Thermal comfort and draught assessment in a modern open office building in Tallinn

Abstract

Modern office building users have high expectations about the working environment and thermal comfort, which requires the installation of complex technical systems such as combined cooling and ventilation. Room conditioning units of these systems must ensure temperature and ventilation control in a way that air velocity is low and the air temperature in acceptable range. Achieving air distribution avoiding draught is one of the key elements of a thermal comfort in modern office landscape. Higher air velocity in occupied zone is easily perceived as draught, which causes occupant dissatisfaction and complaints, as well as decrease in the productivity or effective floor space area. To reduce complaints, room air temperature setpoints or ventilation airflow rates are often modified, which may result in higher heating energy demand. In addition, excessive heating setpoint rise will not only consume more energy, but may cause health problems. Compared to cellular offices it is more difficult to ensure thermal comfort conditions in open office spaces where there are no walls for air flows. In addition, due to the higher number of employees it is more difficult to meet satisfactory conditions for everyone. The aim of this study was to evaluate thermal comfort parameters such as room air temperature, air speed and supply air temperature and how the users sense it in a modern office building in Tallinn, Estonia. Design room air temperature setpoints and air exchange rate were evaluated on open office spaces. Measured data with web-based indoor climate questionnaire was analysed. Results show which design and measured parameters make it possible to match the user comfort at all times.

Assessment of downward draught in high-glazing facades in cold climates – experimental and CFD study into draught control with a 21-type radiator

“…Thermal comfort constitutes a central topic in the management of modern buildings, as it is closely related to the well-being of tenants; in office buildings, this is also strictly related to the productivity of employees [1], [2]. One of the biggest sources of complaint from the occupants in working areas consists of indoor air temperature fluctuations, thermal asymmetry and draught of cold air near the windows [2]. The latter is generally defined as air movement that induces an unwanted cooling effect on the body [3].…”

“…A typical solution for contrasting the formation of such downdraught is positioning heat emitters such as radiators or convectors under the window, however this does not eliminate the problem per se. Unfortunately, the most common procedure is overheating the space, with higher supply air temperature than the design value (for instance, 21°C instead of 17°C) [2].…”

A Comparative Study on Cooling Period Thermal Comfort Assessment in Modern Open Office Landscape in Estonia

“…The latter factors also increase the risk of draught in occupied spaces. In several studies, draught rate (DR) has been identified as the main cause of discomfort even if other thermal environment factors are at satisfactory levels [6,15,29,30].…”

On the Procedure of Draught Rate Assessment in Indoor Spaces

“…On this basis, the authors suggested a more careful design of the ventilation systems in classrooms. Recently, Kiil et al [15] reported their assessment of the draught and thermal comfort in an office building. It was found that DR was below 10% in heating and transient period measurements, but the risk of draught was assessed for the intensive cooling mode.…”