# Any thermal insulation calculators?

I want to either make a new dog house or at least improve the current one, which is in a pretty bad shape, since the dog never actually used it and we didn’t take care of it for years.

I read that insulation makes a gigantic difference, especially in winter. The problem is that the current dog house doesn’t have any insulation at all, just wood from which it is made of, so I want to find a insulation calculator to see the difference between a typical insulated dog house and the one I currently have.

If it is easier, can someone just explain me how heat loss is calculated and what are imperial and what metric units I should know to do the calculations?

You need the U-Value (Thermal Transmittance)

Thermal transmittance, commonly known as the U-value, is a measure of the rate of heat loss of a building component. The U-value is the sum of the combined thermal resistances of all the elements in a construction, including surfaces, air spaces, and the effects of any thermal bridges, air gaps and fixings.

The U-value is expressed in watts per square metre, per degree kelvin, or W/m2K.

There is a table of common materials here that might help. Nothing I could find for dog houses, but any commercial product should be able to quote a U-value.

http://www.diydata.com/information/u_values/u_values.php

Just to be clear - lower is better.

Before you get too crazy with insulating the dog house, umm, how does the door work? The dog houses I have seen just have an opening…

Alternately, you can use the R-value (thermal resistance) where R=1/U …

Whatever you do, insulate the floor. The ground is a HUGE heat sink, and insulating from that is important.

Going to the trouble of calculating it is probably a waste of time. 2" rigid polyurethane foam has generally the best R-value per inch (5, for a total of 10), is relatively durable, easy to cut and shape, and is obtainable from just about any home improvement store. I agree with the other commenters that the door and the floor are critical, because drafts and direct contact with cold surfaces will negate any benefit from insulating the “shell” of the doghouse.

This is true for framed floors, where there’s an air space between the ground and the floor (which should be vented to the outside) … the freezing air fills in and cools the wood floor …

However … if it’s a concrete slab floor or just bare dirt … then the ground becomes a heat source in winter and a heat sink in summer … it’s not much of an effect but I’m assuming your SO isn’t chasing you out there during blizzards …

ETA: The most important consideration is making the dog house as air tight as possible … insulation only inhibits conduction of heat … it’s the convection of heat that matters most and air is one of the best convectors around … once you seal all the drafts such a small space may be easily heated with just body heat …

If that were true then insulation wouldn’t be required in basements and under slabs. At the very least, the ground temperature is still too cold in the winter, though it can be pleasant in the summer. Either way, it’s not so much about heat transferring up and down, but side to side. The dirt or especially a concrete floor will quickly get cold from conduction under the walls of the building. Most building codes require a minimum of 2" of rigid foam going at least two feet down and two feet in from the perimeter to stop this. In something as small as a doghouse, creating a protective shell of insulation inside should suffice. It’s not like the thing is on poured concrete foundations or anything like that.

I’ve never installed insulation under monolithic pours … I’ve seen it installed on the outside of the stem walls but never under the slab … perhaps it’s a local thing …

And don’t make the doghouse too large for the size of the dog, as this will make it too large for the dog’s body to heat.

Huh? How on earth does that work? I’ve lived on ground floors (over uninsulated Basements) too often to not know how cold the damn floor gets through concrete. Have you ever felt how cold a Piece of rock lying directly on the ground gets in the winter?

Maybe it’s a northern vs southern climate kind of situation. The “mean earth temperature” which is the temperature several feet underground is not constant geographically. It varies from the low 40s in upper Minnesota to nearly 80 degrees in southern Florida. It roughly correlates with the mean air temperature over the year. So yeah, an uninsulated basement in Montana, Wisconsin, or upstate New York is going to be very cold, whereas one in southern California, Texas, or Georgia is going to be pleasantly cool, but not enough to get free air conditioning from. Plus a concrete floor, which is almost always at the lowest point of a house, and which also tends to be in the most damp part of the house, is not going to be warm all by itself unless you’re a Brit and think 50 degrees is balmy

Since the OP was talking about insulation for winter, I assumed he was living in northern climate. Insulation against heat in hot climate is also possible (hence some People build their homes half into the earth, like Tatooine), but requires Delta T in Addition to U: how many hours until the temperature Change gets through the insulation material.

And yes, I know about earth heating Systems: but that’s achieved with many meters of copper coil that run several meters deep (and a heat exchanger) to collect small changes over a wide area. That’s different from a tiny slab of concrete, on which the dog is lying directly - that will only leach heat from the dog.

Okay, we seem to be talking about different things here, then. If you pour a wide slab of concrete (no cellar) as foundation for a house, you don’t put heat insulation under it, only a Special foil against water if necessary. But you put some insulation on the top before you build the floor (not polystyrene for heavy Walking on).

In the case of a doghouse with an existing concrete slab, and no other floor, if the dog is lying directly on the concrete, its Body heat would leeach away. So you would put the insulation on top, and then let the dog lie on it. But it would have either be sturdy, or covered by Wood, so the dog doesn’t damage it.