Happiness is a warm home :: Good :: New Zealand’s guide to sustainable living

Happiness is a warm home

Home » Magazine » Good, issue 1 » The goods » Happiness is a warm home

By Andy Kenworthy

Okay, we admit it. This is an article about insulation. It is probably the most boring consumer product on the market, but getting decent insulation for your home is so damn important we’re writing about it anyway.

The following two statements about your home threaten to undermine two great pillars of New Zealand mythology.

One: The primary purpose of a house is to shelter you and your family from the elements. It’s not to have somewhere to keep your trampoline, park the boat and show off to the neighbours.

Two: It gets cold, wet and windy in New Zealand. Yes, even in the north. We do not live on a tropical island nestling on the Equator.

Too many Kiwi homes have little or no insulation. Many feature drafts in which you could test the aerodynamics of a light aircraft. When heating systems are used in these places, warm air rushes out of the house so fast it almost changes your hairstyle.

Sadly, our climatic delusions are also shared by some who profess green building credentials. What’s the point of having a super-efficient solid wood stove or heat pump if there’s no insulation in the loft? It’s like going out in the snow with two hot water bottles strapped under your arms because you can’t be bothered to put on a hat.

If you want to face reality, save cash and be green, it pays to consider proper insulation from the moment you consider buying or building.

The location of your home, the material the house is built from, and the quality of the work together form your first line of defence against heat and cold. Get this right, and you may not need insulation or heating at all. Sun-facing windows with angled blinds or eaves let in winter sun and block out the heat of the summer. Inside, a ‘thermal mass’ floor of concrete can be installed to absorb and slow-release the sun’s heat.

But there’s no doubt that simply insulating an existing building can radically improve its energy efficiency. Most of us could benefit from increasing the insulation in our homes, making them—and us—warmer, more comfortable and healthier as a result.

So here’s a list of the main types of insulation on offer. Remember, any insulation is eco-friendly—but if we’re going to nitpick, some are friendlier than others.

Insulation’s ‘R value’ measures how good the material is at containing heat. The higher the R value, the better the material is, provided it’s properly installed. All guide prices quoted are for new, but it could be worth keeping an eye on Trade Me for a bargain.

Through a glass warmly

Surprisingly, glass or fibreglass insulation is among the greenest you can buy. It can contain up to 80% recycled glass and can itself be recycled if kept dry (great compared to mineral wool, which can contain up to just 15% of recycled industry mineral waste). Both can be sourced from New Zealand. Installers need protective clothing and a mask or respirator to prevent inhalation of small fibres and minor skin irritation.

Eco-rating: 4/5
Approx efficiency rating: R2.2–R4.6
Best for: floors, ceilings, walls
Brands: Pink Batts Ultra, manufactured in Auckland and Christchurch, is the only insulation accredited by Environmental Choice New Zealand.
Guide prices per m²: $6.50–$20

The most natural, baa none?

Wool insulation is made from more than 95% natural sheep’s wool, and you can find brands using 100% recycled material. It’s non-toxic, non-irritant, easy to use and available Kiwi-made, but check to see if it is blended with preservatives, polyester or resin. The latter provide added strength and prevent the wool from slumping in wall cavities over time, but could prevent reuse and may emit low levels of potentially hazardous emissions when first installed.

Eco-rating: 4/5
Approx efficiency rating: R1.8–R3 for single layer fleece
Best for: floors, ceiling and roofs
Brands: Christchurch-based Latitude Insulation and ecoinsulation.co.nz both offer insulation using 100% recycled sheep wool, either as a loose fill or fleece panel.
Guide prices per m²: $7–$16

Rip it up and start again

Paper insulation can be up to 100% recycled and Kiwi-made. Check the level of obligatory fire-retardants and pest retardants, which are mixed with the paper and can be up to 35% of the content. The material can be dusty to install, cannot be recycled again, and some versions may slump if used in walls. But it’s effective—and a good price.

Eco-rating: 4/5
Approx efficiency rating: R2.5 for 100mm
Best for: floors and ceilings
Brands: The Natural Insulation Company in Orewa, among others, installs insulation made from 100% recycled paper.
Guide prices per m²: $9 installed

A touch of the 1980s

Polyester insulation is synthetic, and based on petrochemicals. It is either heat-treated or mixed with adhesive binding agents to ensure it holds its shape. Some companies use chemical binding agents which may contain formaldehyde, so check labels and websites. Some 100%-polyester insulation includes recycled polyester fibre, and polyester/wool blends can contain a high proportion of both recycled wool and polyester off-cuts diverted from landfill. It can be Kiwi-made and comes in handy blankets, segments, and loose fill. Dust masks are recommended during installation.

