Natural Ventilated Basement Space
Name: Saw E Sean
This proposal aims to study the design of the natural ventilation system in a basement car park that could enhance the indoor air quality. The prairie dog burrows was studied as the biomimicry strategy to induced airflow into the under-level basement space.
Project Description - The growth in the number of motorcars registered in Malaysia has led to the increased demand for parking facilities. Unlike the car park on the ground, the basement car park has a rather static and enclosed environment due to its position under the ground. Thus, the compact basement space must have a sufficient air exchange for better indoor air quality. With most of the basement car parks relies on the mechanical ventilation system to maintain acceptable air quality, a hybrid system with natural ventilation as a backup could significantly reduce the energy consumption of a building. The prairie dog burrow was studied as the biomimicry strategy for passive ventilation of the under-level basement space. Prairie dogs are highly social rodents that build extensive underground burrows in the plains of North America to house their family groups. The opening of the burrow which is also known as a mound was built by prairie dogs to induce airflow into the burrow. The primary entrance with a wide and round profile is known as a dome mound, while the secondary entrance with a narrow base and tall structure is known as a crater mound. The prototype model base on the burrow mound system was built to investigate the capability of the proposal. The final result concludes that the biomimicry strategy could ventilate the underground basement space in whatever wind direction. Thus, placing 2 of the crater mounds toward the prevailing wind direction together with a dome mound at the opposite end could achieve optimum ventilation performance. The main constraint of the burrow mound feature is the occupation of space and could affect the overall aesthetic value of a building. Further exploration could be focus on the attempt to transform the burrow mound structure into an architectural feature that could enhance the spatial quality of the building.
NATURAL VENTILATION IN BASEMENT STRUCTURE
When designing a naturally ventilated basement structure, the most common challenge is to incorporate enough openings within the compact underground space.
Code requirements are commonly determined as the ratio between the free external openings and the floor area for natural ventilation.
Generally, free openings are in the range of 1/50 to 1/20 of the floor area, with at least half should be in two opposing walls.
Under certain circumstances, shafts or air wells were implemented to fulfill the natural ventilation requirement. According to Uniform Building By-laws 1984, the minimum width of the air well shall be 2.5m in any direction.
TYPE OF BASEMENT STRUCTURE AND VENTILATION STRATEGIES
Biological Mimicry System
Burrowing serves a variety of functions including denning and rearing of young, protection of eggs, shelter from predators and protection from climatic stress, socialization, access to below-ground food sources, food caching, and sites for seasonal hibernation or estivation. (Butler, 1992). Prairie dogs is a vertebrate species and a highly social rodents that build extensive underground burrows in the plains of North America to house their family groups. Black-tailed prairie dogs (Cynomys ludovicianus) build burrows approximately 12 cm in diameter, 10-30 m long, and I-5 m deep with two or three entrances (Sheets et al. 1971). Entrances are encircled by conspicuous mounds of soil that may reach 1 m in height and 2.5 m in diameter (King 1955).