High-rise buildings also bring high occupancy density. In residential buildings, the heat released into rooms is from domestic appliances including cooking, kettles, entertainment, lighting and occupants’ activities. In office buildings, the heat is released from office equipment including computers, printers, artificial lighting and human activities. Due to the excessive use of glass external fa?ades, solar radiation significantly increases the solar gains in summer thereby causing thermal discomfort.
There are various definitions of thermal comfort. In heat balance theory, Fanger defines thermal comfort as a status where ‘people would feel neither cold nor hot’ (Fanger 1972). A person’s thermal sensation is affected by the physical environment and personal factors. The physical environment includes parameters of air temperature, mean radiant temperature, relative air velocity and water vapour pressure in ambient air (humidity). The personal factors include metabolic rate (heat production in the body) and clothing level. Thus, there are both physical and non-physical factors influencing the thermal comfort of subjects. In addition to the physical environmental factors and personal factors, some other factors, e.g. anthropological and psychological factors, could also affect thermal sensations. These include age, gender, lighting and the occupant’s state of health.
According to the thermal comfort survey in high-rise residential buildings in Chongqing and Shanghai, China, it is revealed that there were no significant discrepancies of the occupant thermal comfort satisfaction in summer among the residents living in lower, middle and higher levels of the building. This is because air conditioning is popularly used in this area in summer regardless of the number of floors (Shi et al. 2007; Wang et al. 2012).
Recommendations for Office Environments
Fanger (1972) describes a method for the use of the PMV (Predicted Mean Vote) and PPD (Predicted Percentage Dissatisfied) in practical applications.
Table 4.1 lists the recommended indoor thermal comfort criteria for offices.
As demonstrated in Table 4.1, the indoor climates are classified in terms of either temperature or PMV-PPD ranges, such as categories A, B and C in ISO7730 and categories I, II and III in EN15251 and the Chinese standard. These standards can be used to assess the indoor thermal environment via dynamic thermal simulation by counting the number of hours that are within the thermal comfort zone according to the different standards.