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re: 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??
 
>> >see solar today sept/oct 1995.

>> that sort of house (house 1 below, essentially a trombe wall house)
>> is fairly expensive and low-performance, as solar houses go, and needs a
>> separate solar water heating system.
 
>r13 walls are far below the r24 walls that are in the avis home walls.

ok. let's change them all to r24.

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, if you cripple it slightly more.

>> 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?

>what's your limit, will?

let's use 80 f as a house upper temp limit, disguised below as:

205 tu=80'upper temp limit for wall store houses (f)

john d. muccigrosso  wrote:
>wstewart@patriot.net wrote:

>| nick provides a simple (but spaggetti) code exercise that somehow support
>| his thesis statements.  note below how many temperatures 'magically' end 
>| up at 70 f.  the answer is buried in the 'code'.
>| 
>| >                direct        isolated      isolated      isolated
>| >                gain,         gain,         gain and      store
>| > day            wall store    wall store    store         temp
>
>hmmm, seems to me that the first 3 columns of temps are air temp, or at
>least living quarters temp including walls and stuff. the 70 degree limit
>would then be regulated by the homeowner who opens a window or closes a
>vent (or has some automatic (magic?) mechanism do this) so that the temp
>doesn't exceed 70.

right. or 80 f now, as below. btw, a nice way to do winter ventilation
for a house might be to move open a hinged piece of foil-faced foamboard
with a $50 honeywell damper actuator that uses 2 watts when it is moving,
and 0 watts when in a fixed position, connected to a cooling thermostat.
a less accurate and leakier way might be to use an automatic foundation vent
with some aluminum louvers that move with a bimetallic spring, such as
leslie-locke's fv-1b, which home depot sells for $11.83. drill a hole in
the aluminum bracket covering the spiral spring and adjust the spring mount
with a screwdriver so the vent is open at 80 f, and mount it inside-out,
so the spring is exposed to house air.

>if the house gets above 70, that would be nice for those who like it hot,
>i guess, and would make the house cool down to an unacceptable temp more
>slowly, but probably wouldn't be desirable for most people.

agreed. here's the race again, with some nrel numbers for providence, ri...

they're off!

               direct        isolated      isolated     isolated
               gain, wall    gain, wall    gain and     store
day            store         store         store        temp
 
 0             33.8 f        33.8 f        33.8 f        33.8 f
 1             44.7025       44.7025       44.7025       44.7025 
 2   house 1   53.4434       54.97771      55.51239      55.51239 
 3   is a      59.8625       63.8481       65.32996      65.32996 
 4             64.57653      71.50574      70            74.24631 
 5   s         68.03838      78.11644      70 house 3    82.60956 
 6   l         70.58069      80            70 is always  90.72779 
 7   o         72.4477       80 the        70 the same.  98.60819 
 8   w         73.81877      80 ritual     70 a good     106.2577 
 9             74.82566      80 thermal    70 house for  113.6831 
 10  starter.  75.5651       80 curtains   70 reptiles?  120.891 
 11            76.10812      80 help       70            127.8877 
 12            76.5069       80 house      70            134.6794 
 13            76.79975      80 2.         70            141.2722 
 14            77.01482      80            70            147.6718 

house 1 one never quite makes it to 80 f, in 2 weeks of average december
weather. i would say house 2 is too hot, but chacun a son chaleur...
btw, these are max temps for houses 1 and 2. they will be cooler at night,
vs house 3, which could be cooler at night, if it had a setback thermostat.

house 2 now has a fairly respectable rc time constant of 256 hours, and its
performance is not bad... house 1 is much poorer, with about 45 hours.
will's avis house might be about 53 hours, including the water walls,
with all the curtains drawn 24 hour a day, if they work perfectly. 
how much do they cost, will? and how do air leaks affect them?

now let's turn off the sun again...

