The impact of insulation products on the environment

find out what insulation products are best for both your property and the environment.

There are a lot of claims about the environmental friendliness of different types of insulation products. These claims can have a big influence on what you decide to use in your home, so lets take a closer look.

Glasswool insulation often includes the use of a high percentage of recycled glass cullet, although some virgin sand is required. Phenol formaldehyde binders are commonly used, and formaldehyde emissions can be produced during manufacture at low levels. Boron may also be used as a flame retardant and as a treatment against microbial growth which ensures its longevity.

Glasswool products generally use up a lot of heat energy in the manufacturing process compared to other form of insulation. However, these products can be packaged much more tightly for transport than many other products, making it better for the environment with less shipping emissions transporting it from the factory to your place.

Polymer-based materials, such as polyesters and polystyrenes are made from plastic, some of which is recycled plastic. The amount of heat energy used in the manufacturing process is less than glasswool Insulation, which is an advantage. However, the product cannot be as tightly packaged so it is not possible to transport as much glasswool.

Sheep’s wool insulation, often perceived as being the most environmentally friendly, is derived from sheep – a renewable resource. However, chemicals and grease-laden effluent from the scouring process may adversely impact waterways if good controls are not in place. Sheep’s wool is also often treated with borate to resist pests, fire and mould. In New Zealand sheep’s wool insulation is commonly blended with polyester fibres to reduce slumping in wall cavities. These products can often be up to 70% polyester and 30% sheep’s wool.

Mineral wools are derived from non-renewable sources such as virgin rock and iron ore blast furnace slag which is a waste product from the iron making process. Like Glasswool Insulation, phenol formaldehyde is commonly used to bind the fibres.

Cellulose insulation, which is no longer common in New Zealand, is most commonly derived from recycled paper. It is typically composed of 80% recycled paper and 20% fire retardants, insect resist agents and acrylic binders3. Borates are commonly used as flame retardants and insect resist agents, and can be leached from the paper if it gets wet. The additives in cellulose insulation may make it difficult to recycle at end-of-life.

In summary, all insulation products will have environmental advantages and disadvantages. It is difficult to say which, if any, are more environmentally friendly. Therefore spending 2-3x more on a perceived ‘environmentally friendly product’ may not deliver a lot of benefit. You would be a lot better investing in higher R-Values (thermal rating), where it is known to improve energy efficiency of properties.

Premier Insulation and Goldtex Insulation offer a full range of products and in a good position to be impartial when discussing insulation products in the context of the environmental impact they may have. Contact us now for a free quote.

A guideline to retrofitting insulation

When it comes to retrofitting insulation, it pays to do your homework before you start working on your home.  The costs involved in getting insulation retrofitted into an existing property will vary greatly depending on a number of factors, as listed below.


Competition in the main centers is always likely to be greater therefore it will be possible to negotiate better deals.  Furthermore, the supplier companies will likely have the stock and operations in the main centers, which means the more regionally isolated your property is the more likely you will have to pay a ‘travel/freight’ premium.

Type of Insulation

Minimum R-Values (thermal resistance) for retrofitting homes in NZ
Zone 1 and 2Zone 3
CeilingR 2.9CeilingR 3.3
UnderfloorR 1.3UnderfloorR 1.3

The most common products used in retrofitting homes is glasswool in the ceiling and polyester underfloor.

Quality of Existing Insulation

Many properties may already have some insulation, but will often not meet the minimum requirements.  However, if the existing product is of good quality, you may only need a simple ‘top-up’ product which will be a lot more affordable than replacing the lot.


Sometimes factors like access may add costs, such as ensuring the manholes are big enough to get products into the underfloor or ceiling.  In some cases, getting to hard to reach places may incur an extra cost.

Pricing example for Retrofitting a 100m2 residential property

The following is a typical cost of retrofitting insulation in a residential property in Auckland.  This example assumes there is no existing insulation and that there is good access to ceiling and underfloor.

  • Floor area of house (liveable area, does not include garage)= 100m2.
  • Suspended timber subfloor.
  • Minimum standards only for insulation to meet requirements. Ceiling = R2.9Glasswool, underfloor = R1.5 Polyester.

Supply and Install cost ceiling Supply and install cost underfloor

  • Supply and install cost ceiling – $1,330.00
  • Supply and install cost underfloor – $1,450.00
  • Plus GST – $417.00
  • Total (Including GST) – $3,197.00

Funding options

We have a range of funding options available to you, including Finance Now, adding to your mortgage, or using a council funding scheme (if available in your area).  You will not pay any more than normal prices to use these schemes. More information is available at:

Discounts and other promotions

Do your homework on pricing before you make a final decision.  There are companies that offer customers big discounts if they sign up immediately, but often are just inflating their ‘trade’ price and then offering a ‘discount’ as an incentive to buy now.  Discounted prices offered may be no better than the standard market prices and can sometimes be higher.  Get a competitive price from Premier Insulation to compare against. We’ll suggest the best product options for your property and will give you a clear price to do the job.  Premier can also offer funding options to help you get the insulation installed now and pay later.