The Nam House, designed by CTA, Creative Architects, is built with the owner's desire to connect his house with the surrounding environment, especially his mother's house which is located on the continuous plot. The house is divided into three distinct blocks, two of the blocks are located at the front and back of the plot, while the third block acts as a connecting element between the other two.
The house focuses on a bioclimatic design, following 5 climate control strategies to achieve thermal comfort. The first strategy focuses on good structural insulation. Building walls with a separation of layers to prevent heat transfer through the structural surface. The second strategy is based on using a sloped mortar joint.
The third strategy is to improve natural ventilation. Due to the use of glass in the house there is a greater risk of the famous greenhouse effect occurring. In order to avoid this phenomenon, doors and windows are used that incorporate a system of Z-shaped blinds. The fourth strategy ensures that the moment in which the temperature reaches its maximum point during the day on the internal surface of the structure (ceiling and wall) does not coincide with the owner's activity time. The fifth strategy seeks to reduce the ambient temperature by using aquatic plants.
Nam house by CTA, Creative Architects. Photograph by Hiroyuki Oki.
Project description by CTA, Creative Architects
CONTEXT
Position: The building is located in Thu Duc city which situated in HCM city, being one of the biggest cities in Vietnam. According to some science studies recently, the city’s temperature seems to be higher 8-11 degree Celsius in comparison with rural areas with the same climate.
Life: Our daily life cycle is formed by 3 statuses: Working – Exhausting – Healing. In which, healing throughout entertaining, relaxing and sleeping are indispensable to regain balance to our bodies after a whole day of hard-working. But this cycle is usually inhibited by unfavorable climate which leads to mental and physical stress. This stress might be generated by lack of comfort in living accommodation leading to poor efficiency and cause asthenia.
Climate: Earth’s temperature is increasing gradually. As observed, Vietnam has set a record of excessive temperature to 44.1 degree Celsius. In fact, the comfortable environment temperature of our bodies is barely 24-28 Celsius degrees. On top of that, our bodies sweat at 28-32 degree Celsius and get thermal shock above 32 degree Celsius. Surprisingly, under current climatic conditions, the highest record of temperature is broken rapidly every few years past. Additionally, Thu Duc lies in the tropical monsoon climate with many heavy rain and blazing hot days throughout the year.
¨Therefore, our greatest concerns about designing modern tropical architecture is climate comfort.¨
CONCEPT
Nam house is situated in a minor alley, given by their grandparents throughout many generations traditionally, hence their neighborhoods are close relatives. To be more specific, the abutting house belong to the owner’s mother and the other adjoining land area is also the property of their relatives. Thus, the owner’s desire is to connect their home with the surroundings environment, especially their mother’s house beside.Consequently, the designing process comes to a solution in which the building would be split into 3 distinctive blocks, with 2 soilid blocks at front and back of the house connected by a void block in between.
- The front block is designed for garage, toilet, entrance, bedroom and study room. Because of the privacy functioning, this block is mainly covered with dense walls.
- The back block is arranged for 2 bedrooms,bathroom and a laundry area . These are also private spaces so we also decided to surround it with dense walls.
- The middle block is built for the dining area, this is an open space created to connect with the natural elements and the owner’s mother house. Even though opening both sides of the house induces a large amount of sun light going through, the 2 blocks at both ends appeared as a shelter prevent a part of the sun light effectively.
BICLIMATIC ARCHITECURAL DESIGN SOLUTIONS
5 climate control design strategies for achieving thermal comfort in tropical modern architecture.
1. Structural insulation:
Heat transfer through the house structure can be divided into 3 stages:
- In phase 1, the exterior of the building receives heat from solar radiation or heat transfer from the surrounding environment.
- In phase 2, the heat is transferred from the outer surface to the inner surface by conduction.
- In phase 3, the heat is transferred from the inner surface to the indoor spaces in the form of convection and heat radiation.
The wall layers separation solution aims to prevent heat transfer through the structural surface. The outer shell of the building is protected by a 250mm thick wall, consisting of 3 layers:
- First layer: a solid brick layer that blocks most of the heat from sunlight. This layer has the advantage of great heat resistance but the disadvantage is the heat retaining for a long period of time.
- Second layer: the air layer that completely separates the inner wall from the outer wall which is constantly being heated by the sun. Thereby minimizing the heat transfer from the outer wall to the inner wall.
- Third layer: the inner wall layer built with 4-hole brick walls. Utilizing the 4 hollow holes structure, this can increase the air cushion layer reducing heat transfer (To be specific, heat appears because the air layer is heated due to close contact with the outer wall layer although the air helps prevent heat transfer. But the air itself contact with the outer wall layer continuously heated by the sunlight, the air is also heated up. Nevetheless, the amount of heat transferred is much less than the phenomenon of direct heat conduction).
Passing through three layers of structure, the heat from the sun has been entirely blocked. Simultaneously, the outer wall only have 80mm of thickness can release heat very briskly when the sun goes down.
2. Minimizing solar heat gain:
The outer wall surface is the place that receives the most direct sunlight in all the house. In order to lessen the amount of heat shine through the house, we need to reduce this surface area. The heat offload solution is using raked motar joint: The outer walls is built with bricks have size 40 x 80 x 180, these bricks are connected by a 10mm thick mortar layer. This mortar layer is built 10mm below the surface. By using this building technique, with various sun angles, it creates a shadow area on the wall surface, the area of this mortar layer accounts for 20% of the total wall surface. This built-in joint can help the wall be shaded from 70-80% effectively. Sometime small changes can create a big breakthrough, this detail helped the wall to decrease 14-16% of the heat directly radiated the walls.
