Solid Floor & Roof Insulation

[Swarm]

The bees don't seem to care, it's the beekeepers.

 

[oliver90owner]

Think about it just a little bit.

Colder air goes downwards, warmer rises (because of density differences). With the entrance at the bottom of the hive, that air (if warmer, would slowly percolate sideways and rise outside to be replaced by the air with temperature at that level. Otherwise the warm air stays inside the hive - apart from inevitable gas movement by diffusion.

Hives close to the ground are likely to experience colder air at the entrance than those on taller stands (although taller structures may be subject to more wind effects). Bottom line will be that the bottom of the hive, whether solid floor or OMF will be around outside ambient, give or take.

The main difference between solid floors and OMF is any draughts, which affect the bees, and radiated heat from the cluster.

The cluster outer temperature will never drop below about 8 1/2 degrees Celsius - or the outer bees would drop off - so if the bees are well up the comb, there will be little difference.

This is where extra deeps are better, as the cluster can be higher in the comb, so less affected by any air disturbance just within the OMF and will lose less radiated heat because of the comb absorption (unless infrared goes straight through wax) of radiated heat.

At the roof one does not want any warm air leaking out, taking important warmth away from the hive. Hence lots of insulation and no holes. The hive walls will lose about the same amount of heat, dependent on the delta between inside and out, but as the walls are generally separated from the cluster by frames, the losses aresubstantially less than the potential losses through holes in their ceiling and poor insulation.

The worst scenario is being cold and getting cold condensation, from a poorly insulated roof, dripping on the cluster.

Simple really.

 

[Finman]

Hives close to the ground are likely to experience colder air at the entrance than those on taller stands (although taller structures may be subject to more wind effects).

Simple really.

Are you sure that 30 cm makes a practical difference?
.

 

[mintmoth]

Put insulation in roof, block off any roof vents, they are not needed, cover feed hole completely whenever not in use for feeding.

One of my hives is so fussy about draughts through the feed hole of a CB that if I leave a rapid feeder over the hole empty for just a day, they propolise all round the cup part and I have to crack it apart before refilling so they can reach the syrup again.

 

[jenkinsbrynmair]

Are you sure that 30 cm makes a practical difference?
.

According to SWMBO it does

 

[Poly Hive]

Do you not think the bees are trying to tell you something mintmoth?

Listen to the bees? Let the bees tell you??

They hate that hole mate. So do something about it??


PH

 

[Murox]

Are you sure that 30 cm makes a practical difference?
.

Scientifically, 12 cm makes a difference; in the practical world probably not significant at all unless the hive entrance is bathed in cold mists and fog. Cooler, denser, higher pressure air flows TOWARDS warmer air that is less dense and has a lower pressure.

 

[Finman]

Scientifically, 12 cm makes a difference; in the practical world probably not significant at all unless the hive entrance is bathed in cold mists and fog. Cooler, denser, higher pressure air flows TOWARDS warmer air that is less dense and has a lower pressure.

Thanks but! I cannot see any science in that. Science is never that stupid.

 

[Walrus]

From my travels to meet beekeepers all over the place it seems to me that most agree on insulating the roof to prevent condensation dripping down on the cluster. The condensation will be on the side walls & sometimes that can lead to a bit of mould on outside frames. Brother Adam used to remove the outside combs over winter ( they were the oldest blackest ones moved there on purpose) & foundation went in the hives to bring it back up to 10 frames in Spring.

Successful commercial beekeepers use both solid and mesh floors. In America it seems to be mostly solid floors but there are quite a few using them in the UK too. I changed from OMF to solid after trying both; my bees did better on solid floor, but I'm in quite a windy location. At least with OMF you can slide in the board to prevent drafts if needed.

With respect to upper ventilation holes there is a stark difference between those with very long cold Winters and the rest of us. It seems that a ventilation hole upstairs is needed in long cold winters - based on what beekeepers do, some of whom are extremely wise so I don't doubt that they know what works for them.

 

[Murox]

Thanks but! I cannot see any science in that. Science is never that stupid.

I wasn't going to offer a pile of scientific stuff, just making the point that altitude matters. Air has mass, there is more mass pressing down onto a single point at sea-level than on a single point on the summit of Everest. The difference in how much air is pressing down on a point also influences how dense the air is in a particular location, and then there is temperature as well. Air density decreases with increasing altitude, as does air pressure. It also changes with variations in temperature or humidity, this all influences how air masses move....at any single point/location in the air, the air pressure pressing on that point is THE SAME from all directions: the sides, the top, the bottom. But, if you move just a little up, at the new point/location, while the air pressure presses identically from all sides, the actual amount of air pressure is just a bit less than it was down below.
Cooler, denser, higher pressure air flows TOWARDS warmer air that is less dense and has a lower pressure.

