When you decide to design your home, one of the things to note is the criteria of a healthy home. No matter how small it is the house you have planned, you have to remember that your house is a living space. You will spend much of your time in the this environment. Thus the health factor of a house will greatly affect the health of its inhabitants. Today we will discuss two important aspects of your urban house: air flow and natural light.
Utilization of an airflow or more often known as natural ventilation, has been applied to buildings since ancient times. The work of architecture in some periods has shown the application of natural ventilation as an important element of a building.
The natural innate principle itself is quite simple. In addition to exploiting the inter-space temperature difference, natural air flow in your house also emerges as a consequence of wind and air pressure differences. Some of the features of natural ventilation include: natural air flow throughout the room from two or more openings located in different side of the wall (cross-ventilation), in addition to flowing horizontally the air also flows vertically (hot air is wasted up in the substitution of cool air), and controlled air humidity (prevent mold on walls or cabinets).
The three most frequently used approaches to planning natural ventilation according to Emmerich et.al (2001) fall into three types: a) natural wind-driven cross ventilation approach, b) natural airborne approach by exploiting differences in air density (buoyancy-driven stack ventilation), and c) the natural ventilation on one side of the building (single sided ventilation). 
To make it easier to understand the application of these three approaches in reality, I show you some pictures of wall openings for natural cross-ventilation (as well as natural lighting) in one of the residential buildings I designed.
The picture above is a simple schematic drawing that explains the basic principles of natural airflow design approach. The image on the left side is the expected natural air flow between horizontal spaces (wind-driven ventilation principle), while the right-hand image represents the natural airflow on a building’s section (buoyancy-driven ventilation principle). When you are designing the opening for natural ventilation (and possibly at the same time for natural lighting), you should consider the position of the aperture towards the direction of the average annual airflow.
The photo above is a photo of a house that I designed (on going). From the photo you know that there are openings on the wall and also the openings for upper ventilation. These openings have function to flow the air between the spaces in the same floor and to flow air from the lower chamber to the upper room and at the same time remove the hot air out of the building.
By incorporating this approach, the conditions inside the building are cool enough (compared to the temperature in the outer part of the building) although the roof itself is a metal roof. Therefore it can be said that the design of natural ventilation is quite successful.
If you want to plan ventilation and wall openings for natural ventilation you could use the above approach. To facilitate / help check or simulate the airflow that may occur in your home, you can use a software. One of the simplest software and can be utilized to see the possibilities of airflow pattern in your urban home is the Android app named “Wind Tunnel“.
Android app is free and easy to use (does not require special skills) that can be used even by ordinary people. Meanwhile, to know the direction of wind and speed, you can try the application of metSKY made by Weather and Climate Prediction Laboratory, ITB, Bandung. This App displays weather information to you from the result of the numerical predictions made on the WCPL ITB server (note: Currently this app seems to only provide information for the city of Bandung). You can also take advantage of other apps like Wind Tracker, and so forth.
The next important element of your house is natural lighting. Urban house with sufficient and good natural lighting will be able to maintain indoor temperature and humidity. This condition will make your house healthier.
The basic principle of natural lighting in a building is actually simple: “gather enough light but withstand the direct sunlight”, especially sunlight at special times (e.g afternoons). This is because the afternoon sun light is typically hot and not quite comfortable. While the morning sun light which is beneficial to the health of the room should be directed into the room. This morning light also useful to reduce the possibility of fungus and the emergence of bad bacteria in your house.
Things to consider when designing a wall opening to get natural lighting into the room are two: a) the position of the sun throughout the year, and b) the falling angle of the sun light in the plane of the wall.
Location where the building will be built, and the direction of sun light in general are the things that an architect will consider when designing the layout of the room. For example, the bedroom will be positioned on the east side of the building (or the other possible side) in order to get an optimal supply of morning sunlight, while avoiding the heat of afternoon sun light.
To help you make measurements, there is a tool called sky protactor / daylight factor protactor. The working principle of this tool is more or less: The sky protactor arc is placed on the floor plan perpendicular to the planned wall opening field. This is simply because there are three components of light entering into a room: a) Sky Component (SC) (ie light beam / light entering directly from the sky / outdoors), b) Externally Reflected Component (ERC) (ie incoming light to the room after bouncing in nearby buildings), and c) Internally Reflected Component (IRC) (ie the light before touching the end point bounces in the second room / reflection after ERC).
Well, to facilitate you an expert named Dr. Andrew Marsh has created great software that you can use to plan natural lighting in your urban house. Please follow this link to download it. I also use the software made by Dr. Andrew Marsh is for the work of my Final Project as a student.
That’s it. Thank you! 🙂
 Emmerich, S. J., Dols, W. S., & Axley, J. W. (2001). Natural ventilation review and plan for design and analysis tools. US Department of Commerce, Technology Administration, National Institute of Standards and Technology.
 Some pictures taken from pixabay.com