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The Advantages of Wood Fibre Insulation

Wood Fibre: it’s all in the trees…

Wood Fibre insulation is a fairly recent addition to the EWI Pro insulation catalogue, offering many advantages for end-users. Today’s blog is going to be looking at a few of the many reasons why you would want to insulate your home using the most natural of all insulation materials: Wood Fibre. 

Looking for a more general idea of how external wall insulation can benefit you and your home? Check out our dedicated blog here.

Wood Fibre is Eco Friendly

One of the main advantages of Wood Fibre insulation is how environmentally friendly it is. We source our Wood Fibre insulation from a company called Pavatex, who aim to ensure that their Wood Fibre production process is as eco-friendly as possible. Pavatex are sustainable and environmentally conscious at every turn, creating their Diffutherm insulation boards from waste shavings created by local sawmills that use wood from sustainable forests. Indeed, Pavatex claim not to use ‘any old wood’ for their eco friendly insulation, a statement that is further emphasised by their prestigious NaturePlus certification.

Wood Fibre offsets an impressive 1.6 tonnes of carbon for every ton of material. From the environmentally conscious timber sourcing and manufacturing process, to the actual purpose of the product (reducing energy consumption in homes), Pavatex have done everything in their power to make their Wood Fibre the most eco-friendly it can possibly be. It’s also 100% recyclable and compostable, so at the end of its long lifespan the Wood Fibre can be safely disposed of in a non-harmful way.

Wood Fibre is Breathable

Wood Fibre insulation is naturally vapour permeable. This means that water vapour can travel through the material from the inside to escape on the outside, an essential asset for most buildings in order to prevent damp and structural decay. This is an essential advantage of using Wood Fibre insulation when it comes to older homes. Popularly used with a highly breathable silicone render, or even a traditional lime render, Wood Fibre insulation systems offer a high performance solution for even the oldest of the UK housing stock.

Wood Fibre has a low thermal conductivity

Going back to basic science, wood is a poor thermal conductor and therefore has excellent insulating capabilities. In terms of U-values, a 200mm thick board of Wood Fibre attached to a 215mm thick solid brick wall can bring the U-value of the wall down to new-build standards – 0.18w/m2k.

Wood Fibre is Fire Safe

Fire safety for cladding materials is understandably a large concern for many homeowners since the Grenfell tragedy, however Wood Fibre insulation is rated a Class E combustible material. This is because rather than encouraging the flames to grow, the timber typically chars which in turn slows down the spread of fire.

Wood Fibre insulation offers a tight thermal envelope and improved indoor air quality

Another advantage of Wood Fibre insulation is that because external wall insulation is secured to the exterior of a property, the thermal envelope is much more complete than with internal insulation as there are practically no gaps in the insulation. This leaves no room (literally) for thermal bridges, which means that the overall effectiveness of the insulation is much higher. What makes Wood Fibre unique is that it’s incredibly easy to install because it is tongue and grooved, meaning the boards slot together seamlessly so gaps between boards are minimised.

As well as this, because Wood Fibre insulation is such a clean material, it does not release any kind of harmful chemicals and its insulating capabilities prevents harmful emissions from entering the property through the building fabric. Indoor air quality is therefore much higher with Wood Fibre insulation.

Wood Fibre Provides Sun Protection on Lightweight Buildings

This advantage of Wood Fibre insulation goes hand in hand with its abilities to prevent heat loss. Wood Fibre insulation keeps buildings significantly cooler during hot summer days where solar gain is at a maximum. This is because it has the highest thermal mass properties of all insulation materials; this means that Wood Fibre can absorb and retain heat, slowing down the rate at which it enters the interior space. This is ideal for lightweight building structures, such as timber and steel frame, where protection against solar gain is at a minimum.

Not only does this reduce energy bills by minimising the need for air conditioning during the summer months, it dramatically improves the thermal comfort of the building, improving lifestyle and wellbeing.

So there you have it! Wood Fibre is a remarkable insulation material that can offer a building many of its numerous advantages. We’ve previously written a blog all about our Wood Fibre insulation so for more information check that out, or if you’re looking to compare Wood Fibre with our other insulation materials then have a read of our blog post ‘the best type of insulation for EWI?’.

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building regulations and U-values, EWI, external wall insulation and U values

External Insulation for Passive Houses?

