The ventilation of buildings is used to maintain indoor air quality and thermal comfort. In order to attain these objectives, airflow rate should be controlled. The minimal airflow rate is determined by indoor air quality requirements so that the maximal concentration for every pollutant is lower than the maximum admitted. By changing the airflow, comfort [...]
Nov 032010
In most cases, buildings are erected to protect their occupants from the external environment (e.g. extreme temperatures, wind, rain, noise, radiation, etc.) and, therefore, to provide them with a good indoor environment. A building that is well adapted to its climate protects its occupants against the extreme conditions observed outdoors without creating uncomfortable internal conditions. According to Pierre Lavigne (Chatelet et al, 1998), the internal climate in a free-running building (that is, without any heating or cooling system running) should be at least as comfortable as the outdoor climate. Because of changes in their clothing, occupants require different temperatures in order to be comfortable (the so-called ‘comfort temperatures’) during summer or winter. Therefore, the comfort ‘zone’ (the range of comfortable temperatures) is higher in summer than in winter. A well-adapted building has a good thermal insulation, appropriate passive solar gains (including moveable and efficient shading systems) and adaptive ventilation devices. In summer, it is protected against solar radiation and designed for passive cooling. In winter, it uses solar gain to increase the internal temperature. The result is a building that, in most European climates, provides comfort without energy sources other than the sun during most of the year. The energy use for heating is strongly reduced as a result of a shorter heating season. Cooling is not required as long as the internal heat load stays within reasonable limits. On the other hand, a poorly adapted building is not well insulated and protected against solar radiation. It is designed neither for an efficient use of solar energy, nor for passive cooling. Its free-floating internal temperature is then too low in winter and too high in summer. Expensive and energy-consuming systems have to be installed in order to compensate for this misfit between the building and its surrounding climate. Such poorly adapted buildings will require heating in winter and cooling in summer and are the cause of the belief that the use of large amounts of energy is necessary for comfort.
 Extreme urbanizationExtreme urbanization during the last years has resulted in important economic, social, energy and environmental problems. Over-consumption of resources and environmental pollution are among the major problems in cities of the developed world, while poverty and lack of infrastructures comprise the main problems in the cities of the less developed world. Urbanization increases the energy [...] |
Energy characteristics of urban buildings in less developed countriesThe tremendous increase in the world’s population and in urbanization is the main source for the continuous increase of energy demand in the less developed countries (LDCs). Although the current consumption of LDCs represents almost one third of that of the OECD countries, it is expected to reach the same figures by 2015 (ICLEI, 1993). [...] |