B10 - Double Glazing

Double glazing creates an insulating layer of air or inert gas between two panes of glass, reducing the amount of heat that is lost through windows.

It can halve heat loss, improve the comfort of your home and reduce condensation and noise.

There are various double glazing options available. These are:

• new double- or triple-glazed windows.
• secondary glazing, for example, by installing an aluminium framed secondary glaze on the inside of existing single-glazed windows to form a sealed, insulating air gap.
• do-it-yourself (DIY) window insulation kits (available online or from most hardware stores), which involve attaching a thin plastic film to the existing window sashes or frames to create a layer of still air that acts as insulation. These can significantly reduce heat loss and condensation.
• low emissivity (low-E) window film, which involves coating the existing window glass with a special thin plastic film that reflects radiant heat. Low-E window film is available at hardware stores.

There are currently no schemes operating that offer direct assistance for double glazing. However, Work and Income may be able to help cover some of the costs through a Special Needs Grant or Temporary Additional Support.

Pros

• Double glazing, secondary glazing and DIY insulation kits can reduce heat loss through windows by around 60 percent.
• Low-E window film can reduce heat loss through windows by up to 25 percent.
• DIY window insulation kits are relatively cheap and simple to install.
• Low-E film can reduce the amount of heat and UV light coming in, which can reduce overheating in summer.

Cons

• Both double glazing and secondary glazing can be expensive. A cheaper alternative may be to ensure that you have adequate curtains covering your windows.
• Floor and ceiling insulation needs to be up to standard to get the full benefit of double glazing.
• Window seals must be in good working order or condensation can occur.
• DIY window insulation is only designed to last one season and can leave a stain on your windows if left for longer.
• Low-E film can limit the amount of free, passive heat your home gets from the sun in winter.
• Some people find DIY window kits and low-E films aesthetically unappealing.

What do I need in order to take this option?

• You will need adequate funding to pay for your chosen double-glazing option.
• Your existing windows and window frames must be in a good condition.
• If you decide to go with DIY insulation or low-E films, you will need some DIY skills or you will need to know people who can help you. Alternatively, you could hire a local handyman.

Could this option limit my future choices?

No, improving the comfort of your home will help you remain there longer.

For more information

• The Energy Efficiency and Conservation Authority (EECA), Double Glazing. See: www.eeca.govt.nz
• Some councils have sustainable/eco home design advisors who can provide advice on how to make your home warmer. See: www.ecodesignadvisor.org.nz/
• SuperGold, for information on businesses that provide double-glazing services in areas around the country. See: www.supergold.govt.nz/
• Consumer, Winter Heating Guide. See: www.consumer.org.nz/topics/winter-heating-guide
• Work and Income, Special Needs Grant. See: www.workandincome.govt.nz/products/a-z-benefits/special-needs-grant.html
• Work and Income, Temporary Additional Support. See: www.workandincome.govt.nz/products/a-z-benefits/temporary-additional-support.html