Are energy efficient homes making us ILL? No. Lousy ventilation systems are.

black mold
CC BY 2.0 Satemkemit on Flickr

The always calm and reliable Daily Mail titles its story Are energy efficient homes making us ILL? Toxic mould caused by poor air circulation could trigger 'sick building syndrome'. The article breathlessly begins:

Energy efficient buildings are an important part of tackling the world’s energy crisis. But while these structures can keep draughts out, they also have a hidden threat lurking within. Deep within their crevices and corners, green buildings are susceptible to trapping humid air in which toxic mould can spread.

They say that the problem affects between 30 and 50 per cent of new or refurbished buildings, although they are writing from a naturally mouldy country and results may differ in drier climes. But in fact it is true, the problem has been known since the seventies when buildings started getting sealed up to save energy, and the solutions are well known. It has nothing to do with the buildings being energy efficient and has everything to do with crummy ventilation and bad design.

If you have a sealed building without ventilation, people showering, cooking or just breathing and sweating are going to add moisture to the air. If the walls are cooler than the air then that moisture is going to condense. If the moisture condenses on that hairy paper covered stuff we call drywall it is going to allow mould growth.

hrv ceiling drawing

The answer is controlling humidity through ventilation (preferably with a heat recovery ventilator) and lots of insulation properly installed so that the walls are not so cool. This is a problem in every building, whatever the age or energy efficiency; the old ones just leak so much air that the humidity doesn't build up in winter. They can still get just as mouldy in other seasons and often do.

In fact, the worst cases are among the very poor, where lots of people are packed into small spaces all the time. The leaky, crowded homes of aboriginal people in Canada are among the worst in the world for this. The headline should read Crowded, substandard housing is making us ILL.

But that's not news for the front page of the Daily Mail.

Speaking of one renovation that went wrong, a courthouse in Alberta, Tang Lee, a professor of architecture and environmental design is quoted noting...

that the situation is a stark reminder that even in pursuit of saving energy, human health should be a major concern in designing and retrofitting the enclosed spaces where people spend most of their lives.

One would have thought that was obvious, and it is; the building they use for discussion in this story has been closed since 2001 after years of problems. We really have known about this since the seventies.

Why is this still happening when everyone knows what the problem is?

The fact that this is still happening is a disgraceful reflection of the state of the building industry. You cannot seal up a building without considering ventilation and humidity. That people do is an indictment of builders, the building codes and officials, and the customers who would rather pay for granite counters than a heat recovery ventilator. And it's not just moisture that can build up, it's VOCs and formaldehyde and other chemicals. I wrote a few years ago:

The real message, both with LEED towers and single family houses, is that you cannot worry about energy savings without worrying about air quality, they go hand in hand. If you make a building energy efficient then you have to worry about VOCs, formaldehyde, fire retardants and every other chemical that can build up; an efficient house has to be a healthy house.

The Daily Mail is scaring people away from fixing their homes by claiming that energy efficient buildings will make people sick, and commenters are saying "that's why I love my draughty old house." They should be ashamed of themselves, but they never are.

Are energy efficient homes making us ILL? No. Lousy ventilation systems are.
The Daily Mail digs up old news to scare people away from insulating and sealing their homes. This is stupid and wrong.

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