Thermal Comfort Design Research Articles

Assessment of productivity loss in air-conditioned buildings using PMV index

This theoretical study reports on the assessment of productivity loss in air-conditioned office buildings using the PMV approach and makes use of Wyon’s reviews [D.P. Wyon, P.O. Fanger, B.W. Olesen, C.J.K. Pedersen, The mental performance of subjects clothed for comfort at two different air temperatures, Ergonomics 18 (1975) 358–374; D.P. Wyon, Individual microclimate control: required range, probable benefits and current feasibility, in: Proceedings of Indoor Air ’96, Institute of Public Health, Tokyo, 1996; D.P. Wyon, Indoor environmental effects on productivity. IAQ 96 Paths to better building environments/Keynote address. Y. Kevin. Atlanta, ASHRAE, pp. 5–15] as the basis to compare and to relate how the productivity loss could be minimised through improved thermal comfort design criteria. The finding shows that task-related performance is significant correlated with the human perception of thermal environment that in turn is dependent on temperatures. Different combinations of thermal criteria (air velocity, clo, metabolic, etc.) can lead to similar PMV value and the PMV equation is useful to predict productivity loss that is due to the rate of change in thermal conditions. The study also highlights the issues that remain to be resolved in future research.

Displacement ventilation environments with chilled ceilings: thermal comfort design within the context of the BS EN ISO7730 versus adaptive debate

The current design standard BS EN ISO7730 [Moderate thermal environments—determination of the PMV and PPD indices and specification of the conditions for thermal comfort, International Standards Organisation (1995)] is based upon the work of Fanger, and essentially comprises a steady-state human heat balance model that leads to a prediction of the sensation of human thermal comfort for a given set of thermal conditions. The model was derived from laboratory-based measurements conducted in the mid-1960s in relatively ‘conventional’ environments. However, a chilled ceiling operated in combination with displacement ventilation represents a more sophisticated environment as compared with the original conditions in which the Fanger model was derived. This raised a question about the applicability of the current standard when designing for thermal comfort in offices equipped with chilled ceiling/displacement ventilation systems. This paper presents findings from an EPSRC-funded study that sought to answer the above question. Human test subjects (184 in total) carried out sedentary office-type work in a well-controlled environmental test room that simulated an office fitted with the above system. Measurements of environmental variables were taken at a number of locations near the subjects, each of whom wore a typical office clothing ensemble. The reported thermal comfort sensations were compared with values predicted from BS EN ISO7730 over a range of system operating conditions. It was shown that the current standard BS EN ISO7730 may be used, without modification, when designing for the thermal comfort of sedentary workers in offices equipped with chilled ceiling/displacement ventilation systems. These findings are interpreted within the context of a proposed modification to thermal comfort design standards that includes adaptive effects, and the influence of BS EN ISO7730 on the development of other radiant surface/displacement ventilation configurations is discussed.

The availability of daylight from tropical skies—a case study of Malaysia

In Malaysia, no long-term daylight data are measured. It was only recently that the need to measure the availability of daylight became urgent when the importance of daylighting in buildings was rediscovered. The hourly daylight availability has been simulated for the Malaysian sky using daylight modelling techniques based on empirical and measured solar irradiation and cloud cover data. This paper presents the techniques involved in producing exterior illuminance data. These data were then compared with measured illuminance at Shah Alam and Bangi, Malaysia. The global illuminance levels are generally high, with values exceeding 80,000 lux at noon during the months when solar irradiation is highest. Even during the months when the ground receives less solar irradiation, the peak illuminance can reach 60,000 lux. Applications and uses of such data are in daylighting design, both for visual and thermal comfort, task illuminance and energy-conscious design of buildings. Recommendations are made at the end of the paper on the various climatic data that are required to be measured for overall daylighting design applications.

The Effect of Diffuser's Location on Thermal Comfort Analysis with Different Air Distribution Strategies

The evaluation of various ventilation strategies for optimal ther mal comfort design in terms of predicted mean vote index was investigated. The major parameter is the inlet/outlet diffuser's locations in the occupied region. The location effects of the inlet and outlet diffusers at the ceiling/walls on thermal com fort were examined every 0 4 meter. Eight different air distribution systems includ ing single inlet-single outlet and single inlet-double outlets arrangements were studied in an indoor environment. Also, an experimental validation was conducted. The comparison results between prediction and test are quite good.

