Article: Speak Easy

The Future  Of Insulation with with Michael BoturThe Future Of Insulation with with Michael Botur

In the next 30 years there is likely to be a manned (and womanned) mission to Mars.

If the Marstronauts want to be as warm as the Mars rover, they’ll need a special layer of solid silica aerogel as insulation. That space age technology is nicknamed “solid smoke” because it is 99.8% air. Aerogel is one thousand times less dense than glass, extraordinarily lightweight, cheap and easy to launch and fly to Mars. When the astronauts settle, some boffins reckon they’ll keep their habitat warm by pumping a mixture of water and antifreeze through a pipe to collect heat and transfer it into a thermally insulated tank which will act as a large heat energy storage device…. Just like your hot water cylinder at home.

We’re actually way ahead of Mars in many ways, in terms of how we trap heat in our homes using building materials like concrete, brick and metal which have high thermal mass. 

The parts which SHOULD take part in insulating a home are:

• Hot water cylinder (for older homes): Heating a home’s hot water is typically
behind one-third of the average power bill. If you don’t have an insulating wrap
around your cylinder, it’s important to get that sorted. They cost around $50 from
your local hardware stores. These wraps usually have insulating fibre on the inside
and reflective silver coating on the outside. You can even get a hot water cylinder
PRE-heater, which is just a disc of metal which captures solar heat and applies that
heat to your water before it’s piped into the cylinder.

• Roof:  Heat rises, so don’t let it escape through holes in the roof and an
unprotected attic. If your ceiling is insulated but the joists of the wooden beams are
still visible, it’s a good idea to install another layer of insulation on top of the
existing one.

• Between floors: Insulate for warmth and to reduce noise transmission. It’s hard to
retrofit, though.

• Floors: Houses in contact with ground soil need vapour barriers such as polythene
to reduce dampness rising through the floorboards.

Many of us with older houses have cavities in our walls where noise gets in and heat gets out. Don’t expect any older house to have insulation built into the walls. Glass wool / fibreglass was only invented in 1938; you still get the odd house today with zero insulation, although modern building codes require this. In fact, there are three climate zones in the country, and new houses must have insulation put in to match the required thermal resistance rating.  Additionally, total window area must be ≤ 30% of the total exterior wall area; the combined window area of the east, south and west walls must be ≤ 30% of the combined area of these walls; skylights must be ≤ 1.2m².

Should you have insulation blown into your walls? It depends. I’ll tell you what to consider, at any rate. Urea formaldehyde (UFFI) foam, when blown into walls, hardens as it dries. That’s often the type of blown-in wall insulation offered (although other options are glass wool, macerated cellulose paper, mineral wool, polystyrene (EPS) beads or polyurethane foam).

If choosing this rather invasive and expensive (though very beneficial) option, you’ll want your wall insulation to have a high level of thermal resistance value (R-value). EnergyWise notes that uninsulated weatherboard wall has about R0.5 insulation value (very low) and UFFI blown-in wall insulation is likely to raise that to R1.6. Taking the wall linings off and installing bulk insulation gives you an R-value of about R1.8 - R2.4… but there are many warnings about interfering with cladding. Any hole in cladding can let moisture get in, so that’s best avoided.

Older houses and houses with brick veneer cladding often don’t have building paper as part of the weathertightness setup behind the wall, so note that injected or blown-in insulation can only be retrofitted if there is undamaged wall underlay or building paper present. 

Head to Energywise’s webpage for more information about insulation, and head to for more information about Mars.

Michael Botur has published journalism in NZ Herald, Herald on Sunday, Sunday Star-Times and Mana and he writes a lot of fiction. He moved to Whangarei in 2015 and was ecstatic to be able to afford a house here.

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