Ferdinand Oswald (2015), Reduce A/C: Reducing the Utilisation of Air Conditioning in High-Rise Buildings in Subtropical and Tropical Climate Regions, Institute of Architecture Technology; 1st reviewer: Roger Riewe, 2nd reviewer: Werner Sobek; 681 pages, German.
Over recent decades, residents of large tropical and subtropical cities living in modern buildings have been making increasing use of split-air conditioning systems. The utilisation and power consumption of these systems in humid and hot subtropical regions is colossal, the latter being a major disadvantage of air conditioners. Split system air conditioning emits huge amounts of heat into the outer air, leading to an overheating of the urban environment. Statistical calculations suggest that urban populations will almost double by 2050, increasing from 3.5 to 6.3 billion. Hence, energy demand for cooling would also nearly double by 2050. It is also likely that further extreme densification will occur, especially in large cities in subtropical and tropical regions, thus leading to an increase in problems concerning higher power consumption and an exacerbation of the heat island effect. Given that urban residents will not want to do without air conditioning, these growth prognoses present an enormous challenge for both power production and climate balance. In future, agglomerations in tropical and subtropical regions will have to deal with an increase in problems such as the capacity overload of energy supplies and local climate change. The problem definition outlined above raises a number of questions that will be clarified in the course of this doctoral thesis. Based on Hong Kong as an exemplary case study, an introductory investigation will find out what effects the invention of air conditioning had on the development of national high-rise typologies and whether such typologies would have been possible without air conditioning. The second section of this work defines various terms, including that of comfort. Here, the aim is also to ascertain the parameters upon which comfort is dependent and to find out whether these are actually measurable. This analysis of terminology then leads to another key question: how do we achieve a pleasant indoor climate in the tropics and subtropics? The main question in this doctoral thesis is concerned with the possibility of employing architectural means to provide sufficient comfort in those regions without having to use air conditioners. Other questions linked to this central theme include the following: which traditional and modern architectural means and technologies could improve indoor comfort by exploiting prevailing weather conditions, without having to accept the negative characteristics of air conditioning? How can architects promote the potential of such technologies and traditional concepts, or even initiate them? Which factors need to be taken into account in the early planning stages of a building in order to reduce the use of air conditioning? A case study analysis in the fourth part of this study will present answers to these questions. At the same time, it will become clear which factors play a role in shaping high-rise typologies in the subtropics and tropics with respect to the effectivity of passive cooling methods. Part 5 continues with an investigation into building structures based on specific parameters that will illustrate how indoor comfort in the tropics and subtropics is affected by dwelling density, floor area per person, volume, surface area-to-volume ratio (S/V) and building permeability in the sense of compactness and foldings of building volumes. Based on the research results of IAT, it will be ascertained as to which possibilities there are to modify existing high-rises in Hong Kong in order to improve natural cross ventilation and thus, also indoor comfort. A further investigation will look into possible means of reducing noise exposure while façade apertures are open for cross ventilation. A final appraisal of the results of this paper will also specify areas in which important future research is needed.
This dissertation was published in English unter the title “Reduce A/C – Reducing the utilisation of air conditioning in high-rise buildings in subtropical and tropical climate regions”, has 395 pages and the ISBN 978-3-85125-430-3.