PLEA2006 - The 23 rd Conference on Passive and Low Energy Architecture, Geneva, Switzerland, 6-8 September 2006 Five Locations to Represent World Climates Khaled Mansy Oklahoma State University, Stillwater, Oklahoma, USA ABSTRACT: In the pioneering book of Victor Olgyay “Design with Climate”, 1963, he selected four American cities to represent four distinct climatic regions. Since then, the same four American cities have been used in other publications to represent the four distinct climatic regions: hot-humid, hot- arid, temperate, and cold. This paper presents a model to select international cities to represent the world’s distinct climatic regions. Indeed, the two major climatic influences on buildings’ environmental performance are solar radiation and outside temperature. Consequently, a meaningful representation of world climates should equally consider the geographic location (latitude) and global distribution of ambient temperatures. In the suggested model, three locations were selected within each of the five world climatic zones. Then, a set of criteria is used to narrow the selection by eliminating locations that do not meet certain conditions. In accordance with the published climatic data and in reference to ASHRAE classification of world climates, the five representative locations were found to be: Singapore (tropical), Cairo (hot-arid), Milan (temperate), Ft. Smith (cold), and Resolute (polar). The paper suggests that these five cities be used as reference to world climates and to establish distinct sets of regional bioclimatic recommendations for the design of buildings. Keywords: climate, bio-climatic analysis, bio-climatic design, design strategies 1. INTRODUCTION In the field of bioclimatic design, comparisons are often made between strategies that are appropriate for different climates. Being focused on North America, early bioclimatic research made a reference to climatic regions that exist within the North American continent. In his pioneering book “Design with Climate”, 1963, Victor Olgyay selected four American cities to represent four distinct climatic regions, which are: City of Minneapolis, MN (cold), New York, NY – New Jersey, NJ area (temperate), City of Phoenix, AZ (hot-arid), and City of Miami, FL (hot-humid) [1]. This paper presents a model to select international cities to represent the world’s distinct climatic regions. 2. WORLD CLIMATES According to the meteorological data and studies, the world’s distinct climatic regions are five (and not four), which are: (1) tropical, (2) sub-tropical, (3) temperate, (4) sub-polar, and (5) polar. These five climatic regions cover the two hemispheres, north and south, respectively from the equator to the pole. However, in most bioclimatic literature, the polar region is usually ignored or excluded. Because the polar region is almost uninhibited, it receives much less attention than other regions. In order to select international cities to serve as representative locations for the five World’s distinct climates, an initial selection is made based on the two major factors that make local climate, i.e., outdoor temperature and solar radiation. Then, the selection process excluded locations that are affected by non- typical characteristics that may significantly modify the macro-climatic conditions of the encompassing region. This selection process is explained in the following sections. 3. INITIAL SELECTION 3.1 Envelope load as a criterion In bioclimatic comparisons (between different locations), envelope load is the load component that makes a difference in the environmental performance of buildings. Envelope load occurs mainly due to two climatic factors, which are: (1) outdoor temperature and (2) solar radiation. That is why in this initial selection phase, the objective is to pick candidate locations that cover a full range of distribution of these two factors from the Equator to the Pole. 3.2 Candidate Locations The candidate locations were selected to exhibit an even geographic distribution of the recorded weather data in the Northern Hemisphere. These locations are selected on 15 degrees increments in latitude angles starting from the equator, i.e., 0 o , 15 o , 30 o , 45 o , 60 o , and 75 o NL. These intervals do also coincide with mid latitudes of climate belts that run parallel to the equator [2]. At each latitude circle, the atmosphere has a certain thickness that gradually decreases from equator to pole, which is a fact that significantly affects local solar intensities at sea level due to the filtration effect of the atmosphere. All chosen cities lie in the Northern Hemisphere. Locations close to latitude 15 o NL are excluded since they are still within the tropical belt. Three candidate locations are selected for each climatic region thereof,