Adaptive temperature limits for air-conditioned museums in temperate climates

Indoor temperature (T) and relative humidity (RH) are important for collection preservation and thermal comfort in museums. In the 20th century, the notion evolved that T and RH need to be stringently controlled, often resulting in excessive energy consumption. However, recent studies have shown that controlled fluctuations are permissible, enabling improved energy efficiency. Consequently, the thermal comfort requirements are increasingly important to determine temperature limits, but knowledge is limited. Therefore, a thermal comfort survey study and indoor measurements were conducted at Hermitage Amsterdam museum in Amsterdam, the Netherlands for one year, including: (1) monitoring of existing conditions (T = 21°C, RH = 50%); and (2) an intervention in which T is controlled based on an adaptive comfort approach (T = 19.5–24°C, RH = 50%). The results show that the thermal comfort of the existing conditions is far from optimum; visitors feel too cool in summer and slightly too warm in winter. The adaptive temperature limits were developed to improve thermal comfort significantly without endangering the collection, thereby saving energy. Furthermore, facilitating visitors to adapt their clothing may contribute to enlarging the temperature bandwidth and improve (individual) thermal comfort.</p

The applicability of displacement ventilation for individual control of a microclimate

This paper introduces the desk displacement ventilation concept, which combines displacement ventilation with task conditioning. The experimental setup and results of full-scale steady-state and transient measurements and numerical simulations are described for a typical office configuration. Results are used to evaluate the concept with regard to the micro/macroclimate and thermal comfort. The steady-state results show that the separation between the micro- and macroclimate, which is characteristic of task conditioning, is less pronounced and may require improvement of the concept. This effect is investigated further via transient experiments. Results of the transient study show that the application of the displacement ventilation principle for task conditioning purposes is not suitable for standard office configurations. It should at least be supported by an additional system that introduces the air at higher velocity close to the occupant, of which several system types are already available today.</p

Effects of different cooling principles on thermal sensation and physiological responses

Applying low exergy cooling concepts in the built environment allows reduction of high quality energy sources. However, application of low exergy cooling systems can result in whole body and local discomfort of the occupants. Non-uniform thermal conditions, which may occur due to application of lowex systems, can be responsible for discomfort. However, in some cases combinations of local and general discomfort factors, for example draught under warm conditions, may not be uncomfortable. Two different cooling principles were studied: passive and active cooling. Active cooling occurred through either convection or radiation. Ten healthy male subjects (age: 20-29; BMI: 18-25) were exposed to four different experimental cases: (a) passive cooling through convection and (b) active cooling through convection, and active cooling by radiation via the (c) ceiling or (d) floor. Physiological and thermal sensation data indicate significant differences between the different cases

Influence of thermophysiology on thermal behavior: the essentials of categorization

Predicted energy use of dwellings often deviates from the actual energy use. Thermoregulatory behavior of the occupant might explain this difference. Such behavior is influenced by thermal sensation and thermal comfort. These subjective ratings in turn are linked to physiological parameters such as core and skin temperatures. However, it is unclear which physiological parameters best predict thermoregulatory behavior. The objective of this research was to study physiological parameters that potentially can be used to predict thermoregulatory behavior. Sixteen healthy females (18-30years) were exposed to two dynamic temperature protocols: a gradual increase (+4K/h, ranging from 24 degrees C to 32 degrees C) and a gradual decrease in ambient temperature (-4K/h, ranging from 24 degrees C to 16 degrees C). During the experiments physiological responses, thermal sensation, thermal preference and the intention of thermoregulatory behavior were measured. Thermal sensation is highly correlated with thermal preference (r=-0.933, P<0.001). The skin temperature of the wrist best predicts thermal sensation (R2=0.558, P<0.001) and therefore seems useful as a physiological parameter to predict the intention of thermoregulatory behavior. When the subjects are categorized based on their thermal sensation votes, more precise predictions of thermal sensation can be made. This categorization therefore can be of value for the determination of the actual energy use of occupant in dwellings

Exergy analysis:Tthe effect of relative humidity, air temperature and effective clothing insulation on thermal comfort

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