The central region of Saudi Arabia has a special architectural heritage of mud and adobe housing. It has a very hot and dry climate in the summer and is cold and dry in the winter. The region is surrounded by three deserts which have a great influence on the climate of the region and hence its architecture. The wind drives sandstorms and dust from the deserts and the sun’s radiation heats the surroundings. It is interesting that the traditional houses in this region, built from only mud, are relatively cool in the summer and warm in the winter. The strategy for natural ventilation, which uses the courtyard of the house along with small triangular openings, together with the thermal capacity of the walls, provides very effective ventilation for the house and also provide a thermally  comfortable  space. 

The use of the courtyard and the triangular openings as elements for  natural ventilation has been discussed in the previous chapters. In this chapter, experimental work will be described relating to measurements of both natural ventilation and thermal performance of traditional courtyard houses.

The description of the required house type needed was a mud house with a central courtyard and no windows on the external elevations except for the small triangular  openings. It was first considered  that finding houses with these specifications would be easy, but it was not. First the search started in the city of  Riyadh, seeking out the old parts of the city. But most of the houses in the old parts of the city had been demolished by the municipality. Some old houses still exist and were in good condition, but they had larger windows and thus did not have the required specifications. Click here to see the root taken seeking this type of house.

The search for the required house type revealed  more than fifteen shapes and arrangements of triangular openings. These openings ranged from one simple triangle and one simple square to many different combinations of shapes and arrangements. Click here to see these shapes.

In the field work there were two experiments carried out involving the measurement of  the thermal performance of the tested house and the measurement of its ventilation rate. For the first experiment, the equipment used were individual data loggers that measure air temperature, surface temperature and relative humidity (TinyTalk II Data Logger). Hot wire anemometer was used to measure outdoor air speed. For the second experiment, a small device developed at the Welsh School of Architecture for measuring smoke concentration in the air was used to measure ventilation rates in the tested houses the accuracy of which is about +/-12%, 

During this field trip there were two experiments to be undertaken:

·      Experiment 1: to measure the thermal performance of mud houses;

·      Experiment 2: to measure the ventilation rate in these houses.

Most houses tested were insecure and tottering or did not have doors. Also they were in isolated areas and it was impossible to leave or have someone to watch the experimental equipment required for the thermal performance test. Therefore, the first two case studies were tested for both thermal and ventilation tests because they were in a secured area used as a monument area, and the other seven houses were tested for ventilation only.

The thermal test required that the temperature of the air inside the tested room and the surface temperature of the wall be measured. Click here to see a photo of this part.  In addition, the relative humidity of the house, the outdoor air temperature was also measured. The data collected in this phase will be further analyzed in Chapter Eight and compared to theoretical  prediction using the building energy model HTB2 . 

The measurement of the ventilation rate of each room was performed by using smoke pellets as a smoke generator and a battery operated smoke sensor. Click here to see a photo of this part. Smoke was released in the room and the sensor measured its concentration in the air every second. The level of smoke concentration in the air prior to the experiment was calibrated to zero by adjusting the smoke sensor level to zero. After the release of smoke in the air, its level of concentration rose sharply. Air was allowed to pass through the openings as in normal conditions to clear the smoke from the room, the normal ventilation process of the space.  When the smoke clears the data logger would read the zero level again. These readings were then transferred to a small data logger which measures the micro-volts signals sent to it by the sensor. The readings of the data logger were plotted as a curve. The point where the curve starts to decline was converted into a straight line from which the slope of the line can be obtained to represent the ventilation rate of the room.