Thermal comfort in chilled ceiling and displacement ventilation environments: vertical radiant temperature asymmetry effects

The paper presents some of the findings from a broader investigation aimed at determining thermal comfort design conditions for combined chilled ceiling/displacement ventilation environments. A typical chilled ceiling/displacement ventilation office has been created within a laboratory test room, in which the ceiling temperature can be varied over a range of typical operating values; the thermal comfort of eight female test subjects was then measured in the test room over the range of ceiling temperatures. Vertical radiant temperature asymmetry was found to have an insignificant effect on the overall thermal comfort of the seated occupants for the typical range of ceiling temperatures that would be encountered in practice in such combination environments. There was a slight trend for the reported sensation of ‘freshness’ to increase as ceiling temperature was reduced though this requires further study. It is concluded that existing guidance regarding toleration of radiant asymmetry is valid for thermal comfort design of chilled ceiling/displacement ventilation environments

96/04286 Thermal comfort and building design in the tropical climates

96/04286 Thermal comfort and building design in the tropical climates

96/04285 A theoretical investigation of the best heat demand for public baths

In Malaysia, no long-term daylight data are measured. It was only recently that the need to measure the availability of daylight became urgent when the importance of daylighting in buildings was rediscovered. The hourly daylight availability has been simulated for the Malaysian sky using daylight modelling techniques based on empirical and measured solar irradiation and cloud cover data. This paper presents the techniques involved in producing exterior illuminance data. These data were then compared with measured illuminance at Shah Alam and Bangi, Malaysia. The global illuminance levels are generally high, with values exceeding 80,000 lux at noon during the months when solar irradiation is highest. Even during the months when the ground receives less solar irradiation, the peak illuminance can reach 60,000 lux. Applications and uses of such data are in daylighting design, both for visual and thermal comfort, task illuminance and energy-conscious design of buildings. Recommendations are made at the end of the paper on the various climatic data that are required to be measured for overall daylighting design applications.

A knowledge based CAAD system for determining thermal comfort design strategies

A computer-aided design system for determining thermal comfort design strategies is presented. The system is based on a knowledge base which stores the existing information concerning thermal comfort rules of thumb, and precise procedural calculations which facilitates the defining of thermal comfort design strategies that best suite the local climatic conditions and the specific constrains of the design problem at hand.

Thermal comfort and building design in the tropical climates

For people living in warm humid climates the perception of comfort is influenced by long-term conditioning to high temperatures and humidity. Clothing and personal habits are influenced by exterior conditions, as are expectations of comfort. A study of occupants of urban housing in Bangladesh indicates tolerance to high temperatures and very high humidities for comfort. Given the climate of the region and little experience of air conditioning this is not unexpected. Building design in urban areas is marked by the increasing popularity of multi-storeyed appatment blocks, where the choice of wall thickness and exposure to radiation can make significant contribution to indoor comfort. Simple means such as cool surfaces and ceiling fans are able to provide comfort.

B104 人体周辺の自然対流の可視化による観察とその応用について

A human body transfers about 35 percent of its metabolic heat to the ambient air by convection. This heat causes upward natural convection around the body. The characters of the convection were observed by infrared photography and smoke wire photography technics. Its velocity reached to about 0.25 m/s at 0.3 m above the head, and its flow rate was about 40 1/s. As the results of it, the convection heat transfer coefficient at the lower leg was about two times of it at the torso. The concentration of occupant produce carbon dioxide was higher in the overhead region than in the lower region of.a room. It is important to consider the influecne of the natural convection in thermal comfort and ventilation design.

A knowledge-based system for computer-aided architectural design for energy savings and thermal comfort

This paper describes EKSPRO, a knowledge-based system integrating a 3-D computer-aided design system for materials, heating, ventilation, lighting equipment, building codes and occupational health regulations, and design guidelines user-defined by architects and engineers. The system features an object-oriented predicate logic knowledge representation, and interfaces with calculation packages (CAD, thermal balance, illumination, daylight).

Helicopter pilot suits for offshore application A survey of thermal comfort and ergonomic design

The objective of this study was to determine the existing problems associated with helicopter pilot survival suits currently in use. A survey was conducted of helicopter pilots from both Canadian commercial and military disciplines. Pilots commented on eight different types of survival suits. Reduced thermal comfort as well as lack of ventilation were the two most common criticisms of the pilot suits. The ‘greenhouse’ effect, common to helicopter cockpits, results in hot working ambients both in summer and winter. The air cooling mechanisms employed in summer may cause a ‘chilling’ effect following an on-ground stand-by where cockpit temperatures may reach 40°C. Thermal stress may also be induced with high cockpit temperatures caused by the sun's radiation in winter and summer. Suit design was another area considered. 72% and 86% of military and commercial pilots respectively felt their freedom of movement was hindered by their survival suits. Certain designs were considered more hazardous than others with regard to clips and hooks catching switches on the control panel. Difficulty in donning suits appeared to be a univrsal problem irrespective of type of suit used. Lack of comfort and movement in addition to thermal stress may lead to reduced time to fatigue and, thus, occurrence of errors and accidents. The results of this survey reflect the inadequacies of the helicopter pilot survival suits presently in use. It is suggested that evaluation of these suits be made on the basis of their ventilation capabilities, ergonomic design and thermal properties in a variety of ambient environments.