The natural design of wool fibre allows it to 'breathe' by actively absorbing and releasing moisture in the air. This is a huge benefit for home insulation, as it means the air inside is conditioned to be drier, as well as warmer in cold weather and cooler in hot weather.



Wool fibres are hygroscopic –ᅠthat means wool is able to absorb and release moisture vapour in the air. It is the only fibre with this property used for insulation in New Zealand.


As temperature becomes cooler, wool absorbs moisture from the air. As moisture is absorbed, energy is released in the form of heat ~ helping offset the drop in air temperature.  As the air around wool fibre is heated, wool releases moisture from within the fibre as vapour, absorbing energy in return ~ which has a cooling effect.


The net result is Terra Lana wool insulation can act like a thermal mass, opposing the change in temperature, creating a more comfortable living environment.  Brilliant!


TYPICAL NIGHT CYCLE (cooling external temperature)

How wool breathes as insulation, warming diagram showing moisture absorbed from room and heat radiated back

Moisture in the air is absorbed by wool, releasing energy to inhibit the cooling process.



How wool breathes as insulation, cooling diagram showing moisture released from wool and heat absorbed, cooling room

Moisture is released as vapour out of the wool in exchange for heat energy, helping to cool the room.


The result is a drier, warmer home in cold weather and a cooler home in hot weather, with more even temperature throughout.


This phenomena is the reason why sheep can survive in extremely hot and cold environments.  The fleece evens out the peaks so that the body of the sheep stays comfortable.



Within specially designed construction systems that include vapour permeable internal linings and building wraps with ventilated building cavities,  Terra Lana can reduce moisture and condensation, making the air drier and warmer by egressing water out of the home through the moisture wicking wool insulation.



Drier air is much easier, quicker and cheaper to heat and feels more comfortable. It’s healthier too, as dampness can cause mould and mildew that is otherwise a threat to both your health and your house.



As Terra Lana 'breathes' the wool fibre actually removes toxins from the air around it!

Sick building syndrome is a well documented illness caused by toxins emitted from building materials and home furnishings (such as formaldehyde) and from moulds and mildew. Terra Lana works against that for you as it absorbs airborne toxins, locking them away in its cellular structure. Amazing.



Terra Lana will not only enhance your home by making it warmer longer and easier to heat, but more healthy too. When tomorrow finally comes, you’ll appreciate how you’ve saved on energy, on health, home maintenance, not having to re-insulate, and on environmental impact.

We have heard it so many times before “once you have insulated with wool you will never look back."


Wrap your home in the superior natural warmth of Terra Lana Wool Blend Insulation ~ it’s the natural choice for your home, family and future.




To enhance the breathability of Terra Lana wool insulation, we recommend using adjacent building materials with high vapour permeability. To create a truly breathable, warm and healthy living environment, free of nasty chemicals found in many common building materials, you will need to use a breathable construction system—where the inner and outer linings are breathable or ventilated.





Wool is an incredible natural technology.  The structure of the fibre is a complex and ingenious solution for not only insulating, but also regulating temperature.  It's designed to keep sheep comfortable, so they are warmer and drier in harsh winter conditions, but also cooler in the heat of summer.


The process of insulating and 'breathing' with moisture and heat transfer is enabled by various aspects of the fibre construction. Within the fibres, strands of microfibres make up a hollow membrane complex called medula. These enables the fibre to trap insulative air and also to absorb and adsorb moisture.


Around the outside scales give rigidity but allow air and moisture to be absorbed.  The scales also act as hooks, holding the fibres in place against each other so that the fleece (or insulation blanket in our case) holds it's loft – which maintains it's insulative properties.


Back within, the compostion of the strands create a strong, durable natural 'crimp' to the fibres – a waviness, that give the wool it's loft as the fibres push apart from each other trapping pockets of still air between them as a thermal barrier.


wool fibre construction cross section, microscope imagewool structure diagram



© Terra Lana Products Ltd 2014 - 2017