Project: Siegel House Case Study
Conclusions and Summary
The Siegel House
The main problems the Siegels had with their house seem to have been caused by the
thermosiphon-loop design. It does not seem to have worked well in this application.
(Perhaps that's why the first owners left after only 2 years.) The Siegels had significant
problems with its performance, and they modified their house substantially to correct for
it. They added central heating and air-conditioning, and blocked the ducts underneath the
living room in an effort to keep their house comfortable. As shown in our investigation,
we believe that because the thermosiphon loop does not work, the sunspace overheats and
the thermal mass provides no benefit.
The Siegels also seem to some problems stemming from the design of other parts of the
house. Mainly, they want to use their sunspace as a part of their everyday living area,
but the space by its nature is not suited for that. It's clear from discussions with the
Siegels, and they way the space is furnished, that they would like to spend much more time
there than they are able to now. But, sunspaces are swing spaces which get much hotter and
colder than is comfortable because of how much glazing they contain. We showed that the
concrete slab helps a little to moderate the temperature swings in the space, but the
radiant temperature extremes counteract the slab influence to make the space
uncomfortable. The Siegels are considering a remodel to make the sunspace more usable.
Also, the Siegels have to deal with the stack effect created in their two-story living
room. The open space there provides a great room for relaxing or dining, but it comes at a
price. The temperature at ground level can sometimes be 10 degrees cooler than it is at
the top of the room, and heating the room for comfort at ground level probably requires
more energy than a similar sized room that was only one story.
Though the Siegels had some real problems with the physical performance of their house,
they are nonetheless quite happy with both it and Village Homes. Their love of the house,
and commitment to the ideas behind Village Homes were pervasive in our discussions with
them. They particularly enjoy the community feeling generated by the subdivision's
Through analyzing the data we obtained in this investigation, we began to wonder about the
original design of the house. Certainly river rock was chosen for thermal mass because it
has a smooth surface which would reduce the resistance to air passing over it through the
tubes. Was it smooth enough, though? Would air move through it forced only by the pressure
difference created in the sunspace? Based on the anecdotal evidence of the Siegel house
pre-modification, there was not enough pressure to move the air effectively. Some small
fans would have possibly provided adequate airflow and improved the performance of the
system. This approach may not have been used by the original designers because of a taboo
against "hybrid" systems in the late '70s, but If small fans would have helped,
consider the cost savings of those fans versus central heating and air-conditioning.
We learned a lot about performing a field investigation through performing one ourselves.
We did many things wrong that we'll try to correct next time, but we'd like to point out
one thing we believe we did right to help anyone else who is contemplating doing a study
like this one.
Even before we looked at any data or made any graphs, having only spoken with the Siegels
and inspected their house, we made some fascinating discoveries. These discoveries
eventually influenced the hypotheses we formed and established the basis for our
understanding of the house. We strongly recommend taking some time at the beginning of a
project to do an exploratory visit of the site. A visit before any hypotheses are decided
can open new lines of thinking and help focus an investigation. It certainly did ours.
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