What is a Passive House?

Passive Houses and external wall insulation are two hot topics within the energy efficiency and insulation industries. Passive House is a construction concept that originally began in Germany; initially coined ‘passivhaus,’ it is generally known as an energy efficient, environmentally friendly house that practically requires no heating. The building is constructed in such a way that it is tightly sealed in a thermal envelope which allows very little heat to escape, so that essentially a room can be warmed simply by light from the sun, body heat or the heat from small electrical appliances. 

There are three things that a house needs to achieve before it can be considered a Passive House:

  • A Passive House needs to have primary energy demands (such as warm water, heating, house appliances) lower than 120 kWh/m2a
  • A Passive House needs to have heating demands lower than 15 kWh per square meter annually.
  • A Passive House must pass a pressure test and the pressure must be limited to 50 Pascals with the pressure differential not exceeding 0.6 times a room’s volume per hour.

A Passive House has a high level of insulation. That includes the doors, windows (triple glazed), walls, floors and roof. However, as we know, houses need proper ventilation – therefore Passive Houses also require a mechanical ventilation system.

Excellent indoor air quality is a characteristic that Passive Houses possess, and this is achieved through the mechanical ventilator exchanging the air from inside with the air from outside. These are great for being energy efficient, because during the process of heat exchange the ventilators can transfer the fresh air into the room at the same time as heating up/cooling down the fresh air. This means that Passive Houses are able to exist without the frequent or constant use of conventional heating systems, many only have one radiator in the bathroom for drying off towels.

External Wall Insulation on Passive Houses

So, as previously mentioned, Passive Houses require an outstanding amount of insulation; typically a Passive House wall will have a U-value of 0.15m/m2k. Luckily, external wall insulation would do the job perfectly if you get it at the right thickness. EPS, Mineral Wool and Wood Fibre have low enough U-values to be able to obtain the required level of insulation for a passive house.

However, the insulation needs to be totally sealed against thermal bridging– which means absolutely no gaps. This is because gaps in the insulation break the thermal envelope and, especially in highly insulated houses, reduce the effectiveness of the insulation. Thermal Bridging can cause damp and condensation – which can be far more detrimental to a passive house than a regular house.

Which EWI System is Best for a Passive House?

To achieve Passive House U-values on a 215mm solid brick wall, 270mm of Mineral Wool would be required. Mineral Wool is highly breathable so it’s great for a Passive House construction where ventilation and air quality are key in order to prevent damp. Due to the fact that Mineral Wool is made of a renewable material (volcanic rock), it’s also in keeping with the ethos of the Passive House. Rockwool is made by spinning volcanic rock in a furnace at a high temperature to create a cotton candy-like texture, and then it’s compressed into dense, flat insulation boards. Rock is not a very good heat conductor, and the fibres from the spun rock provide air pockets, which is what makes it a great insulation material.

In keeping with the Passive House rules, the EWI-225 Premium Adhesive, designed for use in Rockwool systems, is also ideal because it is breathable, strong and waterproof.

To finish off the system, for a Passive House you will want to use a Silicone Render. Again, this works really well in conjunction with the Rockwool system because of its breathability. Silicone Render is hydrophobic (water repelling) so moisture will essentially bounce off its surface, safeguarding the system against damp.

Wood Fibre Insulation for Passive Houses

Our most environmentally friendly insulation material is our Wood Fibre insulation, which we source from Pavatex. To achieve Passive House U-values with Wood Fibre on a 215mm solid brick wall, you would need 240mm of insulation. Wood Fibre is a highly versatile insulation material, offering excellent thermal performance. Our Wood Fibre insulation is completely recyclable and holds the prestigious title of being NaturePlus certified. The fact that this insulation is so highly renewable and environmentally friendly means that really it’s ideal for Passive Houses where environmental consciousness is at the forefront of the building design. Passive Houses also require a high level of breathability, and Wood Fibre is the most recommended insulation material to achieve this.

Building a Passive House is a highly technical procedure, and external wall insulation could definitely play a part in helping to mimic the Passive House standards. Our sales team are experts on all of our products and will be able to give you any technical advice about their technical specifications and usage. Feel free to contact us for any questions regarding our materials or get yourself a free materials quote using our calculator!