Man installing insulation.
Research report
April 2021

Insulation buying guide

We explain your home insulation options.

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22 Apr 2021
E verses Eco

I discovered that many new builds are using polystyrene as insulation, especially under concrete flooring. O.K when in airtight situations, but who will pick up the tab decades ahead when homes are being altered or demolished and it is degrading?

Walter M.
19 Apr 2021
Carbon footprint considerations?

I'm disappointed that there isn't any comparison of the carbon footprint of the various insulations aka embodied carbon. Wool and macerated paper (referred to as cellulose some places overseas) would get a boost with considered and foams would fair badly. Generally I would like to see Consumer start to include carbon footprint in its rankings.

Antonia A.
19 Apr 2021
Sound advice

I would really like to know how these insulation’s stack up in sound conductivity vs heat conductivity. Specifically between floors...

Derek B.
18 Apr 2021
Insulating existing weatherboard walls

There seems to be much controversy about filling existing walls with foam etc.
What’s the truth?

Joanna S.
18 Apr 2021
Effect of increasing the R value on insulation

I would be interested to know the effect of increasing levels of insulation. Does doubling the R value halve the heat loss?
Also, how much does underfloor insulation reduce heat loss compared to ceiling insulation?
Do or should installers removing old foil insulation turn off the power to the house while they are under the house?

Andreas S.
18 Apr 2021
Buying guide?

Maybe it's just me, but I was expecting to find a "buying guide" and not just a copy of one can find in the internet? So what brands/products are out there and how do they perform, especially cost wise, this would be something I'm interested in.

Chris S.
18 Apr 2021
New builds and major refurbs beware the invisible thermal T-Rex in the equation:

Windows! Compared to walls, windows are a thermal black hole that can suck heat out of a room at a prodigious rate.

Do you need all those windows? Do they really need to be so large? South and SW facing windows provide zero thermal gain at any time and are thus permanent losers energy wise. In a S. facing bathroom with obscure glass they're a complete waste of time & money, especially with the advent of LED lighting systems.

Those massive picture windows looking over not much really may sound like the bees knees, but wait till the cold draughts and heating bills roll in, you'll wish you hadn't. I did.


17 Apr 2021
Insulation installation

The average householder would not know if their insulation was installed correctly but it would pay to at least get into the ceiling to check it yourself if you can. When my sister-in-law had her house renovated she paid to have extra insulation installed in the ceiling. She went up there afterwards to discover that large areas had not been filled correctly with big gaps and pieces missing. They had done a totally unprofessional job that was more or less a waste of time. It makes you wonder who you can trust these days.

Lloyd B.
17 Apr 2021
Better insulation, and higher standards coming soon

Polyisocyanurate (PIR) insulation such as Kingspan is even better, but remember MBIE has just released a consultation document on the higher standards they intend to introduce in November

Alison H.
17 Apr 2021
Subsidised insulation programme

I expected your article to draw attention to EECA(Energy Efficience & Conservation Authority) and their Warmer Kiwi Homes grants. Some members may qualify for these. Perhaps you are relying on the Eco Design Advisor to inform people of all their options around this. But not everyone will bring in such an advisor.

Richard W.
17 Apr 2021
Polyester Fill not new its mainstream

Can you please change your article to represent the current situation on main installation fibre's used in NZ. Polyester installation is a main stream product that deserves it own title and wording. your article is actually not up to date with current practices in NZ without this. comments please?