Comparative Study on the Influence of Window To Wall Ratio on Energy Consumption and Ventilation Performance in Office Building of Temperate Humid Climate: a Case Study in Rash

Document Type : Original Article


1 Department of Architecture , Rasht Branch, Islamic Azad University, Rasht, Iran

2 Department of Architecture and Urban Planning, Imam Khomeini International University, Qazvin, Iran.

3 Department of Architecture, Rasht Branch, Islamic Azad University, Rasht, Iran


The natural ventilation and the energy consumption are very important characteristics in buildings. Representation of the patterns for better natural ventilation performance versus lower increase in energy consumption is significant and useful. This study is simulating an office building in the temperate and humid climate of Rasht in Iran, and calculated the annual ventilation and the energy consumption for heating, cooling and total energy using Design Builder v 5.4. This simulation investigated variations in the window-to-wall (WWR) the building in cardinal directions. Accordingly, the influence index of consumed energies and ventilation from a change in WWR was calculated in cardinal directions. Moreover, the changes in total energy consumption and ventilation indices based on WWR were defined, calculated, and qualitatively analyzed. In the west direction, for the WWR of larger than 20%, a relative jump in total energy consumption is achieved. The ventilation and total energy consumption increased with increasing WWR from 10% to 15% and 20%. Also, for an increase to 25%, the lowest kew/kvw is attained and demonstrates the appropriate value. The heating energy consumption is positively affected by an increase in windows area in the north direction. In the south direction, WWR decrease from 25% to 10% showed better ratio of energy to ventilation indices. With increasing WWR from 25% to 30%, the low index ratio of 0.17 is achieved, demonstrating a larger increase in ventilation than in energy consumption and was considered as the suggested WWR. In the east direction, increment of WWR from 15% to 20% is a more appropriate option, as the ventilation index significantly increases with slight increase in energy consumption. Thus, using these indices and their analyses, engineering models of fenestration design of office buildings in the climate of Rasht to be improved in terms of energy consumption and ventilation.


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