Mass floors are 32 inches (0.8 meter) thick inside the insulated envelope. the 5-inch slab with radiant tubes sits on 27 inches of compacted gravel with fines.
this system provides many times the heat storage of the slab alone and is intended as a backup for the space heating.
Conservation was the
the entire exterior of the house is one piece of
r- 28 spray foam with traditional southwestern
stucco. it sticks well to the mass walls, creates a
breathable, waterproof surface that lasts a long
time, plus it creates an airtight barrier.
guiding principal, followed by
use of the smallest needed
amount of energy to meet
the home’s needs.
to avoid freezing within the energy-recovery
ventilator (Erv), the unit is typically paired with
an electric preheater. but to avoid this energy
use, builders ran a 6-inch-diameter pre-heat duct
through the solar-heated mass floor and then to
design is simple and low-tech: We mount a flat
reflector above the solar collector, which is tilted
perpendicular to the average winter sun angle so
as to maximize midwinter gain.
Concentrating the sun’s energy can be a fire
hazard. But, because these are flat reflectors, there
is no concentration or the associated fire hazard.
Our northern New Mexico winters have gotten
cloudier in recent years, requiring an increase
in collection area. In years past, I installed solar
thermal panels at 70 degrees to point at the lower
range of the winter sun, to protect from summer overheating. Now I use the more powerful
55 degrees ( 20 degrees plus latitude), which is
vulnerable to summer overheating. The partial
shadow cast by the overhanging reflector protects from summer overheating, while still supplying enough heat for the domestic hot water.
(More details in the June 8, 2010, issue of Solar@
The system is also designed to trickle some
heat into the radiant floor’s deep zone during
the summer. It may seem as though that would
add heat to the air in the house, but as long as the
floor temperature remains lower than the inside
air temperature, no heat is transferred to the living space. With 270 tons of mass in the floor,
some heat is needed in the summer to maintain
the temperature at about 70° F ( 21° C). The
high-mass floor takes longer to heat than a typical 4-inch slab, so preventing it from overcooling
Industry data reveal that absorbing heat with
a concrete floor to cool a room in summer is ineffective; therefore giving up the cooling effect of
the floor is not an issue.
42 June 2011 SOLAR TODAY solartoday.org
Copyright © 2011 by the American Solar Energy Society Inc. All rights reserved.