Eco-rating: 3/5
Approx efficiency rating: R1.8–R3.4
Best for: floors, ceilings, walls
Brands: Autex Industries offers heat-treated products with up to 70% recycled fibre.
Guide prices per m²: $12–$18

Pack it like an appliance

Polystyrene insulation is a petrochemical-based, synthetic, rigid foam with added fire retardant. It’s used as cladding and insulation, or in underfloor slabs, exterior walls, and ceilings. Polystyrene ‘pods’ are available for concrete flooring, and polystyrene insulation can be sandwiched in preformed concrete slabs and blocks. It’s toxic if burnt, and some thin extruded polystyrenes may emit ozone gases. Polystyrene can also crumble into small particles which should not be inhaled or allowed to enter soil and water. It can be recycled for insulation if it has not been broken up, and some recycled polystyrene is available through specialised suppliers and waste recovery centres. Otherwise, most is imported.

Eco-rating: 2/5
Approx efficiency rating: R2.5–R3 for 100mm
Best for: floors, ceilings, walls
Brands: Bondor New Zealand’s Retrotherm is up to 50% recycled.
Guide prices per m²: $5–$9

The roast dinner approach

Flexible sheets of this metallic foil can be used as the outer layers of a sandwich with other insulating materials bonded between it. Stapling this in place must be done with extreme care to avoid electrocution from piercing household cables. Although some is manufactured and supplied in New Zealand, it can’t be recycled and is difficult to reuse.

Eco-rating: 2/5
Approx efficiency rating: No R value—enhances other insulations
Best for: underfloor spaces
Brands: Foil is foil (but the stuff you wrap cold pizza in probably won’t do). If you’re after a trusted name, Pink Batts does the Flamestop and Sisalation brands of underfloor foil.
Guide prices per m²: $2–$3

Anonymous comments are queued before publishing and it may take some time before they appear. Please consider creating an account and your comment will appear automatically. If you already have an account, please log in.

Mark de Jong
www.asphaltinabag.co.nz

Sun July 06, 2008 @ 09:53 PM

Just thought I would let you all know about a great new Insulation product called Nansulate, Carbon friendly, low voc and amazing Insulation properties in a simple Paint on Insulation product called Nansulate

Ingo Ratsdorf

Tue August 26, 2008 @ 02:34 PM

Some comments to add:
wool is not en environmentally friendly product as it's sourcing uses masive amounts of water, cleaning agents and other chemicals. In a life cycle assesment, woolen carpet is the worst eco performer. It needs to be made moth resistant, even then there have ben reported incidents with moth attacks from NZ and from overseas.

Glass fibre insulation is treated as possibly carcinogenic, especially in the US. In Germany it is treated as hazardous waste.

One insulation type is not listed here: timber fibre boards and blankets. Currently not produced in NZ, but a very good eco performer, CO2 storage, non slumping, compostable. Example: http://www.steico.com

Ingo ratsdorf

Tue August 26, 2008 @ 02:52 PM

In reply to the Nansulate post:
Interestingly enough, the http://www.nansulate.com website does not give any K, U or R value and reading through the comparisons and facts, the energy savings and temperature difference is minimal, especially considering that you should never get 45 deg C in your house, unless the design went wrong. And how much would you have to pay to get three coats inside and outside? And how would you overcome gaps and airleaks?

US Consumer

Sat October 18, 2008 @ 02:42 AM

To Ingo: The proof is in the product. I challenge you to try it. I have, and Nansulate works I assure you. It's easy to criticize from your keyboard, but it's hard to admit that you're wrong. You up for the challenge?

By the way, Nansulate will fill in some cracks and gaps. Those cracks and gaps which are too large need to be filled in some other way (as always). Nansulate is not a miracle fix-all - it's an excellent thermal barrier. But the fact remains, if you coat the inside walls and ceilings (only those which butt up against the exterior), then that is a lot of surface area which now will minimally transfer heat. That will help, no matter what. FYI, you don't need to coat the interior and exterior... only one or the other. I recommend interior, so the weather doesn't shorten the life of the coating due to harsh conditions (same as with paint, although Nansulate is more durable than paint).

FYI, the core ingredient is NM-Oxide, which has a K value of .027 (which is VERY good; you didn't look too hard on the site if you didn't find that info).