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a house race
12 jun 1996
william r stewart   wrote:
>nick pine wrote:
>> william r stewart   wrote:
>> >nomad29 wrote:
>> >> i've just taken a job in ri and have decided to have a passive solar home
>> >> built.  i'm  looking for a competent architect/solar engineer and builder
>> >> for the project.  any ideas??
>> 
>> it's a good idea to find an engineer to help.

or a physicist...

>> >> also i'm seriously concidering a large massonary heater system for the
>> >> house.  any feelings pro or con??
>> 
>> did you say you wanted a "solar" house? :-)
>
>a home can be passive solar and have a fireplace.

right... a friend of mine has a beautiful, seaworthy deep keel 28' cape dory
sailboat, with a small inboard diesel engine, federally-registered with the
merchant marine as an "oil screw," to reduce taxes and let him clear customs
more easily :-) would you hang an outboard motor on your america's cup boat?
 
>> >i've selected a modular home built by avis america, who participated with
>> >doe...

>> sounds good...

did you say doe? :-)

>> >see solar today sept/oct 1995.
>> 
>> that sort of house (house 1 below, essentially a trombe wall house)
>
>it is not a trombe wall house.

it's essentially a trombe wall house, from a thermal point of view.
direct gain, storage at close to room temp, ritual night insulation...
this has been around since 1881, with variations. it's time to do it better.

>> is fairly expensive and low-performance, as solar houses go, and needs a
>> separate solar water heating system.
 
>you'll have to pardon our local eccentric, nick pine.  his ideas are the only
>ones worth considering.  if you don't believe that, just ask him...
 
norman saunders, pe, howard reichmuth, pe, william shurcliff, phd,
william beckman, phd, john duffie, phd, and steve baer make a lot of
sense to me. i've talked with them all. norman and steve are american
solar energy society passive solar pioneers, and i've spent a few days 
talking over solar closets with each of them in person. i had the good
fortune to drive norman from boston to lewiston, maine in february, for 
the maine solar energy association's sustainable building conference,
where norman was one of the speakers at the session i moderated on
passive heating and cooling techniques. norman is amazing. he's 80 years
old now, and he got into solar heating in 1944. at the moment, he's
helping design solar houses in pennsylvania, california, and the uk.
of course, he's no will stewart :-)

>nick provides a simple (but spaggetti) code exercise that somehow support
>his thesis statements.

your cs degree is showing... :-) how many 3rd graders can understand c?
how many cs graduates are willing to understand simple physics, involving
ashrae-type r-value calculations?

>note below how many temperatures 'magically' end up at 70 f.

this is the magic of temperature control by ventilation in the winter...
in houses with thermal stores with  no  insulation between the heat store
and the living space, like yours, you have to live inside the heat store.
so, during sunny weather, if you want to store heat for more cloudy days,
you have to live in a warmer house. how warm a house can you tolerate?
these houses work better if you are willing to let their indoor temps rise
to a high value in sunny times, and walk around in t-shirts and shorts in 
december. i picked 70 f as the upper limit for this sunny day house temp
limit. perhaps i should have picked 80 f. are you willing to live in a
house that is 80 f in december? the results don't change much.

>the answer is buried in the 'code'.

not all that buried...  compare this to some inscrutable c constructs:

>> 230 if tm1>70 then tm1=70'overheating limit in sunny weather

>>                direct        isolated      isolated      isolated
>>                gain,         gain,         gain and      store
>> day            wall store    wall store    store         temp
>> 
>>  0             36 f          36 f          36 f          36 f
>>  1             51.625        51.625        51.625        51.625
>>  2             62.06671      63.92594      64.2358       64.2358
>>  3             69.04458      70            70            74.41387
>>  4             70            70            70            83.32878
>>  5             70            70            70            91.93831
...

>>  13            70            70            70            151.004
>>  14            70            70            70            157.2953
>> turn off the sun...
>>  15            58.72116      64.11539      70            150.1516
>>  16            51.18385      59.24927      70            143.111
>>  17            46.1469       55.22536      70            136.1719
>>  18            42.78086      51.89789      70            129.3329
>>  19            40.53144      49.14633      70            122.5925
>>  20            39.02822      46.87101      70            115.9493
>>  21            38.02367      44.98949      70            109.402
>>  22            37.35235      43.43362      70            102.9491
>>  23            36.90374      42.14703      70            96.58922
>>  24            36.60394      41.08312      70            90.32111
>>  25            36.4036       40.20335      70            84.14339
>>  26            36.26971      39.47585      70            78.05479
>>  27            36.18024      38.87426      70            72.054
>>  28            36.12045      38.37679      66.13976      66.13976
>>  29            36.08049      37.96542      60.92326      60.92326
>>  30            36.05379      37.62525      56.60962      56.60962
                      ^             ^                          ^
these are simple exponential decays |         so is this ------       
      well-known in heatflow                  but who cares, until it
                                              cools to 70 f?

>> 10 'a house race, among three 8' cube contenders, each having
>> 20 '  r13 walls, one 8'x8' r2 window, and 4096 btu/f of thermal mass.
>
>r13 walls are far below the r24 walls that are in the avis home walls.

i suppose your house will be larger than an 8' cube too. this was just
an example of how the same materials can be arranged well or not so well,
from a solar performance point of view.

>the r2 windows ignore the window shade insulation that would be used.

true. that's house 2 above, if you cripple it slightly more.

>> 30 '  house 1: a direct gain house with thermal mass in the walls.
>> 40 '  house 2: an isolated gain house with thermal mass in the walls.
>> 50 '  house 3: an isolated gain house with isolated thermal mass store.
>> 60 open "hrout" for output as #1
>> 70 print#1,"they're off!"
...

>> 210 e1=24*(tm1-36)*64/rwind+24*(tm1-36)*5*64/rwall
>> 220 tm1=tm1+(sunin-e1)/c'new thermal store temp
>> 230 if tm1>70 then tm1=70'overheating limit in sunny weather^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
>i've never heard of this rule before; where did you come up with this, nick?

that's my guess at how warm a house somebody might tolerate in sunny
winter weather. what's your limit, will? another issue for direct gain
houses is privacy, as kurt smith of avis mentions. or lack thereof, and
the interaction with house temperatures. one can only take off so much
clothing, with all those windows, especially near washington, dc.

>the thermal store can be far above the ambient temperature of the room. 

a few degrees above, for a few minutes... recall the half-hour time constant
for these water walls. we have discussed that before, but you didn't seem
to be listening. you are in a difficult psychological posture. try this:
t(t) = 70 + (80-70)exp(-t/30), where t is in minutes.

>this explains why you don't understand the concept of a masonry heater
>fireplance.

i understand such fireplances, but what do they have to do with solar heating?

>do you think that the thermal store is simply going to stop accepting
>heat input?

is this a metaphysical or a physical question? the heat goes in one side
of those (opaque, window blocking?) water walls and out both sides, almost
immediately, heating the room air. this is similar to a person for whom 
ideas go in one ear and out the other. mark twain said perhaps such a person
should take out his brain and dance on it, to soften it up.
 
>have you no shame?

i tell the truth, as i see it.

cheers,

nick



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