 15            65.27026      75.575        70            143.5775 
 16            56.64535<--   71.56485      70            139.5151 
 17  houses    50.31143      67.93063      70   look     135.4845 
 18  1 and 2   45.65995 too  64.63714      70   how      131.4854 
 19  get cold  42.24403 cold 61.65241      70   nicely   127.5176 
 20  very      39.73546      58.94749      70   house 3  123.5807 
 21  quickly   37.89323  --> 56.49616      70   rides    119.6746 
 22  since     36.54034      54.27465      70   out      115.799 
 23  their     35.54681      52.2614       70   almost   111.9537 
 24  thermal   34.81719      50.4369       70   3 weeks  108.1385 
 25  mass      34.28137      48.78343      70   of       104.353 
 26  was       33.88788      47.28499      70   cloudy   100.5971 
 27  never     33.59892      45.92702      70   weather  96.87059 
 28  very      33.3867       44.69636      70   tra la   93.17316 
 29  warm...   33.23086      43.58108      70   tra la   89.50462 
 30  and       33.11641      42.57035      70   ...      85.86474 
 31  house 1   33.03237      41.65438      70   :-)      82.25331 
 32  has that  32.97064      40.82428      70            78.67008 
 33  b i g     32.92532      40.072        70            75.11484 
 34  bare      32.89203      39.39025      70            71.58738 
 35  window.   32.86759      38.77242      68.08748      68.08748 

looks like house 3 finishes 19 days ahead of the nearest contender,
if you call 68 f and 80 f comfortable interior temperatures.

10 'a house race, among three 8' cube contenders, each having
20 '  r24 walls, one 8'x8' r2 window, and 4096 btu/f of thermal mass.
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,
80 print#1,"they're off!"
100 print#1,"               direct        isolated      isolated     isolated"
110 print#1,"               gain, wall    gain, wall    gain and     store"
120 print#1,"day            store         store         store        temp"
130 print#1,
140 'warmup over a long string of average december days
150 rwind=2'us r-value of window
160 rwall=24'us r-value of walls
170 c=4096'thermal mass (btu/f)
180 ta=32.8'average outdoor december temp in providence, ri (f)
190 sunin=8*8*900*.92*.92'average daily solar input (btu)
200 tm1=ta:tm2=ta:tm3=ta'initialize thermal mass temperatures
205 tu=80'upper temp limit for wall store houses (f)
210 tlim=ta'initialize limiting temp for isolated store house
220 for day=1 to 14'warmup over two weeks of average december days
240 e1=24*(tm1-ta)*64/rwind+24*(tm1-ta)*5*64/rwall
250 tm1=tm1+(sunin-e1)/c'calculate new thermal mass temp
260 if tm1>tu then tm1=tu'ventilate house to limit indoor temp
270 e2=6*(tm2-ta)*64/rwind+18*(tm2-ta)*64/rwall+24*(tm2-ta)*5*64/rwall
280 tm2=tm2+(sunin-e2)/c
290 if tm2>tu then tm2=tu
300 e3=6*(tm3-tlim)*32/rwind+18*(tm3-ta)*32/rwall'south wall loss
310 e3=e3+24*(tlim-ta)*(32+5*64)/rwall
320 tm3=tm3+(sunin-e3)/c
330 if tm3<70 then tlim=tm3 else tlim=70
340 if tm3>212 then tm3=212'water boils
350 print#1, day,tm1,tm2,tlim,tm3
370 next day
380 'coming into the backstretch, a string of cloudy days
390 sunin=0'turn off the sun
400 print#1,"turn off the sun..."
410 for day=15 to 35'simulate three weeks of cloudy days
430 e1=24*(tm1-ta)*64/rwind+24*(tm1-ta)*5*64/rwall
440 tm1=tm1+(sunin-e1)/c
450 e2=0*(tm2-ta)*64/rwind+24*(tm2-ta)*64/rwall+24*(tm2-ta)*5*64/rwall
460 tm2=tm2+(sunin-e2)/c
470 e3=0*(tm3-tlim)*32/rwind+24*(tm3-ta)*32/rwall'south wall loss
480 e3=e3+24*(tlim-ta)*(32+5*64)/rwall
490 tm3=tm3+(sunin-e3)/c
500 if tm3<70 then tlim=tm3 else tlim=70
520 print#1,day,tm1,tm2,tlim,tm3
540 next day
550 close
 
nick



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