Heating, Insulation and Condensation Problems in New Zealand Homes

Most migrants to New Zealand notice very quickly that New Zealand homes tend to be colder and damper than houses in the UK.

There are things you can do to improve the winter living conditions in a New Zealand home, and they don't necessarily cost the earth. The following article is intended to give you an idea of what to expect when looking at New Zealand property, and how much the common problems will cost to rectify in a typical New Zealand home. We've also provided some examples of what Jeremy's family have done to improve their 40-year-old brick veneer home since they emigrated in 2002.

1. Heating 
2. Insulation
3. Windows
4. Ventilation and Condensation
5. Grants and Funding
6. Conclusion

Heating

Central heating is very uncommon in New Zealand homes, and is one of the things that new emigrants and New Zealanders returning from the UK tend to miss most.

Kiwis tend to heat their homes room-by-room, with living areas a priority. You may find the vestiges of an oil-fired central heating system in an older home in the south, but the oil shock in the early 1970s put paid to this. Neither electricity nor natural gas has ever been cheap enough in New Zealand for UK-style boilers and radiators to become popular.

The typical heating arrangement in a Kiwi home is a wood burner, heat pump, pellet fire or gas fire in the main living area. In some areas gas needs to be delivered in big bottles that sit outside the house - piped or reticulated household gas is not available everywhere in New Zealand. There is often a night store or panel heater in the hallway to heat the rest of the house, with free-standing electric oil filled radiators common where bedrooms need to be heated.

You can install central heating in a new or existing home, generally with ducted heat pumps or boilers burning wood pellets, but this is still relatively uncommon and expensive compared to a UK central heating system.

New Zealanders are increasingly aware that their homes are cold, and that this is a health issue rather than just a comfort one. Some local councils provide grants and low-interest loans to home owners and landlords looking to upgrade their heating and insulation, such as the Clean Heat Project in Christchurch and Canterbury.

In our late 1960's brick veneer Christchurch home, we have a big heat pump in the open plan living/dining/kitchen area, which replaced an inefficient, smoky wood burner. We really love our heat pump, which cost just under $5,000 to buy and have installed. We find that it can often be turned off on sunny days even in the middle of winter as we have huge windows. We've been experimenting with leaving it on at a low temperature over-night on really cold nights, which is apparently better for the heat pump and more energy-efficient than turning it on when we get up in the morning – it keeps the house warmer, and does not seem to add noticeably to the power bill for our place, but apparently this varies from home to home.

We also have a night store heater in the hallway that we keep on for around 4 months of the year – it takes the chill off the bedrooms. We used small oil-filled radiators in the kid's rooms when they were tiny. We only have one room where the bed is against an outside wall, and found that getting a good thick wooden bed-head to keep the bed away from the wall helped to keep the mattress dryer and warmer.

Other than that, we rely on the Kiwi system of extra blankets on the bed and flannelette pyjamas in winter, and probably wear an extra layer of clothing during the day.

Insulation

New houses were not required to be fully insulated (ceiling and walls) in some areas of NZ until 1978 - New Zealand houses can be very cold in the winter.

An typical New Zealand home without insulation loses around 30-50% of its heat through the roof, 18-24% through the walls, 21-31% through the windows, 12-14% through the floor and 5-9% through air leakage.

Fibreglass batting, loose cellulose and wool insulation products are very effective in the roof ($1000 - $2000 for a typical house), and there are various foil and polystyrene products that can be fitted under draughty wooden floors ($1500 - $2000 for a typical house).

Walls are harder to retrofit with insulation - there is a foam that can be pumped in, but it is contentious (particularly in brick homes). Cellulose can also be pumped in from the exterior, but there are apparently concerns that this will sag over time, and even a small gap in insulation can dramatically reduce its effectiveness. Another method of insulating walls is to remove the plaster board from the inside of a room and tuck in insulation, often while redecorating or renovating.

We had a thin layer of fibreglass batting in our roof, but topped this up with a thick layer of loose cellulose fluff – we have a low roof line than pretty much ruled our putting in more batts. There was a noticeable difference in how warm the house is in winter, and it also seems a wee bit cooler during the summer. We also had foil stapled in under our wooden floor, which also helped a bit. There are some safety concerns with underfloor foil - several people have electrocuted themselves installing it - so it is best to leave this to the professionals. There are better underfloor insulation products available now.

We have not insulated our walls yet - there are insulating paints and plaster products coming on to the market all the time, which we watch with great interest, but we're planning to put in fibreglass batts (in the colder south-facing bedrooms especially) when we renovate in a couple of years.

Windows

Aluminium is the most common window frame material in New Zealand, and most New Zealand homes are single glazed.

Replacement aluminium-framed double-glazing is quite expensive ($20,000 + for a house). Double glazing is around 30% more expensive than single glazing, and is now mandatory for new homes in colder areas of New Zealand. A number of older homes have had their original wooden windows replaced with single-glazed aluminium joinery, probably as much for ease of maintenance as warmth. Aluminium is an excellent conductor, so if you get any condensation in your home it will appear on the window joinery – even if the windows are double-glazed.

