Mglc Marcel Loomans

Differences between young adults and elderly in thermal comfort, productivity, and thermal physiology in response to a moderate temperature drift and a steady-state condition.

UNLABELLED Results from naturally ventilated buildings show that allowing the indoor temperature to drift does not necessarily result in thermal discomfort and may allow for a reduction in energy use. However, for stationary conditions, several studies indicate that the thermal neutral temperature and optimum thermal condition differ between young adults and elderly. There is a lack of studies that describe the effect of aging on thermal comfort and productivity during a moderate temperature drift. In this study, the effect of a moderate temperature drift on physiological responses, thermal comfort, and productivity of eight young adults (age 22-25 year) and eight older subjects (age 67-73 year) was investigated. They were exposed to two different conditions: S1-a control condition; constant temperature of 21.5 degrees C; duration: 8 h; and S2-a transient condition; temperature range: 17-25 degrees C, duration: 8 h, temperature drift: first 4 h: +2 K/h, last 4 h: -2 K/h. The results indicate that thermal sensation of the elderly was, in general, 0.5 scale units lower in comparison with their younger counterparts. Furthermore, the elderly showed more distal vasoconstriction during both conditions. Nevertheless, TS of the elderly was related to air temperature only, while TS of the younger adults also was related to skin temperature. During the constant temperature session, the elderly preferred a higher temperature in comparison with the young adults. PRACTICAL IMPLICATIONS Because the stock of fossil fuels is limited, energy savings play an important role. Thermal comfort is one of the most important performance indicators to successfully apply measures to reduce the energy need in buildings. Allowing drifts in indoor temperature is one of the options to reduce the energy demand. This study contributes to the knowledge concerning the effects of a moderate temperature drift and the age of the inhabitants on their thermal comfort.

The influence of local effects on thermal sensation under non-uniform environmental conditions - Gender differences in thermophysiology, thermal comfort and productivity during convective and radiant cooling

Applying high temperature cooling concepts, i.e. high temperature cooling (T(supply) is 16-20°C) HVAC systems, in the built environment allows the reduction in the use of (high quality) energy. However, application of high temperature cooling systems can result in whole body and local discomfort of the occupants. Non-uniform thermal conditions, which may occur due to application of high temperature cooling systems, can be responsible for discomfort. Contradictions in literature exist regarding the validity of the often used predicted mean vote (PMV) index for both genders, and the index is not intended for evaluating the discomfort due to non-uniform environmental conditions. In some cases, however, combinations of local and general discomfort factors, for example draught under warm conditions, may not be uncomfortable. The objective of this study was to investigate gender differences in thermophysiology, thermal comfort and productivity in response to thermal non-uniform environmental conditions. Twenty healthy subjects (10 males and 10 females, age 20-29 years) were exposed to two different experimental conditions: a convective cooling situation (CC) and a radiant cooling situation (RC). During the experiments physiological responses, thermal comfort and productivity were measured. The results show that under both experimental conditions the actual mean thermal sensation votes significantly differ from the PMV-index; the subjects are feeling colder than predicted. Furthermore, the females are more uncomfortable and dissatisfied compared to the males. For females, the local sensations and skin temperatures of the extremities have a significant influence on whole body thermal sensation and are therefore important to consider under non-uniform environmental conditions.

Impact of Available and Perceived Control on Comfort and Health in European Office Buildings

The objective of this study was to find out how perceived control and access to control options like operable windows and thermostats affect the comfort and health of European office workers. For this, the Health Optimisation Protocol for Energy-efficient Buildings database was re-analysed. Statistical analyses were conducted to find out what the impact is of available controls on perceived control of building occupants. Furthermore, the effect of perceived control on comfort and health (building-related symptoms) of building occupants was determined. Overall, no significant correlations were found between available controls and perceived control. Solar shading, however, was an exception. On the other hand, between perceived control and comfort or health, multiple significant correlations were found. Occupants are more comfortable in buildings in which the amount of perceived control over temperature, ventilation and noise is high. Perceived control also has an impact on the incidence of building related symptoms, also if one looks at combinations of perceived control (e.g. control over temperature and ventilation).

