Frequently Asked Questions


How much money will I save by insulating my ceiling?

Most New Zealand homes built before 1980 are poorly insulated and under heated.

By insulating your home, you may notice a decrease in your average power bill, but the most noticeable change will be an increase in the warmth, comfort and health of your home.


How much will it cost to insulate my home?

Every home is different and a variety of factors will influence your personal quote. Below is a rough guide of how much it might cost to insulate your home: 



Insulation TypeSmall house (50-80m2)Medium house (80-120m2)Large house (120-170m2)Extra large house (170-220m2)
Ceiling full layer$1256 - $2010$2010 - $3015$3015 - $4272$4272 - $5528
Ceiling top up$1064 - $1702$1702 - $2553$2553 - $3617$3617 - $4681
Underfloor$1211 - $1938$1938 - $2907$2907 - $4119$4119 - $5330
Polythene ground vapour barrier$431 - $690$690 - $1035$1035 - $1467$1467 - $1898
Retrofit foil removal$57 - $91$91 - $136$136 - 193

$193 - $250



Over winter, I get very heavy amounts of condensation on the inside of my windows.  I do have good quality lined curtains, what can I do to reduce this?

If you have wooden window frames, secondary glazing products like window kits, available on our online shop, will improve your window insulation.  If you have aluminium frames, cut a piece of bubble wrap to the window size, and stick it on by spraying a little water on the window, then placing the wrap to help reduce condensation build up and heat loss.


My house is very damp in winter, what can I do?

You need to reduce the relative humidity of the air in your home. This requires a combination of sufficient heating, ventilation and insulation.

  • Heating: by introducing low level heating, the temperature of internal surfaces will rise. This will reduce cooling of any damp air and, as a result, the amount of condensation. Ideally, low level background heating should be continuous, as any short bursts of heat may not result in a suitable rise in surface temperatures.
  • Ventilation: adequate ventilation is essential to allow damp air to escape from the home before condensation occurs. Using extractor fans in the kitchen and bathroom can prove very effective in reducing condensation, as well as ventilating by opening windows daily for 10 minutes.
  • Insulation: insulating a house well makes it easier and cheaper to heat. It raises the temperature of windows and the surface of exterior walls, thus lowering the humidity and further avoiding mould growth and condensation.


My home is very draughty in winter, what can I do?

Draughts are caused by cold air forcing its way through gaps around doors and windows. It is hard to keep a draughty house warm and comfortable. By blocking the gap, you will stop the draught. Even modern, well insulated homes have draughts.

For wooden windows frames, use V-Seal, this is a flexible, adhesive-backed vinyl strip that folds into a V shape to fill gaps from 2mm to 8mm. Draught stopping for aluminium frames needs to be done by a professional, e.g. Exceed.


Draught stop external doors with automatic weather seals available from the hardware store, and brush strips which fill the gap beneath the door.  Gaps in skirting and floorboards can be filled with a flexible sealant that will last for many years. Lighting can also cause issues with draughts - find out more here.


My windows are double glazed, do I still need curtains?

Curtain and double glazing are not really replacements for one another. Curtains will build on the insulation value of the window as a whole. The R value of a basic double glazed aluminium window is R0.26 – actually not much higher than single glazed with a wooden frame. Effective curtains can increase the overall R-value to over R0.5, which will significantly reduce heat loss at night.


I turned on my underfloor heating for the first time and my power bill was above $500, is this the reason?

It is highly likely. Typically underfloor heating is 150watts/m² and up to 200watts/m² for some under carpet systems. So, even if only part of the ground floor has embedded cables, say 50m², then 7-10kW is likely to be the electrical draw under full load. If the system is on for 10 hours a day, and electricity costs 18cents/kWh (assumed to be a mix of night and day rate tariffs) the cost would be $540 for 30 days.

Should I leave my heat pump running 24/7?

Best practice would say that no heating appliance should be used 24 hours a day. Clever use of a heat pump is using it as required. If you are not at home during the day, there is no need to run your heat pump during the day. In this situation, and with good insulation, a couple of hours in the morning and a few hours in the evening should suffice. For example, when running a 3.5kW heat pump for a couple of hours in the morning and four hours in the evening you could expect to pay around $40 a month. In saying this, a number of people that are home during the day and are often up during the night, leave the heat pump running 24/7 and find this affordable. You also should avoid turning the heat pump off and on as the room heats to the ideal temperature - use the correct settings, and leave the heat pump on for the duration of time you are in the room.


Should I use the door to door heat pump cleaning companies?

Householders are being charged $135 to clean a heat pump, a job that heat pump suppliers say does not require a specialist and takes just minutes. Heat pump manufacturers give similar advice. The indoor filters should be cleaned regularly and vegetation kept clear of the outdoor unit. See Mitsubishi's Quick Clean Kit for information about how to do this.


My home gets very hot in summer, should I use the heat pump to cool my home?

The most effective way to keep your home cool over summer is to use curtains or blinds to shade direct sunlight, especially on the North and West facing windows. Also check that the ceiling is well insulated. If you run the heat pump for 8 hours a day, this could cost up to $2.00 a day.


We’re going away for a few days, should we turn off the hot water cylinder?

Yes. Turning a hot water cylinder off, even just for short periods will always be more energy efficient than leaving it on.


What does it mean if hot water has started spilling onto my roof?

If hot water is venting on the roof then check out the following:

  • It might be caused by the water in the hot water cylinder boiling, indicating a faulty thermostat.
  • If it is a low-medium pressure hot water cylinder with a pressure reducing valve (PRV), the problem could be a faulty thermostat, a faulty PRV, or a faulty pressure relief valve (if fitted).
  • If it is a mains pressure cylinder it could either be a faulty thermostat or the pressure relief valve may be faulty.
  • Solutions will require a visit from either an electrician or plumber.
  • Call us for help finding the cause.


My cylinder is an “A” grade model, do I still need a cylinder wrap?

While an A grade cylinder is certainly better, it will still have standing losses of between 1.8 to 2.45kWh/day. If a wrap can be fitted, savings could be up to $45/year if paying about 20 cents/kWh. You can buy cylinder wraps online here

Community Energy Action


(0800 438 9276)

+64 3 374 7222


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