Influence of Windows on the Energy Balance of Apartment Buildings

Author/Editor

Kholoud Hassouneh

Date

2007

Language

English

Keywords

energy balance, apartment buildings, windows

Institution

University of Jordan

Advisor

Prof. Abdulsalam AI-Shboul

Abstract

The influence of windows on the energy balance of apartment buildings in Amman is investigated, calculations were made using self developed simulation software (SDS), the SDS is based on the ASHRAE tables for solar heat gain calculation and cooling load factor for latitude 32°, where Amman city is located, the software is also based on the climatic data of Amman and equations which calculate heat gain and loss, and equations which calculate fuel consumption and saving of money and energy. Mathematical operations of the software are made by an excel program.
The calculations of energy saving were made through two steps to find out the influence of windows on the energy balance of apartment buildings in Amman. The first step is to make calculations for a room of 4*4 m2 with one exposed wall. Variations of the type of glazing using eight types of glazing (clear glass, Type A, B, C, D, E, F, and G) were made to find out the most appropriate type of glazing in each direction. Also, the orientation of window is changeable in the main four directions (North, South, East and West). The area of glazing varies also in different orientation to find the influence of window area on the thermal balance of the building.
The results show that if energy efficient windows are used, the flexibility of choosing the glazed area and orientation increases. Also, it has been found that choosing a large area of glazing in south, east and west orientations can decrease heating costs in winter. The present study shows that glass type A and clear glass are the most energy efficient windows in the south, east and west directions, while glass type B is the most energy efficient window in the north direction.
The second step is to study the energy performance of windows for an apartment building in Amman in order to select the most energy efficient windows that can save more energy and reduce heating load in winter. This step has been achieved depending on the results obtained from the energy calculations in the first step and by using the SDS to calculate the percentage of saving energy and saving fuel and money through time.
The results of investigating the energy performance of an apartment building in Amman show that a combination of glass type A and glass type B is can save money and energy. The best choice for the south, east and west orientations is glass type A or clear glass because they can save energy and money through time and the increasing area in these three directions is recommended to save more energy.
The study of glass cost and amount of saving energy in the north direction shows that reducing area of glazing in the north direction can save both money and energy. Glass type B is recommended in the north direction because it can reduce energy losses and save energy in the north direction and increasing the area of glazing using type B can save energy in the north direction. However, the capital cost of glass type B is too high and it is not feasible economically to be used.
A comparison between the capital cost of the different types of glass combinations and amount of saved money in a certain number of years has been carried out. The comparison can be used as a guide for selecting the best type of glazing which save more money. Also, the payback period for the cost of glazing is considered as another guide for selecting the best window type and size. The payback period of clear glass is less than other types, while the payback period of glass type A and B is reasonable. The results show that the glazing combination which consists of clear glass or glass type A for south, east and west directions and no glass or a small size of glass type B for north direction are recommended to be used for the residential apartments in Amman. So, it is recommended to increase the window size in the south, east and west directions and to reduce the window size in the north direction to be small as possible.