[BLDG-SIM] passive solar, round 2: Energy-10
Lee Elson
lee.elson at jpl.nasa.gov
Fri May 13 16:06:58 PDT 2005
In an earlier email, I wrote:
I'm designing a 3500 sq foot residence at a 5000' desert-like elevation
(Nevada).
The site has good sun exposure and the climate is generally dry. Typical
temperatures in Feb are 20-40 F. The building is mostly oriented
east-west and has
a 2' deep insulated rock floor (for thermal mass) with active air
recirculation.
ICF's will be used as well as tile over concrete (above rock floor) in
south
facing rooms.
I received many very useful responses regarding how to simulate this
building. As a result, I've acquired and tried to master Energy-10 (I
was using eQuest, but that's another story). I've done 2 simulations of
the building where the only difference is that I use either clear double
glazing or double low-e glazing *on the south side*. All other sides use
double low-e glazing. The reason for doing this is that many sources
strongly suggest that using low-e glass on the south side will inhibit
much of the solar gain. The results show that the low-e case requires
about 1/2 the heating as the clear case. Thinking that this might be due
to thermal mass, I increased the thermal mass and that helped reduce the
heating needs of the clear case by about 15%.
My thinking is that for the clear glass case, I'm loosing more heat when
there is no sun than I'm gaining when there is sun, relative to the
low-e case. In reality, this can be helped by covering the windows when
there is no sun, but I don't know how to simulate this in Energy-10. Is
there a way to change the U-value at night?
Any suggestions?
Lee Elson
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