An architectural tool set for mitigating indoor pollution
When we submitted the Air Revert project to the Future Architecture platform’s call for ideas, we were busy designing a building made out of earth for a young Chinese entrepreneur who had little understanding of building construction but a good intuition for business. At one meeting we were explaining to him the benefits of earth construction, particularly in terms of thermal regulation, when he suddenly stared at me and asked whether plasters made from earth can purify the air. It was a good question. We knew that the Ancient Romans used to purify air with clay filters, but we could not account for why ancient air filtering technologies are totally absent in contemporary buildings.
Indoor air pollution is a major killer in Asia, therefore air purification systems are a lucrative business. In China, for instance, extreme levels of air pollution mean that windows in new buildings cannot be opened, so all ventilation depends on centralised inbuilt systems. Over time, this machinery gradually fails due to maintenance issues and residents can be subjected to asphyxiation inside their own homes. According to the World Health Organisation, this accounts for some 3.8 million deaths a year. 1
This is not just an urban problem. Winds can carry poisonous ultrafine particles thousands of kilometres from the source of pollution. Air currents passing industrial coal plants in Ukraine, for example, travel as far as natural reserves in Slovenia or the Adriatic coast of Italy. Scientists are only just starting to understand the impact of these tiny particles and their migration. They are by far the hardest particles to measure and mitigate and are the most dangerous to human health.
The easiest way to control particulate matter (PM) pollution would be to ban diesel cars and the use of coal, but could architecture also help deal with the problem? We think it should be able to do so, there are plenty of effective individual systems based on both high and low technologies available. The difficult part is that air pollution, including that from mould and toxins, varies a lot, so an integrated system with a range of capacities would be required. However, despite humankind’s vast knowledge of traditional air purification systems, there are no common solutions, particularly when it comes to integrative systems that bring together many traditional, lower-tech technologies. Air Revert explores this technological niche by performing empirical tests on the interconnection of low-tech systems in order to answer a problem that high-tech doesn’t seem able or willing to tackle. It combines simple indoor materials, air convection systems and a few climate control devices. It could beused in hospitals, schools and dwellings located in highly polluted areas. The system is scalable and likely to reach patenting at a later stage.
How Air Revert works
There are three main models we are working with, all quite simple. The Enclosed Filtering Chambers involve the connection of different low-tech air filtering systems, each of which is built within its own chamber. Each chamber contains short segments of terracotta pipes and ends in an electric vent, which is in turn connected to the next filtering chamber and ensures the air flows through the system. This modular air conductor brings together the benefits of different filtering systems, from bentonite clay to activated coal, plant roots, oil nebulisers, diffusers, pressure chambers and filters, each of which helps filter a specific kind of air pollution.
The Enclosed Filtering Pipe is an enclosed clay pipe that works as an air purifying system. Certain kinds of clay have filtering capacities. For example, bentonite clay mixed with activated coal acts as a filtering material when it is kept sufficiently moist and polluted air brushes against the damp clay surface. The model consists of a single irregular clay shaft with alternating wide and narrow sections that create pressure differences as air is blown through the pipe. These pressure differences create turbulence inside the pipe so that polluted air is forced against its damp interior surface.
Finally, the Exposed Filtering Surface works in the same way as the enclosed filtering pipe but instead of a pipe you have an entire surface, such as a wall or ceiling, which filters air when it is blown against its purifying surface. In this system the ceiling is covered with a clay plaster. Clay plaster needs a certain humidity level in order to act as a purifying element. The surface has a number of vents and a sprinkler system that keeps the plaster moist, allowing it to act as a retainer for purifying agents such as oils and activated carbon. The system also regulates indoor humidity, especially in highly-heated spaces where the air tends to get extremely dry.
Air Revert is still in its early stages. Step one, researching ancient and low-tech systems and step two, empirically testing these systems to ascertain practical limitation with models, are complete. The next stage is to find technical and research partners, such as universities and research institutions, in order to develop a testing method for these models. ■