Building Orientation and Glazing Location

The orientation of buildings affect the indoor thermal climate in two ways; firstly, the orientation with regards to the sun (solar radiation from different orientations substantially affects the internal environment), and secondly, the orientation of the building with regards to the direction of the prevailing wind (Olgyay, 1992). However, the correct building orientation is something that can be learned from historic designs. As Galloway (2004, p. 6) describes, “our ancestors understood the orientation of their living areas…and how to distribute thermal energy to other living spaces” because they took advantage of the solar energy rays from the sun. Therefore, the orientation of vernacular structures could be inspiring to architects interested in passive climate control (Naciri, 2007). For example, Taleghani et al. (2014) states that a north-south courtyard direction in Iran has the shortest duration of solar radiation and is recommended in hot climates, whilst an east-west courtyard direction has the longest duration of solar radiation and is more favourable in colder regions. Moreover, in Tables 3.1 to 3.4 of Chapter 3, Soliemanipour (2015) shows that:

The orientation of traditional buildings in a hot and dry climate is NW-SE with a central courtyard and a water feature. In hot and humid climates, the orientation is towards the wind from the sea with smaller central courtyards and covered deep verandas (street and corridors). In temperate humid the orientation towards south with plan proportion of 1 to 3 for (narrow plan for more cross ventilation in humid climate). Also in cold climates the building have rectangular plan with orientation towards the sun radiation and therefore the large windows are be placed in the southern front of the buildings.

Apart from the traditional buildings, research has also been conducted into the appropriate orientation of tall buildings and the appropriate glazing location. Faizi et al. (2011) conducted an analysis on tall buildings (with no atria) with square and rectangular plan shape and with different orientations in Tehran. He believes that the most to least translucent façades of rooms (in this thesis, it is the office’s external window) are most energy efficient in the order of south, east, west and north sides in this order for Tehran as it receives the most solar radiation and the most day light access. So for more solar gains it is best to align the building on east-west axis for more south solar gains. However, for least energy loss it is best to have minimum façade on north where no sun penetrates (rectangular plan building aligned on N-S axis).

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Moreover, BHRC (2007) and Faizi et al. (2011) state that, due to the low thermal resistance compared to other parts of outer surfaces, translucent layers should not be located on the undesirable and cold fronts of buildings (north façade). Iranian Regulations (BHRC, 2010) verify that the most to least energy efficient angles to have translucent facades are south, east and north. The north façade is the coldest facade because there is no heat gain on this angle in summer or in winter. However, the north façade windows could be of benefit in providing cool air on hot days. Also in summer sun angle is high on south facades so the sun cannot penetrate deep inside unlike in winter when the sun angle is low. Nevertheless, both Faizi et al. (2011) and Iranian Regulations (BHRC, 2010) agree that the south and then east are the best locations for the external windows of rooms for lowering energy consumption. Moreover, Khodabakhsh and Mofidi (2001) also say that the least amount of elevation should be targeted by solar radiation in arid (hot and dry) climates. Hence, large exposure of translucent facades towards sun is not favourable in arid climate.

Tahbaz (2008) also worked on a high-rise building with a rectangular plan shape in Tehran and on a north-south axis orientation, which was blocked on the east and west. Tahbaz concluded that the elongation of the building toward the south-north axis and open spaces (free plan) with minimal interior walls within the flats, helps the building to act as a wind tunnel for the local breeze, as there is no preventative element to terminate the air flow. However, Tahbaz did not check the east-west orientation with the north and south facades, which were blocked by neighbour buildings. Therefore, the conclusion is not complete in terms of best orientation.

Another example is theKaveh Glass head office in Tehran which has a passive design. It is known that the key element of this building is its orientation on an exact east-west direction (Reischer, 2016).

Nevertheless, Iran’s regulations state that the buildings could utilise a fair amount of solar energy in winter if they are orientated towards the south; having more translucent layers on this façade helps to gain more of the sun’s radiant energy, which is especially beneficial during cold days and the shortest days (BHRC, 2010). Thus, in warm seasons it is generally most energy efficient to orientate building on a north-south axis and in cool seasons along the east-west axis. Therefore the orientation of north, east, west and south will be rechecked for the prototype designs in Tehran to determine the effect on energy consumption. In addition, the orientation of the façade on which the atrium is located is important as it has 100% glass façade. For example, Hastaie (2000) suggests that it is better not to construct an east-west

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linear atria because this orientation admits low angle sunlight in summer. Therefore, this thesis also investigates the effect of different atria placement and the building orientation on thermal comfort and energy load of a building.