Further Questions

Any investigation of this sort seems to create more questions than it answers. Here are a few ideas about which we wish we knew more.

A more in-depth investigation of thermal mass in the Siegel House

For thermal mass to be effective, a significant temperature difference must exist between the mass and the space it is meant to influence. This temperature difference can be established in two ways. First, in schemes like the thermal-siphon loop design, the mass can be heated above the temperature of the space to create a heat flow from the mass to the space. This condition is clearly not met due to the blocked ducts in the Siegel House.

Secondly, if there is no direct energy source, thermal mass can still be effective if the temperature of a space "swings" enough. If at some point in the day, the temperature of the space is higher than the mass, heat will flow from the space to the mass, cooling the space. If at another point in the day the mass is warmer than the space, heat will flow from the mass to the space, heating the space.With larger differences in temperature, the effect becomes more significant. With only small difference in temperature, the effect is hardly noticeable. The installation of central heating and cooling to the Siegel House works against this effect. Central heating or cooling controlled by a thermostat maintains a space at a constant temperature through most of the day. If a night-time setback is used, then the thermal mass may have a detrimental effect. The reason is that if a space is heated all day, some of that heat will transfer into the thermal mass requiring extra energy to heat the space adequately. If the space is allowed to cool down at night when no one is using it, it is then that the thermal mass will release heat to the room, right when the occupants are not there to use it.

It was beyond the scope of our investigation, but an interesting hypothesis to test in this house would be that the thermal mass has a detrimental effect on energy use in the house.

An estimate of the Energy Efficiency of the Siegel House

Try as we might, we were unable to get the utility bills for the Siegel House, so we really don't have a very good idea of whether or not this is a very energy efficient house. Some research into the utility data could go a long way toward answering this question. Energy use data could be compared to houses of similar size to get a feel for how good this house is.

Recommendation for Remodel

The Siegels expressed their desire to make the sunspace a more useable part of their house. This quick study identified some of the many reasons why the sunspace is currently not a very comfortable place to be for large parts of the day. Tackling this problem of how to make the space more useable would be a great way to come to grips with the many building performance issues at work in the Siegel House.

Comments to author: vitalsigns@
ced.berkeley.edu

All contents copyright (C) 1998. Vital Signs Project. All rights reserved.

Created: 04/23/96
Revised: 09/09/02

http://www-archfp.ced.berkeley.edu/vitalsigns/workup/siegel_house/sgl_more.html