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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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