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
>> 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
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
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.