Influence of user interaction with internal blinds on the energy efficiency of office buildings

The objective of this study was to evaluate the influence of the interaction of users with internal blinds on the energy efficiency of an office building. Firstly, based on the results obtained from the application of questionnaires to users of an office building located in Florianópolis, southern Brazil, three behavioural patterns (two passive and one active) were identified. The first passive behaviour consists of maintaining the internal blinds open at all times while the second group of passive users is comprised of those who keep the internal blinds closed at all times, throughout the year. The active user tends to open the internal blinds upon arrival at the workplace and to close them when solar radiation higher than 50 W/m2 is perceived on the work surface. The influence of behavioural patterns on the energy efficiency of buildings was investigated by performing computer simulations using DIVA for Rhino plug-in. Users who keep the internal blinds open are associated with greater daylight use, but also with increases in the thermal load inside the building. On the other hand, users who keep the internal blinds closed at all times contribute by reducing the energy consumption required for cooling, but they also reduce the daylight use. Active users tend to be associated with an intermediate energy consumption compared to the passive behavioural patterns for both lighting and cooling, as there is a balance between daylight use and thermal load when the blinds are adjusted. The increase in the average energy consumption, compared to the active users, was 5.3% for the users who keep the blinds open and 26.1% for those who keep the internal blinds closed. Thus, as a general trend, it was noted that user interaction with the internal blinds is important in terms of achieving gains in building energy efficiency. The behaviour of the active users results in lower energy consumption when compared to passive users and thus it is important to make users aware of their influence on achieving more energy efficient buildings.