Automation is everywhere around us - our homes, furniture, offices, cars, and even our clothing; we have become so accustomed to being surrounded by automated systems that we have forgotten what life was like without them. And while automation has noticeably improved the quality of interior spaces with solutions like purified air and temperature control, nothing compares to the natural cool breeze of mother nature.
But just like everything else in architecture, there is no one size fits all; what works in Tanzania cannot work in Switzerland or Colombia. This is due to several reasons, such as the difference in wind direction, average temperature, spatial needs, and environmental restrictions (or lack thereof). In this article, we take a look at natural ventilation in all its forms, and how architects have employed this passive solution in different contexts.
What is ventilation, and why is it important?
Air movement is created by the rising of warm and the lowering of cool air. As the air above the land gets warmer, it rises and creates an area of low pressure. When air continues to rise, it cools and moves towards water surfaces, where it falls and creates an area of high pressure, and pushes cold air towards the land. This movement of areas is what creates the wind.
In architecture, ventilation is bringing in outdoor air and distributing it into a space. It is mostly known in three different types: mechanical, natural, and mixed-mode. Managing the air exchange and circulation with the outdoors is crucial for a comfortable atmosphere. Whether this is done by mechanical or natural means, stable air currents release humidity and provide an infiltrated air flow, providing healthy air for breathing. A successful ventilation system must be aligned with the project's context, which includes the geographical location, the material it is built in, its architecture as a whole, and the habits of users occupying the space.
But as of recent, people have become a lot more environmentally-aware, opting for more passive solutions to reduce energy consumption and carbon footprint. This awareness pushed aside automated HVAC systems, and replaced them with wind, a natural, free, renewable, and healthy natural resource that is sufficiently able to improve the air quality of spaces. In Daniel A. Barber's book Modern Architecture and Climate: Design before Air Conditioning, the author explores how leading architects of the twentieth century incorporated climate-mediating strategies into their designs, and how regional approaches to climate adaptability were essential to the development of modern architecture.
Types of Natural Ventilation
Natural ventilation is the use of environmentally-friendly systems that do not require any automated or mechanical solutions. In addition to being more ecological, natural ventilation is also more cost-efficient, and relies on natural external factors such as the wind and the temperature of the interior space and its surroundings.
Single-Sided Ventilation
Single sided ventilation is the use of openings on one side of a building. This is used to naturally ventilate the space of projects with limited area. Single sided ventilation systems are also used in projects where cross ventilation cannot be provided, due to structural or environmental constraints. Keep in mind though that this type of ventilation generates the least air circulation when it comes to natural ventilation systems.
Cross Ventilation
Cross ventilation is when the openings in a structure are arranged on opposite or adjacent walls, allowing air to enter from both sides, cross the space, and exit from the opposite direction. This system is usually used in buildings located in climatic zones with higher temperatures, as it creates constant air renewal within the building, reducing the internal temperature.
Stack Ventilation
Stack ventilation introduces cooler air from the outside into the building at a low level, which gradually becomes warmer as it gets exposed to heat sources within the space. This causes the now-warm air to rise and leave the space through openings situated at a higher level. Usually, stack ventilation is more effective in tall buildings with central atriums, but can also be useful in buildings where cross ventilation is not able to penetrate sufficiently throughout the space. In order for this ventilation system to work properly, the indoor temperature has to be higher than the outside, which is why it may not always be efficient enough to use on its own.
Chimney Effect
In vertical buildings, the chimney effect is constantly used. Cold air produces pressure under the warm air, forcing it to go upwards. In this case, however, opened areas in the project's center or towers allow that same air to circulate throughout the indoor environment, leaving through the roof, clerestory, zenithal openings, or wind exhausts.
Natural Ventilation in Different Contexts
Whether it's for environmental or economic reasons, some architects are unable to utilize automated ventilation solutions in their projects, and have to rely on passive systems instead. For it to be efficient, natural ventilation relies on several factors. The overall shape, scale, orientation, location, and material used in a project can determine how much air is entering and circulating within a space, and how efficient it is. In theory, air must enter and exit through openings in the architecture such as windows, facade perforations, doors, solar chimneys, or wind towers. In terms of structure, projects with curved walls and partitions allow for more air circulation. Other influential factors include local climate, proximity to rivers, lakes, or the sea, and pollution rates around the project.
