thermal comfort

Increasing demand for energy efficiency places new requirements on energy use in historic buildings. Efficient energy use is essential if a historic building is to be used and preserved, especially buildings with conventional uses such as residential buildings and offices. This paper presents results which combine energy auditing with building energy simulation and an indoor environment survey among the occupants of the building. Both when comparing simulations with measurements as well as with survey results good agreement was found.

This document compiles papers produced by staff and collaborators of the Indoor Environment Department at Lawrence Berkeley National Laboratory for presentation at the Indoor Air 2002 Conference, to be held June 30 – July 5, 2002 in Monterey, California. The Indoor Air Conference, held every three years, is the largest international conference on indoor air quality and was last held in the United States during 1981.

This paper discusses the potential of passive cooling techniques for Malaysian modern houses with the aim of reducing air-conditioning usage. A full-scale field experiment was carried out to reveal the detailed indoor thermal environment for various ventilation strategies. Night ventilation was found to be better than daytime ventilation, full-day ventilation and no ventilation in terms of air temperature reductions during the day and night. Night ventilation improves thermal comfort more than the other ventilation conditions based on operative temperature.

Thermal comfort and indoor air quality (IAQ) play a vital role in creating a pleasant and healthier indoor environment for occupants. The supply air conditions and the concentration of CO2 contaminant present in the supply air can decide the comfort level and purity of air in indoor environments. In this study, an effort was made to investigate the combined effect of a chilled ceiling and displacement ventilation (CC-DV) air conditioning (A/C) system that would possibly achieve good thermal comfort and IAQ in a proposed office building subjected to hot and humid climatic conditions.

The performance of stratum ventilation, a recently developed ventilation strategy, is assessed in terms of thermal comfort and indoor air quality using experimental and computational fluid dynamics (CFD) techniques. The case of a typical Hong Kong workshop under local thermal boundary conditions is used to examine the ventilation system. Various factors including percentage dissatisfied (PD) and mean air age/CO2 were computed to determine the system performance. The stratum ventilation is shown to produce improved indoor air quality and thermal comfort for this particular case study.

Stratum ventilation is a recently proposed air distribution system. It works by creating a layer of fresher air in the occupants' breathing zone. This is achieved by placing large supply inlets along the side-walls of the room just above the height of the occupants. Fresh air is emitted into the room and gradually loses momentum. The supply velocity is sufficiently strong to provide fresh air directly to the occupants without space mixing.

Mixing and displacement ventilation are common systems in commercial buildings, while mixing ventilation is used in residential buildings. Displacement ventilation provides fresh air to the occupied zone in a more efficient way than mixing ventilation but it is important to know how well it works with a floor system for heating or cooling. Can, for example, a floor heating system warm up the supply air too fast and destroy the displacement effect?

There are various demands for air-conditioning in each office space resulting from the variability of thermal distribution caused by a bias of heat sources. Furthermore, individual demands on the thermal environment are diverse. Therefore, it is difficult to satisfy all demands using conventional air-conditioning systems since these assume perfect mixing. Instead, demand may vary with the result that some spaces could be excessively or unnecessarily cooled. This paper examines an airflow and temperature control for personal air-conditioning.

The gradual shift from the traditional approach of outdoor processes of habitation in Ghana to the indoor, coupled with an ingress of solar radiation, liberates excess heat into buildings and makes occupants feel uncomfortable. A straightforward response has been the adoption of air conditioners. This has resulted in high peak electricity demand and excess emissions of greenhouse gases into the atmosphere.

Designing for natural ventilation became permissible across an extended range of climate zones in 2004 with the incorporation of an adaptive model into ASHRAE's comfort standard (ASHRAE, 2004). This mainstreaming of adaptive comfort was further reinforced with the introduction in 2007 of a European standard (EN, 2007) that mirrored ASHRAE's precedent. Despite broad international acceptance and application of the concept, there remains a gap in the fundamental theoretical underpinnings of the adaptive comfort approach.