English

This research concentrates on evaporative cooling, a sustainable and alternative way to cool a roof surface by taking advantage of the properties of porous materials. During periods of rain or high humidity nights, water sorbents store moisture in their small pores inside their particles. During a warm sunny day, the latent heat released due to evaporation of moisture, maintains the surface temperature at low level. Lower roof temperatures contribute to smaller heat flow inside the building while reducing the cooling load.

European CEN Standard EN 15251 (2007) requires indoor thermal comfort conditions to be assessed and to fall within a category system for different levels of expectation and building purpose.  The COMMONCENSE project has prepared and provided information about the energy implications of the Standard and in particular whether the Standard is encouraging high-energy buildings in the case of new buildings and major rehabilitations.

This paper presents an investigation into solutions for the system design of a centralized DCV system in multi-family dwellings. The design focused on simple and inexpensive solutions. A cost benefit estimate showed that the initial cost of implementing DCV in a system with an efficient heat exchanger should not exceed 3400 DKK per dwelling in regions with weather conditions similar to the Danish climate. A design expected to fulfil this requirement was investigated in detail with regard to its electricity consumption by evaluation of different control strategies.

In this paper, a long-term numerical study which examines the unique airflow pattern and the corresponding VOC distribution within a typical apartment building in the severe cold region of China is described. A VOC model was developed to simulate the time-dependent emission rates with adsorption and desorption. This model was then integrated with COMIS, a multi-zone airflow model. The target VOC for study was benzene. The results show various downward tendencies for benzene concentrations in all the dwellings.

Unlike cold climate regions, where natural ventilation is not preferred during winter, natural ventilation is always preferred in Hong Kong for cooling because of the subtropical climate. It also provides better indoor environment quality and energy conservation. Natural ventilation performance of a residential unit is affected by internal as well as external factors. External factors are often subject to constraints beyond the control of site planners and architects.

Carbon monoxide (CO) concentration data from 1999-2006, monitored at 5 different pollution stations in a high-rise mega city (Hong Kong), were collected and investigated. The spatio-temporal characteristics of urban CO concentration profiles were obtained. A new approach was put forward to examine the relationship between urban CO concentration and different wind flow patterns.

To clarify the indoor climate in Japanese college classrooms, an air-conditioned, mechanically ventilated classroom of a university was surveyed. Temperatures, humidity and carbon dioxide (CO2) concentration in winter and summer were measured before, during and after lessons. The airtightness of the room and the airflow rate of the ventilation system were also measured. In winter, at an outdoor air temperature around 0 ºC and with the thermostat temperature of the air conditioners set to 30 ºC, the vertical difference in room air temperature exceeded 10 ºC.

The need to protect susceptible patients from cross-infection resulting from airborne pathogens is essential in hospitals, especially when patient immunity is either suppressed due to medical procedures or compromised by ailment. Personalised ventilation (PV) is a method of creating a local zone of high air quality around such patients. However, contemporary PV techniques are based on mechanical ventilation, which adds to the energy burden of healthcare buildings. In single-bed wards, a potential source of infection could be other occupants such as visitors and healthcare workers.

A non isothermal horizontal jet issuing from a round nozzle distanced from a wall is investigated experimentally. We consider four cases: an isothermal jet, a hot air jet, a cold air jet interacting with the wall and a cold air jet falling down without reaching the wall. The jet expansion rates show two categories. These are (1) an isothermal jet and cold jet not adhering to the wall, with a vertical expansion rate higher than the lateral rate and (2) a non isothermal jet adhering to the wall, with a lateral expansion rate higher than the vertical one.

The temperature of human skin is determined by the human thermoregulatory system which reacts to changes in the thermal balance between a human body and the environment. For this reason, skin temperature can be used as the quickest predictor for the assessment of local comfort or discomfort. This paper presents the outcome of case study experiments carried out to determine which of the skin temperature measurement points (specified in accordance with the ISO 9886 standard) can be used to determine local and general thermal comfort.