DriTherm® Cavity Slab 32 is the ‘bee’s knees’ for winter hive

By Knauf Insulation UK & Ireland
March 21, 2023

In the run up to Christmas, temperatures around our St Helens manufacturing plant plummeted to an icy -7°C – temperatures that can have a devastating impact on honeybees. With this in mind, Knauf Insulation’s beekeeper-in-residence Brian Seddon has put 100mm DriTherm® Cavity Slab 32 to good use to keep his seven beehives warm over winter. We caught up with Brian to find out more. 

Brian, why is it important to protect bees from the cold? 

Extreme cold and damp weather is dangerous to bees, as I discovered a few years ago when I lost all my hives. Like most beekeepers, I use British Standard National Beehives. They’re a great lightweight design, but the walls are only about 20mm thick, so they aren’t very effective from stopping the heat from inside the hive escaping. This means there’s little protection for the colony from the cold over winter.  

To keep warm, honeybees huddle together and shiver, and to maintain their energy, they eat honey. At low temperatures, the bees use all the energy from the stored honey to keep themselves warm.  

What prompted you to use our DriTherm® Cavity Slab 32? 

While there are winter hive options, they all have disadvantages. For example, WBC Hives have inner and outer walls, but they’re cumbersome and don’t contain any insulation.  

I’d started working with the Knauf Insulation Community Team at St Helens during the summer of 2021 to set up an urban honeybee project at Ravenhead Dam in the grounds of the manufacturing plant. So, last year, when winter was approaching it seemed obvious to explore whether I could use their mineral wool insulation to develop a better, more thermally efficient winter hive. 

DriTherm® Cavity Slab 32 is a glass mineral wool insulation with a thermal conductivity of 0.032 W/mK. I did some calculations and worked out that it would cut the rate of heat loss from the hive from around 4 watts to about 0.25 watts. So, I decided to trial it by insulating three of my hives in Thatto Heath (the Ravenhead ones hadn’t been set up at that time). 

How did you install it? 

I designed and built lightweight winter covers for the hives. These comprise a wood-framed box with louvered outer panels, which creates cavities for the hive roof and walls. Then I filled the wall and roof cavities with the insulation.  

I left the base uninsulated to allow air flow to help prevent condensation, as that can result in mould which creates other issues for the bees. 

How did the trial go? 

It was extremely successful, and all three hives survived the winter despite sub-zero temperatures. I was pleased with how easy the DriTherm® Cavity Slab 32 was to install; it’s flexible and I could cut to the exact size I needed. And because the insulation is lightweight, the hive covers are too, which is a big advantage as beekeepers need to lift the hives to check the bees have enough honey to sustain them until spring. 

As a result, this year, I have built insulated covers for my five new hives which are based in the Ravenhead region. Thanks to DriTherm® Cavity Slab 32, I’m confident that I won’t be losing any colonies to cold this winter – or in the future.