Civil Engineering Reference
In-Depth Information
reservations regarding this. My own two-storey straw bale house in Heathcote, Victoria,
with its concrete floor and slate tiles downstairs is terrific in summer when the floor is
cool, contributing to the low temperatures in the house on the hottest days, but it is
equally as cool in winter. Had we taken advantage of the warmth from the northern
winter sun, the cold floor problem would have been significantly reduced but this was not
to be.
Our property has views over the McIvor Ranges to the south so we sacrificed the
passive solar heat to take advantage of the views to the south. Our floor is quite cool, a
direct consequence of the concrete sitting on the cool ground. To some degree, had foam
insulation been installed around, if not beneath, the slab it would have reduced the
cooling effect of the ground beneath the slab, but the mass of the floor is still significant
in its own right.
Concrete floors, passive solar heating and thermal mass
If you have a large mass of material that is cool, such as a concrete floor, and you want to
heat it, you must displace the coolness with the warmth. To achieve a neutral temperature
takes a huge amount of energy. However, timber floors with appropriate insulation are
more likely to gain a neutral temperature with much less heat generation as the heat is
contained within the cocoon of the room without having to convert a cold mass first. The
benefits of thermal mass can work against you.
The surface of the concrete slab was once viewed as a material to be covered with
carpet or tiles of some sort but this is changing. I currently have a client building a house
in one of Melbourne's outer suburbs using straw bale on a concrete slab. The surface of
the slab has been ground back to expose the aggregate of the concrete and to give a very
flat and smooth surface. They have then stained the concrete and sealed it. The effect is
quite dramatic.
