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Cleanair system said to cut energy costs by up to 25 percent


October 4, 2010

The University of Copenhagen's Prof. Matthew Johnson, inventor of the Cleanair system

The University of Copenhagen's Prof. Matthew Johnson, inventor of the Cleanair system

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According to the University of Copenhagen’s Prof. Matthew Johnson, approximately one-sixth of the energy consumed in the world is used for heating, cooling and dehumidifying air in buildings. Because that air accumulates toxins and pathogens, he explains, it must constantly be expelled and replaced with new air that’s drawn in from outside. That new air must then be heated, cooled and/or dehumidified all over again. If only the air already in buildings could be cleaned up and reused, far less energy would be used on continuously conditioning fresh air. That’s why Johnson has invented the Cleanair system.

“Every second we pump air into our houses that is too hot, too cold or too moist. And then we spend billions of kilowatts treating that air,” he said. “If we could clean the air, we could recycle air that already has the perfect temperature.”

Apparently, that’s what his system does. It involves a patented system called Photochemical Air Purification, which incorporates ultraviolet light and photochemical reactions similar to those that occur in the Earth’s atmosphere. This combination is said to remove particles, viruses, ozone, bacteria, organic solvents and hydrocarbons from indoor air, allowing buildings to reduce their energy use by up to 25 percent.

Within minutes of being turned on, Cleanair reportedly removed 40 different compounds from the air in an office building on the U Copenhagen campus. What percentage of those compounds remained in the air was not stated.

Needless to say, cleaner air not only saves money, but should also pose less of a health risk to the people who breathe it. To that end, Johnson is now looking into how effective his system would be at removing volatile organic compounds from industrial smokestack emissions.

Cleanair was unveiled to the public at last week’s World Climate Solutions conference in Copenhagen.

All images courtesy University of Copenhagen

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

Wow! Who works in a building that draws in and heats/cools fresh air from outside? I never have. Every building I have ever worked in (and every home I have ever lived in) draws air from inside returns through an air filter. (I\'m looking at the air filter installed in the air return in my office ceiling right now.)

Once again, Europeans are \"discovering\" something American\'s have taken for granted for almost a century.

Mark Petereit

Well Mark you don\'t have to be rude about something you might not have a clue about. If what you said is true than I\'m sorry for you ... when will have the chance to breathe some fresh air ??? I understand that you are only breathing, in the office, air that is being recycled ... please look in the mirror and if your face is green you might want to take a fresh breathe because you just ran out of oxigen :(

Ciprian Danila

I think the industrial application of this filtering technology should be studied further. Hopefully, it can provide a cheaper alternative to the very expensive pollution control technology available today in the western world. China and India could use less expensive controls, which would make cleaner air more economically feasible.

Alternatively, if you want to combine lower HVAC bills and cleaner air, why not install a green roof? Green roofs filter fine particulate air pollution, and reduce HVAC costs by 20-30%, as well as reducing storm water runoff. Currently mandated in some places (http://cleanerairforcities.blogspot.com/2009/06/where-green-roofs-are-law.html), they are a cheaper alternative to the more expensive point pollution controls.


Sorry Mark. Outside air must be brought into a building. Think about a structure that has 4 entrances on the first floor but 2800 people working in it... Where does the O2 come from?


For most older homes and commercial buildings, recycling indoor air is the norm. It is not without its problems. From Wikipedia \"Indoor Air Quality.\" \"One way of quantitatively ensuring the health of indoor air is by the frequency of effective turnover of interior air by replacement with outside air.\" And, \"Generally, outdoor country air is better than indoor city air.\" The entire article is worth reading. Professor Johnson will have a challenge dealing with ASRAE, local code officials, et al, for commercial installations, but I wish him well. His best success may come from residential and industrial applications.

Bruce H. Anderson

@ Mark Peterit - nah cummon, it would not be newsworthy if that was the case. This invention is about cleaning the air properly - not just filtering it through some cloth or charcoal. And plenty of air conditioners pull in air from outside! I think it might be something new. Airconditioning as it is is NOT good for you! You\'re breathing in all sorts for crap. This guy might be on to something.


What about the Oxygen level after being consumed in breathing and the level of CO2 after exhale, if there are many people are there, for example in a Movie theater?

How it may be replanished?

Best regards,


A. P. Singh

Mike, I my part of the U.S., in commercial buildings, there is an absolute minimum of 10% outside air that has to be brought into the buildings.

How well does an average air filter work in your home for taking out the kind of contaminants mentioned above.

It would seem to me the Europeans are quite a bit ahead of us in this technology.

Your home furnace brings in outside air for heating combustion, you are a slave to the outside environment in the winter. That air would would serve you better if it were tempered, or brought closer to inside air temperature prior to combustion, your heating bill would go down too.

Add all these things together and you cam imagine how much more comfortable your home and work environment would be.

Robert Sr

What happens if we run our office air through an algae bubbler instead? Do we gain the same benifit as well as some added oxygen (and maybe biofeul), or do we end up with an office that smells like an aquarium?

Charles Bosse

The main problem I see is in any sealed building with the air scrubbed over and over is CO2 steadily increasing and O2 steadily decreasing until everybody passes out.

It doesn\'t take much of a CO2 increase or O2 decrease to kill people and nothing in either the picture or the write up seems to address those issues.


Mark, do some research before you make such an arrogant and uneducated comment!

Who works in a building that draws in outside air? Everyone, including you. It is required by code in most/all areas that in commercial buildings a certain amount of fresh air must be drawn in. Typically I believe it is 10-20% fresh air per unit time. The specific rate varies based on occupancy levels, what the building is used for, size of the building, etc. There are standards defined by ASHRAE that cover this.

Now moving on... I agree with some of the other comments regarding the ever-rising CO2 levels. You can see from the diagram that this system seems to be converting various gasses into O2, but I wonder if it is enough. Might still have to pull in some outside air (though not as much).

Brian R

I like the system advocated decades ago by former NASA researcher Bill Wolverton, who created it for the enclosed environment of a space station. He potted certain types of indoor plants in containers with soil over activated carbon, with an exhaust fan underneath. Types included philodendrons, spider plants, aloe and several ferns. Not only did the plants themselves remove some gaseous contaminants like formaldehyde, the air drawn through the soil and carbon would be filtered, and the captured contaminants would be broken down by soil microbes. As an added benefit, plants also brighten up the office/home/whatever. And they produce a little bit of oxygen.

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