Mechanical Ventilation to reduce condensation and heat the bedrooms?

Filed under Choosing a heating appliance, Damp and Mould, Ventilation and Air Quality, Space Heating, Ventilation Solutions.

June 29th, 2010

Has anyone here had a Lossnay ventilation system installed, or any other system that draws fresh air from outside (not the roof)? I already have a heat pump, but need something to reduce condensation and heat the bedrooms. But I’m worried about noise, and the cost.

2 Comments

wellington, August 19th, 2010 on 1:55 am

I will post advice on the Lossnay Ventilation system in the next few days but in the meantime I suggest you see another discussion thread on mechanical systems at http://energyadvice.org.nz/?p=438

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wellington, August 20th, 2010 on 4:02 am

For a more detailed report on the Lossnay Ventilation System and other positive and balanced pressure ventilation systems I recommend reading the Energy Efficiency Conservation Authority Home Ventilation report that can be downloaded from the Energywise webpage http://www.energywise.govt.nz/node/5112 .

The EECA report attributes problems in New Zealand houses associated with insufficient ventilation to building improvements that have made modern houses more airtight and to the presence of more water vapour and chemical pollutants in modern homes due to an increased use of showers, unflued gas heaters, unvented clothes drying, chemical containing building products, furnishings and cleaning products (see the excerpt from the report appended below).

“Airtight construction in newer housing is mainly a result of using sheet material internal lining, accurately framed components, and sealed tightly framed windows. But a number of these features are being retrofitted into older homes, with consequent reductions in air infiltration e.g. retrofit aluminium framed windows replacing older wooden framed windows9. As well as structural factors, lifestyle and behavioural factors are reducing previous forms of ventilation in houses. Windows are increasingly being kept closed for security reasons. Less use of open fires is resulting in unused fireplaces being closed off or dismantled. At the same time activities within the house are contributing to potentially lower indoor air quality (IAQ). Water vapour has increased with the greater use of showers, unflued gas heaters and unvented clothes drying. There are also concerns about chemicals in household cleaners, wall and floor coverings, fabrics etc. Research over the last decade on the chronic under-heating and relative coldness of New Zealands houses also raises related concerns about dampness and a lack of ventilation. This relationship is well stated by the Asthma Regional Coordinating Council of New
England: Uncomfortable homes can make people take action that makes a home unhealthy. A lack of comfort can lead to a lack of ventilation and over-humidification. If people are cold they wont ventilate their home. If people cant afford to heat their home they wont ventilate their home10.

While the EECA report evidences the need for improved ventilation in New Zealand homes, in many if not most New Zealand homes good levels of indoor air quality can be achieved by limiting indoor moisture sources and using natural ventilation – ie. windows, without need for more than spot supplementary mechanical ventilation – ie. a moisture extraction fan in the bathroom. Whether it be a positive or balanced pressure system, getting a mechanical ventilation system installed into your house will be expensive (in excess of $2000) and if you are experiencing moisture problems I recommend you start with simple, cheap and cost effective measures to address these problems before you spend money unnecessarily on a mechanical ventilation system.

First up I recommend taking measures to reduce water vapour and harmful chemicals in your home. I recommend that you: check that your plumbing pipes and drainpipes are not leaking or blocked and that the ground under your house is well draining, use lids on pots, dry clothes outside on the washing line, boil only the amount of water you are going to use and reduce the number of pot plants inside. In conjunction with reducing moisture production I recommend increasing your use of natural ventilation – opening windows slightly during the day, along with improving the insulation performance of your home and heating your home sensibly using a clean efficient heater. Installing a Showerdome or moisture extraction fan in the bathroom, or using a mobile dehumidifier in living rooms and bedrooms are really good economical options to deal with localised moisture problems. Using a dehumidifier in combination with a clean efficient heating appliance such as a heat pump or clean efficient wood burner present will also enable you to heat your home much cheaper and using much less energy.

If you are seriously considering getting a home ventilation system installed and you read the EECA report, note that while the EECA report suggests that balanced pressure systems typically cost between $5000-$7000 installed, in an internet review of Home Ventilation systems, Consumer suggests that the price for getting a Mitsubishi Lossnay Ventilation System installed can be as low as $2999 (the cheapest balanced pressure system on their list).

Seth Hickling
Home Energy Advisor
Wellington

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