Building an energy-efficient home thanks to Knauf’s Earthwool Cavity Insulation

Thinkinsulation - cavity wall insulation

Its the height of summer and with the Euros, Wimbledon and Olympics all vying for our attention, we are maybe more concerned about the performance of Team GB than the potential problem of heat loss in our homes. But with summer already cooling to autumn and winter soon upon us , its concerning to know that around a third of all heat in an un-insulated home escapes through the walls. With the rising cost of electricity, gas and other fuels this wasted energy is not only bad news for our pocket but for the environment too, as it depletes precious fossil fuel sources and pollutes the atmosphere through unnecessary energy generation.

With this in mind those of you, like me, who are extending their homes need to give careful consideration to the construction of their new property or extension. But where to begin, how should we insulate our homes and what standards should we set out to achieve?

The government recognises this problem and has set minimum standards for insulation, in order to contribute to its target to reduce greenhouse gas emissions by 80 per cent by 2050. Subsequently, it is important to ensure that any alterations undertaken adhere to the latest thermal efficiency standards as outlined by Approved Document L1B of the Building Regulations. These guidelines offer technical advice, with respect to the conservation of fuel and power, to ensure that extensions to existing dwellings meet recommended minimum thermal performance standards.

This is great, but at Easy Green Towers we not only want to keep our friendly Building Inspector happy by meeting the minimum requirements of the Building Regulations, we also plan to use the greenest products wherever possible.

Earthwool Dri Therm

Thankfully this is where the experts at have been able to help. Hearing about our project to extend and improve our home, first explained that the energy performance of a wall is determined by calculating its U-value, which is a measure of how much heat will flow through the wall. The lower the U-value the better, as this indicates a more energy efficient and better insulated wall construction.

The installation of full-fill glass mineral wool insulation into the cavity is instrumental in achieving the target U-value of 0.28 W/m2K and were not only able to recommend but also kindly supplied the latest cavity wall insulation for us to trial, Earthwool Dritherm Cavity Slabs by leading manufacturer Knauf.

Earthwool cavity slab installation

Earthwool DriTherm Cavity Slabs, provide a cost effective solution. They are made from non-combustible glass mineral wool and knit together at the joints of the cavity, preventing air movement and infiltration through or around the insulation, ensuring optimal thermal performance.

Certified by the British Board of Agrèment (BBA), Earthwool DriTherm Cavity Slabs contain a water-repellent silicone additive to prevent the insulation from transmitting water or moisture from the outer to the inner leaf, and are certified for use in all exposure zones.

Earthwool DriTherm Cavity Slabs also boast superior environmental credentials as they are made using recycled glass bottles and manufactured with ECOSE® Technology, a unique formaldehyde-free binder based on rapidly renewable materials instead of petro-based chemicals. Earthwool DriTherm Cavity Slabs have Zero Global Warming Potential, Zero Ozone Depletion Potential, and have an A+ generic BRE Green Guide Rating.

For added confidence, Earthwool DriTherm Cavity Slabs also come with a 50 Year Guarantee, which covers thermal conductivity and water resistance.

Safe in the knowledge we had the correct specification, how did we find actually using the product?

fitting Earthwool cavity slabs

The Earthwool Dritherm Cavity slabs come shrink wrapped in bales, which is great for storing on site since it keeps the insulation nice and dry. Whilst the bales look quite big, they are still light enough to move around by hand. Installation itself is very simple and anyone with basic DIY skills would have no problems. Working in conjunction with our bricklayer, the insulation was fitted between the 2 layers of brickwork as the wall was constructed. Easily cut with a knife, the insulation was very easy to manipulate, particularly when care was needed to ensure the whole cavity was filled and that the slabs were fitted right into corners and window openings to avoid any ‘cold spots’.

It really is as simple as that, no mess and no waste (other than the shrink wrap packaging) and we can already feel the rosy glow from our new cavity walls – even without the roof on!

To summarise, we have been very impressed with’s expert advice and the superior quality and usability of Knauf’s eco-friendly product. Not only is it incredibly easy to install, being manufactured from recycled glass bottles (which is fully recyclable at the end of it’s life), Earthwool is a sustainable product which is kinder on our earth’s resources, plus it’s performance is guaranteed to match the performance of it’s less green competitors at no extra cost.

We’ll be back with more eco-insulation blogs very soon as we tackle the thermal insulation of the ground floor and loft and acoustic installation of the new 1st floor, to hear how we get on with those, stay tuned.

For more information on Earthwool visit or if you need more advice on how to save energy and money in the home, head over  to the very informative site.

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