The average daily moisture production inside a home can be as much 10litres – that’s around 2.2 gallons. And a typical clothes-drying load can add a further 2.5litres, based on a family with two children.
So there is a lot of moisture ‘sloshing’ around in our homes, which can lead to an unhealthy level of humidity in a household environment. This is according to research by the Mackintosh Environmental Architecture Research Unit (MEARU).
So the issue of drying domestic washing is a common problem in all housing types across private and social housing sectors, and is one which does not appear to be adequately tackled, even in exemplar new housing low energy projects.
Due to awareness of the energy consumption of tumble dryers, many residents are choosing to dry clothes passively within their home. The impact of this incurs not only a severe energy penalty via increased heating demand, but also a potential health risk due to the higher moisture levels.
High moisture is associated with dust mites and increased mould spore concentrations as well as generally poor indoor air quality.
Although there has been a large body of research relating damp housing to ill health, the MEARU study is the first to track the specific implications of passive indoor drying.
In terms of dust mite growth, known to be causal for asthma in sensitised individuals, passive indoor drying adds to the problem in already over-moist and poorly ventilated homes.
The heating season average of 87% drying passively indoors rises to 96% in spring.
The study also points out that fragrances in softeners are unregulated They can produce a hazardous carcinogenic – acetaldehyde.
The alternative of machine drying all clothes is estimated to have significantly greater primary energy impacts and carbon impacts compared with passive drying in a dedicated enclosed space.
Using tumble dryers, the average power use per person annually is three times greater than for washing machines. The energy consumption of washing machines varies by a factor of five and per cycle by a factor of over four. Which does not correspond well with respective high and low values measured in use.
Ironing is estimated to use some five times less power than washing machines but also adds moisture to indoor spaces.
Amongst many other things, the findings of the MEARU research suggest practical retrofit solutions, which can be applied to most existing house types, including, enhanced outdoor drying facilities.
More information: www.homelaundrystudy.net
Top photos show how drying inside the bathroom can cause severe damp