Where is the warmth in a house?
People are building houses that should keep warm in winter with little heating.
Some parts of the house will stay warmer than other parts. Which parts? How warm?
Answers are not easily found. I hope this temperature record from a house with only personal heating may be useful. This was a time when the house was under extreme stress due to cold weather.
Over a five-day period in winter 2016, I read thermometers frequently at a number of stations around the house. I have selected those stations that form profiles from top to bottom of two wings of the house: the two-storied west wing, and the east wing that is one-storied with a clearstory.
To find how my house differs from yours, see the note below: “Key features of the house”.
Selected thermometer stations
In the West Wing (two-storied)
OUTDOORS, upstairs veranda (+4.7 metres);
Wall upstairs at head height (+4.2 metres);
Wall downstairs at head height (+1.5 metres);
Floor slab surface downstairs (0.0 metres);
Garden subsoil at -0.75 metres.
In the East Wing (single-storied)
Clearstory space at +3.5 metres;
Wall in the hallway at head height (+1.5 metres);
OUTDOORS, in a Gill Screen (+1.5 metres);
Floor slab surface in the en-suite (0.0 metres);
Solid “heat bank” beneath the floor slab (-0.75 metres).
Part I: Average temperature values
In the ground under the floor slab the temperature would be just warm enough for winter comfort. Above the floor slab, the higher you go, the colder it gets.
The graph above plots mean temperature against height above the floor slab. (The mean temperature is the time-average over the five days.)
Comparing east wing, west wing, and outdoors
The single-storied east wing was several degrees warmer at all heights than the two-storied west wing. The east wing has advantages: thermal mass, perimeter insulation in the footings, less shading, and a more compact shape.
The west wing was much too cold for comfort without heating.
Even the west wing was six degrees warmer than the mean outdoor temperatures.
Temperature change with height
At this time, temperatures underground were far warmer than in the air above. The subsoil “heat bank” under the east wing was the only thermometer station to have a mean temperature high enough to reach the human “Adaptive Comfort Zone” (plotted on a graph here).
The surface of the floor slabs was a little cooler than the subsoil, and the ground-floor rooms were cooler still. The upstairs room was even cooler than the room below: it is a thermal failure!
The clearstory space at the top of the east wing hallway was very slightly warmer (on average) than the room below.
Outdoors, the upstairs veranda was warmer than the Gill Screen due to conduction of heat through the wall of the house.
The graph in this post was amended 14/06/2017 to correct three uncalibrated values:
Subsoil (heat bank) was increased by 0.6°.
Subsoil (garden) was decreased by 0.5°.
Gill Screen was decreased by 0.4°.
See Part II
A companion post: “House June warmth profiles: II” will give details of the temperature cycles at different heights.
Key features of the house
This is a high-mass solar-passive house, built in Australian Building Code Zone 4 of hot dry summers and cool winters, as in Tamworth, Mildura and Kalgoorlie. It is stud-framed in cypress-pine on concrete slabs-on-ground with brick perimeter footings. There are internal brick walls for thermal mass. There is reflective foil insulation, and fibreglass batts that add R=2 in the walls and R=3 in the ceiling. Windows are double-glazed, and heavy pelmeted curtains operate on a timer daily.
The main east wing of the house is single-storied. It contains nearly all the brickwork thermal mass and most of the clearstory windows. There is insulation on the inside face of the perimeter footings.
The west wing of the house is two-storied, lacks those features, and is shaded by a large tree. Being tall and narrow, it loses a lot of heat.
There is detailed information with many photos in “My House Page”.