UPVC windows are available in New Zealand but uncommon - apparently when UPVC windows were first introduced to NZ some decades ago, they did not last long in the strong sun. The technology has moved on, but they remain an expensive window option.

If you are thinking about replacing windows, a good place to start your research is the Window Association of New Zealand website, which has information on the WERS window rating scheme , which will give you an idea of how well the different joinery and glazing options will work to heat, cool and reduce condensation in your home.

Our home has huge floor-to-ceiling windows on all down the warm north-facing side, and smaller but plentiful windows everywhere else. The original wooden joinery was replaced with single-glazed aluminium around 15 years ago in all but 2 bedrooms. A large conservatory was added at the same time. The aluminium windows have channels and drains at the bottom to allow condensation to drain off.

We've held off replacing any windows, mainly because we're planning to renovate in a couple of years and want to get them all done at once. We have a lot of condensation in our home, with windows that require wiping most days in the winter despite the house being kept at a reasonably warm temperature (well, for New Zealand anyway...). We will look at UPVC windows and the new thermally broken (insulated aluminium frame) windows when we do replace the joinery, and will definitely double-glaze!

In the mean-time, we have good thick thermal-lined curtains, and curtain rails without a gap at the top. Just as important in the summer, we have installed blinds and UV-blocking net curtains in the north-facing rooms. They are not particularly beautiful, but they do keep the rooms a lot cooler, and can be folded away in the winter when we need all the sun we can get.

Ventilation and Condensation

We've mentioned condensation a fair bit above – manifesting itself in windows that are wet on the inside, condensation is symptom of the dampness in many New Zealand homes.

It is mainly confined to the winter months, and can be as light as a faint misting on the bottom edge of the window or as severe as drops of water that cover and run down the window and frame. If you don't wipe it off, it will cause mould on aluminium windows and rot wooden ones.

Condensation on windows is a symptom of:

• inadequate ventilation,
• inadequate insulation, and
• inadequate heating.

It is a real catch-22 – you stop up all the gaps and limit opening your windows in the winter because you'll lose all your precious heat, but this prevents air circulating and the damp air you end up with is much harder to heat. Newer homes have better insulation, so are less prone to condensation problems – but if even a brand new home has inadequate ventilation, it can have moisture problems.

If your New Zealand home has a condensation problem, it is probably best to get your insulation upgraded, and address any sources of excess moisture in your home, such as:

• Dry clothes outside – or in a properly vented dryer.
• Keep the bathroom door closed when you bathe or shower
• Get extractor fans fitted in the bathroom and kitchen. They need to vent to the outside rather than into your roof space.
• If you have wooden floors, check the ground under your house. If it is wet, consider installing heavy-duty plastic to prevent this dampness from rising up into your house.
• Air your house as regularly as possible.
• Avoid un-flued (portable) gas heaters – they don't only create moisture problems, they are pretty toxic.
• Make sure your gutters are clear, get any roof leaks fixed (leaks can be hard to track down on iron roofs), and make sure your storm water drains are not blocked.

If you have eliminated as much moisture as possible and still have condensation problems, it may be worth looking at mechanical forms of ventilation. There is a good discussion of these on the SmarterHomes  website. You can also control condensation with portable dehumidifiers, but these cost quite a bit to run and only control condensation in small areas rather than sorting out the moisture problem in the whole house.

Our home has a condensation problem in the winter months, especially when there is a heavy frost. We are in a really low-lying damp part of Papanui, so having polythene installed under our wooden floors when they were insulated with foil has helped quite a bit, as does leaving the heat pump on overnight at a low heat – this only really helps in the living area where the heat pump is, but it does both keep the air temperature up and encourage air to circulate a bit.

We found that both the existing bathroom and kitchen fans vented into the roof space, so we have had “mushrooms” attached to the roof to vent them outside. This has made a noticeable difference to the condensation in the bedrooms closest to the bathroom.

Installing more insulation has also helped with the condensation, so the problem is a lot better than when we first moved in to our home – but we still have to wipe our windows down in the winter. Once we have renovated in a couple of years, we expect the wall insulation and double glazing to make a really big difference. In the meantime, we are looking at installing a heat exchange system. A fully ducted system will be around $6,000 for our home.

Grants and Funding

As well as local council initiatives to improve heating and insulation in New Zealand homes, such as Canterbury's Clean Heat program mentioned above, there are nationwide grants available from the Energy Efficiency and Conservation Authority or ECCA. Check here for further information on the funding that is currently available.

Conclusion

If you are buying anything other than a very new home in New Zealand, and you plan to stay there for a few years, you probably need to plan to spend some money on heating and insulation.

You may not recoup all of these costs if you come to sell quickly, as insulation in particular is relatively undervalued in the New Zealand real estate market, especially compared to a new bathroom or kitchen – but your home will be a much nicer place to live!

As in our separate article on the general design and layout of New Zealand homes, we recommend the Consumerbuild and SmarterHomes websites as excellent resources on all aspects of housing in New Zealand.

At Broadbase International we specialise in helping British migrants make a confident start to their new lives. Please contact us if you have any questions about the financial side of life in New Zealand, and don't forget to order your free copy of our comprehensive New Zealand Guide.