The Eastgate / Mick Pearce
Harare, Zimbabwe
The Eastgate Center employs passive and energy‑efficient climate control solutions to cool residents, inspired by termite mounds. The climate of Harare requires buildings to be cool all around the year, which means that the purchase, installation, and maintenance of a traditional air-conditioning is crucial. However, doing so has immediate and long-term costs, so the architect created a self-regulating ventilation system that would maintain the building's temperatures to suit workers and residents.
Obafemi Awolowo University / Arieh Sharon and A.A. Egbor
Osun, Nigeria
Originally known as the University of Ife, the modernist Bauhaus-inspired university was a product of politics, design, and climate. Although Sharon wanted to rely solely on modernism for the project, Nigeria's critical climate forced the architects to find inspiration from local architecture and think of passive solutions for their design. In fact, Sharon travelled to Mexico City to search for a model for the building. The team of architects decided to work around the skin and envelope of the building by perforating the facades and implementing screens to create better shading devices and ventilation. "They inverted a pyramid, using the upper floors to shade the lower floors, freeing up the ground floor to open corridors, columns and patios. The landscape beneath the building is continuous and a very smart positioning of the buildings allows for the free circulation of air through the buildings, an architecture without doors. Yet it also protects people from heavy rain, through balconies and canopies, and protects from the harsh sun, as well as constantly being ventilated."
Lee House / Eduardo Glycerio + Studio MK27 - Marcio Kogan
Porto Feliz, Brazil
The Lee House is organized in a single volume ground-floor site with rooms opening out to the garden. All of the windows in the living room are recessed and prolonged towards the pool deck, crossing to the other side of the lot and creating an extension of the external space. To fit the climate of the interior of the State of São Paulo, which has elevated temperatures almost every day of the year, traditional vernacular architecture along with Brazilian modernism were used in the project. The living room has cross-ventilation, which greatly lowers the internal temperature. The other rooms are protected by wooden muxarabi (or musharrabiya) panels, placed on sliding doors which filter the sun without removing the ventilation.
Empresa de Desarrollo Urbano (Urban Development Company Headquarters
Medellin, Colombia
Constructed on the site of the former EDU headquarters on San Antonio Park, the project aims to act as a benchmark for sustainable public buildings in Medellin, embracing the mantra of “building that breath". A perforated outer skin composed of high-quality prefabricated elements creates an internal solar chimney to refresh the external cold air. The materials used generate thermal mass control and thermodynamic concepts - convex and thermal forces - which generate air currents in the workspaces.
Stepping Park House / VTN Architects
Ho Chi Minh City, Vietnam
Text description provided by the architects. Due to the extensive parks adjacent to the site, the house acts as an extension of its environment by integrating the greenery of the park into the interior of the house. A large void was created by cutting the volume through the three floors, in the diagonal direction of the section. The void incorporates both circulation elements and natural elements like plants and trees, providing the private rooms with additional natural light. The void that is opened diagonally upwards brings natural ventilation through the house, as a result of the chimney effect. In that way the use of air conditioners is minimized.
Farming Kindergarten / VTN Architects
Bien Hoa, Vietnam
Text description provided by the architects. Increased droughts, floods and salinization jeopardize food supplies, while numerous motorbikes cause daily congestion and air pollution in the cities. Rapid urbanization deprives Vietnamese children of green lands and playgrounds, thus relationship with nature. Farming Kindergarten is a challenge to counter these issues. The green roof is a triple-ring shape drawn with a single stroke, encircling three courtyards inside as safe playgrounds. The building is made of a continuous narrow strip with two side operable windows which maximize the cross ventilation and natural lighting. Additionally, architectural and mechanical energy-saving methods are comprehensively applied including but not limited to: green roof as insulation, green facade as shading and solar water heating. As a result, the kindergarten is operated without air conditioners in the classrooms despite being located in a harsh tropical climate.