 

[user 6228]

Think about it just a little bit.

Colder air goes downwards, warmer rises (because of density differences). With the entrance at the bottom of the hive, that air (if warmer, would slowly percolate sideways and rise outside to be replaced by the air with temperature at that level. Otherwise the warm air stays inside the hive - apart from inevitable gas movement by diffusion.

Hives close to the ground are likely to experience colder air at the entrance than those on taller stands (although taller structures may be subject to more wind effects). Bottom line will be that the bottom of the hive, whether solid floor or OMF will be around outside ambient, give or take.

The main difference between solid floors and OMF is any draughts, which affect the bees, and radiated heat from the cluster.

The cluster outer temperature will never drop below about 8 1/2 degrees Celsius - or the outer bees would drop off - so if the bees are well up the comb, there will be little difference.

This is where extra deeps are better, as the cluster can be higher in the comb, so less affected by any air disturbance just within the OMF and will lose less radiated heat because of the comb absorption (unless infrared goes straight through wax) of radiated heat.

At the roof one does not want any warm air leaking out, taking important warmth away from the hive. Hence lots of insulation and no holes. The hive walls will lose about the same amount of heat, dependent on the delta between inside and out, but as the walls are generally separated from the cluster by frames, the losses aresubstantially less than the potential losses through holes in their ceiling and poor insulation.

The worst scenario is being cold and getting cold condensation, from a poorly insulated roof, dripping on the cluster.

Simple really.

I object to the last line seriously the above is a very good description -

if you "scratch any deeper" it gets complicated - very complicated quickly

: Note: bees wax is transparent to infrared.and the cells vary from really good insulator to relatively good conductor depending on contents or lack of them.- just some of the complications.

 

[Apiarisnt]

: Note: bees wax is transparent to infrared..

Not sure that radiation is really relevant in this situation, remembering Stefan–Boltzmann law... Would be interested to hear your views, Derek.

 

[oliver90owner]

All bodies emit radiation if above 0K. A cluster is at, or above 280K but not a perfect black body. The radiated heat is certainly a minor element, but not one that DM would ignore in his calculations.

 

[user 6228]

All bodies emit radiation if above 0K. A cluster is at, or above 280K but not a perfect black body. The radiated heat is certainly a minor element, but not one that DM would ignore in his calculations.

if the ground is -10C and the bees are +34C then a rough number on the radiation loss through the mesh with using b(T1^4-T0^4) (temperatures in K)
~3Watts .
if the bees are clustered then both the surface temp (10C) and area radiating are lower
which makes takes it down to 1W. (which why the snow melts under the hives?)
Not insignificant if the cluster is only generating 7W
but the losses are actually quite a bit smaller due to complex things like viewfactors and emmissivities... radiation calcs get very very very complicated which is no doubt why they are often ommitted.
Look at the amazon book "Look Inside" of "Thermal radiation heat transfer" by John R Howell et al. to get a taste of it.

 

[gbee]

All bodies emit radiation if above 0K. A cluster is at, or above 280K but not a perfect black body. The radiated heat is certainly a minor element, but not one that DM would ignore in his calculations.

I will be doing the OMF tray half in approach for this my first year. However, I have made a wooden tray not using the metal one for this precise reason. Having a metal thermal heat sink under the hive just seems insane. Didn’t read this anywhere it just made sense.

 

[madasafish]

I will be doing the OMF tray half in approach for this my first year. However, I have made a wooden tray not using the metal one for this precise reason. Having a metal thermal heat sink under the hive just seems insane. Didn’t read this anywhere it just made sense.

I leave OMF trays in place in winter times to prevent draughts. A metal floor for a hive - as you describe - is plain nuts - and expensive..

 

[MuswellMetro]

I leave OMF trays in place in winter times to prevent draughts. A metal floor for a hive - as you describe - is plain nuts - and expensive..

we may need metal trays as oil baths for Small hive beetle traps under SHB type OMFs ( slightly larger mesh holes than a varroa mesh floor)

 

[user 6228]

a metal tray below a still air gap of 50mm or more under the floor is going to have very little effect on heat loss. still air heated from above is a very good insulator so long as you dont get air movement

 

[madasafish]

a metal tray below a still air gap of 50mm or more under the floor is going to have very little effect on heat loss. still air heated from above is a very good insulator so long as you dont get air movement

Given the winter gales we get, still air is a winter luxury

 

[Apiarisnt]

.... losses are actually quite a bit smaller due to complex things like viewfactors and emmissivities... radiation calcs get very very very complicated which is no doubt why they are often ommitted...

Should we expect BIBBA to admit that the emissivity of AMM is greater than that of other breeds, as more closely resembling black body radiation?...