2007

Karjalainen, Sami

The overall aim of the work is to improve office occupants' control over room temperature by improving the usability of user interfaces of heating and cooling systems. Both qualitative and quantitative methods were employed to study office occupants as users of room temperature controls. The work started with qualitative interviews taken in actual context, in the offices of the participants. The problems with thermostats were found to be diverse and fundamental. Next, in a quantitative interview survey, users were studied with a large and nationally representative sample: 1 000 Finnish office occupants answered questions concerning the office environment. Additionally, to simulate the real use of thermostats, controlled experiments were taken. Based on the results of the preceding user studies, user interface prototypes for room temperature control were next developed with a user-centred approach. As the definitive result of the work, usability guidelines for room temperature controls were developed. The usability guidelines are based on the user research performed in this work and the experiences gained from the user interface development. The usability guidelines are: (1) keep occupants in the loop, (2) visibility, identification and reachability of temperature controls, (3) shared temperature controls with heating and cooling systems, (4) acceptable default settings, (5) simplicity of interface, (6) clear way to adjust room temperature, (7) advice on comfortable room temperatures, (8) clear and sufficient feedback after adjustment, (9) fast effect on room temperature, (10) adequate effect on room temperature, (11) informative help, (12) aesthetic design and (13) females as test users in real-life situations.