Performance Assessment of an Operating Theatre Design Using CFD Simulation and Tracer Gas Measurements

This paper advocates application of the performance-based approach to arrive at improved, innovative and more functional buildings. It does so by describing the development of a performance assessment methodology for the assessment of the efficiency of a ventilation system in an operating theatre. This assessment is performed in the design and use phase to adhere to the performance-based approach definition. The developed methodology was tested in a real case study with an innovative down-flow plenum. The focus was on the low infection rate functional requirement. The results from the case study indicated that the assessment methodology functions and that the innovative down-flow systems, that was the topic of the case study, adhered to the requirements set. Some parts of the methodology, however, allow openings for further research. On the other hand, a similar assessment can be extended to other requirements, such as thermal comfort, hypothermia, etc.

Modelling and simulation of a jet fan for controlled air flow in large enclosures

Jet fans are applied for control of air flow and support of pollutant dispersal in large enclosures. In The Netherlands, application is well known for car parks as part of the fire safety design. In the design phase often the Computational Fluid Dynamics (CFD)-technique is used to verify the fire safety level afforded by the application of jet fans. However, very little is known on the modelling requirements of jet fans in CFD. This includes paucity on experimental data that can be applied for validation of the jet fan model. In this study results are presented as measurements for a specific type of jet fan in a large enclosure and of validation of modelling characteristics of the jet fan in CFD. Both free and near-wall positioning have been investigated and a modelling proposal is made. For the modelling of the jet fan, point-of-departure is a low complexity, as the model generally will have to be included in large computational domains. Applicability of the developed approach and assessment of efficiency of jet fan positioning in large enclosures is shown through a case study.

Selecting an appopriate tool for airflow simulation in buildings

With the advancement of technology, and with the widespread availability of simulation tools, we are forced to consider which simulation tool would be appropriate for a particular problem. This seemingly trivial decision is in reality not very easy to make. Very often this leads to the practice of using the most sophisticated tool available for every problem. The levels of resolution and complexity of simulations are directly related to the accuracy of the simulation and to the total cost of the simulation process. A simple tool may be cheaper, but there is a high risk of inaccuracy. An advanced tool could be more accurate, but it needs a huge amount of resource in terms of computing power, labour, and the advanced knowledge to perform the simulation and interpret the results. This paper proposes a guideline for selecting a simulation tool for airflow prediction. Sensitivity analysis is selected as the tool for decision making. A case study is used to highlight the proposed method.

Personal control over temperature in winter in Dutch office buildings

A field study was conducted during the heating season in nine modern office buildings in the Netherlands. A first objective of the study was to investigate what kind of control Dutch office workers have over temperature in winter (available control), to map how often these controls are used (exercised control) and to identify how much control the office workers perceive to have over temperature in winter (perceived control). A second objective was to objectify the amount of control over temperature in winter with thermostat effectiveness measurements. The third objective was to investigate how available control and exercised control impact the level of control over indoor climate in winter as experienced by office workers (perceived control). The study consisted of (i) a systematic inventory of relevant building and HVAC system characteristics, (ii) a questionnaire among building occupants, and (iii) indoor climate measurements; concerning the latter, to evaluate the effectiveness of controls, dynamic experiments have been performed. These experiments consisted of manual adjustments of thermostats by the researchers. After these interventions, response times and step responses for room temperature were identified to quantify how effective controls were in changing room temperature. The outcomes of the study can be used to improve temperature control in existing and new office buildings.

Simulation and measurement of the stationary and transient characteristics of the hot sphere anemometer

The omni-directional hot sphere anemometer, that applies a separate reference point for the temperature correction, currently is the most practical device that is used for the measurement of indoor air flows. The anemometer has been investigated, experimentally and numerically, with regard to stationary and transient aspects for application in the indoor air flow field. Significant deviations result when specific stationary restrictions and corrections are not recognised. The transient investigation shows a significant influence of the damping on the measurement signal in the frequency range that also prevails at indoor air flows. The measured turbulence intensity can be underestimated by approximately 20%. This may result in a 50% deviation of the percentage of dissatisfied (PD) as is found in the definition of draught.

Ventilation of operating theatres requires a performance

M. Loomans , W. van Houdt , A. Lemaire , J. Hensen Eindhoven University of Technology, Netherlands, Hospital Gooi-Noord, Netherlands, TNO, Netherlands Background: Due to infection risk, high demands are set for the air quality in operating theatres. As humans form the most important contamination source, ventilation of operating theatres is required. This is normally realised using a downflow plenum.

P22.02 Estimating operating room ventilation system performance in realistic scenarios

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