Keeping warm and dry

The average New Zealand home produces around eight litres of moisture a day. Cooking, cleaning, showering and even breathing emit moisture into the air. If not removed, this moisture can lead to condensation, mould, fungi and dust mites; all major respiratory illness triggers. Around 15% of New Zealanders are allergic to moulds, spores and their toxic by-products, resulting in asthma, headaches, sneezing and skin conditions such as eczema. 

In addition to being a health hazard, a moist home can be uncomfortable to live in, hard to heat and can rot, resulting in structural damage over time.

So, how can we get a warmer, drier home?

 

Ventilation and insulation – the basics of a dry home

When it’s cold outside, it’s tempting to batten down the hatches and keep that icy air outside of the home. But ventilation is very important; it helps circulate air in your home, allowing moisture and airborne pollutants to escape and fresh air to be drawn into the home. Effective ventilation can also help keep the home cool in summer and warm in winter. If you are building or renovating, be sure to factor extractor fans in your plans, particularly in moisture-ridden areas such as the kitchen, bathroom and laundry.

If you’re not in the process of building or redesigning your home, it is possible to ‘passively ventilate’ your home on fine days by opening doors, windows, vents and louvers to let stale air escape, while bringing fresh air in. Opening doors and windows on both sides of the house encourages air flow and gives fresh air the ability to circulate properly. This is known as cross-flow ventilation. Even just 15 minutes of cross-flow ventilation through your home will help freshen the air and reduce moisture.
Insulation also contributes to a drier home. By helping to keep the air inside your home warm, and because it also keeps surfaces (such as windows and walls) warm, moisture won’t form on them when the cold outside air hits them, thereby reducing condensation.

Reduce moisture inside the home

There are many painless lifestyle changes that you can make that will have a big impact on the amount of moisture in your home.

• Reduce moisture from steam by opening windows in the bathroom when bathing and in the kitchen when cooking and using extractor fans to remove moist air from these areas. Vent the extractor fans to the outside and not to the roof. Use lids on cooking pots.

• Invest in clothes airers so that you can dry your clothes outside when possible.
• Cross-ventilate your home on fine days.
• Remove any existing mould in the home using a bleach solution (mix 9 parts water to one part household bleach and wipe with a cloth).
• Avoid using un-flued gas heating.
• Underfloor heating effectively and efficiently heats the home from the ground up.  
• Vent your clothes dryer to the outside.

Dehumidifiers
Electrical and non-electrical dehumidifiers are an ideal way to help reduce the humidity levels (moisture) from damp areas in your home and help maintain the recommended indoor humidity level between 40% and 50%.
 
Electrical dehumidifiers
A dehumidifier will quickly remove moisture from the air inside your home. The first considerations are the size of your house and how many of the rooms suffer from damp? Dehumidifiers come in a range of sizes extracting as much as 30 litres of moisture from the air per day.
Small and portable ones can be moved around the house as required, and two small dehumidifiers may be a better option than one large one, depending on your needs. If you have a consistent source of damp in a room caused by a leaky roof or floor, buy the most powerful dehumidifier you can find. And if it is for bedroom use, look for a noise-free option or consider DampRid products, which are non-electrical and, therefore, silent.
DampRid
DampRid is a non-electric moisture absorber, which prevents the growth of mould and mildew and controls the humidity at a safe level, so that plants, animals and clothing will not be damaged. It utilises white pellets that absorb excess air moisture and liquefy it into a brine solution.
To remove damp, musty odours, use DampRid Refillable Room Fresheners, which absorb stagnant air smells. Another convenient product is DampRid Hanging Closet Freshener, which will last four to six weeks and keep clothes fresh and dry in the wardrobe.
Reduce moisture outside the home
Much of a home’s moisture can come from outside moisture, so if your home is extensively damp, check the outside area is not a contributing factor.

• Mend any leaks in guttering and plumbing.
• Ensure that the ground around the home has adequate drainage to reduce moisture build-up and damp air around the home.
• If you’re building or renovating, consider installing double-glazed windows, which provide better insulation.
• Lay heavy polythene plastic under the house to make the home easier to heat and keep dry.
• Ventilate enclosed sub-floor spaces.

Keeping the home warm
A damp home is uncomfortable and difficult to heat, while a warm home is not only more comfortable, it is also much healthier for the inhabitants. Keeping your home warm through passive heating or mechanical heating has the additional benefit of reduced moisture.

• Close your curtains before it gets dark to help keep the heat in.
• Up to 20% of home heating is lost through draughts. Draught-proof your windows and doors, block up unused chimneys and stop draughts around doors and windows.
• Insulate the home. If you can’t afford to do it all at once, start with the ceiling. As hot air rises, most of the home’s heat is lost through the ceiling.
• Use healthy forms of heating and stay away from un-flued gas heaters. Heat pumps provide efficient home heating and water bottles might be cheap and cheerful but they are certainly effective. Rinnai offers Energysaver power-flued gas heaters, which deliver superior air quality and have endorsement from the Asthma Foundation.
• Trim back any trees that block sunlight from entering your home.

Heat pumps
When used correctly, heat pumps are highly cost efficient. Using less energy than other equivalent electric heaters, some heat pumps also incorporate air filters to remove dust and pollens from the air. When choosing a heat pump, consider how many rooms you need to heat – a single room, or do you require a multi-system to heat up to four areas or a fully ducted system to heat an entire house?
 
The following table gives a guide as to the heat pump capacity required to heat your home.

Area to be heated*	Heat pump capacity
15 to 25m²	3,000 Watts
25 to 35m²	4,000 Watts
30 to 40m²	4,500 Watts
40 to 50m²	5,500 Watts
45 to 55m²	6,000 Watts
50 to 60m²	6,500 Watts
55 to 65m²	7,000 Watts
60 to 75m²	8,000 Watts
* Ceiling height approx 2.4m, single-storey dwelling, well insulated.