Heat-sinking basements/slabs

I was more than dismayed to learn that a local builder, having lost its accreditation as a Built Green builder, was guiding the owners of a multi-family residence currently under construction toward non-sustainable energy ideas. It was bad enough that the manager of this project was not interested in adding solar hot water to the system, he wasn't even willing to build in the copper pipes to enable such in the future. This is typical of most builders today, and it is sad.

This week I learned that this same company had neglected to add insulation under the slab of the building, including the portion that was to have had in-floor heating. This is against current building codes.

Why? Because even in this mild climate (relative to the rest of Canada at least) the ground underneath the slabs or basements of our buildings is less than 15 degrees C. The ground does insulate somewhat. But the earth is a heat sink, one that continuously grabs heat energy from our uninsulated basements and slabs. While this heat loss is not as great as in uninsulated attics or the windows of most homes, it does make a real difference to the heating bills, and especially the comfort of its occupants.

At one time I thought, as do most people, that heat rises. This is true of convective heat energy. This is why upper floors of buildings are often warmer than are the lower floors.

However, most energy movement in homes is through radiant heat transfer. Sunlight is the best known source of radiant heat. Similarly, radiant heat moves in all directions, and particularly moves toward cold surfaces.

As a result a cold floor continually sucks heat energy out of that living space. Uninsulated floors cost us a lot of energy.

What a huge difference it made to my house when I insulated the basement floor, even with only R-10 insulation.

I can only hope that builders and architects soon catch up to this truth.

All of us will benefit.