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re: aluminized mylar window treatment
17 aug 2005
gary wrote:
>>>i'd never give up the daytime view, and putting r10 panels in and out
>>>each night is too much work...
>> how often do you look out at night?
>rarely -- it would be easy to give up the night view.
>how about an insulated wall between the low-mass sunspace with lots
>of south windows, and the living space?
>i'm a bit lost here. could you explain that in more detail.
that way, you can have the window gain during the day (with warm air
circulating between the house and the sunspace) without much window
heat loss at night, when the sunspace gets cold.
this is an architectural issue in how people enjoy views and use space.
we like views, and it's natural to put windows on living spaces that
are warm 24-hours a day, but that wastes energy at night, when views are
less interesting and windows are often covered with shades. so why not
put the windows and views on sunspaces and occupy them during the day and
move back into the 24-hour heated space at night? people rarely do that.
i'm not sure why. it is more complex, with an extra wall. maybe the extra
cost and complexity isn't worth the energy savings, for most people. or
maybe they just don't think about the energy savings.
>my offending big windows face just a touch north of east.
you need to rotate your house.
>...the south exposure is hard to take advantage of --
>the garage takes up half of it...
fertile solar air heater territory...
>...the way the rooms are arranged makes it hard to use the other half
>even if i was willing to do major wall surgery (which i am :-).
good...
>i have made some use of the garage part of the south exposure with this:
http://www.builditsolar.com/projects/spaceheating/garcol.htm
good...
>but, i am hard put to find any way other than active collectors on the
>south roof (which i am thinking seriously about) to use the rest of
>the south exposure.
bad...
>i guess one possibility would be to build a low mass sunspace south
>from the half south wall of the house not used by the garage, but
>getting the heat from the sunspace to where its needed, and providing
>some type of heat storage seem like difficult problems?
warm air rises. fans can help. you might store heat in a low-e massy
ceiling or some fin-tubes under a low-e ceiling in the living space.
nick
here's my plan for a 1-hour lecture at the pa renewable energy festival,
http://www.paenergyfest.com, on 9/23/05:
how to heat houses with sunspaces
houses need several times more heat energy than electrical energy, and
solar heat can be a hundred times cheaper than solar electricity, not
counting valuable floorspace. ohm's law applies to both...
sunspaces with lots of thermal mass cost a lot and collect solar heat
inefficiently. low-mass sunspaces get cold and lose little heat to the
outdoors at night. windows to living spaces lose heat all night and on
cloudy days. how often do we need to look out windows at night?
a sunspace can be a simple air heater, eg polycarbonate "solar siding."
people can use deeper sunspaces, with shading and venting for comfort.
a lean-to greenhouse made with double-curved 1x3s can cost less than
a dollar per square foot.
a small sunspace that collects little heat compared to what a house needs
doesn't need thermal storage. a larger one might store heat in a ceiling,
as in the excellent barra system, virtually unknown in the us.
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