Vedana Restaurant / VTN Architects
Vietnam
Text description provided by the architects. Embedded itself at the edge of Cuc Phuong, a forest situated in the foothills of mountains and diverse vegetation, Vedana Restaurant is a part of the Vedana Resort masterplan. The three-gabled circular roof, spanning as large as 1050 sqm, is assembled from two stacked ring-shaped roofs and a dome roof on top, that is detached by light strips, respectively. The restaurant is positioned strategically next to an artificial lake that functions as a natural air-conditioner. Making use of the lake is essential concerning the hot and humid weather during the summer in Cuc Phuong Commune in particular and northern Vietnam in general.
Stacked House / Studio Lotus
New Delhi, India
Text description provided by the architects. Daylight, ventilation, interconnectedness and privacy inform the design of this house which sits in a dense part of the Panchsheel Enclave neighborhood in New Delhi. The team took on the challenge of creating an airy, day-lit sanctuary that would remain naturally illuminated, with all rooms cross-ventilated throughout the day despite the restrictive site conditions. To further aid ventilation and diffusion of natural light in the living spaces, the linear stairwell connecting all floors has been placed along the southern façade, owing to it receiving the lowest levels of illumination and a small sky-lit courtyard has been created at the south-east corner of the site.
Jalal-abad Villa / Hajm.e.Sabz
Jalal Abad, Iran
Text description provided by the architects. This building located at the rural context of Isfahan margin. It has been tried to improve local construction techniques, using passive cooling ventilation system and training local contractor to build this building. This space designed in a way to have the capability to connect to the pergola enlarged to provide shade at the outdoor sitting and protect the main façade from severe sunshine. Building has a typical Iranian Badger-Windcatcher that provides enough height to place the water tank. In addition, it is a traditional passive way to ventilate the building (as shown in the diagram). Traditional brick used as main wall material at outer and inner façade with a layer of insulation between them. The use of wind towers as a passive technic for summer ventilations and the restoration of a traditional approach for Iranian buildings is another feature of the construction.
Laayoune Technology School / Saad El Kabbaj + Driss Kettani + Mohamed Amine Siana
Safi, Morocco
Text description provided by the architects. The various buildings are fragmented to allow maximum natural ventilation and lighting and are connected by a set of external paths, squares, covered squares, mineral gardens to justly enhance this notion of urbanity. The architectural vocabulary is solid, geometric and plays with the contrast-ocher-exterior and interior-light. Different sun protection devices are used: brise-soleil, double skin, protected walkways etc. The materials used are minimized to emphasize abstraction and coherence of the whole while meeting the need of sustainability and easy maintenance.
Ventilation Towers for the Northern Link / Rundquist Arkitekter
Stockholm, Sweden
Text description provided by the architects. The function of the towers is to ventilate the air from Northern Link’s traffic tunnel and to reduce the emission levels at its entrances. The construction is 20 m high and is shaped as a super-triangle that pivots upwards, along its axis. The internal geometry and structure helps optimizing the exhaust air flow; the larger space at the bend into the tower and at the top, where the triangle sections are wider, reduces the air resistance at the exit. The towers’ function is to divert the polluted air inside the Northern Link traffic tunnels to reduce emission levels at the tunnel entrances. An underground duct connects each tunnel with the corresponding tower. Fans of the channel have been designed to create a specific airflow through the ventilation towers for emissions at tunnel portals will be sufficiently low. The tower's interior geometry and structure affect the resistance for the outflowing air and thus the air flow. The towers have been optimized to function in harmony with the architectural form.
Resources:
- How Is Wind Direction Determined?
- How to Implement Passive Solar Design in Your Architecture Projects
- Cross Ventilation, the Chimney Effect and Other Concepts of Natural Ventilation
- Natural Ventilation Isn't the Most Efficient Solution in All Cases
- Natural Ventilation for Infection Control in Health-Care Settings.
This article is part of the ArchDaily Topic: Automation in Architecture. Every month we explore a topic in-depth through articles, interviews, news, and projects. Learn more about our monthly topics. As always, at ArchDaily we welcome the contributions of our readers; if you want to submit an article or project, contact us.
