fresh air into workstation via cooling jet, seems to have a positive effect on subjective measures in slightly warm office environment (Publication IV). Inadequate air conditioning appears to affect thermal comfort (Publication II) and perceived indoor air quality (Publication III), which are bothimproved by the cooling jet (Publication IV). Results from objective measures show that cognitive performance may not be as sensitive tochanges in temperature as suggested by Seppänen et al. (2006a) and that the effect oftemperature on performance is task dependent (Publication II). Results also suggests that emissions from occupants, i.e. human bioeffluents do not have as strong effect as previously seen with emissions from external pollution source (Seppänen et al., 2006b; Publication III). However, according to subjective measures, the disturbance of heat on performance seems to be increased by slightly warm temperature (Publication II) and by low ventilation rate with elevated levels of human bioeffluents (Publication III). Slightly warm temperature also seems to increase the disturbance of stuffiness (Publication II). The cooling jet appears to decrease the disturbanceof heat and the disturbance of stuffiness in slightly warm temperature (Publication IV). The energy consumption and risk of draught are among the main problems when air conditioning systems are used in offices with high thermal load, such as open-plan offices with high density of workstations. One solution may be to allow slightly elevated temperatures in the space and to provide local cooling using jet with fresh air into the workstation. This kind of solution together with personal control over the airflow allows occupants to adjust the individual thermal environment to gain better thermal comfort while energy consumption of air conditioning could be reduced. More research is needed to find the optimum indoor environment solution regarding energy savings and occupants' comfort, in which room air temperature is slightly raised and individual control over the thermal environment at workstation is provided via cooling jet.
Translated title of the contributionSisäilmaston vaikutus kokemukseen ja työsuoriutumiseen toimistotyössä
Original languageEnglish
QualificationDoctor's degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Siren, Kai, Supervising Professor
  • Hongisto, V., Thesis Advisor, External person
  • Melikov, Arsen Krikor, Thesis Advisor
Publisher
Print ISBNs978-952-60-7765-9
Electronic ISBNs978-952-60-7766-6
Publication statusPublished - 2017
MoE publication typeG5 Doctoral dissertation (article)

Keywords

  • airflow
  • thermal comfort
  • indoor air quality
  • cooling jet

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